back to indexAvi Loeb: Aliens, Black Holes, and the Mystery of the Oumuamua | Lex Fridman Podcast #154
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The following is a conversation with Avi Loeb, an astrophysicist, astronomer,
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and cosmologist at Harvard. He has authored over 800 papers and written 8 books,
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including his latest, called Extraterrestrial, The First Sign of Intelligent Life Beyond Earth.
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It'll be released in a couple of weeks, so go preorder it now to show support for what I think
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is truly an important book in that it serves as a strong example of a scientist being both
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rigorous and open minded about the question of intelligent alien civilizations in our universe.
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Quick mention of our sponsors, Zero Fasting App for intermittent fasting, Element Electrolyte
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As a side note, let me say a bit more about why Avi's work is so exciting to me and I think to
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a lot of people. In 2017, a strange interstellar object, now named Oumuamua, was detected traveling
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through our solar system. Based on the evidence we have, it had strange characteristics which
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made it not like any asteroid or comet that we've seen before. Avi was one of the only
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world class scientists who fearlessly suggested that we should be open minded about whether it
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is naturally made or in fact is an artifact of an intelligent alien civilization. In fact,
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he suggested that the more likely explanation given the evidence is the latter hypothesis.
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But we also talk about a lot of fascinating mysteries in our universe including black holes,
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dark matter, the big bang, and close to speed of light space travel. The theme throughout is that
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in scientific pursuits, the weird things, the anomalies, the ideas that right now are considered
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taboo should not be ignored if we are to have a chance at finding the next big breakthrough,
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the next big paradigm shift, and also if we are to inspire the world with the power and beauty
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of science. If you enjoy this thing, subscribe on YouTube, review on Apple Podcast, follow on Spotify,
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support on Patreon, or connect with me on Twitter at Lex Friedman. And now, here's my conversation
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with Avi Loeb. In the introduction to your new book, Extraterrestrial, you write,
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this book confronts one of the universe's most profound questions, are we alone? Over time,
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this question has been framed in different ways. Is life here on Earth the only life in the universe?
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Are humans the only sentient intelligence in the vastness of space and time? A better, more precise
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framing of this question would be this. Throughout the expanse of space and over the lifetime of the
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universe, are there now or have ever been other sentient civilizations that, like ours, explored
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the stars and left evidence of their efforts? So let me ask, are we alone? That's an excellent
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question. For me, the answer is sort of clear because I start from the principle of modesty.
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You know, if we believe that we are alone and special and unique, that shows arrogance. My
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daughters, when they were infants, they tended to think that they are special, unique, and then they
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went out to the street and realized that other kids are very much like them. And then they
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developed a sense of a better perspective about themselves. And I think the only reason that we
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are still thinking that we are special is because we haven't searched well enough to find others
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that might even be better than us. And, you know, I say that because I look at the newspaper every
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morning and I see that we do foolish things. We are not necessarily the most intelligent ones.
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And if you think about it, if you open a recipe book, you see that out of the same ingredients,
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you can make very different cakes, depending on how you put them together and how you heat them
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up. And what is the chance that by taking the soup of chemicals that existed on earth and cooking it
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one way to get our life, that you got the best cake possible? I mean, we are probably not the
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sharpest cookie in the jar. And my question is, I mean, it's pretty obvious to me that we are
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probably not alone because half of all the sun like stars we know now as astronomers, half of
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the sun like stars from the Kepler satellite data have a planet the size of the earth, roughly at
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the same distance that the earth is from the sun. And that means that they can have liquid water on
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their surface and the chemistry of life as we know it. So if you roll the dice billions of times,
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just within the Milky Way galaxy, and then you have tens of billions of galaxies like it within
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the observable volume of the universe, it would be extremely arrogant to think that we are special.
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I would think that we are sort of middle of the road, typical forms of life. And that's why
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nobody pays attention to us. If you go down the street on a sidewalk and you see an ant,
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you don't pay attention or a special respect to that ant, you just continue to walk. And
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so I think that we are sort of average, not very interesting, not exciting, so nobody cares about
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us. We tend to think that we are special, but that's a sign of immaturity. And we're very early
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on in our development. Yes, that's another thing that we have our technology only for 100 years,
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and it's evolving exponentially right now on a three year timescale. So imagine what would happen
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in a hundred years, in a thousand years, in a million years or in a billion years. Now, the Sun
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is actually relatively late in the star formation history of the universe. Most of the Sun like stars
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formed earlier, and some of them already died, you know, became white dwarfs. And so if you imagine
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that a civilization like ours existed around a typical Sun like star, by now, if they survived,
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they could be a billion years old. And then imagine a billion year technology, it would
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look like magic to us, you know, an approximation to God, we wouldn't be able to understand it.
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And so in my view, we should be humble. And by the way, we should probably just listen and not speak,
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because there is a risk, right? If you are inferior, there is a risk if you speak too loudly,
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something bad may happen to you. You mentioned, we should be humble also in the sense,
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with the analogy to ants, that they might be better than us. So there's a kind of scale that
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we're talking about. And in the question, you mentioned the word sentient. So sentience,
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or maybe the more basic formulation is consciousness. Do you think that this
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thing within us humans in terms of the typical life form of consciousness is the essential
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element that permeates other, if there's other alien civilizations out there, that they have
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something like consciousness as well? Or is this, I guess I'm asking, can you try to untangle the
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word sentient? Yeah, so that's a good question. I think what is most abundant, depending on how
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long it survives. So if you look at us, as an example, we are now, we do have consciousness
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and we do have technology. But the technologies that we are developing are also means for our
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own destruction, as we can tell. You know, we can change the climate if we are not careful enough.
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We can go into nuclear wars. So we are developing means for our own destruction through
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self inflicted wounds. And it might well be that creatures like us are not long lived, that
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crocodiles on other planets live for billions of years. They don't destroy themselves, they live
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naturally. And so if you look around, the most common thing would be dumb animals that live for
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long times, you know, not those that have conscious. But in terms of changing the environment, I think
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since, I mean, humans develop tools, they develop the ability to construct technologies that would
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lift us from this planet that we were born in. And that's something animals without a
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conscious, consciousness cannot really do. And so I, you know, in terms of looking for things
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that are new, that went beyond the circumstances they were born into, I would think that even if
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they're short lived, these are the creatures that made the biggest difference to their environment.
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And we can search for them, you know, even if they're short lived, and most of the civilizations
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are dead by now. Even if that's the case. That's sad to think about, by the way.
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Well, but if you look on Earth, that, you know, there are lots of cultures that existed throughout
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time, and they're dead by now. The Mayan culture was very sophisticated, died. But we can find
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evidence for it and learn about it just by archaeology, digging into the ground, looking.
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And so we can do the same thing in space, look for dead civilizations. And perhaps we can learn a
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lesson why they died and behave better so that we will not share the same fate. So I think, you know,
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there is a lesson to be learned from the sky. And by the way, I should also say, if we find
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a technology that we have not dreamed of, that we can import to Earth, that may be a better
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strategy for making a fortune than going to Silicon Valley or going to Wall Street. Because
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you make a jump start into something of the future. So that's one way to do the leap is
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actually to find, to literally discover versus come up with the idea in our own limited human
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capacity, like a cognitive capacity. It would look like, it would feel like cheating in an exam
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where you look over the shoulder of a student next to you. Yeah. But it's not good on an exam,
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but it is good when you're coming up with technology that could change the fabric of
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human civilization. But there is, you know, in my neck of the woods of artificial intelligence,
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there's a lot of trajectories one can imagine of creating very powerful beings,
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the technology that's essentially, you know, you can call super intelligence that could achieve
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space exploration, all those kinds of things without consciousness, without something that
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to us humans looks like consciousness. And there, you know, there is a sad feeling I have that
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consciousness too, in terms of us being humble, is a thing we humans take too seriously. That it's,
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we think it's special just because we have it. But it could be a thing that's actually holding
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us back in some kind of way. It may well be. It may well be. I should say something about AI,
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because I do think it offers a very important step into the future. If you look at the Old
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Testament, the Bible, there is this story about Noah's Ark that you might know about. Noah
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knew about a great flood that is about to endanger all life on earth. So he decided to build an ark.
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And the Bible actually talks about specifically what the size of this ark was, what the dimensions
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were. Turns out it was quite similar to Oumuamua that we will discuss in a few minutes. But at any
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event, he built this ark and he put animals on it so that they were saved from the great flood.
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Now, you can think about doing the same on earth, because there are risks for future catastrophes.
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You know, we could have the self inflicted wounds that we were talking about, like nuclear war,
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changing the climate. Or there could be an asteroid impacting us, just like the dinosaurs
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died. The dinosaurs didn't have science, astronomy. They couldn't have a warning system.
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But there was this big stone, big rock that approached them. It must have been a beautiful
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sight. Just when it was approaching, it got very big and then smashed them and killed them. So
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you could have a catastrophe like that. Or in a billion years, the sun will basically boil off
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all the oceans on earth. And currently all our eggs are in one basket, but we can spread them.
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It's sort of like the printing press, if you think about it. The revolution that Gutenberg
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brought is there were very few copies of the Bible at the time, and each of them was precious
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because it was handwritten. But once the printing press produced multiple copies, you know,
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if something bad happened to one of the copies, it wasn't a catastrophe. You know, it wasn't
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disaster because you had many more copies. And so if we have copies of life here on earth elsewhere,
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then we avoid the risk of it being eliminated by a single point breakdown, catastrophe.
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So the question is, can we build NOx spaceship that will carry life as we know it? Now,
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you might think we have to put elephants and whales and birds on a big spaceship, but that's
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not true because all you need to know is the DNA making, the genetic making of these animals,
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put it on a computer system that has AI plus a 3D printer so that this CubeSat, which is rather
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small, can go with this information to another planet and use the raw materials there to produce
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synthetic life. And that would be a way of producing copies, just like the Gutenberg printing press.
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Yeah, and it doesn't have to be exact copies of the humans, it could just contain some basic
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elements of life and then have enough life on board that it could reproduce the process of
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evolution on another place. So I mean, that also makes you sad, of course, because you confront
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the mortality of your own little precious consciousness and all your own memories and
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knowledge and all that stuff. But who cares? I care about mine, right? And you care about yours.
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No, no, I actually don't. If you're an astronomer, one thing that you learn from the universe
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is to be modest because you're not so significant. I mean, think about it, all these emperors and
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kings that conquered a piece of land on Earth and were extremely proud. You see these images
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of kings and emperors that usually are alpha males and they stand strong and they're very
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proud of themselves. But if you think about it, there are 10 to the power 20 planets like the
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Earth in the observable volume of the universe. And this view of conquering a piece of land and
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even conquering all of Earth is just like an ant hugging a single grain of sand on the landscape
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of a huge beach. That's not very impressive. So you can't be arrogant. If you see the big picture,
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you have to be humble. Also, we are short lived. Within 100 years, that's it. So what does it teach
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you? First to be humble, modest. You never have significant powers relative to the big scheme
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of things. And second, you should appreciate every day that you live and learn about the world.
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Humble and still grateful. Yes, exactly. Well, let's talk about probably the most interesting
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object I've heard about and also the most fun to pronounce. Oumuamua. Can you tell me the story
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of this object and why it may be an important event in human history? And is it possibly a piece
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of alien technology? Right. So this is the first object that was spotted close to Earth from
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outside the solar system. And it was found on October 19th, 2017. And at that time, it was
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receding away from us. And at first, astronomers thought it must be a piece of rock, you know,
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just like all the asteroids and comets that we have seen from within the solar system.
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And it just came from another star. I should say that the actual discovery of this object
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was surprising to me because a decade earlier, I wrote the first paper together with Ed Turner
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and Amaya Moro Martin that tried to predict whether the same telescope that was surveying
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the sky, PanSTARRS from Hawaii, would find anything from interstellar space, given what
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we know about the solar system. So if you assume that other planetary systems have similar
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abundance of rocks and you just calculate how many should be ejected into interstellar space,
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the conclusion is no, we shouldn't find anything with PanSTARRS. To me, I apologize for probably
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revealing my stupidity, but it was surprising to me that so few interstellar objects from outside
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this whole system have ever been detected. No, nothing. None has been. You do maybe talk about
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it that there has been one or two rocks since then. Well, since then, there was one called
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the Borisov. It was discovered by an amateur Russian astronomer, Gennady Borisov. And that one
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looked like a comet. And just like a comet from within the solar system. But this is a really
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important point. Sorry to interrupt it. You showed that it's unlikely that a rock from another solar
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system would arrive to ours. Right. And so the actual detection of this one was surprising by
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itself to me. Yes. But then, so at first they thought maybe it's a comet or an asteroid,
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but then it didn't look like anything we've seen before. Borisov did look like a comet. So people
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asked me afterwards and said, you know, doesn't it convince you if Borisov looks like a comet,
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doesn't it convince you that Oumuamua is also natural? And I said, you know, when I went on the
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first date with my wife, she looked special to me. And since then I met many women. That didn't
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change my opinion of my wife. So, you know, that's not an argument. Anyway, so why did the Oumuamua
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look weird? Let me explain. So first of all, astronomers monitored the amount of light,
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sunlight that it reflects. And it was tumbling, spinning every eight hours. And as it was spinning,
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the brightness that we saw from that direction, we couldn't resolve it because it's tiny. It's
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about a hundred meters, a few hundred feet, size of a football field. And we cannot, from Earth,
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with existing telescopes, we cannot resolve it. The only way to actually get a photograph of it
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is to send a camera close to it. And that was not possible at the time that Oumuamua was discovered
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because it was already moving away from us faster than any rocket we can send. It's sort of like a
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guest that appeared for dinner. And then by the time we realized that it's weird, the guest is
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already out the front door into the dark street. What we would like to find is an object like it
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approaching us, because then you can send the camera irrespective of how fast it moves. And
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if we were to find it in July 2017, that would have been possible because it was approaching us
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at that time. Actually, I was visiting Mount Haleakala in Maui, Hawaii with my family for
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vacation at that time in July 2017, but nobody knew at the observatory that the Oumuamua is
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very close. That's sad to think about that we had the opportunity at that time to send up a camera.
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But don't worry. I mean, there will be more. There will be more because I operate by the Copernican
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principle, which says we don't live at a special place and we don't live at a special time. And
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that means if we surveyed the sky for a few years and we had sensitivity to this region between us
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and the sun, and we found this object with PanStars, there should be many more that we
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will find in the future with surveys that might be even better. And actually, in three years
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timescale, there would be the so called LSST. That's a survey of the Vera Rubin Observatory
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that would be much more sensitive and could potentially find an Oumuamua like object
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every month. OK, so I'm just waiting for that. And the main reason for me to alert everyone
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to the unusual properties of Oumuamua is with the hope that next time around, when we see
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something as unusual, we would take a photograph or we would get as much evidence as possible
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because science is based on evidence, not on prejudice. And we will get back to that theme.
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So anyway, let me let me point out some of the properties, actually, the elongated nature,
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all those kinds of things. So the light curve, the amount of light, sunlight that was reflected
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from it was changing over eight hours by a factor of 10, meaning that the area of this
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object, even though we can't resolve it, the area on the sky that reflects sunlight was
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bigger by a factor of 10 in some phases as it was tumbling around than in other phases.
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So even if you take a piece of paper that is razor thin, you know, there is a very small
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likelihood that it's exactly edge on and getting a factor of 10 change in the area that you see
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on the sky is huge. It's much more than any. It means that the object has an unusual geometry.
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It's at least a factor of a few more than any of the comets or asteroids that we have seen before.
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You mentioned reflectivity. So it's not just the geometry, but
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the properties of the surface of that thing. Well, if you assume the reflectivity is the same,
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then it's just geometry. If you assume the reflectivity may change, then it could be
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a combination of the area that you see and the reflectivity because different directions may
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reflect differently. But the point is that it's very extreme. And actually the best fit
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to the light curve that we saw was of a flat object. Unlike all the cartoons that you have seen
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of a cigar shape, a flat object at the 90% confidence gives a better model for the way
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that the light varied. So like flat meaning like a pancake.
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Like a pancake. Exactly. And so that's, you know, the very first unusual property. But to me,
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it was not unusual enough to think that it might be artificial. It was not significant enough.
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Then there was no cometary tail, you know, no dust, no gas around this object. And the
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Spitzer Space Telescope really searched very deeply for carbon based molecules. There was nothing.
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So it's definitely not a comet the way people expected it to be.
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Can you maybe briefly mention what properties a comet that you're referring to usually has?
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Right. So a comet is a rock that has some water ice on the surface. So you can think of it as an
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icy rock. Actually comets were discovered a long time ago, but the first model that was developed
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for them was by Fred Whipple, who was at Harvard. And I think the legend goes that he got the idea
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from walking through Harvard Square and seeing during a winter day and seeing these icy rocks,
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you know. So a comet is icy and an asteroid is not.
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It's just a rock. It's just a rock.
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Yeah. So when you have ice on the surface, when the rock gets close to the sun,
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the sunlight warms it up and the ice sublimates, evaporates. Because the one thing about ice,
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water ice, is it doesn't become liquid if you warm it up in vacuum, you know, without
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an external pressure. It just goes straight into gas. And that's what you see as the tail of a
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comet. The only way to get liquid water is to have an atmosphere like on Earth that has an external
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pressure. Only then you get liquid. And that's why it's essential to have an atmosphere to a planet
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in order to have liquid water and the chemistry of life. So if you look at Mars, Mars lost its
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atmosphere and therefore no liquid water on the surface anymore. I mean, there may have been early
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and that's what the Perseverance survey, you know, the Perseverance mission will try to find out
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whether it had liquid water, whether there was life perhaps on it at the time, but at some point
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it lost its atmosphere and then the liquid water was gone. So the only reason that we can live on
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Earth is because of the atmosphere. But a comet is in vacuum pretty much. And then when it gets
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warmed up on the surface, the water becomes, the water ice becomes gas and then you see this
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cometary tail behind it. In addition to water, there are all kinds of carbon based molecules
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or dust that comes off the surface. And those are detectable. Yeah, it's easy to detect. It's very
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prominent. You see these cometary tails that look very prominent because they reflect sunlight
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and you can see them. In fact, it's sometimes difficult to see the nucleus of the comet
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because it's surrounded and shrouded with, and in this case, there was no trace of anything.
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That's fascinating. Now you might say, okay, it's not a comet. So that's what the community said.
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Okay, it's not a, no problem. It's still a rock, you know, it's not a comet,
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but it's just a rock, bare rock. You know, okay, no problem. Then, and that's the thing that
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convinced me to write about it. And then in June 2018, you know, significantly later,
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there was a report that in fact the object exhibited an excess push in addition to the
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force of gravity. So the sun acts on it by gravity, but then there was an extra push
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on this object that was figured out from the orbit that you can trace. And the question was,
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what is this excess push? So for comets, you get the rocket effect. When you evaporate gas,
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you know, just like a jet engine on an airplane, you throw, a jet engine is very simple. You throw
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the gas back and it pushes the airplane forward. That's all. That's how the jet. So in a case of
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a comet, you throw gas in the direction of the sun because it, and then you get a push.
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Okay. So in the case of comets, you can get a push, but there was no cometary tail. So then
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people say, oh, wait a second. Is it an asteroid? No, but it behaves like a comet, but it doesn't
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look like a comet. So what, well, forget about it. Business as usual. So that's what they mean
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by a non gravitation acceleration. So that's interesting. So like the primary force acting
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on something like just a rock, like an asteroid would be like, you can predict the trajectory
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based on the gravity, based on gravity. And so here there's detected movement that's not,
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cannot be accounted purely by the gravity of the sun. And if it was a comet, you would need about
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a 10th of the mass of this comet, the weight of this comet to be evaporated in order to give it.
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And there was no sign of that. No sign. 10% of the mass evaporating. It's huge. Think about it.
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A hundred meter size object losing 10% of its mass. You can't miss that.
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So that's super weird.
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Is there a good explanation, is there in your mind a possible explanation for this?
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So I operated just like Sherlock Holmes in a way. I said, okay, what are the possibilities? And
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the only thing I could think, so I ruled out everything else. And I said, it must be the
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sunlight reflected off it. Okay. So the sunlight reflects off the surface and gives it a push,
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just like you get a push on a sail on a boat, you know, from the wind reflecting off it.
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Now, in order for this to be effective, it turns out the object needs to be extremely thin.
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It turns out it needs to be less than a millimeter thick. Nature does not produce such things.
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But we produce it because it's called the technology of a light sail. So we are,
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for space exploration, we are exploring this technology because it has the benefit of
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not needing to carry the fuel with the spacecraft. So you don't have the fuel, you just have a
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sail and it's being pushed either by sunlight or by a laser beam or whatever. So perhaps this is
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the light sail. So this is actually the same technology with the Starshot project. Yes.
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So people afterwards say, okay, you work on this project, you imagine. No, that's a pretty good
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explanation, right? Obviously, my imagination is limited by what I know. So I would not deny that
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working on light sails expanded my ability to imagine this possibility. But let me offer another
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interesting anecdote. In September this year, 2020, there was another object found,
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and it was given the name 2020SO by the Minor Planet Center. This is an organization actually
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in Cambridge, Massachusetts, that gives names to astronomical objects found in the solar system.
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And they gave it that name 2020SO because, you know, it looked like an object in the solar system
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and it moved in an orbit that is similar to the orbit of the Earth, but not the same exactly.
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And therefore it was bound to the Sun, but it also exhibited a deviation from what you expect
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based on gravity. So the astronomers that found it extrapolated back in time and found that
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in 1966, it intercepted the Earth. And then they went to the history books and they realized,
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oh, there was a mission called Lunar Lander Surveyor 2 that had a rocket booster. It was
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a failed mission, but there was a rocket booster that was kicked into space. And presumably this
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is the rocket booster that we're seeing. Now, this rocket booster was sufficiently hollow and thin
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for us to recognize that it's pushed by sunlight. So here is my point. We can tell from the orbit
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of an object, obviously this object didn't have any cometary tail. It was artificially made. We
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know that it was made by us and it did deviate from an orbit of a rock. So just by seeing
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something that doesn't have cometary tail and deviates from an orbit shaped by gravity,
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we can tell that it's artificial. In the case of Oumuamua, it couldn't have been sent by humans
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because it just passed near us for a few months. We know exactly what we were doing at that time.
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And also it was moving faster than any object that we can launch. And so obviously it came from
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outside the solar system. And the question is who produced it? Now, I should say that when I walk
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on vacation on the beach, I often see natural objects like seashells that are beautiful and I
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look at them. And every now and then I stumble on a plastic bottle that was artificially produced.
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And my point is that maybe Oumuamua was a message in a bottle. And this is simply another window
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into searching for artifacts from other civilizations. Where do you think it could have
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come from? And if it's so, okay, from a scientific perspective, the narrow minded view, as we'll
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probably talk about throughout, is, you know, you kind of want to stick to the things that,
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to naturally originating objects like asteroids and comets. Okay, that's the space of possible
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hypotheses. And then if we expand beyond that, you start to think, okay, these are artificially
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constructed. Like you just said, it could be by humans. It could be by whatever that means,
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by some kind of extraterrestrial alien civilizations. If it's the alien civilization
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variety, what is this object then? That's an excellent question. And let me lay out,
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I mean, we don't have enough evidence to tell. If we had a photograph, perhaps we would have
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more information. But there is one other peculiar fact about Oumuamua. Well, other than it was very
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shiny, that I didn't mention, you know, we didn't detect any heat from it. And that implies that
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it's rather small and shiny. But the other peculiar fact is that it came from a very special frame of
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reference. So it's sort of like finding a car in a parking lot, in a public parking lot, that,
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you know, you can't really tell where it came from. So there is this frame of reference where
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you average over the motions of all the stars in the neighborhood of the Sun. So you find the
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so called local standard of rest of the galaxy. And that's a frame of reference that is obtained
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by averaging the random motions of all the stars. And the Sun is moving relative to that frame at
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some speed. But this object was at rest in that frame. And only one in 500 stars is so much at
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rest in that frame. And that's why I was saying it's like a parking lot. It was parked there,
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and we bumped into it. So the relative speed between the solar system and this object is just
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because we are moving. It was sitting still. Now you ask yourself, why is it so unusual in that
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context? You know why? Because if it was expelled from another planetary system, most likely it will
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carry the speed of the host star that it came from. Because it was, you know, the most loosely
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bound objects are in the periphery of the planetary system, and they move very slowly relative to the
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star. And so they carry the, when they are ripped apart from the planetary system, most of the
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objects will have the residual motion of the star roughly relative to the local star. But this one
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was at rest in the local star. Now, one thing I can think of, if there is a grid of road posts,
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you know, like for navigation system, so that you can find your way in the local frame, then that
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would be one possibility. These are like little sensors of, that's fascinating to think about. So
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there could be, I mean, not necessarily literally a grid, but just evenly, in some definition of
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evenly spread out set of objects like these that are just out there. A lot of them. Another
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possibility is that these are relay stations, you know, for communication. You might think,
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in order to communicate, you need a huge beacon, a very powerful beacon. But it's not true. Because
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even on Earth, you know, we have these relay stations. So you have a not so powerful beacon.
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So it can be heard only out to a limited distance, but then you relay the message.
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And it could be one of those. Now, after it collided with the solar system, of course,
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it got a kick. So it's just like a billiard ball, you know, we gave it a kick by colliding with,
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but most of them are not colliding with stars. And so that's one possibility. Okay. And there
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should be numerous, lots of them, if that's the case. The other possibility is that it's a probe,
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you know, that was sent in the direction of the habitable region around the Sun to find out if
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there is life. Now, it takes tens of thousands of years for such a probe to traverse the solar
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system from the outer edge of the Oort cloud, all the way to where we are. And, you know,
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it's a long journey. So when it started the journey from the edge of the solar system to
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get to us now, you know, we were rather primitive back then, you know, we still didn't have any
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technology, there was no reason to visit, you know, there was grass around and so forth. But,
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you know, maybe it is a probe. So you said 10,000 years, that's faster. So it takes that long.
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Tens of thousands, yes. Tens of thousands of years. Yeah. Yeah. And the other thing I should
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say is, you know, it could be just an outer layer of something else, like, you know, something that
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was ripped apart, like a surface of an instrument. And you can have lots of these pieces, you know,
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if something breaks, lots of these pieces spread out, like space junk. And, you know, that...
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It could be just space junk from an alien civilization.
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Yes. So it's kind of...
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I should tell you about space junk. Let me...
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Yes. What do you mean by space junk?
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So, I think, you know, you might ask, why aren't they looking for us? One possibility
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is that we are not interesting, like we were talking about ants. Another possibility,
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you know, if there are millions or billions of years into their technological development,
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they created their own habitat, their own cocoon, where they feel comfortable, they have everything
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they need. And it's risky for them to establish communication with other... So they have their
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own cocoon and they close off. They don't care about anything else. Now, in that case, you might
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say, oh, so how can we find about them if they are closed off? The answer is they still have to
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deposit trash, right? That is something from the law of thermodynamics. There must be some production
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of trash. And, you know, we can still find about them just like investigative journalists going
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through the trash cans of celebrities in Hollywood, you know. You can learn about the private lives
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of those celebrities by looking at the trash.
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It's fascinating to think, you know, if we are the ants in this picture,
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if this thing is a water bottle, or if it's like a smartphone, like where on the spectrum of
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possible objects of space, because there's a lot of interesting trash. How interesting is this trash?
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But imagine a caveman seeing a cell phone. The caveman would think, since the caveman played
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with rocks all of his life, he would say, it's a rock, just like my fellow astronomers said.
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Yes, exactly. That's brilliantly put. Actually, as a scientist, do you hope it's a water bottle
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Because I hope it's even more than a smartphone. I hope that it's something that is really
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That's funny. See, I'm the opposite. I feel like I hope it's a water bottle because
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at least we have a hope with our current set of skills to understand it. A caveman has no way of
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understanding the smartphone. It's like, it will be like, I feel like a caveman has more to learn
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from the plastic water bottle than they do from the smartphone.
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But suppose we figure it out. If we, for example, come close to it and learn what it's made of.
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And I guess a smartphone is full of like thousands of different technologies that we could
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probably pick at. Do you have a sense of where a hypothesis of where is the cocoon that it
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might have come from?
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No, because, okay, so first of all, you know, the solar system, the outermost edge of the
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solar system is called the Oort cloud. It's a cloud of icy rocks of different sizes that were
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left over from the formation of the solar system. And it's thought to be roughly a ball or a
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sphere. And it's halfway, the extent of it is roughly halfway to the nearest star. Okay, so you
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can imagine each planetary system basically touching the Oort clouds of those stars that are
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near us are touching each other. Space is full of these billiard balls that are very densely
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packed. And what that means is any object that you see, irrespective of whether it came from
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the local standard. So we said that this object is special because it came from a local standard
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of rest. But even if it didn't, you would never be able to trace where it came from because all
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these Oort clouds overlap. So if you take some direction in the sky, you will cross as many
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stars as you have in that direction. Like, there is no way to tell which Oort cloud it came from.
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So yes, I didn't realize how densely packed everything was from the perspective of the Oort
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cloud. And that's really interesting. So yeah, it could be nearby, it could be very far away.
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Yeah, we have no clue.
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You said cocoon. And you kind of paint, I think in the book, I've read a lot of your articles too
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on the Scientific American, which are brilliant. So I'm kind of mixing things up in my head a
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little bit. But what does that cocoon look like? What does a civilization that's able to harness
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the power of multiple suns, for example, look like? When you imagine possible civilizations that are
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a million years more advanced than us, what do you think that actually looks like?
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I think it's very different than we can imagine. By the way, I should start from the point that
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even biological life, just without technology getting into the game, could look like something
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we have never seen before. Take, for example, the nearest star, which is Proxima Centauri.
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It's four and a quarter light years away. So they will know about the results of the 2016 elections
link |
only next month, in February 2021. It's very far away. But if you think about it, this star is a
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dwarf star, and it's twice as cold as the sun. And it emits mostly infrared radiation. So if there
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are any creatures on the planet close to it that is habitable, which is called Proxima B, there is
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a planet in the habitable zone, in the zone just at the right distance where, in principle, liquid
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water can be on the surface. If there are any animals there, they have infrared eyes because
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our eyes were designed to be sensitive to where most of the sunlight is in the visible range.
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But Proxima Centauri emits mostly infrared. So in the nearest star system, these animals would be
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quite strange. They would have eyes that are detectors of infrared, very different from ours.
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Moreover, this planet, Proxima B, faces the star always with the same side. So it has a permanent
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day side and a permanent night side. And obviously the creatures that would evolve on the permanent
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day side, which is much warmer, would be quite different than those on the permanent night side.
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Between them, there would be a permanent sunset strip. And my daughters said that that's the best
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opportunity for high value real estate because you will see the sunset throughout your life,
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right? The sun never sets on this trip. So these worlds are out of our imagination.
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Just even the individual creatures, the sensor suite that they're operating with
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might be very different. Very different. So I think when we see something like that,
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we would be shocked not to speak about seeing technology. So I don't even dare to imagine.
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And I think obviously we can bury our head in the sand and say, it's never aliens,
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like many of my colleagues say. And it's a self fulfilling prophecy. If you never look,
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you will never find. If you're not ready to find wonderful things, you will never discover them.
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And the other thing I would like to say is reality doesn't care whether you ignore it or not.
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You can ignore reality, but it's still there. So we can all agree, based on Twitter,
link |
that aliens don't exist. That Umuamua was a rock. We can all agree. And you will get a lot of likes,
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we will have a big crowd of supporters, and everyone will be happy and give each other
link |
awards and honors and so forth. But Umuamua might still be an alien artifact. Who cares
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what humans agree on? There is a reality out there. And we have to be modest enough to recognize
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that we should make our statements based on evidence. Science is not about ourselves. It's
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not about glorifying our image. It's not about getting honors, prizes. A lot of the academic
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activity is geared towards creating your echo chamber where you have students, postdocs,
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repeating your mantras so that your voice is heard loudly so that you can get more honors,
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prizes, recognition. That's not the purpose of science. The purpose is to figure out what nature
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is. And in the process of doing that, it's a learning experience. You make mistakes. Einstein
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made three mistakes at the end of his career. He argued that in the 1930s, he argued that black
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holes don't exist, gravitational waves don't exist, and quantum mechanics doesn't have spooky action
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at a distance. And all three turned out to be wrong. So the point is that if you work at the
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frontier, then you make mistakes. It's inevitable because you can't tell what is true or not.
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And avoiding making mistakes in order to preserve your image makes you extremely boring. You will
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get a prize, but you will be a boring scientist because you will keep repeating things we already
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know. If you want to make progress, if you want to innovate, you have to take risks and you have
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to look at the evidence. It's a dialogue with nature. You don't know the truth in advance. You
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let nature tell you, educate you, and then you realize that what you thought before is incorrect.
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And a lot of my colleagues prefer to be in a state where they have a monologue. You know,
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if you look at these people that work on string theory, they have a monologue. They know what,
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and in fact, their monologue is centered on anti de Sitter space, which we don't live in now.
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To me, it's just like the Olympics. You define a hundred meters and you say,
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whoever runs these hundred meters is the best athlete, the fastest. And it's completely
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arbitrary. You could have decided it would be 50 meters or 20 meters. Who cares? You just measure
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the ability of people this way. So you define anti de Sitter space as a space where you do your
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mathematical gymnastics, and then you find who can do it the best. And you give jobs based on that.
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You give prizes. But as we said before, you know, nature doesn't care about, you know,
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the prizes that you give to each other. It cares, you know, it has its own reality and we should
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figure it out. And it's not about us. The scientific activity is about figuring out nature. And
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sometimes we may be wrong. Our image will not be preserved. But that's the fun, you know. Kids
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explore the world out of curiosity. And I always want to maintain my childhood curiosity. And I
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don't care about the labels that I have. In fact, having tenure is exactly the opportunity to behave
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like a child because you can make mistakes. And I was asked by the Harvard Gazette, you know,
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the Pravda of Harvard, what is the one thing that you would like to change about the world?
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And I said, I would like my colleagues to behave more like kids. That's the one thing I would like
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them to do. Because something bad happens to these kids when they become tenured professors.
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They start to worry about their ego and about themselves more than about the purpose of science,
link |
which is, you know, curiosity driven, figuring out from evidence. Evidence is the key. So when
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an object shows anomalies like Oumuamua, what's the problem discussing, you know, whether it's
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artificial or not? You know, so there was, I should tell you, there was a mainstream
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paper in Nature published saying it must be natural. That's it. It's unusual, but it must
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be natural, period. And then at the same time, some other mainstream scientists tried to explain
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the properties. And they came up with interpretations like it's a dust bunny,
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you know, the kind that you find in a household, a collection of dust particles pushed by sunlight,
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something we have never seen before. Or it's a hydrogen iceberg. It actually evaporates like
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a comet, but hydrogen is transparent. You don't see it. And that's why we don't see the cometary
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tail. Again, we have never seen something like that. In both cases, the objects would not
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survive the long journey. We discussed it in a paper that I wrote afterwards. But my point is,
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those that tried to explain the unusual properties went into great length at discussing things that
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we have never seen before. Okay? So even when you think about a natural origin, you have to come up
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with scenarios of things that were never seen before. And by the way, they look less plausible
link |
to me personally. But my point is, if we discuss things that were never seen before,
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why not discuss, why not contemplate an artificial origin? What's the problem?
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Why do people have this pushback? You know, I worked on dark matter, and we don't know what
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most of the matter in the universe is. It's called dark matter. It's just an acronym because we have
link |
no clue. We simply don't know. So it could be all kinds of particles. And over the years, people
link |
suggested weakly interacting massive particles, axions, all kinds of particles. And experiments
link |
were made. They cost hundreds of millions of dollars. They put upper limits, constraints
link |
that ruled out many of the possibilities that were proposed as natural initially. The mainstream
link |
community regarded it as a mainstream activity to search the nature of the dark matter.
link |
And nobody complained that it's speculative to consider weakly interacting massive particles.
link |
Now, I ask you, why is it speculative to consider extraterrestrial technologies? We have a proof
link |
that it exists here on Earth. We also know that the conditions of Earth are reproduced
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in billions of systems throughout the Milky Way galaxy. So what's more conservative than to say,
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if you arrange for similar conditions, you get the same outcome. How can you imagine this to be
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speculative? It's not speculative at all. And nevertheless, it's regarded the periphery. And
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at the same time, you have physicists, theoretical physicists, working on extra dimensions, super
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symmetry, super string theory, the multiverse. Maybe we live in a simulation. All of these ideas
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that have no grounding in reality, some of which sound to me like, you know, just like what someone
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would say. Science fiction, basically. Because you have no way to test it, you know, through
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experiments. And experiments really are key. It's not just the nuance. You say, okay, forget about
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experiments. As some philosophers try to say, you know, if there is a consensus, what's the problem?
link |
The point is, it's key. Then that's what Galileo found. It's key to have feedback from reality.
link |
You know, you can think that you have a billion dollars or that you are more rich than, you know,
link |
Elon Musk. That's fine. You can feel very happy about it. You can talk about it with your friends
link |
and all of you will be happy and think about what you can do with the money. Then you go to
link |
an ATM machine and you make an experiment. You check how much money you have in your checking
link |
account. And if it turns out that, you know, you don't have much, you can't materialize your dreams.
link |
Okay. So you realize, you have a reality check. And my point is, without experiments giving you
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a reality check, without the ATM machine showing you whether your ideas are bankrupt or not,
link |
without putting skin in the game. And by skin in the game, I mean, don't just talk about
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theoretical ideas. Make them testable. If you don't make them testable, they're worthless.
link |
They're just like theology that is not testable. By the way, theology has some tests. Let me give you
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three examples. It turns out that my book already inspired a PhD student at Harvard in the English
link |
department to pursue a PhD in that direction. And she invited me to the PhD exam a couple of months
link |
ago. And in the exam, one of the examiners, a professor, asked her, do you know why Giordano
link |
Bruno was burnt at the stake? And she said, no, I think it's because he was an obnoxious
link |
guy and irritated a lot of people, which is true. But the professor said, no,
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it's because Giordano Bruno said that other stars are just like the sun,
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and they could have a planet like the Earth around them that could host life. And that
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was offensive to the church. Why was it offensive? Because there is the possibility that this life
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sinned. And if that life sinned on planets around other stars, it should have been saved by Christ.
link |
And then you need multiple copies of Christ. And that's unacceptable. How can you have duplicates
link |
of Christ? And so they burned the guy. I'm just like loading this all in because that's kind of
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brilliant. So he was actually already, it's not just about the stars, it's anticipating that there
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could be other life forms. Like why, if this star, if there's other stars, why would it be special?
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Why would our star be special? He was making the right argument. And he would just follow that
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all along to say like, there should be other Earth like places, there should be other life forms.
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And then there needs to be copies of Christ. Yeah, so that was offensive. So I said to that
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professor, I said, great, I wanted to introduce some scientific tone to the discussion. And I said,
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this is great because now you basically laid the foundation for an experimental test of this
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theology. What is the test? We now know that other stars are like the sun and we know they have
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planets like the Earth around them. So suppose we find life there and we figure out that they sinned,
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then we ask them, did you witness Christ? And if they say no, it means that this theology
link |
is ruled out. So there is an experimental test. So this is experimental test number one.
link |
Another experimental test, in the Bible, in the Old Testament, Abraham
link |
was heard the voice, the voice of God to sacrifice his son, right? Only son. And that's what the
link |
story says. Now, suppose Abraham, my name, by the way, had a voice memo up on his cell phone. He
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could have pressed this up and recorded the voice of God. And that would have been experimental
link |
evidence that God exists, right? Fortunately, he didn't, but it's an experimental test, right?
link |
There is a third example I should tell, and that is Elie Wiesel attributed this story to Martin
link |
Buber, but it's not clear whether it's true or not. At any event, the story goes that Martin
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Buber, you know, he was a philosopher and he said, you know, the Christians, you know,
link |
the Messiah arrived already and will come back again in the future. The Jews argue the Messiah
link |
never came and will arrive in the future. So he said, why argue? Both sides agree that the Messiah
link |
will arrive in the future. When the Messiah arrives, we can ask whether he or she will arrive
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in the future. When the Messiah arrives, we can ask whether he or she came before, you know, like
link |
visited us and then figure it out. And one side. So again, experimental test of a theology. So even
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theology, if it puts a skin in the game, you know, if it makes a prediction, could be tested, right?
link |
So why can't string theories test themselves? Or why can't, you know, even cosmic inflation? That's
link |
a model that, you know, one of the inventors from MIT, Alan Guth, argues that it's not falsifiable.
link |
My point is a theory that cannot be falsified is not helpful because it means that you can't
link |
make progress. You cannot improve your understanding of nature. The only way for us to
link |
learn about nature is by making hypotheses that are testable, doing the experiments and learning
link |
whether we are correct or not. So B, and coupled that with a curiosity and open mindedness that
link |
allows us to explore all kinds of possible hypotheses, but always the pursuit of those,
link |
the scientific rigor around those hypotheses is ultimately get evidence. Knowledge of what nature
link |
is should be a dialogue with nature. Yes. Rather than a monologue. Monologue, beautifully put.
link |
Can we talk a little bit about the Drake equation? Another framework from which to have this kind of
link |
discussion about possible civilizations out there. So let me ask, within the context of the Drake
link |
equation or maybe bigger, how many alien civilizations do you think are out there?
link |
Well, it's hard to tell because the Drake equation is again quantifying our ignorance. It's just a set
link |
of factors. The only one that we know, or actually two that we know quite well is the rate of star
link |
formation in the Milky Way galaxy, which we measured by now, and the frequency of planets
link |
like the Earth around stars and at the right distance to have life. But other than that,
link |
there are lots of implicit assumptions about all the other factors that will enable us to detect
link |
the signal. Now, I should say the Drake equation has a very limited validity just for signals from
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civilizations that are transmitting at the time that you're observing them. However, we can do
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much better than that. We can look for artifacts that they left behind. Even if they are dead,
link |
you can look for industrial pollution in the atmosphere of planets. Why do I bring this up?
link |
Why do I bring this up? Again, to show you the conservatism of the mainstream in astronomy.
link |
And by the way, I have leadership positions. I was chair of the astronomy department for nine
link |
years, the longest serving chair at Harvard. And I'm the chair of the board on physics and astronomy
link |
of the National Academies. It's a primary board. And I'm director of two centers at Harvard and so
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forth. So I do represent the community in various ways. But at the same time, I'm a little bit
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disappointed by the conservatism that people have. And so let me give you an illustration of that.
link |
So the astronomy community actually is going right now through the process of defining its goals for
link |
the next decade. And there are proposals for telescopes that would cost billions of dollars
link |
and whose goal is to find evidence for oxygen in the atmosphere of planets around other stars,
link |
with the idea that this would be a marker, a signature of life. Now, the problem with that
link |
is Earth didn't have much oxygen in its atmosphere for the first two billion years. Roughly half of
link |
its life, it didn't have much oxygen. But it had life. It had microbial life. It's not
link |
it's not clear yet as of yet what the origin is for the rise in the oxygen level after two
link |
billion years, about 2.4 billion years ago. But we know that a planet can have life without oxygen
link |
in the atmosphere because Earth did it. The second problem with this approach is that you can have
link |
oxygen from natural processes. You can break water molecules and make oxygen. So even if you find it,
link |
it will never tell you that for sure life exists there. And so even with these billions of dollars,
link |
the mainstream community will never be confident whether there is life. Now, how can it be
link |
confident? There is actually a way. If instead of looking with the same instruments, if you look for
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molecules that indicate industrial pollution, for example, CFCs that are produced by refrigerating
link |
systems or industries here on Earth, that they do the ozone layer, you can search for that. And
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I wrote a paper five years ago suggesting that. Now, what's the problem? You can just tell NASA,
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I want to build this telescope to search for oxygen, but also for industrial pollution.
link |
Nobody would say that because it sounds like on the periphery of the field. And I ask you,
link |
why would? Hilarious. Because that's exactly, I mean, that would be saying is quite brilliant. I
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mean, because it's a really strong signal. And if life, if there's alien civilizations out there,
link |
then they're probably going to be many of them. And they're probably going to be more advanced
link |
than us. And they're probably going to have something like industrial pollution, which would
link |
be a much stronger signal than some basic gas, which could have a lot of different explanations.
link |
So like something like oxygen or, I mean, we could talk about signs of life on Venus and so on.
link |
But if you want a strong signal, it would be pollution. I love how garbage is.
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No, but the pollution, you have to understand, we think of pollution as a problem,
link |
but on a planet that was too cold, for example, to have a comfortable life on it, you can imagine
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terraforming it and putting a blanket of polluting gases such that it will be warmer. And that would
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be a positive change. So if an industrial or a technological civilization wants to terraform a
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planet that otherwise is too cold for them, they will do it. So what's the problem of defining it
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as a search goal using the same technologies? The problem is that there is a taboo. We're not
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supposed to discuss extraterrestrial intelligence. There is no funding for this subject, not much,
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very little. And young people, because of the bullying on Twitter, you know, all the social
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media and elsewhere, young people with talent that are curious about these questions do not enter
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this field of study. And obviously, if you step on the grass, it will never grow, right? So if you
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don't give funding, obviously, you know, the mainstream community says, look, nothing was
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discovered so far. Obviously, nothing would be discovered. If talented people go to other
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districts, you never search for it well enough, you will never find anything. I mean, look at
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gravitational wave astrophysics. It's a completely new window into the universe, pioneered by Ray
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Weiss at MIT. And at first, it was ridiculed. And thanks to some administrators at the National
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Science Foundation, it received funding, despite the fact that the mainstream of the astronomy
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community was very resistant to it. And now it's considered a frontier. So all these people that
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I remember as a young postdoc, these people that bashed this field and said bad things about
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people, you know, said nothing will come out of it. Now they say, oh, yeah, of course, you know,
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the Nobel Prize was given to the LIGO collaboration. Of course, now they are supportive
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of it. But my point is, if you suppress innovation early on, there are lots of missed opportunities.
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The discovery of exoplanets is one example. You know, in 1952, there was an astronomer called
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the name Otto Struve. And he wrote a paper saying, why don't we search for Jupiter like planets
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close to their host star? Because if they're close enough, they would move the star back and forth,
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and we can detect the signal. And so astronomers on time allocation committees of telescopes
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for 40 years argued, this is not possible because we know why Jupiter resides so far from the Sun.
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You cannot have Jupiter so close because there is this region where ice forms far from the Sun.
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And beyond that region is where Jupiter like planets can form. There was a theory behind
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it which ended up being wrong by today's standards. But anyway, they did not give time
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on telescopes to search for such systems until the first system was discovered
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four decades after Otto Struve's paper. And the Nobel Prize was awarded to that
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just a couple of years ago. And then you ask yourself, okay, so science still made progress.
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What's the problem? The problem is that this baby came out barely, and there was a delay of
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four decades. So the progress was delayed. And I wonder how many babies were not born because of
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this resistance. So there must be ideas that are as good as this one that were suppressed because
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they were bullied, because people ridiculed them, that were actually good ideas. And these are missed
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opportunities, babies that were never born. And I'm willing to push this frontier of the search
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for technologies or technological signatures of other civilizations. Because when I was young,
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I was in the military in Israel. It's obligatory to serve. And there was this saying that one of
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the soldiers sometimes has to put his body on the barbed wire so that others can go through.
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And I'm willing to suffer the pain so that younger people in the future will be able to speak freely
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about the possibility that some of the anomalies we find in the sky are due to technological
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signatures. And it's quite obvious. This is why I like the folks in artificial intelligence space,
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Elon Musk and a few others speak about this. And they look at the long arc. They say like,
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what, you know, this kind of, you know, you can call it like first principles thinking,
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or you can call it anything really is like, if we just zoom out from our current bickering and our
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current, like discussions in the what science is doing, look at the long arc of the trajectory
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we're headed at. Which questions are obviously fundamental to science? And it should be asked,
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and which is the space of hypothesis we should be exploring? And like exoplanets is a really
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good example of one that was like an obvious one. I recently talked to Sarah Seager, and it was very
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taboo when she was starting out to work on an exoplanet. And that was even in the 90s. And like
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it's obvious should not be a taboo subject. And to me, I mean, I'm probably ignorant, but to me,
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exoplanets seems like it's ridiculous that that would ever be a taboo subject to not fund,
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to not explore. That's very, but even for her, it's now taboo to say, like what, you know, to look for
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industrial pollution, right? Right. And I find that ridiculous. I'll tell you why. She can't take
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the next step. It's ridiculous for another reason. Not because of just the scientific benefits that
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we might have by exploring it, but because the public cares about these questions. And the public
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funds science. So how dare the scientists shy away from addressing these questions,
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if they have the technology to do it. It's like saying, I don't want to look through
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Galileo's telescope. It's exactly the same. You have the technology to explore this question,
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to find the evidence and you shy away from it. You might ask, why do people shy away from it?
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And perhaps it's because of the fact that there is science fiction. I'm not a fan of science fiction,
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because it has an element to it that violates the laws of physics in many of the books and the
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films. And I cannot enjoy these things when I see the laws of physics violated. But who cares that
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the, you know, the fact that there is science fiction. I mean, if you have the scientific
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methodology to address the same subject, I don't care that other people, you know, spoke nonsense
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about this subject or said things that make no sense. Who cares? You do your scientific work,
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just like you explore the dark matter. You explore the possibility that umuamua is an
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artifact. You just look for evidence and try to deduce what it means. And I have no problem with
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doing that. To me, it sounds like any other scientific question that we have. And given
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the public's interest, we have an obligation to do that. By the way, science to me is not
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an occupation of the elite. It doesn't allow me to feel superior to other humans that are unable to
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understand the math. To me, it's a way of life. You know, if there is a problem in the faucet or
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in the pipe at home, I try to figure out what the problem is. And with a plumber, we figure it out
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and we look at the clues. And the same thing in science. You look at the evidence, you try to
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figure out what it means. It's common sense in a way. And it shouldn't be regarded as something
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removed from the public. It should be a reflection of the public's interest. And I think it's
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actually a crime to resist the public. If the public says, I care about this, and you say,
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no, no, no, that's not sophisticated enough for me. I want to do intellectual gymnastics on
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anti the sitter space. To me, that's a crime. Yes, I 100% agree. So it's hilarious that the very,
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not hilarious, it's sad, that people who are trained in the scientific community to have the
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tools to explore this world, to be children, to be the most effective at being children,
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are the ones that resist being children the most. But there is a large number of people
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that embrace the childlike wonder about the world and may not necessarily have the tools to do it.
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That's the more general public. And so, I wonder if I could ask you and talk to you a little bit
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about UFO sightings. That there's people, quote unquote believers, there's hundreds of thousands
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of UFO sightings. And I've consumed some of the things that people have said about it. And one
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thing I really like about it is how excited they are by the possibility. It's almost like this
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childlike wonder about the world out there. It's not a fear, it's an excitement. Do you think,
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because we're talking about this possibly extraterrestrial object that visited, that flew
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by Earth, do you think it's possible that out of those hundreds of thousands of UFO sightings,
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one is an actual, one or some number is an actual sighting of a nonhuman, some alien technology.
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And that we're not, we did not, we're too close minded to look and to see.
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I think to answer this question, we need better evidence. My starting point, as I said,
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out of modesty is that we are not particularly interesting. And therefore I would be hard pressed
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to imagine that someone wants to really spy on us. So I would think, as a starting point,
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that we don't deserve attention and we shouldn't expect someone, but who knows.
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Now, the problem that I have with UFO sighting reports is that 50 years ago, there were some
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reports of fuzzy images, saucer like things. By now, our technologies are much better. Our cameras
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are much more sensitive. These fuzzy images should have turned into crisp, clear images
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of things that we are confident about. And they haven't turned that way. It's always on the border
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line of believability. And because of that, I believe that it might be most likely artifacts
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of our instruments or some natural phenomena that we are unable to understand. Now, of course,
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the reason you must examine those, if, for example, pilots report about them or
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the military finds evidence for them, is because it may pose a national security threat. If another
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country has technologies that we don't know about and they're spying on us, we need to know about
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it. And therefore we should examine everything that looks unusual. But to associate it with an
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alien life is a little too far for me until we have evidence that stands up to the level of
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scientific credence, that we are 100% sure that from multiple detectors and through a scientific
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process. Now, again, if the scientific community shies away from these reports, we will never have
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that. It's like saying, I don't want to take photographs of something because I know what it is,
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then you will never know what it is. But I think if some scientist, if grants, let's put it this
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way, if funding will be given to scientists to follow on some of these reports and use scientific
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instruments that are capable of detecting those sightings with much better resolution, with much
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better information, that would be great because it will clarify the matter. These are not,
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as you said, hundreds of thousands, these are not once in a lifetime events. So it's possible to
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take scientific instrumentation and explore, go to the ocean where someone reported that there are
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frequent events that are unusual and check it out, do a scientific experiment. Why only do experiments
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deep into the ocean and look at the oceanography or do other things. We can do scientific
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investigation of these sightings and figure out what they mean. I'm very much in favor of that,
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but until we have the evidence, I would be doubtful as to what they actually mean.
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Yeah, we'll have to be humble and acknowledge that we're not that interesting. It's kind of,
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you're making me realize that because it's so taboo, that the people that have the equipment,
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uh, meaning, and we're not just talking, everybody has cameras now, but to have a large scale,
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like a sensor network that collects data that regularly collects, just like we look at the
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weather, we're collecting information and then we can then access that information when there is
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reports and like have it not be a taboo thing where there's like millions or billions of dollars
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or billions of dollars funding this effort that by the way, inspires millions of people.
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This is exactly what you're talking about. It's like the scientific community is afraid of a
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topic that inspires millions of people. It's absurd. But if you put blinders on your eyes,
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you don't see it. Right. I should say that we do have meteors that we see. These are rocks
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that by chance happen to collide with the earth and they, if they're small, they burn up in the
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atmosphere. But if they're big enough, tens of meters or more, hundreds of meters, the outer
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layer burns up, but then the core of the object makes it through. And this is our chance of putting
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our hands around an object if this meteor came from interstellar space. So one path of discovery
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is to search for interstellar meteors. And with a student of mine, we actually looked through the
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record and we thought that we found one example of a meteor that was reported that might have come
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from interstellar space. And then another approach is, for example, to look at the moon. The moon is
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different from the earth in the sense that it doesn't have an atmosphere. So objects do not
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burn up on their way to it. It's sort of like a museum. It collects everything. Of rocks from out
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there in deep space. Yeah. And there is no geological activity on the moon. So on earth,
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every hundred million years, you know, we could have had computer terminals on earth that could
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have been a civilization like ours with electronic equipment. Yes. More than a hundred million years
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ago. And it's completely lost. You cannot excavate and find it, evidence for it, because in
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archaeological digs, because the earth is being mixed on these timescales. And everything that
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was on the surface more than a hundred million years ago is buried deep inside the earth right
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now because of geological activity. Fascinating to think about, by the way. Yeah. But on the moon,
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this doesn't happen. The only thing that happens on the moon is you have objects impacting the moon
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and they go 10 meters deep. So they produce some dust, but the moon keeps everything. It's like a
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museum. It keeps everything on the surface. So if we go to the moon, I would highly recommend
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regarding it as an archaeological site. Yes. And looking for objects that are strange. Maybe it
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collected some trash, you know, from interstellar space. If we could just linger on the Drake
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equation for a little bit. We kind of talked about there's a lot of uncertainty in the parameters
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and the Drake equation itself is very limited. But I think the parameters are interesting in
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themselves, even if it's limited, because I think each one is within the reach of science,
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right? Did you get the evidence for it? I mean, a few I find really interesting,
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could be interesting to get your comment on. So the one with the most variance, I would say,
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from my perspective, is the length that civilizations last. However you define it. In the Drake
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equation, it's the length of how long you're communicating. Yeah, transmitting.
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Transmitting. Just like you said, that's a wrong way to think about it, because we can be detecting
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some other outputs of the civilizations, etc. But if we just define broadly how long those
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civilizations last, do you have a sense of how long they might last? Like what are the great
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filters that might destroy civilizations that we should be thinking about? And how can
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science give us more hints on this topic? So I, as I mentioned before, operate by the
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Copernican principle, meaning that we are not special. We don't live in a special place
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and not in a special time. And by the way, it's just modesty encapsulated in scientific terms,
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right? You're saying, I'm not special, you know, I find conditions here, they exist
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everywhere. So if you adopt the Copernican principle, you basically say, our civilization
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transmitted radio signals for a hundred years, roughly, so probably it would last another
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hundred or a few hundred and that's it. Because we don't live at a special time.
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So that's, you know, well, of course, if we get our act together and we somehow start
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to cooperate rather than fighting each other, killing each other, you know, wasting a lot
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of resources on things that would destroy our planet, maybe we can lengthen that period
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if we get smarter. But the most natural assumption is to say that we will live into the future as
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much as we lived from the time that we start to develop the means for our own destruction,
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the technologies we have, which is quite pessimistic, I must say. So several centuries,
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that's what I would give, unless we get our act, unless we become more intelligent
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than the newspapers report every day. Okay. Point number one. Second, and by the way,
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this is relevant, I should say, because there was a report about perhaps a radio signal detected
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from Proxima Centauri. What do you make of that signal? Oh, I think it's some Australian guy with
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a cell phone next to the observatory or something like that, because it was the Parkes Telescope in
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Australia. Okay. So it's human created noise. Yeah. Which is always the worry because actually
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the same observatory, the Parkes Observatory, detected a couple of years ago some signal
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and then they realized that it comes back at lunchtime. Yes. And they said, okay, what could
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it be? And then they figured out that it must be the microwave oven in the observatory because
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someone was opening it before it finished and it was creating this radio signal that they detected
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with a telescope every lunchtime. So just a cautionary remark. But the reason I think it's
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human made, without getting to the technical details, is because of this very short window
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by which we were transmitting radio signals out of the lifetime of the Earth. As I said,
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100 years out of four and a half billion years that the Earth existed. So what's the chance
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that another civilization, a twin civilization of ours, is transmitting radio signals exactly
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at the time that we are looking with our radio telescopes? 10 to the minus 7. And the other
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argument I have is that they detected it in a very narrow band of frequencies and that makes it
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cannot be through natural processes, very narrow band, just like some radio transmissions that we
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produce. But if it were to come from the habitable zone, from a transmitter on the surface of Proxima
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b, this is the planet that orbits Proxima Centauri, then I calculated that the frequency
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would drift through the Doppler effect. Just like when you hear a siren on the street, when the car
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approaches you, it has a different pitch than when it recedes away from you, that's the Doppler
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effect. And when the planet orbits the star, Proxima Centauri, you would see or detect a
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different frequency when the planet approaches us as compared to when it recedes. So there should
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be a frequency drift just because of the motion of the planet. And I calculated that it must be
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much bigger than observed. So it cannot just be a transmitter sitting on the planet and sending in
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our direction a radio signal unless they want to cancel the Doppler effect. But then they need to
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know about us because in a different direction, it will not be cancelled. Only in our direction,
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they can cancel it perfectly. So there is this direction of Proxima Centauri, but I have a
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problem imagining a transmitter on the surface of a planet in the habitable zone emitting it.
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But my main issue is really with the likelihood, given what we know about ourselves.
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Right. In terms of the duration of the civilization.
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The Copernican principle. Yeah.
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So nevertheless, this particular signal is likely to be a human interference, perhaps. But
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do you find Proxima be interesting? Or the more general question is, do you think we humans
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will venture out into outside our solar system and potentially colonize other habitable planets?
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Actually, I am involved in a project whose goal is to develop the technology that would allow us
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to leave the solar system and visit the nearest stars. And that is called the Star Shot. In 2015,
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May 2015, an entrepreneur from Silicon Valley, Yuri Milner, came to my office at Harvard and said,
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would you be interested in leading a project that would do that in our lifetime? Because as we
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discussed before, to traverse those distances with existing rockets would take tens of thousands of
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years. And that's too long. For example, to get to Proxima Centauri with the kind of
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spacecrafts that we already sent, like New Horizons or Voyager 1, Voyager 2, you needed to
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send them when the first humans left Africa, so that they would arrive there now. And that's a
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long time to wait. So Yuri wanted to do it within a lifetime, 10, 20 years, meaning it has to move
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at a fraction of the speed of light. So can we send a spacecraft that would be moving at the
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fraction of the speed of light? And I said, let me look into that for six months. And with my
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students and postdocs, we arrived to the conclusion that the only technology that can do that is the
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light sail technology, where you basically produce a very powerful laser beam on Earth. So you can
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collect sunlight with photovoltaic cells or whatever and then convert it into stored energy
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and then produce a very powerful laser beam that is 100 gigawatts and focus it on a sail in space
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that is roughly the size of a person, a couple of meters or a few meters, that weighs only a gram
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or a few grams, very thin. And through the math, you can show that you can propel such a sail,
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if you shine on it for a few minutes, it will traverse the distance that is five times the
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distance to the moon, and it will get to a fifth of the speed of light. Sounds crazy. But I've
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talked to a bunch of people and they're like, I know it sounds crazy, but it's actually,
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it will work. This is one of those, it's beautiful. I mean, this is science.
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And the point is, people didn't get excited about space since the Apollo era. And it's about time,
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you know, for us to go into space. A couple of months ago, I was asked to participate in a debate
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organized by IBM and Bloomberg News. And the discussion centered on the question,
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is the space race between the US and China good for humanity? Oh, interesting. And all the other
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debaters were worried about the military threats. And I just couldn't understand what they're
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talking about, because military threats come from hovering above the surface of the Earth, right?
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And we live on a two dimensional surface, we live on the surface of the Earth. But space is
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all about the third dimension, getting far from Earth. So if you go to Mars, or you go to a star,
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another star, there is no military threat. What are we talking about? Space is all about,
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you know, feeling that, you know, we are one civilization, in fact, not fighting each other,
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just going far, and having aspirations for something that goes beyond military threats.
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So why would we be worried that the space race will lead?
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That's actually brilliant. I didn't, you know, there's something in our discourse about it,
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the space race is sometimes made synonymous with like the Cold War or something like that.
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Or with wars. But really, yeah, there was a lot of ego tied up in that. I remember,
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I mean, it's still to this day, there's a lot of pride that Russians,
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Soviet Union was the first to space. And there's a lot of pride in the American side that was the
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first on the moon. But yeah, you're exactly right. Like, there's no aggression, there's no wars.
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And beyond that, if you think about the global economy, right now, there is a commercial
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interest. That's why Jeff Bezos and Elon Musk are interested about, you know, Mars and so on.
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There is a commercial interest, which is international. It's driven by money,
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not by pride. And, you know, nations can sign treaties. First of all, there are lots of treaties
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that were signed even before the First World War and the Second World War and the World War took
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place. So who cares, you know, like humans, treaties do not safeguard anything, you know.
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But beyond that, even if nations sign treaties about space exploration, you might still find
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commercial entities that will find a way to get their launches. And, you know, so I think we
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should rethink space. It has nothing to do with national pride. Once again, nothing to do with
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our egos. It's about exploration. And the biggest problem, I think, in human history is that humans
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tend to think about egos and about their own personal image rather than, look at the big
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picture, you know. We will not be around for long. We are just occupying a small space right now.
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Now, let's move out of this, you know, the way that Oscar Wilde said, I think is the best. He said,
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all of us are in the gutters, but some of us are looking at the stars.
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Yeah, and the more of us are looking at the stars, the likelier we are to, for this thing,
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this little experiment we have going on to last a while as opposed to end too quickly. I mean,
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it's not just about science of being humble. It's about the survival of the human species
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as being humble. To me, it's incredibly inspiring, the Starshot project of,
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I mean, there's something magical about being able to go to another habitable planet and take
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a picture even. I mean, within our lifetime, I mean, that, with crazy technology too, which is...
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I should tell you how it was conceived. So, I was at the time, so after six months passed,
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after the visit of Yuri Miller, I was, usually I go in December during the winter break,
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I go to Israel. I used to go to see my family and I get a phone call just before the weekend
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started. I get a phone call, Yuri would like you to present your concept in two weeks at his home.
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And I said, well, thank you for letting me know because I'm actually out of the door of the hotel
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to go to a goat farm in the Negev, in the southern part of Israel, because my wife wanted to have
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to go to a place that is removed from civilization, so to speak.
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So, we went to that goat farm and I need to make the presentation and there was no internet
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connectivity except in the office of the goat farm. So, the following morning at 6am, I sit
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with my back to the office of that goat farm, looking at goats that were newly born and typing
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into my laptop, the presentation, the PowerPoint presentation about our ambitions for visiting the
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nearest star. And that was very surreal to me. Like our origins in many ways,
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this very primitive origins and our dreams of looking out that is brilliant. So that is
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incredibly inspiring to me, but it's also inspiring of putting humans onto other
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moons or planets. I still find going to the moon really exciting. I don't know, maybe I'm just a
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sucker for it, but it's really exciting. And Mars, which is a new place, a new planet, another planet
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that might have life. I mean, there's something magical to that or some traces of previous life.
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You might think that humans cannot really survive and there are risks by going there. But my point
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is, we started from Africa and we got to apartment buildings in Manhattan, right? It's a very
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different environment from the jungles to live in an apartment building in a small cubicle.
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Yes. And it took tens of thousands of years,
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but humans adapted, right? So why couldn't humans also make the leap and adapt to a habitat in
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space? Now you can build a platform that would look like an apartment building in the Bronx
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or somewhere, but have inside of it everything that humans need. And just like the space station,
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but bigger. And it will be a platform in space. And the advantage of that is if something bad
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happens on Earth, you have that complex where humans live. And you can also move it back and
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forth depending on how bright the sun gets. Because within a billion years, the sun would be
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too hot and it will boil off all the oceans on Earth. So we cannot stay here for more than a
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billion years. That's for sure. Yes. So that's a billion years from now. I prefer shorter term
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deadlines. And so there's a lot of threats that we're facing currently. Do you find it exciting
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the possibility of landing on Mars and starting little like building a Manhattan style apartment
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building on Mars and humans occupying it? Do you think from a scientific or an engineering
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perspective, that's a worthy pursuit? I think it's worthy. But the real issue that is often
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underplayed is the risk to the human body from cosmic rays. These are energetic particles
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and we are protected from them by the magnetic field around the Earth that blocks them. But if
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you go to Mars, where there is no such magnetic field to block them, then, you know, a significant
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fraction of the brain cells in your head will be damaged within a year. And the consequences of
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that are not clear. I mean, it's quite possible that humans cannot really survive on the surface.
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Now, it may mean that we need to dig tunnels, go underground or create some protection.
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This is something that can be engineered. Yes. And, you know, we can start from the
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Moon and then move to Mars. That would be a natural progression. But it's a big issue
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that needs to be dealt with. I don't think, you know, it's a showstopper. I think we can overcome
link |
it. But, you know, just like anything in science and technology, you have to work on it for a while,
link |
figure out solutions. But it's not as rosy as Elon Musk talks about. I mean, Elon Musk can
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obviously be optimistic. I think eventually it will boil down to figuring out how to cope with
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this risk, the health risk. Yeah, I mean, in defense of optimism, I find that there's at
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least a correlation, if not their best friends, is optimism and open mindedness. It's a necessary
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precondition to try crazy things. And in that sense, the sense I have about going to Mars,
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if we use today's logic of what kind of benefits we'll get from that, we're never going to go.
link |
And like most decisions we make in life, most decisions we've made as a human species
link |
are irrational if you look at just today. But if you look at the long arc and the
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possibilities that it might bring, just like humans, Europe and destroyed everybody.
link |
But it was a commercial interest that drove that for trade. And, you know, it might happen again,
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in this context, you have people like Jeff Bezos and Elon Musk that are commercially driven to go
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to space. But it doesn't mean that what we will ultimately find is not new worlds that have
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nothing, you know, have much more to offer than just commercial interest. And as a side effect,
link |
almost. Yeah, yeah. And then that's why I think, you know, we should be open minded and explore.
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And, however, at the same time, because of the reasons you pointed out, I'm not optimistic that
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we will survive more than a few centuries into the future, because people do not think long term.
link |
And that means that we will only survive for the short term. I don't know if you have thoughts
link |
about this, but what are the things that worry you the most about, from the great perspective
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of the universe, which is the great filters that destroys intelligent civilizations,
link |
but for our own species here? Like, what are the things that worry you the most?
link |
Yeah, the thing that worries me the most is that people pay attention to how many likes they have
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on Twitter. And rather than, you know, basketball coaches tell the team players, keep your eyes on
link |
the ball, not on the audience. The problem is we keep our eyes on the audience most of the time.
link |
Let's keep our eyes on the ball. And what does that mean? First of all, in the context of science,
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it means pay attention to the evidence. When the evidence looks strange,
link |
then we should figure it out. You know, I went to a seminar about Umuamua at Harvard,
link |
and a colleague of mine that is mainstream, conservative, would never say anything that would
link |
deviate from what everyone else is thinking, said to me after the seminar, I wish this object never
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existed. Now, to me, I mean, I just couldn't hear that. What do you mean, nature is whatever it is,
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you have to pay attention to it. You cannot say, you know, you cannot bury your head in this. I
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mean, you should bless nature for giving you clues about things that you haven't expected.
link |
And I think that's the biggest fault that we are looking for confirmations of things we already
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know, so that we can maintain our pride that we already knew it, and maintain our image,
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not make mistakes, because we already knew it, therefore we expected the right thing.
link |
But science is a learning experience, and sometimes you're wrong. And let's learn from
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those mistakes. And what's the problem about that? Why do we have to get, you know, prizes,
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and why do we get to be honored and maintain our image, when the actual objective of science is
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learning about nature?
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And like you've talked about, anomalies in this case are actually are not things that
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are unfortunate and to be ignored are, in fact, gifts and should be the focus of science.
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Exactly, because that's the way for us to improve our understanding. If you look at quantum
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mechanics, nobody dreamed about it. And it was revolutionary, and we still don't fully understand
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it. It's a pain for us to figure out.
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So I understand from the perspective that's holding our science back, why do you have
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a sense that that's also something that might be a problem for us in terms of the survival
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of human civilization?
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Because when you look at society, it operates by the same principles. People look for affirmation
link |
by groups, and they, you know, people segregate into herds that think like them, especially
link |
these days when social media is so strong, you can find your support group. And if you
link |
don't look for evidence for what you're saying, you can say crazy things as long as there
link |
are enough people supporting what you say. You can even have your newspapers, you can
link |
have everything to support your view, and then, you know, bad things will happen to
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society. Because we're detaching ourselves from reality. And if we detach ourselves
link |
from reality, all the destructive things that naturally can occur in the real world, whether
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from nuclear weapons, all the kinds of threats that we're facing, even we're living through
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a pandemic, the supposed, you know, a much, much worse pandemic could happen. And then
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we could sadly, like we did this one, politicize it in some kind of way and have bickering
link |
in the space of Twitter and politics, as opposed to there's an actual thing that can destroy
link |
the human species.
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Exactly. So the only way for us to maintain, to stay modest and learn about what really
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happens is by looking for evidence. Again, I'm saying, it's not about ourself, you know,
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it's about figuring out what's around us. And if you close yourself by surrounding yourself
link |
with people that are like minded, that refuse to look at the evidence, you can do bad things.
link |
And throughout human history, that's the origin of all the bad things that happen.
link |
And I think it's a key. It's a key to be modest and to look at evidence. And it's
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not a nuance. Now, you might say, Oh, okay, the uneducated person might operate. No,
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it's the scientific community operates this way. My problem is not with people that don't
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have an academic pedigree. It's included everywhere in society.
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On the topic of the discovery of evidence of alien civilizations, which is something
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you touch on in your book, what that idea would do to societies, to the human psyche
link |
and in general, do you think, and you talk about the, I still have trouble pronouncing,
link |
but a Muamua wager, right? What do you think is, can you explain it? And what do you think
link |
in general is the effect that such knowledge might have on human civilization?
link |
Right. So Pascal had this wager about God. And by the way, there are interesting connections
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between theology and the search for extraterrestrial life. It's possible that we were planted on
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this planet by another civilization. We attribute to God powers that belong really to the technological
link |
civilization. But putting that aside, Pascal basically said, there are two possibilities,
link |
there are two possibilities, either God exists or not. And if God exists, the consequences
link |
are quite significant. And therefore, we should consider that possibility differently than
link |
equal weight to both possibilities. And I suggest that we do the same with Muamua or
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other technological signatures, that we keep in mind the consequences and therefore pay
link |
more attention to that possibility. Now, some people say extraordinary claims require extraordinary
link |
evidence. My point is that the term extraordinary is really subjective. For one person, a black hole
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is extraordinary. For another, it's just a consequence of Einstein's theory of gravity. It's
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nothing extraordinary. The same about the type of dark matter, anything. So we should leave the
link |
extraordinary part of that sentence. Just keep evidence, okay? So let's be guided by evidence.
link |
And even if we have extraordinary claims, let's not dismiss them because the evidence is not
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extraordinary enough. Because if we have an image of something and it looks really strange and we
link |
say, oh, the image is not sufficiently sharp, therefore, we should not even pay attention to
link |
this image or not even consider. I think that's a mistake. What we should do is say, look, there is
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some evidence for something unusual. Let's try and build instruments that will give us a better
link |
image. And if you just dismiss extraordinary claims, because you consider them extraordinary,
link |
you avoid discovering things that you haven't expected. And so I believe that along the history
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of astronomy, there are many missed opportunities. And I speak about astronomy, but I'm sure in other
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fields, it's also true. I mean, this is my expertise. For example, you know, the Astrophysical
link |
Journal, which is the main primary publication in astrophysics. If you go before the 1980s,
link |
there are images that were posted in the Astrophysical Journal of giant arcs, you know, arcs
link |
of light surrounding clusters of galaxies. And, you know, you can find it in printed versions of
link |
the Astrophysical Journal. People just ignore it. They put the image, they see the arc, they say,
link |
who knows what it is and just ignore it. And then in the 1980s, the subject of gravitational
link |
lensing became popular. And the idea is that you can deflect light by the force of gravity. And
link |
then you can put a source behind the cluster of galaxies, and then you will get these arcs. And
link |
actually, Einstein predicted it in 1940. And, you know, so these things were expected, but
link |
people just had them in the images, didn't pay attention. So I'm sure there are lost opportunities
link |
sometimes. Even in existing data, you have things that are unusual and exceptional and are not being
link |
addressed. Yeah, you actually, I think you have an article, the data is not enough from quite a few
link |
years ago, where you talk, you know, we can go back to the 70s and 80s, but we can go also to the
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Mayan civilization. Right, the Mayan civilization basically believed in astrology that you can
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forecast the outcome of a war based on the position of the planets. And they had, you know,
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astronomers in their culture had the highest social status. They were priests, they were elevated.
link |
And the reason was that they helped politicians decide when to go to war, because they would tell
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the politicians, you know, the planets would be in this configuration, it's a better chance for you
link |
to win the war, go to war. And in retrospect, they collected wonderful data, but misinterpreted it,
link |
because we now know that the position of Venus or Jupiter or whatever has nothing to do with the
link |
outcome of World War I, World War II, you know, has nothing to do. And so we can have a prejudice
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and collect data without actually doing the right thing with it. That's such a Pisces thing to say.
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I looked up what your astrological sign is.
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Well, so you mentioned Einstein predicted that black holes don't exist, or just didn't, or thought.
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Don't exist in nature.
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Don't exist in nature.
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When Einstein came up with his theory of gravity in 1915, November 1915, a few months later,
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another physicist, Karl Schwarzschild, he was the director of the Potsdam Observatory,
link |
but he was a patriot, a German patriot. So he went into the First World War fighting for Germany.
link |
But while he was at the front, he sent a postcard to Einstein saying, you know,
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a few months after the theory was developed, saying, actually, I found a solution to your
link |
equations. And that was a black hole solution. And then he died a few months later. And Einstein
link |
was a pacifist, and he survived. So the lesson from this story is that if you want to work out
link |
the consequences of a theory, you better be a pacifist. But the point is that this solution
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was known shortly after Einstein came up with his theory. But in 1939, Einstein wrote a paper
link |
in the Annals of Mathematics saying, even though the solution exists,
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I don't think it's realized in nature. And his argument was, if you imagine a star collapsing,
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stars often spin, and the spin will prevent them from making a black hole, collapsing to a point.
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So, I mean, can you maybe, one of the many things you have worked on, you're an expert in,
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is black holes. Can you first say, what are black holes? And second, how do we know that they exist?
link |
Right. So black holes are the ultimate prison. You know, you can check in, but you can never check out.
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You can never check out. Even light cannot escape from them. So there are extreme structures of
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space and time. And there is this so called Schwarzschild radius or the event horizon of
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a black hole. Once you enter into it with a spaceship, you would never be able to tweet
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back to your friends and tell them, by the way, I asked the students in my class, freshman seminar
link |
at Harvard, I said, let me give you two possible journeys that you can take. I said, suppose aliens
link |
come to Earth and suggest that you would board their spaceship, would you do it? And the second
link |
is, suppose you could board a spaceship that will take you into a black hole, would you do it?
link |
So all of them said to the first question, yes, under one condition, that I'll be able to maintain
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my social media contacts and report back, share the experience with them. Personally, I have no
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footprint on social media.
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Yeah, which is as a matter of principle.
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Yeah, my wife asked me when we got married, and I honor that.
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And I told you offline, I need to get married to such a woman. She truly is a special agent.
link |
Well, she was wise enough to recognize the risk. But it saves me time. And it also keeps me away
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from crowds. I don't have the notion of what a lot of other people think, so I can think
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Crowd think, exactly.
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Yeah, exactly. So I was surprised to hear that for students, it's extremely important to share
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experiences. Even if they go on a spaceship with aliens, they still want to brag about it rather
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than look around and see what's going on.
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This is not an option when you go to the black hole, is exactly the point.
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So for the black hole, they said no, because obviously you can find your death after you get
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into it, you crash into singularity. There is this singularity in the center. So inside the event
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horizon, we know that all the matter collects at a point. Now, we can't really predict what happens
link |
at the singularity because Einstein's theory breaks down. And we know why it breaks down,
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because it doesn't have quantum mechanics that talks about small distances. We don't have a
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theory that unifies quantum mechanics and gravity so that it will predict what happens near a
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singularity. And in fact, a couple of years ago, I had a flood in my basement. And I invited a
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plumber to come over and figure out and we found that the sewer was clogged because of
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tree roots that got into it. And we solved the problem. But then I thought to myself,
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well, isn't that what happens at the singularity of a black hole? Because the question is,
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where does the matter go? In the case of a home, I never thought about it, but the water,
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all the water that we use, goes in through the sewer to some reservoir somewhere. And the question
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is, what happens inside a black hole? And one possibility is that there is an object in the
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middle, just like a star, and everything collects there. And the object has the maximum density that
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we can imagine, like Planck density. It's the ultimate density that you can have, where gravity
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is as strong as all the other forces. So you can imagine this object, very dense object at the
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center that collects all the matter. Another possibility is that there is some tunnel just
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like the sewer. It takes the matter into another place. And we don't know the answer. But I wrote
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a Scientific American essay about it, admitting our ignorance. It's a fascinating question. What
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happens to the matter that goes into a black hole? I actually recommend it to some of my colleagues
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that work on string theory. At the closing of a conference, I'm the founding director of the Black
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Hole Initiative at Harvard, which brings together astronomers, physicists, philosophers, and
link |
mathematicians. And we have a conference once a year. And at the end of one of them, since I'm the
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director, I had to summarize. And I said that I wish we could go on a field trip to a black hole
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nearby. And I highly recommend to my colleagues that work on string theory to enter into that
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black hole, because then they can test their theory when they get inside. But one of the
link |
string theorists in the audience, Nimar Khani Hamad, immediately raised his voice and said,
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you have an ulterior motive for sending us into a black hole, which I didn't deny, but at any event.
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Yeah, that's true. That's true. Can you say why we know that black holes exist?
link |
Right. So it's an interesting question because black holes were considered a theoretical
link |
construct. And Einstein even denied their existence in 1939. But then in the mid 1960s, quasars were
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discovered. These are very bright sources of light, 100 times brighter than their host galaxy,
link |
which are point like at the center of galaxies. And it was immediately suggested
link |
by Ed Salpeter in the West and by Yakov Zeldovich in the East, that these are black holes that
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accrete gas, collect gas from their host galaxy that are being fed with gas. And they shine very
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brightly because as the gas falls towards the black holes, just like water running down the sink,
link |
the gas swirls and then rubs against itself and heats up and shines very brightly because it's
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very hot close to the black hole. By viscosity, it heats up. And in the case of black holes,
link |
it's the turbulence, the turbulent viscosity that causes it to heat up. So we get these very bright
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sources of light just from black holes that are supposed to be dark, nothing but black holes.
link |
You know, nothing escapes from them, but they create a violent environment where gas moves
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close to the speed of light and therefore shines very brightly, much more than any other source
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in the sky. And we can see these quasars all the way to the edge of the universe.
link |
So we have evidence now that when the universe was, you know, about 7% of its present age,
link |
you know, infant, already back then you had black holes of a billion times the mass of the sun,
link |
which is quite remarkable. It's like finding giant babies in a nursery, you know, like how can these
link |
black holes grow so fast? You know, less than a billion years after the Big Bang, you already have
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a billion times the mass of the sun in these black holes. And the answer is presumably there are very
link |
quick processes that build them up. They build quickly. Very quickly. And so we see those black
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holes, and that was found in the mid 1960s. But in 2015, exactly 100 years after Einstein came up
link |
with his theory of gravity, the LIGO observatory detected gravitational waves. And these are just
link |
ripples in space and time. So according to Einstein's theory, the innovation, the ingenuity
link |
of Einstein's theory of gravity that was formulated in November 1915 was to say that space and time
link |
are not rigid. You know, they respond to matter. So, for example, if you have two black holes and
link |
they collide, it's just like a stone being thrown on the surface of a pond. They generate waves,
link |
disturbances in space and time that propagate out at the speed of light. These are gravitational
link |
waves. They create a space time storm around them, and then the waves go all the way through
link |
the universe and reach us. And if you have a sensitive enough detector like LIGO, you can
link |
detect these waves. And so it was not just the message that we received for the first time,
link |
gravitational waves, but it was the messenger. So there are two aspects to it. One is the messenger
link |
which is gravitational wave for the first time were detected directly. And the second was the
link |
message, which was a collision of two black holes, because we could see the pattern of the ripples
link |
in space and time. And it was fully consistent with the prediction that Schwarzschild made for
link |
how the space time around the black hole is, because when two black holes collide, you can sort
link |
of map from the message that you get, you can reconstruct what really happened and it's fully
link |
consistent. And in 2017 and 2020, there's two Nobel prizes. That's right. That had to do with the
link |
black holes. Can you maybe describe in the same masterful way that you've already been doing what
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the 2017 was given for the LIGO collaboration for discovering gravitation waves from collisions
link |
of black holes? And the 2020 Nobel prize in physics was given for two things. One was
link |
theoretical work that was done by Roger Penrose in the 1960s, demonstrating that black holes are
link |
inevitable when stars collapse. And it was mostly mathematical work. And actually, Stephen Hawking
link |
also contributed significantly to that frontier. And unfortunately, he is not alive, so he could
link |
not be honored. So Penrose received it on his own. And then two other astronomers received it as well,
link |
Andrea Ghez and Reinhard Genzel, and they provided conclusive evidence that there is a black hole at
link |
the center of the Milky Way galaxy that weighs about 4 million times the mass of the sun. And
link |
they found the evidence from the motion of stars very close to the black hole. Just like we see the
link |
planets moving around the sun, there are stars close to the center of the galaxy and they are
link |
orbiting at very high speeds of other thousands of kilometers per second or thousands of miles per
link |
second per second. Think about it. Which can only be induced at those distances if there is a 4
link |
million solar mass object that is extremely compact. And the only thing that is compatible
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with the constraints is a black hole. And they actually made a movie of the motion of these
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stars around the center. One of them moves around the center over a decade, over timescales that we
link |
can monitor. And it was a breakthrough in a way. So combining LIGO with the detection of a black
link |
hole at the center of the Milky Way and in many other galaxies like quasars, now I would say
link |
black hole research is vogue. It's very much in fashion. We saw it back in 2016 when we established
link |
the black hole initiative. You kind of saw that there's this excitement about in breakthroughs
link |
and discoveries around black holes which are probably one of the most fascinating objects
link |
in the universe. It's up there. They're both terrifying and beautiful and they capture the
link |
entirety of the physics that we know about this universe. I should say the question is where is
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the nearest black hole? Can we visit it? And I wrote a paper with my undergraduate student,
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Amir Siraj, suggesting that perhaps if there is one in the solar system, we can detect it.
link |
I don't know if you heard, but there is a claim that maybe there is a
link |
planet nine in the solar system because we see some anomalies at the outer parts of the solar
link |
system. So some people suggested maybe there is a planet out there that was not yet detected. So
link |
people searched for it, didn't find it. It weighs roughly five times the mass of the earth. And we
link |
said, okay, maybe you can't find it because it's a black hole that was formed early in the universe.
link |
Where do you stand on that?
link |
It could be that the dark matter is made of black holes of this mass. We don't know what
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the dark matter is made of. It could be the black holes. So we said, but there is an experimental
link |
way to test it. And the way to do it is because there is the Oort cloud of icy rocks in the outer
link |
solar system. And if you imagine a black hole there, every now and then a rock will pass close
link |
enough to the black hole to be disrupted by the very strong gravity close to the black hole. And
link |
that would produce a flare that you can observe. And we calculated how frequently these flares
link |
should occur. And with LSST on the Vera Rubin Observatory, we found that you can actually
link |
test this hypothesis. And if you don't see flares, then you can put limits on the existence of a
link |
black hole in the solar system. It would be extremely exciting if there was a black hole,
link |
if planet nine was a black hole, because we could visit it and we can examine it. And it will not
link |
be a matter of an object that is very removed from us. Another thing I should say is it's
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possible that the black hole affected life on Earth. The black hole at the center of the Milky
link |
Way. How? That black hole right now is dormant. It's very faint. But we know that it flares.
link |
When a star like the sun comes close to it, the star will be spaghettified, basically become a
link |
stream of gas, like a spaghetti. And then the gas would fall into the black hole and there would be
link |
a flare. And this process happens once every 10,000 years or so. So we expect that these flares to
link |
occur every 10,000 years. But we also see evidence for the possibility that gas clouds were disrupted
link |
by the black hole, because the stars that are close to the black hole are residing in a single
link |
or two planes. And the only way you can get that is if they formed out of a disk of gas,
link |
just like the planets in the solar system formed. So there is evidence that gas fell into the black
link |
hole and powered possibly a flare. And these flares produce x rays and ultraviolet radiation
link |
that could damage life if the Earth was close enough to the center of the galaxy.
link |
Where we are right now, it's not very risky for us. But there is a theoretical argument that says
link |
the solar system, the sun, was closer to the galactic center early on, and then it migrated
link |
outwards. So maybe in the early stage of the solar system, the conditions were affected,
link |
shaped by these flares of the black hole at the center of the galaxy. And that's why
link |
for the first two billion years, there wasn't any oxygen in the atmosphere, who knows. But
link |
it's just interesting to think that from a theoretical concept that Einstein resisted in 1939,
link |
it may well be that black holes have influence on our life. And that it's just like discovering that
link |
some stranger affected your family and in a way your life. And if that happens to be the case,
link |
a second Nobel Prize should be given, not for just the discovery of this black hole at the
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center of the galaxy, but perhaps for the Nobel Prize in chemistry, for the effect that it had.
link |
For the effect for the interplay that resulted in some kind of, yeah, the chemical effect,
link |
biology, I mean, all those kinds of things in terms of the emergence of life and the creation
link |
of a habitable environment. That's so fascinating. And of course, like you said, dark matter, like
link |
black holes have some... They could be the dark matter in principle, yes. We don't know what the
link |
dark matter is at the moment. Does it make you sad? So you've had an interaction and perhaps
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a bit of a friendship with Stephen Hawking. Does it make you sad that he didn't win the Nobel?
link |
Well, all together, I don't assign great importance to prizes because, you know,
link |
Jean Paul Sartre, who I admired as a teenager, because I was interested in philosophy. When I
link |
grew up on a farm in Israel, I used to collect eggs every afternoon and I would drive the tractor to
link |
the hills of our village and just think about philosophy, read philosophy books. And Jean Paul
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Sartre was one of my favorites. And he was honored with a Nobel Prize in literature. He was a
link |
philosopher primarily, existentialist. And he said, the hell with it. Why should I give
link |
special attention to this committee of people that get their self importance from awarding me
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the prize? Why does that merit my attention? So he gave up on the Nobel Prize. And
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you know, there are two benefits to that. One, that you're not working your entire life in the
link |
direction that would satisfy the will of other people. You work independently, you're not
link |
after these honors. Just for the same reason that if you're not living your life for making a profit
link |
or money, you can live a more fulfilling life because you're not being swayed by the wind,
link |
you know, of how to make money and so forth. The second aspect of it is, you know, that
link |
very often, you know, these prizes, they distort the way we do science because instead of people
link |
willing to take risks, and instead of having announcements only after a group of people
link |
converges with a definite result, you know, the natural progression of science is based on trial
link |
and error, you know, reporting some results, and perhaps they're wrong, but then other people find
link |
perhaps better evidence, and then you figure out what's going on. And that's the natural way that
link |
science is, you know, it's a learning experience. So if you give the public an image by which
link |
scientists are always right, you know, and you know, some of my colleagues say we must do that,
link |
because otherwise the public will never believe us that global warming is really taking place.
link |
But that's not true, because the public would really believe you if you show the evidence. So
link |
the point is, you should be sincere. When the evidence is not absolutely clear, or where there
link |
are disputes about the interpretation of the evidence, we should show ourselves. You know,
link |
the king is naked, okay? There is no point in pretending that the king is dressed,
link |
saying that scientists are always right. Scientists are wrong, frequently. And the only way to make
link |
progress is by evidence, giving us the support that we need to make airtight arguments. So when
link |
you say global warming is taking place, if the evidence is fully supportive, there are no holes
link |
in the argument, then people will be convinced, because you're not trying to fool them. When the
link |
evidence was not complete, you also show them that the evidence is not complete.
link |
And when there's holes, you show that there's holes, and here's the methodology we're using
link |
to try to close those holes. Exactly. Let's be sincere. Why pretend? So if there were no,
link |
in a world where there were no prizes, no honours, we would act like kids, as I said before.
link |
We would really be focusing on the ball and not on the audience. Yeah, the prizes get in the way,
link |
and it's so powerful. Do you think, in some sense, the few people that have turned down the prize
link |
made a much more powerful statement? I don't know if you're familiar in the space of mathematics
link |
with the Fields Medal and Google Perlman turned down the prize. One of the reasons I started
link |
this podcast is I'm going to definitely talk to Putin, I'm definitely talking to Perlman,
link |
and people keep telling me it's impossible. I love hearing that, because I'll talk to both.
link |
Anyway, but do you have a sense of why he turned down the prize,
link |
and is that a powerful statement to you? Well, what I read is that he was disappointed by the
link |
response of the community, the mainstream community, the mathematicians, to his earlier work,
link |
where they dismissed it, they didn't attend to the details, and didn't treat him with proper
link |
respect, because he was not considered one of them. And I think that speaks volumes about the
link |
current scientific culture, which is based on groupthink and on social interaction, rather
link |
than on the merit of the argument, and on the evidence in the context of physics. So in mathematics
link |
there is no empirical basis, you're exploring ideas that are logically consistent, but nevertheless
link |
there is this groupthink. And I think he was so frustrated with his past experience that he didn't
link |
even bother to publish his papers, he just posted them on the archive, and in a way saying, you know,
link |
I know what the answer is, go look at it. And then again, in the long arc of history,
link |
his work on archive will be remembered, and all the prizes, most of the prizes will be forgotten,
link |
that's what people don't kind of think about. When you look at Roger Penrose, for example,
link |
is another fascinating figure, you know, it's possible, and forgive me if this, I'm sure,
link |
my ignorance, but he's also did some work on consciousness. He's been one of the only people
link |
who spoke about consciousness, which for the longest time, and is still arguably outside
link |
the realm of the sciences. It's still seen as a taboo subject, and he was brave enough to explore
link |
it from a physics perspective, from just a philosophical perspective, but like with the rigor,
link |
like proposing different kind of hypotheses of how consciousness might be able to emerge in the brain,
link |
and it's possible that that is the thing he's remembered for if you look 100 years from now,
link |
right? As opposed to the work in the black holes, which fits into what the current scientific
link |
community allows to be the space of what is and isn't science. Yeah, it's really interesting to
link |
look at people that are innovators, where in some phases of their career, their ideas fit into the
link |
social structure that is around them, but in other phases, it doesn't. And when you look at them,
link |
they just operated the same way throughout, and it says more about their environment than about them.
link |
Well, yeah, and I don't know if you know who Max Tegmark is, I just recently talked to him.
link |
He's a friend of mine.
link |
I just recently talked to him again, and he, I mean, he was a little bit more explicit about
link |
saying, you know, being aware, which is something I also recommend, is like being aware where the
link |
scientific community stands, and doing enough to get, like move along into your career, in your
link |
career. And it's the necessary evil, I suppose, if you are one of those out of the box thinkers that
link |
just naturally have this childlike curiosity, which Max definitely is one of them, is sometimes
link |
you have to do some stuff that fits in, you publish and you get tenure and all those kinds of things.
link |
But the tenure is a great privilege because it allows you to, in principle, explore things that
link |
are not accepted by others. And unfortunately, it's not being taken advantage of by most people,
link |
and it's a waste of a very precious resource.
link |
Yeah, absolutely. The space that you kind of touched on that's full of theories and is perhaps
link |
detached from appreciation of empirical evidence, or longing for empirical evidence, or grounding
link |
in empirical evidence, is the theoretical physics community and the interest in unifying the laws
link |
of physics and with the theory of everything. I'm not sure from which direction to approach this
link |
question, but how far away are we from arriving at a theory of everything, do you think? And how
link |
would we, how important is it to try to arrive at it, at this kind of goal of this beautiful simple
link |
theory that unlocks the very, you know, fundamental basis of our nature as we know it? And, you know,
link |
and how, what are the kinds of approaches we need to take to get there?
link |
Yeah, so in physics, the biggest challenge is to unify quantum mechanics with gravity.
link |
And I believe that once we have experimental evidence for how this happens in nature,
link |
in systems that have quantum mechanical effects, but also gravity is important,
link |
then the theory will fall into our lap, okay? But the mistake that is made by the community
link |
right now is to come up with the right theory from scratch. And, you know, Einstein gave the
link |
illusion that you can just sit in your office and understand nature, you know, when he came up with
link |
his general theory of relativity. But, you know, first of all, perhaps he was lucky, but it's not
link |
a rule. The rule is that you need evidence to guide you, especially when dealing with quantum
link |
mechanics, which is really not intuitive. And so there are two places where the two theories meet.
link |
One is black holes, and there is a puzzle there. It's called the information paradox.
link |
In principle, you can throw the Encyclopedia Britannica into a black hole. It's a lot of
link |
information. And then it will be gone because a black hole carries only three properties or
link |
qualities, the mass, the charge, and the spin, according to Einstein. But then when Hawking
link |
tried to bring in quantum mechanics to the game, he realized that black holes have a temperature
link |
and they radiate. This is called Hawking radiation. It was sort of anticipated by
link |
Jacob Bekenstein before him, and Hawking wanted to prove Bekenstein wrong and then figure this out.
link |
And so what it means is black holes eventually evaporate. And they evaporate into radiation that
link |
doesn't carry this information, according to Hawking's calculation. And then the question is,
link |
according to quantum mechanics, information must be preserved. So where did the information go
link |
if a black hole is gone? And where is the information that was encoded in the Encyclopedia
link |
when it went into the black hole? And to that question, we don't have an answer yet. It's one
link |
of those puzzles about black holes. And it touches on the interplay between quantum mechanics and
link |
gravity. Another important question is what happened at the beginning of the universe?
link |
What happened before the Big Bang? And by the way, on that, I should say, you know, there are some
link |
conjectures. In principle, if we figure it out, if we have a theory of quantum gravity,
link |
it's possible to imagine that we will figure out how to create a universe in the laboratory.
link |
And by irritating the vacuum, you might create a baby universe. And if we do that,
link |
it will offer a solution to what happened before the Big Bang. Perhaps the Big Bang emerged from
link |
the laboratory of another civilization. So it's like baby universes are being born out of
link |
laboratories. And inside the baby universe, you have a civilization that brings to existence a
link |
new baby universe. So just like humans, right? We have babies and they make babies. So in principle,
link |
that would solve the problem of why there was a Big Bang and also what happened before the Big
link |
Bang. So we came, our umbilical cord is connected to a laboratory of a civilization that produced
link |
our universe once it figured out quantum gravity, you know. It's baby Big Bangs all the way down.
link |
So if we collect data about how the universe started, we could potentially test
link |
theories of, or it can educate us about how to unify quantum mechanics and gravity.
link |
If we get any information about what happens near the singularity of a black hole,
link |
you know, if we get a sense of, you know, somehow we learn what happens at the same,
link |
that would educate. So there are places where we can search for evidence, but it's very challenging,
link |
I should say. And my point is, you know, the string theorists, they decided that they know
link |
how to approach the problem, that they don't have a single theory. There is a multitude of theories
link |
and it's not tightly constrained and they cannot make predictions about black holes or about the
link |
beginning of the universe. So at the moment I say we're at a loss. And the way I feel about this
link |
concept of the theory of everything, we should wait until we get enough evidence to guide us.
link |
And until then, you know, there are many important problems that we can address,
link |
you know. Why bang our head against the wall on a problem for which we have no guidance?
link |
Right. We don't have a good dance partner in terms of evidence. There's not.
link |
I mean, it'd be interesting, just like you said, I mean, the lab is one place to create
link |
universes or black holes, but it'd be fascinating if there is indeed a black hole in our solar
link |
system that you can interact with. So the problem with the origin of the universe
link |
is all you can do is collect data about it, right? You can't interact with it.
link |
Well, you can, for example, detect gravitational waves that emerged from that. And, you know,
link |
there is an effort to do that and that could potentially tell us something. But yeah,
link |
it's a challenge and that's why we're stuck. So I should say, despite what physicists portray,
link |
that, you know, we live through an exceptional growth in our understanding of the universe,
link |
we're actually pretty much stuck, I would say, because we don't know the nature of the dark
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matter. Most of the matter in the universe, we don't know what it is. And we don't know how
link |
the universe started. We don't know what happens in the interior of a black hole.
link |
Because you've thought quite a bit about dark matter as well. Do you have any kind of hypothesis,
link |
interesting hypothesis? We already mentioned a few about what is dark matter and what are the
link |
possible paths that we could take to unlock the mystery of dark? What is dark matter?
link |
Yeah. So what we need is some anomalies that would hint what the nature of the dark matter is,
link |
or to detect it in the laboratory. There are lots of laboratory experiments searching,
link |
but it's like searching for a needle in a haystack, because there are so many possibilities
link |
for the type of particle that it may be. But maybe at some point, you know, we'll find either
link |
a particle or black holes as the dark matter, or something else. But at the moment...
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Can you also maybe, sorry to interrupt, comment about what is dark matter?
link |
Like what, it's just a name we assign to what?
link |
So most of the community believes that it's a particle that we haven't yet detected. It doesn't
link |
interact with light, so it's dark. But the question is, what does it interact with,
link |
and how can we find it? And for many years, physicists were guided by the idea that
link |
it's some extension of the standard model of particle physics. But then they said,
link |
oh, we will find some clues from the Large Hadron Collider about its nature. Or maybe
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it's related to supersymmetry, which is a new symmetry that we haven't found any evidence for.
link |
In both cases, the Large Hadron Collider did not give us any clues. And other people search for
link |
specific types of particles in the laboratory and didn't find any. A couple of years ago,
link |
actually, around the time that I worked on Oumuamua, I also worked on the possibility that
link |
the dark matter particles may have a small electric charge, which is a speculation, but
link |
nobody complained about it. And, you know, it was published and I regarded it more as
link |
of a speculation than the artificial origin of Oumuamua. And to me, I apply, you know,
link |
as far as I'm concerned, I apply the same scientific tools in both cases. There is an
link |
anomaly that led me to that discussion, which has to do with hydrogen being cold in the early
link |
universe more than we expected. So we suggested maybe the dark matter particles have some small
link |
charge. But then you deal with anomalies by exploring possibilities. That's the only way to
link |
do it, and then collecting more data to check those. And searching for technological signatures
link |
is the same as any other part of our scientific endeavor. We make hypotheses and we collect data,
link |
and I don't see any reason for having a taboo on this subject.
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In your childlike, open minded excitement and approach to science, you're, I think,
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to anyone listening to this, truly inspiring. I mean, the question I think is useful to ask
link |
is by way of advice for young people. A lot of young people listen to this, whether from all
link |
over the world, and teenagers, undergraduate students, even graduate students, even young
link |
faculty, even older faculty, they're all young at heart. Like there's many of them young at heart.
link |
Do you have advice for, but let's focus on the traditionally defined sort of young folks that
link |
kind of graduate. Do you have advice to give to young people like that today about life,
link |
maybe in general, maybe a life of curiosity in the sciences?
link |
Definitely. Well, first, I should confess that I enjoy working with young people much more than
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with senior people. And the reason is they don't carry a baggage of prejudice. They're not so
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self centered. They're open to exploration. My advice, I mean, one of the lessons that
link |
took me a while to learn, and I should say I lost important opportunities as a result of that. So
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I would regard it as a mistake on my behalf, was to believe experts. So, quote unquote. So on a
link |
on a number of occasions, I would come up with an original idea and then suggest it to an expert,
link |
someone that works in the same field for a while. And the expert would dismiss it most of the time
link |
because it's new and was not explored, not because of the merit. And then what happened to me several
link |
times is that someone else would listen to the conversation or would hear me suggesting it.
link |
And I would give up because the expert said no. And then that someone else would develop it so
link |
that it becomes the hottest thing in this field. And once it happened to me multiple times,
link |
I then realized the hell with the experts. They don't know what they're doing. They're
link |
just repeating them. They don't think creatively. They are being threatened by innovation. And it's
link |
the natural reaction of someone that cares about their ego more than about the matter
link |
that we are discussing. And so I said, I don't care how many likes I have on Twitter. I don't
link |
care whether the experts say one thing or another. I will basically exercise my judgment and do the
link |
best I can. Turns out that I'm wrong. I made a mistake. That's part of the scientific endeavor.
link |
And it took me a while to recognize that. And it was a lot of wasted opportunities. So to the
link |
young people, I would recommend don't listen to experts. Carve your own path. Now, of course,
link |
you will be wrong. You should learn from experience, just like kids do. But do it yourself.
link |
Your father died in 2017. Your mother died in 2019. Do you miss them?
link |
Is there a memory, that fond memory that stands out? Or maybe what have you learned from them?
link |
From my mother, I mean, she was very much my inspiration for pursuing intellectual work,
link |
because she studied at the university. And then because of the Second World War,
link |
after the Second World War, she was born in Bulgaria. They immigrated to Israel. And she
link |
and she left university to work on a farm. And later in life, when all the kids left home,
link |
she went back to the university and finished the PhD. But she planted in me the intellectual
link |
curiosity and valuing learning or acquiring knowledge as a very important element in life.
link |
And my love with philosophy came from attending classes that she took at the university.
link |
When I was a teenager, I was fortunate to go to some of these and they inspired me later on. And
link |
I'm very different than my colleagues, as you can tell, because my upbringing was quite different.
link |
And the only reason I'm doing physics or astrophysics is because of circumstances.
link |
At age 18, I was asked to serve in the military. And the only way for me to pursue intellectual
link |
work was to work on physics, because that was the closest to philosophy. And I was good at physics.
link |
So they admitted me to an elite program called LPO that allowed me to finish my PhD
link |
at age 24 and to actually propose the first international project that was funded by the
link |
Star Wars initiative of Ronald Reagan. And that brought me to the US to visit Washington, DC,
link |
where we were funded from. And then on one of the visits, I went to the Institute for Advanced
link |
Study at Princeton and met John Bacall that later offered me a five year fellowship there. Under the
link |
under the condition that I'll switch to astrophysics. At which point, you know, I said,
link |
OK, I cannot give up on this opportunity. I'll do it. Switch to astrophysics. It felt like a forced
link |
marriage, kind of arranged marriage. And then I was offered the position at Harvard because
link |
nobody wanted that. They first selected someone else. And that someone said, I don't want to
link |
become a junior faculty at the Harvard Astronomy Department because the chance for being promoted
link |
are very small. So he took another job. And then I was second in line. They gave it to me. I didn't
link |
care much because I could go back to the farm any day, you know. And after three years, I was
link |
tenured. And eventually, a decade later, became the chair of this department and served for nine years
link |
as the chair of the astronomy department at Harvard. But at that point, it became clear
link |
to me that I'm actually married to the love of my life, even though it was an arranged marriage.
link |
There are many philosophical questions in astrophysics that we can address. But I'm still
link |
very different than my colleagues, you know, that were focusing on technical skills in getting to
link |
this job. So my mother was really extremely instrumental in planting the seeds of thinking
link |
about the big picture in me. Then my father, he was, you know, he was working in the farm.
link |
And we didn't speak much because we sort of understood each other without speaking.
link |
But what he gave me is a sense of, you know, that it's more important to do things than to
link |
talk about them. I love the, I mean, my apologies, but MIT mind and hand. I love that there's
link |
that the root of philosophy that you gain from your mom and the hand, that action is all that
link |
ultimately in the end matters from your dad. That's really powerful. If we could take a small
link |
detour into philosophy, is there by chance any books, authors, whether philosophical or not,
link |
you mentioned Sartre, that stand out to you that were formative in some small or big way,
link |
that perhaps you would recommend to others, maybe when you were very young or maybe later on in life?
link |
Well, actually, yeah, I, you know, I read the number of existentialists that
link |
appealed to me because they were authentic. You know, Sartre, you know, he declined the Nobel
link |
Prize, as we discussed, but he also was mocking people that pretend to be something better than
link |
they are. You know, he was living an authentic life that is sincere. And that's what appealed to me.
link |
And Albert Camus was another French philosopher that advocated existentialism. You know, that
link |
really appealed to me. That's probably my favorite existentialist, Camus. Yeah. Yeah. And he died at
link |
a young age in an accident, unfortunately. And then, you know, people like Nietzsche that, you
link |
know, broke conventions. And I noticed that Nietzsche is still extremely popular. You know,
link |
that's quite surprising. He appeals to the young people of today. It's the childlike wonder
link |
about the world. And he was unapologetic. You know, it's like most philosophers have a very
link |
strict adherence to terminology and to the practices, academic philosophers. And Nietzsche was full of
link |
contradictions. And he just, I mean, he was just this big kid with opinions and thought deeply
link |
about this world. And people are really attracted to that. And surprisingly, there's not enough
link |
people like that throughout history of philosophy. And that's why I think he's still drawn to them.
link |
Yeah. To me, what stands out is his statement that the best way to corrupt the mind of young people
link |
is to tell them that they should agree with the common view, you know. And, you know, it goes back
link |
to the thread that went throughout discussion. Yes. You've kind of suggested that we ought to
link |
be humble about our very own existence and that our existence lasts only a short time. We talked
link |
about you losing your father and your mother. Do you think about your own mortality? Are you afraid
link |
of death? I'm not afraid. You know what, Epicurus, actually Epicurus was a very wise person.
link |
According to Lucretius, Epicurus didn't leave anything in writing. But he said that he's never
link |
afraid of death because as long as he's around, death is not around. And when death will be around,
link |
he will not be around. So he will never meet death. So why should you be worried about something
link |
you will never meet? You know, and it's an interesting philosophy of life. You know,
link |
you shouldn't be afraid of something that you will never encounter, right?
link |
But there's a finiteness to this experience. We live every day.
link |
I mean, I think if we're being honest, we live every day as if it's going to last forever.
link |
We often kind of don't contemplate the fact that it ends. You kind of have plans and goals and you
link |
have these possibilities. You have a kind of lingering thought, especially as you get older
link |
and older and older, that this is, especially when you lose friends, then you start to realize,
link |
you know, it does end. But I don't know if you really are cognizant of that. I mean,
link |
because... But you have to be careful not to be depressed by it, because otherwise you lose the
link |
vitality, right? So I think the most important thing to draw from knowing that you are short lived
link |
is a sense of appreciation that you're alive. That's the first thing. But more importantly,
link |
a sense of modesty, because how can anyone be arrogant if they kept at the same time this
link |
notion that they are short lived? I mean, you cannot be arrogant, because anything that you
link |
advocate for, you know, you will not be around to do that in a hundred years. So people will
link |
just forget and move on, you know. And if you keep that in mind, you know, the Caesars in ancient
link |
Rome, they had a person next to them telling them, don't forget that you are mortal. You know,
link |
there was a person with that duty because the Caesars thought that they are all powerful,
link |
you know. And they had, for a good reason, someone they hired to whisper in their ear,
link |
don't forget that you are mortal. Yeah. Well, you're somebody, one of the most respected,
link |
famous scientists in the world, sitting on a farm, gazing up at the stars. So you seem like
link |
an appropriate person to ask the completely inappropriate question of, what do you think
link |
is the meaning of it all? What's the meaning of life? That's an excellent question. And if we ever
link |
find an alien that we can converse with, I would like to answer this. I would like to ask for an
link |
answer to this question because... Would they have a different opinion, you think? Well, they might be
link |
wiser because they lived around for a while, but I'm afraid they will be silent. I'm afraid they
link |
will not have a good answer. And I think it's the process that you should get satisfied by,
link |
the process of learning you should enjoy. Okay, so it's not so much that there is a meaning.
link |
In fact, there is, as far as I can tell, things just exist, you know. And I think it's inappropriate
link |
for us to assign a meaning for our existence because, as a civilization, we will eventually
link |
perish and nothing will be... Just another planet on which life died. And if you look at the big
link |
scheme of things, who cares? Who cares? And how can we assign significance to what we are doing?
link |
So if you said the meaning of life is this, well, it will not be around in a billion years. So
link |
it cannot be the meaning of life because nothing will be around. So I think we should just enjoy
link |
the process. And it's like many other things in life, you enjoy good food, okay? And you can enjoy
link |
learning. Why? Because it makes you appreciate better the environment that you live in.
link |
And sometimes people think religion, for example, is in conflict with science, spirituality.
link |
That's not true. If you see a watch and you look at it from the outside, you might say,
link |
oh, that's interesting. But then if you start to open it up and learn about how it works,
link |
you appreciate it more. So science is the way to learn about how the world works. And
link |
it's not in conflict to the meaning that you assign to all of this, but it helps you appreciate the
link |
world better. So in fact, I would think that a religious person should promote science because
link |
it gives you a better appreciation of what's around you. It's like if you buy in a grocery,
link |
buy something, a bunch of fruits that are packed together, and you can't see from the outside
link |
exactly what kind of fruits are inside. But if you open it up and study, you appreciate better
link |
the merchandise that you get, right? So you pay the same amount of money, but at least you know
link |
what's inside. So why don't we figure out what the world is about, what the universe contains,
link |
what is the dark matter? It will help us appreciate the bigger picture. And then you can assign
link |
your own flavor to what it means. Ali, I think I'm truly grateful that a person like you,
link |
exists at the center of the scientific community, gives me faith and hope about this big journey
link |
that we call science. So thank you for writing the book you wrote recently. You have many other books
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and articles that I think people should definitely read. And thank you for wasting all this time with
link |
me. It's truly an honor. Thank you so much. It was not a waste at all. And thank you for having me.
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I learned a lot from your questions and your remarks. Thank you. Thank you. Thanks for listening to this
link |
conversation with Avi Loeb. And thank you to our sponsors, Zero Fasting App for intermittent
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fasting, Element Electro Light Drink, Sun Basket Meal Delivery Service, and Pessimist Archive
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History Podcast. So the choice is a fasting app, fasting fuel, fast breaking, delicious meals,
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and a history podcast that has very little, as far as I know, to do with fasting. Choose wisely,
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my friends. And if you wish, click the sponsor links below to get a discount and to support
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this podcast. And now let me leave you some words from Albert Einstein. The important thing is not
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to stop questioning. Curiosity has its own reason for existence. One cannot help but be in awe when
link |
he contemplates the mysteries of eternity, of life, of the marvelous structure of reality. It is enough
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if one tries merely to comprehend a little of this mystery every day. Thank you for listening
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and hope to see you next time.