The following is a conversation with Alex Filipenko, an astrophysicist and professor

of astronomy from Berkeley.

He was a member of both the Supernova Cosmology Project and the HiZ Supernova Search Team

which used observations of the extragalactic supernova to discover that the universe is

accelerating and that this implies the existence of dark energy.

This discovery resulted in the 2011 NOVA Prize for Physics.

Outside of his groundbreaking research, he is a great science communicator and is one

of the most widely admired educators in the world.

I really enjoyed this conversation and am sure Alex will be back again in the future.

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As a side note, let me say that as we talk about in this conversation, the objects that

populate the universe are both awe inspiring and terrifying in their capacity to create

and to destroy us.

Solar flares and asteroids lurking in the darkness of space threaten our humble, fragile

existence here on Earth.

In the chaos, tension, conflict, and social division of 2020, it's easy to forget just

how lucky we humans are to be here, and with a bit of hard work, maybe one day, we'll

venture out towards the stars.

If you enjoy this thing, subscribe on YouTube, review it with Five Stars on Apple Podcast,

follow on Spotify, support on Patreon, or connect with me on Twitter at Lex Friedman.

And now, here's my conversation with Alex Filipenko.

Let's start by talking about the biggest possible thing, the universe.

Will the universe expand forever or collapse on itself?

Well, you know, that's a great question.

It's one of the big questions of cosmology, and of course, we have evidence that the matter

density is sufficiently low that the universe will expand forever.

But not only that, there's this weird repulsive effect, we call it dark energy for want of

a better term, and it appears to be accelerating the expansion of the universe.

So if that continues, the universe will expand forever, but it need not necessarily continue.

It could reverse sign, in which case the universe could, in principle, collapse at some point

in the far, far future.

So in terms of investment advice, if you were to give me and then to bet all my money on

one or the other, where does your intuition currently lie?

Well, right now, I would say that it would expand forever because I think that the dark

energy is likely to be just quantum fluctuations of the vacuum.

The vacuum zero energy state is not a state of zero energy.

That is, the ground state is a state of some elevated energy which has a repulsive effect

to it.

And that will never go away because it's not something that changes with time.

So if the universe is accelerating now, it will forever continue to do so.

And yet, I mean, you so effortlessly mentioned dark energy.

Do we have any understanding of what the heck that thing is?

Well, not really.

But we're getting progressively better observational constraints.

So different theories of what it might be predict different sorts of behavior for the

evolution of the universe.

And we've been measuring the evolution of the universe now.

And the data appear to agree with the predictions of a constant density vacuum energy, a zero

point energy.

But one can't prove that that's what it is because one would have to show that the measured

numbers agree with the predictions to an arbitrary number of decimal places.

And of course, even if you've got 8, 9, 10, 12 decimal places, what if in the 13th one,

the measurements significantly differ from the prediction?

Then the dark energy isn't this vacuum state, ground state energy of the vacuum.

And so then it could be some sort of a field, some sort of a new energy, a little bit like

light, like electromagnetism, but very different from light, that fills space.

And that type of energy could in principle change in the distant future.

It could become gravitationally attractive for all we know.

There is a historical precedent to that, and that is that the inflation with which the

universe began when the universe was just a tiny blink of an eye old, a trillionth of

a trillionth of a trillionth of a second, the universe went whoosh, it exponentially

expanded.

That dark energy like substance, we call it the inflaton, that which inflated the universe,

later decayed into more or less normal gravitationally attractive matter.

So the exponential early expansion of the universe did transition to a deceleration,

which then dominated the universe for about nine billion years.

And now this small amount of dark energy started causing an acceleration about five billion

years ago.

And whether that will continue or not is something that we'd like to answer, but I don't know

that we will anytime soon.

So there could be this interesting field that we don't yet understand that's morphing over

time, that's changing the way the universe is expanding.

I mean, it's funny that you were thinking through this rigorously like an experimentalist.

But what about like the fundamental physics of dark energy?

Is there any understanding of what the heck it is, or is this the kind of the god of the

gaps or the field of the gaps?

So like there must be something there because of what we're observing.

I'm very much a person who believes that there's always a cause, you know, there are no miracles

of a supernatural nature, okay?

So I mean, there are two broad categories, either it's the vacuum zero point energy,

or it's some sort of a new energy field that pervades the universe.

The latter could change with time, the former, the vacuum energy cannot.

So if it turns out that it's one of these new fields, and there are many, many possibilities,

they go by the name of quintessence and things like that, but there are many categories of

those sorts of fields, we try with data to rule them out by comparing the actual measurements

with the predictions.

And some have been ruled out, but many, many others remain to be tested.

And the data just have to become a lot better before we can rule out most of them and become

reasonably convinced that this is a vacuum energy.

So there is hypotheses for different fields, like with names and stuff like that?

Yeah, you know, generically quintessence, like the Aristotelian fifth essence, but there

are many, many versions of quintessence.

There's K essence, there's even ideas that, you know, this isn't something from within

this dark energy, but rather, there are a bunch of, say, bubble universes surrounding

our universe, and this whole idea of the multiverse is not some crazy madman type idea anymore.

It's, you know, real card carrying physicists are seriously considering this possibility

of a multiverse.

And some types of multiverses could have, you know, a bunch of bubbles on the outside,

which gravitationally act outward on our bubble because gravity or gravitons, the quantum

particle that is thought to carry gravity, is thought to traverse the bulk, the space

between these different little bubble membranes and stuff.

And so it's conceivable that these other universes are pulling outward on us.

That's not a favored explanation right now, but really, nothing has been ruled out.

No class of models has been ruled out completely.

Certain examples within classes of models have been ruled out.

But in general, I think we still have really a lot to learn about what's causing this

observed acceleration of the expansion of the universe, be it dark energy or some forces

from the outside, or perhaps, you know, I guess it's conceivable that, and sometimes

I wake up in the middle of the night screaming, that dark energy, that which causes the acceleration,

and dark matter, that which causes galaxies and clusters of galaxies to be bound gravitationally

even though there's not enough visible matter to do so.

Maybe these are our 20th and 21st century Ptolemaic epicycles.

So Ptolemy had a geocentric and Aristotelian view of the world.

Everything goes around Earth.

But in order to explain the backward motion of planets among the stars that happens every

year or two, or sometimes several times a year for Mercury and Venus, you needed the

planets to go around in little circles called epicycles, which themselves then went around

Earth.

And in this part of the epicycle where the planet is going in the direction opposite

to the direction of the overall epicycle, it can appear in projection to be going backward

among the stars, so called retrograde motion.

And it was a brilliant mathematical scheme.

In fact, he could have added epicycles on top of epicycles and reproduced the observed

positions of planets to arbitrary accuracy.

And this is really the beginning of what we now call Fourier analysis, right?

Any periodic function can be represented by a sum of sines and cosines of different periods,

amplitudes, and phases.

So it could have worked arbitrarily well.

But other data show that, in fact, Earth is going around the sun.

So our dark energy and dark matter, just these band aids that we now have to try to explain

the data, but they're just completely wrong.

That's a possibility as well.

And as a scientist, I have to be open to that possibility as an open minded scientist.

How do you put yourself in the mindset of somebody that, or majority of the scientific

community or majority of people believe that the Earth, everything rotates around Earth?

How do you put yourself in that mindset and then take a leap to propose a model that the

sun is, in fact, at the center of the solar system?

Sure.

I mean, so that puts us back in the shoes of Copernicus, right, 500 years ago, where

he had this philosophical preference for the sun being the dominant body in what we now

call the solar system.

The observational evidence in terms of the measured positions of planets was not better

explained by the heliocentric, sun centered system.

It's just that Copernicus saw that the sun is the source of all our light and heat, and

he knew from other studies that it's far away.

So the fact that it appears as big as the moon means it's actually way, way bigger because

even at that time, it was known that the sun is much farther away than the moon.

So he just felt, wow, it's big, it's bright.

What if it's the central thing?

But the observed positions of planets at the time in the early to mid 16th century under

the heliocentric system was not a better match, at least not a significantly better match

than Ptolemy's system, which was quite accurate and lasted 1500 years.

Yeah.

That's so fascinating to think that the philosophical predispositions that you bring to the table

are essential.

So like you have to have a young person come along that has a weird infatuation with the

sun.

Yeah.

That like almost philosophically is like however their upbringing is, they're more ready for

whatever the more the simpler answer is.

Right.

Oh, that's kind of sad.

It's a sad from an individual descendant of eight perspective because then that means

like me, you as a scientist, you're stuck with whatever the heck philosophies you brought

to the table and you might be almost completely unable to think outside this particular box

you've built.

Right.

This is why I'm saying that, you know, as an objective scientist, one needs to have

an open mind to crazy sounding new ideas.

And even Copernicus was very much a man of his time and dedicated his work to the Pope.

He still used circular orbits.

The sun was a little bit off center, it turns out, and a slightly off center circle looks

like a slightly eccentric elliptical orbit.

So then when Kepler, in fact, showed that the orbits are actually in general ellipses,

not circles, the reason that he needed Tuco Brahe's really great data to show that distinction

was that a slightly off center circle is not much different from a slightly eccentric ellipse.

And so there wasn't much difference between Kepler's view and Copernicus's view and Kepler

needed the better data, Tuco Brahe's data.

And so that's, again, a great example of science and observations and experiments working together

with hypotheses and they kind of bounce off each other.

They play off of each other and you continually need more observations.

And it wasn't until Galileo's work around 1610 that actual evidence for the heliocentric

hypothesis emerged.

It came in the form of Venus, the planet Venus, going through all of the possible phases from

new to crescent to quarter to gibbous to full to waning gibbous, third quarter waning crescent,

and then new again.

It turns out in the Ptolemaic system with Venus between Earth and the sun, but always

roughly in the direction of the sun, you could only get the new and crescent phases of Venus.

But the observations showed a full set of phases.

And moreover, when Venus was gibbous or full, that meant it was on the far side of the sun.

That meant it was farther from Earth than when it's crescent, so it should appear smaller

and indeed it did.

So that was the nail in the coffin in a sense.

And then Galileo's other great observation was that Jupiter has moons going around it,

the four Galilean satellites.

And even though Jupiter moves through space, so too do the moons go with it.

So first of all, Earth is not the only thing that has other things going around it.

And secondly, Earth could be moving as Jupiter does and things would move with it.

We wouldn't fly off the surface and our moon wouldn't be left behind and all this kind

of stuff.

So that was a big breakthrough as well, but it wasn't as definitive in my opinion as

the phases of Venus.

Sometimes I'm revealing my ignorance, but I didn't realize how much data they were working

with.

So it wasn't Einstein or Freud thinking in theories.

It was a lot of data and you're playing with it and seeing how to make sense of it.

So it isn't just coming up with completely abstract thought experiments.

It's looking at the data.

Sure.

And you look at Newton's great work, right?

The Principia, it was based in part on Galileo's observations of balls rolling down inclined

planes, supposedly falling off the Leaning Tower of Pisa, but that's probably apocryphal.

In any case, the Roman Catholic Church did history a favor, not that I'm condoning them,

but they placed Galileo under house arrest and that gave Galileo time to publish, to

assemble and publish the results of his experiments that he had done decades earlier.

It's not clear he would have had time to do that, had he not been under house arrest.

And so Newton, of course, very much used Galileo's observations.

Let me ask the old Russian overly philosophical question about death.

So we're talking about the expanding universe.

Sure.

How do you think human civilization will come to an end if we avoid the near term issues

we're having?

Will it be our sun burning out?

Will it be comets?

Oh, okay.

Will it be, what is it?

Do you think we have a shot at reaching the heat death of the universe?

Yeah.

So we're going to leave out the anthropogenic causes of our potential destruction, which

I actually think are greater than the celestial causes.

So if we get lucky and intelligent, I don't know.

So no way will we as humans reach the heat death of the universe.

It's conceivable that machines, which I think will be our evolutionary descendants, might

reach that, although even they will have less and less energy with which to work as time

progresses because eventually even the lowest mass stars burn out, although it takes them

trillions of years to do so.

So the point is that certainly on Earth, there are other celestial threats, existential threats,

comets, exploding stars, the sun burning out.

So we will definitely need to move away from our solar system to other solar systems.

And then the question is, can they keep on propagating to other planetary systems sufficiently

long?

In our own solar system, the sun burning out is not the immediate existential threat.

That'll happen in about five billion years when it becomes a red giant, although I should

hasten to add that within the next one or two billion years, the sun will have brightened

enough that unless there are compensatory atmospheric changes, the oceans will evaporate

away.

They're going to need much less carbon dioxide for the temperatures to be maintained roughly

at their present temperature, and plants wouldn't like that very much.

So you can't lower the carbon dioxide content too much.

So within one or two billion years, probably the oceans will evaporate away.

But on a sooner time scale than that, I would say an asteroid collision leading to a potential

mass extinction, or at least an extinction of complex beings such as ourselves that require

quite special conditions unlike cockroaches and amoebas to survive, one of these civilization

changing asteroids is only one kilometer or so in diameter and bigger, and a true mass

extinction event is 10 kilometers or larger.

Now it's true that we can find and track the orbits of asteroids that might be headed toward

Earth, and if we find them 50 or 100 years before they impact us, then clever applied

physicists and engineers can figure out ways to deflect them.

But at some point, some comet will come in from the deep freeze of the solar system,

and there we have very little warning, months to a year.

What's the deep freeze, sorry to interrupt.

The deep freeze is sort of out beyond Neptune.

There's this thing called the Kuiper Belt, and it consists of a bunch of dirty ice balls

or icy dirt balls.

It's the source of the comets that occasionally come close to the Sun.

And then there's an even bigger area called the Scattered Disk, which is sort of a big

doughnut surrounding the solar system way out there from which other comets come.

And then there's the Oort Cloud, W O O R T after Jan Oort, a Dutch astrophysicist, and

it's the better part of a light year away from the Sun, so a good fraction of the distance

to the nearest star, but that's like a trillion or 10 trillion comet like objects that occasionally

get disturbed by a passing star or whatever, and most of them go flying out of the solar

system, but some go toward the Sun, and they come in with little warning.

By the time we can see them, they're only a year or two away from us.

And moreover, not only is it hard to determine their trajectories sufficiently accurately

to know whether they'll hit a tiny thing like Earth, but outgassing from the comet of gases

when the ices sublimate, that outgassing can change the trajectory just because of conservation

of momentum, right?

It's the rocket effect.

Gases go out in one direction, the object moves in the other direction.

And so since we can't predict how much outgassing there will be and in exactly what direction

because these things are tumbling and rotating and stuff, it's hard to predict the trajectory

with sufficient accuracy to know that it will hit.

And you certainly don't want to deflect a comet that would have missed but you thought

it was going to hit and end up having it hit.

That would be like the ultimate Charlie Brown goat instead of trying to be the hero, right?

He ended up being the goat.

What would you do if it seemed like in a matter of months that there is some nonzero probability,

maybe a high probability that there will be a collision?

So from a scientific perspective, from an engineering perspective, I imagine you would

actually be in the room of people deciding what to do.

What uh, philosophically too.

It's a tough one, right?

Because if you only have a few months, that's not much time in which to deflect it.

Early detection and early action are key because when it's far away, you only have to deflect

it by a tiny little angle.

And then by the time it reaches us, the perpendicular motion is big enough to miss Earth.

All you need is one radius or one diameter of the Earth, right?

That actually means that all you would need to do is slow it down so it arrives four minutes

later or speed it up so it arrives four minutes earlier and Earth will have moved through

one radius in that time.

So it doesn't take much.

But you can imagine if a thing is about to hit you, you have to deflect it 90 degrees

or more, right?

You know, and you don't have much time to do so and you have to slow it down or speed

it up a lot if that's what you're trying to do to it.

And so decades is sufficient time, but months is not sufficient time.

So at that point, I would think the name of the game would be to try to predict where

it would hit.

And if it's in a heavily populated region, try to start an orderly evacuation perhaps.

But you know, that might cause just so much panic that I'm, how would you do with New

York City or Los Angeles or something like that, right?

I might have a different opinion a year ago, I'm a bit disheartened by, you know, in the

movies, there's always extreme competence from the government.

Competence, yeah.

Competence, yeah.

But we expect extreme incompetence, if anything, right?

Yes, no.

So I'm quite disappointed.

But sort of from a medical perspective, I think you're saying there, and a scientific

one, it's almost better to get better and better, maybe telescopes and data collection

to be able to predict the movement of these things, or like come up with totally new technologies

that you can imagine actually sending out, like probes out there to be able to sort of

almost have little finger sensors throughout our solar system to be able to detect stuff.

Well, that's right.

Yeah, monitoring the asteroid belt is very important and 99% of the so called near earth

objects ultimately come from the asteroid belt.

And so there we can track the trajectories and even if there's a close encounter between

two asteroids which deflects one of them toward earth, it's unlikely to be on a collision

course with earth in the immediate future, it's more like tens of years, so that gives

us time.

But we would need to improve our ability to detect the objects that come in from a great

distance.

And those are much rarer, the comets come in, 1% of the collisions perhaps are with

comets that come in without any warning hardly.

So that might be more like a billion or two billion years before one of those hits us.

So maybe we have to worry about the sun getting brighter on that time scale.

I mean, there's the possibility that a star will explode near us in the next couple of

billion years.

But over the course of the history of life on earth, the estimates are that maybe only

one of the mass extinctions was caused by a star blowing up in particular, a special

kind called a gamma ray burst, and I think it's the Ordovician–Silurian extinction

420 or so, 440 million years ago that is speculated to have come from one of these particular

types of exploding stars called gamma ray bursts.

But even there, the evidence is circumstantial.

So those kinds of existential threats are reasonably rare.

The greater danger I think is civilization changing events where it's a much smaller

asteroid, which those are harder to detect, or a giant solar flare that shorts out the

grid in all of North America, let's say.

Now, astronomers are monitoring the sun 24 seven with various satellites and we can tell

when there's a flare or a coronal mass ejection and we can tell that in a day or two, a giant

bundle of energetic particles will arrive and twang the magnetic field of earth and

send all kinds of currents through long distance power lines and that's what shorts out the

transformers and transformers are expensive and hard to replace and hard to transport

and all that kind of stuff.

So if we can warn the power companies and they can shut down the grid before the big

bundle of particle hits, then we will have mitigated much of this.

Now for a big enough bundle of particles, you can get short circuits even over small

distance scales, so not everything will be saved, but at least the whole grid might not

go out.

So again, astronomers, I like to say, support your local astronomer, they may help someday

save humanity by telling the power companies to shut down the grid, finding the asteroid

50 or 100 years before it hits, then having clever physicists and engineers deflect it.

So many of these cosmic threats, cosmic existential threats, we can actually predict and do something

about or observe before they hit and do something about.

So it's terrifying to think that people would listen to this conversation.

It's like when you listen to Bill Gates talk about pandemics in his Ted talk a few years

ago and realizing we should have supported our local astronomer more.

Well, I don't know whether it's more because as I said, I actually think human induced

threats or things that occur naturally on earth, either a natural pandemic or perhaps

a bioengineering type pandemic or something like a super volcano.

There was one event towed by I think it was 70 plus thousand years ago that caused a gigantic

decrease in temperatures on earth because it sent up so much soot that it blocked the

sun.

It's the nuclear winter type disaster scenario that some people including Carl Sagan talked

about decades ago.

What we can see in the history of volcanic eruptions even more recently in the 19th century,

Tambora and other ones, you look at the record and you see rather large dips in temperature

associated with massive volcanic eruptions.

Well these super volcanoes, one of which by the way exists under Yellowstone in the central

US, it's not just one or two states, it's a gigantic region and there's controversy

as to whether it's likely to blow anytime in the next 100,000 years or so.

But that would be perhaps not a mass extinction or perhaps not a complete existential threat

because you have to get rid of the very last humans for that, but at least getting rid

of killing off so many humans, truly billions and billions of humans.

There have been ones tens of thousands of years ago including this one, Toba I think

it's called, where it's estimated that the human population was down to 10,000 or 5,000

individuals, something like that.

If you have a 15 degree drop in temperature over quite a short time, it's not clear that

even with today's advanced technology, we would be able to adequately respond at least

for the vast majority of people.

Maybe some would be in these underground caves where you'd keep the president and a bunch

of other important people, but the typical person is not going to be protected when all

of agriculture is cut off.

It could be hundreds of millions or billions of people starving to death.

Exactly.

That's right.

They don't all die immediately, but they use up their supplies or again, this electrical

grid.

First of toilet paper.

Dash that toilet paper or the electrical grid.

Imagine North America without power for a year.

We've become so dependent, we're no longer the cave people.

They would do just fine.

What do they care about the electrical grid?

What do they care about agriculture, their hunters and gatherers?

But we now have become so used to our way of life that the only real survivors would

be those rugged individualists who live somewhere out in the forest or in a cave somewhere,

completely independent of anyone else.

Yeah.

Recently I recommended, it's totally new to me, this kind of survivalist folks, but there's

a few shows.

There's a lot of shows of those, but I saw one on Netflix and I started watching them

and they make a lot of sense.

They reveal to you how dependent we are on all aspects of this beautiful systems we human

have built and how fragile they are.

Incredibly fragile.

And this whole conversation is making me realize how lucky we are.

Oh, we're incredibly lucky, but we've set ourselves up to be very, very fragile and

we are intrinsically complex biological creatures that except for the fact that we have brains

and minds with which we can try to prevent some of these things or respond to them.

We as a living organism require quite a narrow set of conditions in order to survive.

We're not cockroaches.

We're not going to survive a nuclear war.

So we're kind of this beautiful dance between, we've been talking about astronomy, that astronomy,

the stars like inspires everybody and at the same time, there's this pragmatic aspect that

we're talking about.

And so I see space exploration as the same kind of way that it's reaching out to other

planets, reaching out to the stars, this really beautiful idea.

But if you listen to somebody like Elon Musk, he talks about space exploration as very pragmatic.

Like we have to be, he has this ridiculous way of sounding like an engineer about it,

which is like, it's obvious we need to become a multi planetary species if we were to survive

long term.

So maybe both philosophically in terms of beauty and in terms of practical, what's your

thoughts on space exploration, on the challenges of it, on how much we should be investing

in it and on a personal level, like how excited you are by the possibility of going to Mars,

colonizing Mars and maybe going outside the solar system.

Yeah.

You know, great question.

There's a lot to unpack there of course.

Humans are by their very nature explorers, pioneers.

They want to go out, climb the next mountain, see what's behind it, explore the option depths,

explore space.

This is our destiny to go out there.

And of course, from a pragmatic perspective, yes, we need to plant our seeds elsewhere

really because things could go wrong here on Earth.

Now some people say that's an excuse to not take care of our planet.

Well, we say we're elsewhere and so we don't have to take good care of our planet.

No, we should take the best possible care of our planet.

We should be cognizant of the potential impact of what we're doing.

Nevertheless, it's prudent to have us be elsewhere as well.

So in that regard, I actually agree with Elon.

It'd be good to be on Mars.

That would be yet another place for us from which to explore further.

Would that be a good next step?

Well, it's a good next step.

I happen to disagree with him as to how quickly it will happen.

I think he's very optimistic.

Now you need visionary people like Elon to get people going and to inspire them.

I mean, look at the success he's had with multiple companies.

So maybe he gives this very optimistic timeline in order to be inspirational to those who

are going out there.

And certainly his success with the rocket that is reusable because it landed upright

and all that.

I mean, that's a game changer.

It's sort of like every time you flew from San Francisco to Los Angeles, you discard

the airplane, right?

I mean, that's crazy, right?

So that's a game changer.

But nevertheless, the timescale over which he thinks that there could be a real thriving

colony on Mars, I think is far too optimistic.

What's the biggest challenges to you?

One is just getting rockets, not rockets, but people out there and two is the colonization.

Do you have thoughts about this, the challenges of this kind of prospect?

Yeah, I haven't thought about it in great detail other than recognizing that Mars is

a harsh environment.

Yeah.

You don't have much of an atmosphere there.

You've got less than a percent of Earth's atmosphere.

So you'd need to build some sort of a dome right away, right?

And that would take time.

You need to melt the water that's in the permafrost or have canals dug from which you transport

it from the polar ice caps.

You know, I was reading recently in terms of like, what's the most efficient source

of nutrition for humans that were to live on Mars?

And people should look into this, but it turns out to be insects.

Insects.

Yeah.

So you want, you want to build giant colonies of insects and just be eating them.

Yeah, insects have a lot of protein.

Yeah, a lot of protein.

And they're easy to grow.

Like you can think of them as farming.

Right.

But it's not going to be as easy as growing a whole plot of potatoes like in the movie

The Martian, you know, or something, right?

It's not going to be that easy.

But you know, so there's this thin atmosphere.

It's got the wrong composition.

It's mostly carbon dioxide.

There are these violent dust storms.

The temperatures are generally cold.

You know, you'd need to do a lot of things.

You need to terraform it basically in order to make it nicely livable without some dome

surrounding you.

And if you, and if you insist on a dome, well, that's not going to house that many people,

right?

You know, so let's look, let's look briefly then, you know, we're looking for a new apartment

to move into.

Right.

So let's look outside the solar system.

Do you think you've, you've spoken about exoplanets as well?

Do you think there's possible homes out there for us outside of our solar system?

There are lots and lots of homes.

Possible homes.

There are, there's a planetary system around nearly every star you see in the sky.

And one in five of those is thought to have a roughly Earth like planet.

And that's a relatively new discovery.

Yeah.

It's a new discovery.

I mean, the Kepler satellite, which was flying around above Earth's atmosphere was able to

monitor the brightness of stars with exquisite detail.

And they could detect planets crossing the line of sight between us and the star, thereby

dimming its light for a short time ever so slightly.

And it's amazing.

So there are now thousands and thousands of these exoplanet candidates of which something

like 90% are probably genuine exoplanets.

And you have to remember that only about 1% of stars have their planetary system oriented

edge on to your line of sight, which is what you need for this transit method to work,

right?

Your planetary angle won't work and certainly perpendicular to your line of sight.

That is in the plane of the sky won't work because the planet is orbiting the star and

never crossing your line of sight.

So the fact that they found planets orbiting about 1% of the stars that they looked at

in this field of 150 plus thousand stars, they found planets around 1%.

You then multiply by the inverse of 1%, which is 1% is about what the fraction of the stars

that have their planetary system oriented the right way.

And that already back of the envelope calculation tells you that of order 50 to 100% of all

stars have planets.

And then they've been finding these Earth like planets, et cetera, et cetera.

So there are many potential homes.

The problem is getting there.

So then a typical bright star, Sirius, the brightest star in the sky, maybe not a typical

bright star, but it's 8.7 light years away.

So that means the light took 8.7 years to reach us.

We're seeing it as it was about nine years ago.

So then you ask how long would a rocket take to get there at Earth's escape speed, which

is 11 kilometers per second.

And it turns out it's about a quarter of a million years.

Now that's 10,000 generations.

Let's say a generation of humans is 25 years.

So you'd need this colony of people that is able to sustain itself, all their food, all

their waste disposal, all their water, all the recycling of everything.

For 10,000 generations, they have to commit themselves to living on this vehicle.

I just don't see it happening.

What I see potentially happening, if we avoid self destruction, intentional or unintentional

here on Earth, is that machines will do it, robots that can essentially hibernate.

They don't need to do much of anything for a long, long time as they're traveling.

And moreover, if some energetic charged particle, some cosmic ray, hits the circuitry, it fixes

itself.

Machines can do this.

It's a form of artificial intelligence.

You just tell the thing, fix yourself basically.

And then when you land on the planet, start producing copies of yourself, initially from

materials that were perhaps sent, or you just have a bunch of copies there.

And then they set up factories with which to do this.

This is very, very futuristic, but it's much more feasible, I think, than sending flesh

and blood over interstellar distances, a quarter of a million years to even the nearest stars.

You're subject to all kinds of charged particles and radiation.

You have to shield yourself really well.

That's by the way, one of the problems of going to Mars is that it's not a three day

journey like going to the moon.

You're out there for the better part of a year or two, and you're exposed to lots of

radiation, which typically doesn't do well with living tissue, or living tissue doesn't

do well with the radiation.

And the hope is that the robots, the AI systems might be able to carry the fire of consciousness,

whatever makes us humans, like a little drop of whatever makes us humans so special, not

to be too poetic about it.

No, but I like being poetic about it because it's an amazing question.

Is there something beyond just the bits, the ones and zeros to us?

It's an interesting question.

I like to think that there isn't anything, and that how beautiful it is that our thoughts,

our emotions, our feelings, our compassion all come from these ones and zeros, right?

That to me actually is a beautiful thought.

And the idea that machines, silicon based life effectively, could be our natural evolutionary

descendants, not from a DNA perspective, but they are our creations and they then carry

on.

That to me is a beautiful thought in some ways, but others find it to be a horrific

thought.

So that's exciting to you.

It is exciting to me as well because to me, from a purely an engineering perspective,

I believe it's impossible to create, like whatever systems we create that take over

the world, it's impossible for me to imagine that those systems will not carry some aspect

of what makes humans beautiful.

So like a lot of people have these kind of paperclip ideas that we'll build machines

that are cold inside or philosophers call them zombies.

That naturally the systems that will out compete us on this earth will be cold and non conscious,

not capable of all the human emotions and empathy and compassion and love and hate,

the beautiful mix of what makes us human.

But to me, intelligence requires all of that.

So in order to out compete humans, you better be good at the full picture.

Right.

So artificial general intelligence, in my view, encompasses a lot of these attributes

that you just talked about, curiosity, inquisitiveness, you know, right?

It might look very different than us humans, but it will have some of the magic.

But it'll also be much more able to survive the onslaught of existential threats that

either we bring upon ourselves or don't anticipate here on earth, or that occasionally come from

beyond and there's nothing much we can do about a supernova explosion that just suddenly

goes off.

And really, if we want to move to other planets outside our solar system, I think realistically

that's a much better option than thinking that humans will actually make these gigantic

journeys.

And, you know, then I do this calculation for my class, you know, Einstein's special

theory of relativity says that you can do it in a short amount of time in your own frame

of reference if you go close to the speed of light.

But then you bring in E equals MC squared and you figure out how much energy it takes

to get you accelerated to close enough to the speed of light to make the time scales

short in your own frame of reference.

And the amount of energy is just unfathomable, right?

We can do it at the Large Hadron Collider with protons, you know, we can accelerate

them to 99.9999% of the speed of light, but that's just a proton.

We're gazillions of protons, okay?

And that doesn't even count the rocket that would carry us, the payload.

And you would need to either store the fuel in the rocket, which then requires even more

mass for the rocket or collect fuel along the way, which, you know, is difficult.

And so getting close to the speed of light, I think, is not an option either other than

for a little tiny thing like, you know, Yuri Milner and others are thinking about this,

the Starshot project where they'll send a little tiny camera to Alpha Centauri 4.2 light

years away.

They'll zip past it, take a picture of the exoplanets that we know, orbit that three

or more star system and say hello real quick.

Say hello real quickly and then send the images back to us, okay?

So that's a tiny little thing, right?

Maybe you can accelerate that to, they're hoping, 20% of the speed of light with a whole

bunch of high powered lasers aimed at it.

It's not clear that other countries will allow us to do that, by the way, but that's a very

forward looking thought.

I mean, I very much support the idea, but there's a big difference between sending a

little tiny camera and sending a payload of people with equipment that could then mine

the resources on the exoplanet that they reach and then go forth and multiply, right?

Well, let's talk about the big galactic things and how we might be able to leverage them

to travel fast.

I know this is a little bit science fiction, but, you know, ideas of wormholes and ideas

at the edge of black holes that reveal to us that this fabric of space time could be

messed with, perhaps.

Is that at all an interesting thing for you?

I mean, in looking out at the universe and studying it as you have, is that also a possible,

like a dream for you that we might be able to find clues how we can actually use it to

improve our transportation?

It's an interesting thought.

I'm certainly excited by the potential physics that suggests this kind of faster than light

travel effectively or, you know, cutting the distance to make it very, very short through

a wormhole or something like that.

Possible?

No?

Well, you know, call me not very imaginative, but based on today's knowledge of physics,

which I realize, you know, people have gone down that rabbit hole and, you know, a century

ago, Lord Kelvin, one of the greatest physicists of all time, said that all of fundamental

physics is done, the rest is just engineering, and guess what?

Then came special relativity, quantum physics, general relativity, how wrong he was.

So let me not be another Lord Kelvin.

On the other hand, I think we know a lot more now about what we know and what we don't know

and what the physical limitations are.

And to me, most of these schemes, if not all of them, seem very farfetched, if not impossible.

So travel through wormholes, for example, you know, it appears that for a non rotating

black hole, that's just a complete no go because the singularity is a point like singularity

and you have to reach it to traverse the wormhole and you get squished by the singularity, okay?

Now for a rotating black hole, it turns out there is a way to pass through the event horizon,

the boundary of the black hole, and avoid the singularity and go out the other side

or even traverse the donut hole like singularity.

In the case of a rotating black hole, it's a ring singularity.

So there's actually two theoretical ways you could get through a rotating black hole or

a charged black hole, not that we expect charged black holes to exist in nature because they

would quickly bring in the opposite charge so as to neutralize themselves.

But rotating black holes, definitely a reality.

We now have good evidence for them.

Do they have traversable wormholes?

Probably not because it's still the case that when you go in, you go in with so much energy

that it either squeezes the wormhole shut or you encounter a whole bunch of incoming

and outgoing energy that vaporizes you.

It's called the mass inflation instability, and it just sort of vaporizes you.

Nevertheless, you could imagine, well, you're in some vapor form, but if you make it through,

maybe you could reform or something.

So it's still information.

Yeah, it's still information.

It's scrambled information, but there's a way maybe of bringing it back, right?

But then the thing that really bothers me is that as soon as you have this possibility

of traversal of a wormhole, you have to come to grips with a fundamental problem, and that

is that you could come back to your universe at a time prior to your leaving, and you could

essentially prevent your grandparents from ever meeting.

This is called the grandfather paradox, right?

And if they never met, and if your parents were never born, and if you were never born,

how would you have made the journey to prevent the history from allowing you to exist, right?

It's a violation of causality, of cause and effect.

Now physicists such as myself take causality violation very, very seriously.

We've never seen it.

You took a stand.

Yeah, I mean, it's one of these back to the future type movies, right?

And you have to work things out in such a way that you don't mess things up, right?

Some people say that, well, you come back to the universe, but you come back in such

a way that you cannot affect your journey.

But then that seems kind of contrived to me.

Or some say that you end up in a different universe, and this also goes into the many

different types of the multiverse hypothesis and the many worlds interpretation and all

that.

And then it's not the universe from which you left, right?

And you don't come back to the universe from which you left.

And so you're not really going back in time to the same universe, and you're not even

going forward in time necessarily then to the same universe, right?

You're ending up in some other universe.

So what have you achieved, right?

You've traveled.

You ended up in a different place than you started in more ways than one.

Yeah.

And then there's this idea, the Alcubierre drive, where you warp space time in front

of you so as to greatly reduce the distance, and you can expand the space time behind you.

So you're sort of riding a wave through space time.

But the problem I see with that, beyond the practical difficulties and the energy requirements,

and by the way, how do you get out of this bubble through which you're riding this wave

of space time?

And Miguel Alcubierre acknowledged all these things.

He said this is purely theoretical, fanciful, and all that.

But a fundamental problem I see is that you'd have to get to those places in front of you

so as to change the shape of space time so as to make the journey quickly.

But to get there, you got there in the normal way at a speed considerably less than that

of light.

So in a sense, you haven't saved any time, right?

You might as well have just taken that journey and gotten to where you were going, right?

What have you done?

It's not like you snap your fingers and say, okay, let that space there be compressed,

and then I'll make it over to Alpha Centauri in the next month.

You can't snap your fingers and do that.

Yeah.

But yeah, we're sort of assuming that we can fix all the biological stuff that requires

for humans to persist through that whole process, because ultimately, it might go down to just

extending the life of the human in some form, whether it's through the robot, through the

digital form, or actually just figuring out genetically how to live forever, because that

journey that you mentioned, the long journey, might be different if somehow our understanding

of genetics, of our understanding of our own biology, all that kind of stuff, that's another

trajectory that possibly...

Well, right.

If you could put us into some sort of suspended animation, hibernation or something, and greatly

increase the lifetime, and so these 10,000 generations I talked about, what do they care?

It's just one generation, and they're asleep, okay?

It's a long nap.

So then you can do it.

It's still not easy, right?

Because you've got some big old huge colony, and that just through E equals MC squared,

right?

That's a lot of mass.

That's a lot of stuff to accelerate.

The Newtonian kinetic energy is gigantic, right?

So you're still not home free, but at least you're not trying to do it in a short amount

of clock time, right?

Which if you look at E equals MC squared, requires truly unfathomable amounts of energy,

because the energy is your rest mass, M naught C squared, divided by the square root of one

minus V squared over C squared.

And if your listeners want to just sort of stick into their pocket calculator, as V over

C approaches one, that one over the square root of one minus V squared over C squared

approaches infinity.

So if you wanted to do it in zero time, you'd need an infinite amount of energy.

That's basically why you can't reach, let alone exceed the speed of light, for a particle

moving through a preexisting space.

It's that it takes an infinite amount of energy to do so.

So that's talking about us going somewhere.

What about, one of the things that inspires a lot of folks, including myself, is the possibility

that there's other, that this conversation is happening on another planet in different

forms with intelligent life forms.

So first we could start, as a cosmologist, what's your intuition about whether there

is or isn't intelligent life out there?

Outside of our own?

Yeah, I would say I'm one of the pessimists in that I don't necessarily think that we're

the only ones in the observable universe, which goes out, you know, roughly 14 billion

years in light travel time and more like, you know, 46 billion years when you take into

account the expansion of space.

So the diameter of our observable universe is something like, you know, 90, 92 billion

light years.

That encompasses, you know, a hundred billion to a trillion galaxies with, you know, a hundred

billion stars each.

So now you're talking about something like 10 to the 22nd, 10 to the 23rd power stars

and roughly an equal number of Earth like planets and so on.

So there may well be other intelligent life.

But your sense is our galaxy is not teeming with life.

Yeah, our galaxy, our Milky Way galaxy with several hundred billion stars and potentially

habitable planets is not teeming with intelligent life.

Intelligent.

Yeah, I wouldn't, well, I'll get to the primitive life, the bacteria in a moment, but, you know,

we may well be the only ones in our Milky Way galaxy, at most a handful, I'd say, but

I'd probably side with the school of thought that suggests we're the only ones in our own

galaxy, just because I don't see human intelligence as being a natural evolutionary path for life.

I mean, there's a number of arguments.

First of all, there's been more than 10 billion species of life on Earth in its history.

Everything has approached our level of intelligence and mechanical ability and curiosity.

You know, whales and dolphins appear to be reasonably intelligent, but there's no evidence

that they can think abstract thoughts that they're curious about the world.

They certainly can't build machines with which to study the world.

So that's one argument.

Secondly, we came about as early hominids only four or five million years ago and as

homo sapiens only about a quarter of a million years ago.

So for the vast majority of the history of life on Earth, an intelligent alien zipping

by Earth would have said there's nothing particularly intelligent or mechanically able on Earth.

Okay.

Thirdly, it's not clear that our intelligence is a long term evolutionary advantage.

Now it's clear that in the last 100 years, 200 years, we've improved the lives of hundreds

of millions of people, but at the risk of potentially destroying ourselves either intentionally

or unintentionally or through neglect, as we discussed before.

That's a really interesting point, which is it's possible that they're a huge amount of

intelligent civilizations have been born even through our galaxy, but they live very briefly

and they die.

Flash bulbs in the night.

That brings me to the fourth issue and that is the Fermi paradox.

If they're common, where the hell are they?

Notwithstanding the various UFO reports in Roswell and all that, they just don't meet

the bar.

They don't clear the bar of scientific evidence in my opinion.

So there's no clear evidence that they've ever visited us on Earth here.

And SETI has been now, the search for extraterrestrial intelligence has been scanning the skies and

true, we've only looked a couple of hundred light years out and that's a tiny fraction

of the whole galaxy, a tiny fraction of these hundred billion plus stars.

Nevertheless, if the galaxy were teaming with life, especially intelligent life, you'd expect

some of it to have been far more advanced than ours.

There's nothing special about when the industrial revolution started on Earth.

The chemical evolution of our galaxy was such that billions of years ago, nuclear processing

and stars had built up clouds of gas after their explosion that were rich enough in heavy

elements to have formed Earth like planets, even billions of years ago.

So there could be civilizations that are billions of years ahead of ours.

And if you look at the exponential growth of technology among Homo sapiens in the last

couple of hundred years and you just project that forward, I mean, there's no telling what

they could have achieved even in 1000 or 10,000 years, let alone a million or 10 million or

a billion years.

And if they reach this capability of interstellar travel and colonization, then you can show

that within 10 million years or certainly a hundred million years, you can populate

the whole galaxy.

So then you don't have to have tried to detect them beyond a hundred or a thousand light

years.

They would already be here.

Do you think as a thought experiment, do you think it's possible that they are already

here, but we humans are so human centric that we're just not like our conception of what

intelligent life looks like is, we don't want to acknowledge it.

Like what if trees?

Right.

Right.

Right.

Okay, I guess the, in the form of a question, do you think we'll actually detect intelligent

life if it came to visit us?

Yeah.

I mean, it's like, you know, you're an ant crawling around on a sidewalk somewhere and

do you notice the humans wandering around and the empire state building and you know,

rocket ships flying to the moon and all that kind of stuff, right?

It's conceivable that we haven't detected it and that we're so primitive compared to

them that we're just not able to do so.

Like if you look at dark energy, maybe we call it as a field.

It's just that my own feeling is that in science now through observations and experiments,

we've measured so many things and basically we understand a lot of stuff.

Okay.

Fabric of reality.

Yeah.

The fabric of reality, we understand quite well.

And there are a few little things like dark matter and dark energy that may be some sign

of some super intelligence, but I doubt it.

Okay.

You know, why would some super intelligence be holding clusters of galaxies together?

Why would they be responsible for accelerating the expansion of the universe?

So the point is, is that through science and applied science and engineering, we understand

so much now that I'm not saying we know everything, but we know a hell of a lot.

Okay.

And so there's, it's not like there are lots of mysteries flying around there that are

completely outside our level of exploration or understanding.

Yeah.

From a, I would say from, from a mystery perspective, it seems like the mystery of our own like

cognition and consciousness is much grander than like the degrees of freedom of possible

explanations for what the heck is going on is much greater there than in the, in the

physics of the observed.

How the brain works.

How did life arise?

Yeah.

That's big, big questions.

But they, to me, don't indicate the existence of, of, of an alien or something.

I mean, unless we are the aliens, you know, we could have been contamination from some

rocket ship that, that hit here a long, long time ago and all evidence of it has been destroyed.

But again, that alien would have started out somewhere.

They're not, they're not here watching us right now, right?

They're not among us.

And so though there are expert potential explanations for the Fermi paradox, and one of them that

I kind of like is that the truly intelligent creatures are those that decided not to colonize

the whole galaxy because they'd quickly run out of room there because it's exponential,

right?

You send a probe to a planet, it makes two copies, they go out, they make two copies

each and it's an exponential, right?

They quickly colonize the whole galaxy.

But then the distance to the next galaxy, the next big one like Andromeda, that's two

and a half million light years.

That's a much grander scale now, right?

And so it also could be that the reason they survived this long is that they got over this

tendency that may well exist among sufficiently intelligent creatures, this tendency for aggression

and self destruction, right?

If they bypass that, and that may be one of the great filters if there are more than one,

right?

Then they may not be a type of creature that feels the need to go and say, oh, there's

a nice looking planet and there's a bunch of ants on it, let's go squish them and colonize

it.

No, it could even be the kind of Star Trek like prime directive where you go and explore

worlds, but you don't interfere in any way, right?

And also we call it exploration is beautiful and everything, but there is underlying this

desire to explore is a desire to conquer.

Yeah.

I mean, if we're just being really honest right now for us, it is right.

And you're saying it's possible to separate, but I would venture to say that you wouldn't

that those are coupled.

So I could, I could imagine a civilization that lives on for billions of years that just

stays on, it's like figures out the minimal effort way of just peacefully existing.

It's like a monastery.

Yeah.

And it limits itself.

Yeah.

It limits itself.

You know, it's, it's planted its seeds in a number of places.

So it's not vulnerable to a single point failure, right?

Supernova going off near one of these stars or something, or an asteroid or a comet coming

in from the Oort cloud equivalent of that planetary system and without warning, you

know, thrashing them to bits.

So they've got their seeds in a bunch of places, but they chose not to colonize, colonize the

galaxy.

And they also choose not to interfere with this incredibly prevalent, primitive organism

homo sapiens, right?

Or they, uh, this is like a, they enjoy, this is like a TV show for them.

Yeah.

It could be like a TV show.

Right.

So they just tuned in.

Right.

There are no other possible explanations yet.

I think that to me, the most likely explanation for the peri me paradox is that they really

are very, very rare.

And you know, Carl Sagan estimated a hundred thousand of them.

If there's that many, some of them would have been way ahead of us and, and I think we would

have seen them by now.

If there are a handful, maybe they're there.

But at that point, you're right on this dividing line between being a pessimist and an optimist.

Yeah.

And what are the odds for that?

Right.

What are the things that had to go right for us?

Yeah.

And then, you know, getting back to something you said earlier, let's discuss, you know,

primitive life.

Yeah.

That could be the thing that's difficult to achieve.

Just getting the random molecules together to a point where they start self replicating

and evolving and becoming better and all that.

That's an inordinately difficult thing, I think, though I'm not, you know, some molecular

or cell biologist, but just it's, it's, it's the usual argument.

You know, you're wandering around in the Sahara desert and you stumble across a watch.

Is your, is your initial response, oh, you know, a bunch of sand grains just came together

randomly and formed this watch.

No, you, you think that something formed it or it came from some simpler structure that

then became, you know, more complex.

All right.

It didn't just form.

Well, even the simplest life is, is a very, very complex structure.

Even the, even the simplest prokaryotic cells, not to mention eukaryotic cells, although

that transition may have been the so called great filter as well.

Maybe the cells without a nucleus are relatively easy to form.

And then the big next step is where you have a nucleus, which then provides a lot of energy,

which allows the cell to become much, much more complex and so on.

Interestingly, going from eukaryotic cells, single cells to multicellular organisms does

not appear to be, at least on earth, one of these great filters because there's evidence

that it happened dozens of times independently on earth.

So by, by a really great filter, something that happens very, very rarely, I mean that

we had to get through an obstacle that is just incredibly rare to get through.

And one of the really exciting scientific things is that that particular point is something

that we might be able to discover, even in our lifetimes that find life elsewhere like

Europa or be able to see that would be bad news, right?

Because if we find lots of pretty advanced life, yeah, that would suggest, and especially

if we found some, you know, defunct, you know, fossilized civilization or something somewhere

else that would be bacteria, you mean, defunct civilization of like, oh, I'm sorry, I switched

gears there.

If we, if we found some intelligent or even trilobites right and stuff, you know, elsewhere,

that would be bad news for us because that would mean that the great filter is ahead

of us, you know, right, because it would mean that lots of, lots of things have gotten roughly

to our level.

Yeah.

But, but given the Fermi paradox, if you accept that the Fermi paradox means that there's

no one else out there, you don't necessarily have to accept that, but if you accept that

it means that no one else is out there and yet there are lots of things we found that

are at or roughly at our level, that means that the great filter is ahead of us and that

bodes poorly for our longterm future, you know, it's funny you said, uh, you started by saying

you're a little bit on the pessimistic side, but it's funny because we're doing this kind

of dance between pessimism and optimism because I'm not sure if us being alone in the observable

universe as intelligent beings is pessimistic, well, it's good news in a sense for us because

it means that we made it through, see, if we're the only ones and there are such great

filters, maybe more than one formation of life might be one of them formation of eukaryotic

that is with the nucleus cells being another development of human like intelligence might

be another, right?

There might be several such filters and we were the lucky ones.

And you know, then people say, well then that means you're putting yourself into a special

perspective and every time we've done that we've been wrong and yeah, yeah, I know all

those arguments, but it still could be the case that there's one of us at least per galaxy

or pretend or a hundred or a thousand galaxies and we're sitting here having this conversation

because we exist.

And so there's a, there's an observational selection effect there, right?

Just because we're special doesn't mean that we shouldn't have these conversations about

whether or not we're special, right?

Yeah, so that's, that's so exciting.

That's optimistic.

So that's the, that's the optimistic part that if we don't find other intelligent life

there, it might mean that we're the ones that made it.

And in general, outside the great filter and so on, you know, it's not obvious that the

Stephen Hawking thing, which is, it's not obvious that life out there is going to be kind to

us.

Oh yeah.

So, you know, I knew Hawking and I greatly respect his, his scientific work and in particular

the early work on the unification of general theory of relativity and quantum physics to

two great pillars in modern physics, you know, Hawking radiation and all that fantastic work.

You know, if you were alive, you should have been a recipient of this year's physics Nobel

prize, which was for the discovery of black holes and also by Roger Penrose for the theoretical

work showing that given a star that's massive enough, you basically can't avoid having a

black hole.

Anyway, Hawking, fantastic.

I, I tip my hat to him.

May he rest in peace.

That would have been a heck of a Nobel prize, black holes, heck of a good group.

But, but, but going back to what he said that we shouldn't be broadcasting our presence

to others there, I actually disagree with him respectfully because first of all, we've

been unintentionally broadcasting our presence for a hundred years since the development

of radio and TV.

Okay.

Secondly, any alien that has the capability of coming here and squashing us either already

knows about us and you know, doesn't care because we're just like little ants.

And when there are ants in your kitchen, you tend to squash them.

But if there are ants on the sidewalk and you're walking by, do you feel some great

conviction that you have to squash any of them?

No, you generally don't, right?

We're irrelevant to them.

All they need to do is keep an eye on us to see whether we're approaching the kind of

technological capability and know about them and have intentions of attacking them.

And then they can squash us, right?

Um, you know, they, they could have done it long ago.

Yeah.

They'll, they'll do it if they want to, whether we advertise our presence or not is, is irrelevant.

So I really think that that's not a huge existential threat.

So this is a good place to bring up a difficult topic.

You mentioned, um, they might, they would be paying attention to us to see if we come

up with any crazy technology.

There's folks who have reported UFO sightings.

There's actually, I've recently found out there's a websites that track this, the data,

the data of these reportings, and there's millions of them in the past, uh, several

decades.

So seven decades and so on that they've been recorded and the ufologist community, as they

refer to themselves, you know, one of the ideas that I find compelling from an alien

perspective that they kind of started showing up ever since we figured out how to build

nuclear weapons that we should, uh, so I mean, you know, if I was an LA and I would start

showing up then as well, just, well, why not just observe us from afar?

No, I know.

Right.

I would figure out, but that's why I'm always, uh, keeping a distance and staying blurry,

but very pixelated, very pixelated, you know, that there is a something in the human condition

that a cognition that wants to see, wants to believe beautiful things and, uh, some

are terrifying, some are exciting, uh, goats, Bigfoot is a big fascination for folks.

Yeah.

And, uh, UFO sightings, I think falls into that.

There's people that look at lights in the night sky and I mean, there's, it's kind of

a downer to think in a skeptical sense, to think that that's just a light.

Yeah.

You want to feel like there's something magical there.

Sure.

Uh, I mean, I felt that first when my dad, my dad's a physicist, when he first told me

about ball lightning when I was like a little kid, very weird, very like weird physical

phenomenon.

And he said, his intuition was telling me this as a little kid, uh, like, I really like

math.

His intuition was whoever figures out ball lightning, we'll get a Nobel prize.

Like he, I think that was a side comment he gave me and I decided there when I was like

five years old or whatever, I'm going to win a Nobel prize for figuring out ball lightning.

That was like one of the first sort of sparks of the scientific mindset.

Those mysteries, they capture your imagination.

I think when I speak to people that report UFOs, that's that fire.

That's what I see.

That excitement.

And I understand that.

But what, what do we do with that?

Because there's hundreds of thousands, if not millions, and then the scientific community,

you're like the perfect person.

You have an awesome Einstein shirt.

What, what do we do with those reports?

It's a, most of the scientific community kind of rolls their eyes and dismisses it.

Is it possible that a tiny percent of those folks saw something that's worth deeply investigating?

Sure.

We should investigate it.

It's just one of these things where, you know, they've not brought us a hunk of kryptonite

or something like that, right?

They haven't brought us actual tangible physical evidence with which experiments can be done

in laboratories.

Right.

It's, it's anecdotal evidence.

The photographs are, in some cases, in most cases, I would say quite ambiguous.

I don't know what to think about.

So David Faber is the first person.

He's a Navy pilot, commander, and there's a bunch of them, but he's sort of one of the

most legit pilots and people I've ever met.

The fact that he saw something weird, he doesn't know what the heck it is, but he saw something

weird.

I mean, I don't know what to do with that.

And one on the psychological side, so I'm pretty confident he saw what he says he saw,

which he's not, he's saying it's something weird.

One of the interesting psychological things that worries me is that everybody in the Navy,

everybody in the US government, everybody in the scientific community, just kind of

like pretended that nothing happened.

That kind of instinct.

That's what makes me believe if aliens show up, we would all like just ignore their presence.

That's what bothered me that you don't, you don't investigate it more carefully and use

this opportunity to inspire the world.

So in terms of kryptonite, I think the conspiracy theory folks say that whenever there is some

good hard evidence that scientists would be excited about, there's this kind of conspiracy

that I don't like because it's ultimately negative that the US government will somehow

hide the good evidence to protect it.

Of course, there's some legitimacy to it because you want to protect military secrets, all

that kind of stuff.

But I don't know what to do with this beautiful mess because I think millions of people are

inspired by UFOs and it feels like an opportunity to inspire people about science.

So I would say, as Carl Sagan used to say, extraordinary claims require extraordinary

evidence.

I've quoted him a number of times.

We would welcome such evidence.

On the other hand, a lot of the things that are seen or perhaps even hidden from us, you

could imagine for military purposes, surveillance purposes, the US government doesn't want us

to know.

Or maybe some of these pilots saw Soviet or Israeli or whatever satellites or some of

the crashes that have occurred were later found to be weather balloons or whatever.

When there are more conventional explanations, science tends to stay away from the sensational

ones.

And so it may be that someone else's calling in life is to investigate these phenomena.

And I welcome that as a scientist.

I don't categorically actually deny the possibility that ships of some sort could have visited

us because, as I said earlier, at slow speeds, there's no problem in reaching other stars.

In fact, our Voyager and Pioneer spacecraft in a few million years are going to be in

the vicinity of different stars.

We can even calculate which ones they're going to be in the vicinity of, right?

So there's nothing that breaks any laws of physics if you do it slowly.

But that's different, just having Voyager or Pioneer fly by some star, that's different

from having active aliens altering the trajectory of their vehicle in real time, spying on us,

and then either zipping back to their home planet or sending signals that tell them about

us because they are likely many light years away, and they're not going to have broken

that barrier as well, okay?

So I just, you know, go ahead, study them.

For some young kid who wants to do it, it might be their calling, and that's how they

might find meaning in their lives, is to be the scientist who really explores these things.

I chose not to because at a very young age, I found the evidence, to the degree that I

investigated it, to be really quite unconvincing, and I had other things that I wanted to do.

But I don't categorically deny the possibility, and I think it should be investigated.

Yeah, I mean, this is one of those phenomena that 99.9% of people are almost definitely,

there's conventional explanations, and then there's like mysterious things that probably

have explanations that are a little bit more complicated, but there's not enough to work

with.

I tend to believe that if aliens showed up, there will be plenty of evidence for scientists

to study.

Yeah.

And exactly as you said, avoid your type of spacecraft that could see sort of some kind

of, kind of a dumb thing, almost like a sensor that's like probing, like statistically speaking.

Flying by.

Flying by, maybe lands, maybe there's some kind of robot type of thingies that just like

move around and so on, like in ways that we don't understand.

But I feel like, well, I feel like there'll be plenty of hard, hard to dismiss evidence.

And I also, especially this year, believe that the US government is not sufficiently

competent given the huge amount of evidence that will be revealed from this kind of thing

to conceal all of it.

Right.

At least in modern times, you can say maybe decades ago, but in modern times.

Right, you know, the people I speak to and the reason I bring it up is because so many

people write to me, they're inspired by it.

By the way, I wanted to comment on something you said earlier on, yeah, I had said that

I'm sort of a pessimist in that I think there are very few other intelligent, mechanically

able creatures out there.

But then I said, yes, in a sense, I'm an optimist, as you pointed out, because it means

that we made it through the great filter.

Right.

I meant originally that I'm a pessimist in that I'm pessimistic about the possibility

that there are many, many of us out there, you know, mathematically speaking in the Drake

equation.

Exactly.

Right.

Right.

But it may mean a good thing for our ultimate survival.

Right.

So I'm glad you caught me on that.

Yeah, I definitely agree with you.

It is ultimately an optimistic statement.

But anyway, I think, you know, UFO research is interesting.

And I guess one of the reasons I've not been terribly convinced is that I think there are

some scientists who are investigating this and they've not found any clear evidence.

Now, I must admit, I have not looked through the literature to convince myself that there

are many scientists doing systematic studies of these various reports.

I can't say for sure that there's a critical mass of them, but it's just that you never

get these reports from hardcore scientists.

That's another thing.

And astronomers, you know, what do we do?

We spend our time studying the heavens and you'd think we'd be the ones that are most

likely aside from pilots, perhaps, at seeing weird things in the sky.

And we just never do of the unexplained UFO type nature.

Yeah, I definitely, I try to keep an open mind, but for people who listen, it's actually

really difficult for scientists.

Like I get probably like this year, I've probably gotten over probably maybe over a thousand

emails on the topic of AGI.

It's very difficult to, you know, people write to me, it's like, how can you ignore this

in AGI side?

Like this model, this is obviously the model that's going to achieve general intelligence.

How can you ignore it?

I'm giving you the answer.

Here's my document.

And they're always just these large write ups.

The problem is it's very difficult to weed through a bunch of BS.

It's very possible that you had actually saw the UFO, but you have to acknowledge that

by UFO, I mean, an extraterrestrial life, you have to acknowledge the hundreds of thousands

of people who are a little bit, if not a lot full of BS.

And from a scientist perspective, it's really hard work and it's when there's amazing stuff

out there, it's like, why invest in Bigfoot when evolution in all of its richness is beautiful?

Who cares about a monkey that walks on two feet or eight or whatever?

Like there's a zillion decoys at observatories.

True fact.

We get lots and lots of phone calls when Venus, the evening star, but just really a bright

planet happens to be close to the crescent moon because it's such a striking pair.

This happens once in a while.

And we get these phone calls, oh, there's a UFO next to the moon.

And no, it's Venus.

And so they're just and I'm not saying the best UFO reports are of that nature.

No, there are some much more convincing cases.

And I've seen some of the footage and blah, blah, blah.

But it's just there's so many decoys, right?

So much so much noise that you have to filter out.

And there's only so many scientists.

So it's hard.

There's only so much.

There's only so much time as well.

And you have to choose what problems you work on.

You know, this might be a fun question to ask to kind of explore the idea of the expanding

universe.

Yeah.

So the the radius of the observable universe is 45.7 billion light years.

Yeah.

And the age of the universe is 13.7 billion years.

That's less than the radius of the universe.

How's that possible?

So that's a great question.

So I meant to bring a little a little prop I have with ping pong balls on a rubber hose,

a rubber band.

I use it in many of the lectures that one can find of me online.

But you have in an expanding universe, the space itself between galaxies or more correctly,

clusters of galaxies expanding.

So imagine light going from one cluster to another.

It traverses some distance and then while it's traversing the rest, that part that it

already traveled through continues to expand.

Now 13.7 billion years might have gone by since the light that we are seeing from the

early stages, the so called cosmic microwave background radiation, which is the afterglow

of the Big Bang or the echo of the Big Bang.

Yeah, 13.7 billion years have gone by.

That's how long it's taken that light to reach us.

But while it's been traveling that distance, the parts that it already traveled continue

to expand.

So it's like you're walking on at an airport, you know, on one of these walkways and you're

walking along because you're trying to get to your terminal.

But the walkway is continuing as well.

You end up traveling a greater distance or the same distance faster is another way of

putting it, right?

That's why you get on one of these traveling walkways.

So you get roughly a factor of pi, you know, but it's more like 3.2, I think.

But when you work it all out, you multiply the number of years the universe has been

in existence by, you know, three and a quarter or so.

And that's how you get this 46 billion light year radius.

But how is that, let me ask some nice dumb questions, how is that not traveling faster

than the speed of light?

Yeah, it's not traveling faster than the speed of light because locally at any point, if

you were to measure the light, the photons zipping past, it would not be exceeding the

speed of light.

The speed of light is a locally measured quantity.

After light has traversed some distance, if the rubber band keeps on stretching, then

yes, it looks like the light traveled a greater distance than it would have had the space

not been expanding.

But locally, it never was exceeding the speed of light.

It's just that the distance through which it already traveled then went off and expanded

on its own some more.

And if you give the light credit, so to speak, for having traversed that distance, well,

then it looks like it's going faster than the speed of light.

But that's not how speed works.

And in relativity, also, the other thing that is interesting is that if you take two ping

pong balls that are sufficiently far apart, especially in an accelerating universe, you

can easily have them moving apart from one another faster than the speed of light.

So take two ping pong balls that were originally 400,000 kilometers from each other and let

every centimeter in your rubber band expand to two in one second.

Then suddenly, this 400,000 kilometer distance is 800,000 kilometers.

It went out by 400,000 kilometers in one second.

That exceeds the 300,000 kilometer per second speed of light.

But that light limit, that particle limit in special relativity, applies to objects

moving through a preexisting space.

There's nothing in either special or general relativity that prevents space itself from

expanding faster than the speed of light.

That's no problem.

Einstein wouldn't have had a problem with a universe as observed now by cosmologists.

Yeah, I'm not sure I'm yet ready to deal emotionally with expanding space.

That to me is one of the most awe inspiring things, starting from the Big Bang.

It's definitely abstract.

Space itself is expanding.

Right.

Could you, can we talk about the Big Bang a little bit?

Sure.

Yeah, yeah.

What, so like the entirety of it, the universe, was very small.

Right.

But it was not a point.

It was not a point.

Because if we live in what's called a closed universe now, a sphere or the three dimensional

version of that would be a hypersphere, then regardless of how far back in time you go,

it was always that topological shape.

You can't turn a point suddenly into a shell, okay?

It always had to be a shell.

So when people say, well, the universe started out as a point, that's being kind of flippant,

kind of glib.

It didn't really.

It just started out at a very high density.

And we don't know actually whether it was finite or infinite, I think personally that

it was finite at the time, but it expanded very, very quickly.

Indeed, if it exponentiated and continued in some places to exponentiate, then it could

in fact be infinite right now.

And most cosmologists think that it is infinite.

Wait, wait, wait.

Yeah, sorry.

What infinite, which dimension, mass, size?

Infinite in space.

Infinite in space.

And by that I mean that if you were trying to measure.

There's no boundary.

There's no light to measure its size.

You'd never be able to measure its size because it would always be bigger than the distance

light can travel.

That's what you get in a universe that's accelerating in its expansion.

Okay.

But if a thing was a hypersphere, it's very small, not a point, how can that thing be

infinite?

Well, it expands exponentially.

That's what the inflation theory is all about.

Indeed, at your home institution, Alan Guth is one of the originators of the whole inflationary

universe idea, along with Andre Linde at Stanford University here in the Bay Area.

And others, Alexei Starobinsky and others had similar sorts of ideas.

But in an exponentially expanding universe, if you actually try to make this measurement,

you send light out to try to see it curve back around and hit you in the back of the

head.

But in an exponentially expanding universe, the amount of space remaining to be traversed

is always a bigger and bigger quantity.

So you'll never get there from here.

You'll never reach the back of your head.

So observationally or operationally, it can be thought of as being infinite.

That's one of the best definitions of infinity, by the way.

What's that?

That's one of the best sort of physical manifestations of infinity.

Yeah, yeah.

Because you have to ask, how would you actually measure it?

Now, I sometimes say to my cosmology theoretical friends, well, if I were God and I were outside

this whole thing and I took a godlike slice in time, wouldn't it be finite no matter how

big it is?

And they object and they say, Alex, you can't be outside and take a godlike slice of time,

you know?

Because there's nothing outside.

Well, I'm not, you know, or also, you know, what slice of time you're taking depends on

your motion.

And that's true even in special relativity that slices of time get tilted, in a sense,

if you're moving quickly, the axes, x and t actually become tilted, not perpendicular

to one another.

And you can look at Brian Greene's books and lectures and other things where he imagines

taking a loaf of bread and slicing it in units of time as you progress forward.

But then if you're zipping along relative to that loaf of bread, the slices of time

actually become tilted.

And so it's not even clear what slices of time mean.

But I'm an observational astronomer, I know which end of the telescope to look through.

And the way I understand the infinity is, as I just told you, that operationally or

observationally, there'd be no way of seeing that it's a finite universe, of measuring

a finite universe.

And so in that sense, it's infinite, even if it started out as a finite little dot.

Not a dot, I'm sorry, a finite little hypersphere.

But it didn't really start out there because what happened before that?

Well, we don't know.

So this is where it gets into a lot of speculation.

Let's go, I mean...

Let's go there.

Okay, sure.

So, you know...

The idea of what happened before t equals zero and whether there are other universes

out there, I like to say that these are sort of on the boundaries of science.

They're not just ideas that we wake up at three in the morning to go to the bathroom

and say, oh, well, let's think about what happened before the Big Bang or let there

be a multiplicity of universes.

In other words, we have real testable physics that we can use to draw certain conclusions

that are plausibility arguments based on what we know.

Now, admittedly, there are not really direct tests of these hypotheses.

That's why I call them hypotheses.

They're not really elevated to a theory because a theory in science is really something that

has a lot of experimental or observational support behind it.

So they're hypotheses, but they're not unreasonable hypotheses based on what we know about general

relativity and quantum physics.

And they may have indirect tests in that if you adopt this hypothesis, then there might

be a bunch of things you expect of the universe, and lo and behold, that's what we measure.

But we're not actually measuring anything at t less than zero, or we're not actually

measuring the presence of another universe in this multiverse, and yet there are these

indirect ideas that stem forth.

So it's hard to prove uniqueness, and it's hard to completely convince oneself that a

certain hypothesis must be true.

But the more and more tests you have that it satisfies, let's say there are 50 predictions

it makes, and 49 of them are things that you can measure.

And then the 50th one is the one where you want to measure the actual existence of that

other universe, or what happened before t equals zero, and you can't do that.

But you've satisfied 49 of the other testable predictions, and so that's science, right?

Now a conventional condensed matter physicist or someone who deals with real data in the

laboratory might say, oh, you cosmologists, that's not really science because it's not

directly testable, but I would say it's sort of testable.

But it's not completely testable, and so it's at the boundary, but it's not like we're coming

up with these crazy ideas, among them quantum fluctuations out of nothing, and then inflating

into a universe with, you might say, well, you created a giant amount of energy.

But in fact, this quantum fluctuation out of nothing in a quantum way violates the conservation

of energy.

But who cares?

That was a classical law anyway.

And then an inflating universe maintains whatever energy it had, be it zero or some infinitesimal

amount.

In a sense, the stuff of the universe has a positive energy, but there's a negative

gravitational energy associated with it.

It's like I drop an apple.

I got kinetic energy, energy of motion out of that, but I did work on it to bring it

to that height.

So by going down and gaining energy of motion, positive one, two, three, four, five units

of kinetic energy, it's also gaining or losing, depending on how you want to think of it,

negative one, two, three, four, five units of potential energy, so the total energy remains

the same.

An inflating universe can do that, or other physicists say that energy isn't conserved

in general relativity.

That's another way out of creating a universe out of nothing.

But the point is that this is all based on reasonably well tested physics, and although

these extrapolations seem kind of outrageous at first, they're not completely outrageous.

They're within the realm of what we call science already.

And maybe some young whippersnapper will be able to figure out a way to directly test

what happened before T equals zero or to test for the presence of these other universes,

but right now we don't have a way of doing that.

So speaking of young whippersnappers, Roger Penrose.

So he kind of has a, you know, idea that we, there may be some information that travels

from whatever the heck happened before the Big Bang.

Yeah, maybe.

I kind of doubt it.

So do you think it's possible to detect something, like actually experimentally be able to detect

some, I don't know what it is, radiation, some sort of...

Yeah, and the cosmic microwave background radiation, there may be ways of doing that.

But is it, is it philosophically or practically possible to detect signs that this was before

the Big Bang or is it, or is it what you said, which is like everything we observe will,

as we currently understand, will have to be a creation of this particular observable universe?

Yeah.

I mean, you know, if you, it's very difficult to answer right now because we don't have

a single verified, fully self consistent, experimentally tested quantum theory of gravity.

Right.

And of course the beginning of the universe is a large amount of stuff in a very small

space.

Yeah.

So you need both quantum mechanics and general relativity.

Same thing if our universe re collapses and then bounces back to another Big Bang.

You know, there's also ideas there that some of the information leaks through or survives.

I don't know that we can answer that question right now because we don't have a quantum

theory of gravity that most physicists believe in.

And belief is perhaps the wrong word that most physicists trust because the experimental

evidence favors it.

Yeah.

Right?

Yeah.

There are various forms of string theory.

There's quantum loop gravity.

There are various ideas, but which, if any, will be the one that survives the test of

time and more importantly, within that, the test of experiment and observation.

Yeah.

So my own feeling is probably these things don't survive.

I don't think we've seen any evidence in the cosmic microwave background radiation

of information leaking through.

Similarly, the one way or one of the few ways in which we might test for the presence of

other universes is if they were to collide with ours, that would leave a pattern, a temperature

signature in the cosmic microwave background radiation.

Some astrophysicists claim to have found it, but in my opinion, it's not statistically

significant to the level that would be necessary to have such an amazing claim, right?

It's just a 5% chance that the microwave background had that distribution just by chance.

5% isn't very long odds if you're claiming that instead that you're finding evidence

from another universe.

I mean, it's like if the Large Hadron Collider people had claimed after gathering enough

data to show the Higgs particle when there was a 5% chance it could be just a statistical

fluctuation in their data.

No, they required 5 sigma, 5 standard deviations, which is roughly one chance in 2 million that

this is a statistical fluctuation of no physical greater significance.

Extraordinary claims require extraordinary evidence.

There you go.

It all boils down to that.

And the greater your claim, the greater is the evidence that is needed and the more evidence

you need from independent ways of measuring or of coming to that deduction.

A good example was the accelerating universe.

When we found evidence for it in 1998 with supernovae with exploding stars, it was great

that there were two teams that lent some credibility to the discovery.

But it was not until other astrophysicists used not only that technique, but more importantly,

other independent techniques that had their own potential sources of systematic error

or whatever.

But they all came to the same conclusion and that started giving a much more complete picture

of what was going on and a picture in which most astrophysicists quickly gained confidence.

That's why that idea caught on so quickly is that there were other physicists and astronomers

doing observations completely independent of supernovae that seemed to indicate the

same thing.

Yeah.

That period of your life that work with an incredible team of people that won the Nobel

Prize is just fascinating work.

Oh gosh.

Never in my wildest dreams as a kid did I think that I would be involved, much less

so heavily involved, in a discovery that's so revolutionary.

As a kid, as a scientist, if you're realistic, once you learn a little bit more about how

science is done and you're not going to win a Nobel Prize and be the next Newton or Einstein

or whatever, you just hope that you'll contribute something to humankind's understanding of

how nature works and you'll be satisfied with that.

But here I was in the right place at the right time, a lot of luck, a lot of hard work, and

there it was.

We discovered something that was really amazing and that was the greatest thrill, right?

I couldn't have asked for anything more than being involved in that discovery.

So the couple of teams, the Supernova Cosmology Project and the HiZ Supernova Search Team,

what was the Nobel Prize given for?

It was given for the discovery of the accelerating expansion of the universe, not for the elucidation

of what dark energy is or what causes that expansion, that acceleration, be it universes

on the outside or whatever, it was only for the observational fact.

So first of all, what is the accelerating universe?

So the accelerating universe is simply that if we look at the galaxies moving away from

us right now, we would expect them to be moving away more slowly than they were billions of

years ago.

That's because galaxies have visible matter, which is gravitationally attractive, and dark

matter of an unknown sort that holds galaxies together and holds clusters of galaxies together.

And of course, they then pull on one another and they would tend to retard the expansion

of the universe.

Just as when I toss an apple up, even ignoring air resistance, the mutual gravitational attraction

between Earth and the apple slows the apple down.

If that attraction is great enough, then the apple will someday stop and even come back.

The Big Crunch, you could call it, or the Gnab Gibb, which is Big Bang backwards, right?

That's what could have happened to the universe.

But even if the universe's original expansion energy was so great that it avoids the Big

Crunch, that's like an apple thrown at Earth's escape speed.

It's like the rockets that go to Mars someday, right, with people.

Even then, you'd expect the universe to be slowing down with time.

But we looked back through the history of the universe by looking at progressively more

distant galaxies and by seeing that the evolution of this expansion rate is that in the first

nine billion years, yeah, it was slowing down.

But in the last five billion years, it's been speeding up.

So who asked for that, right, you know?

I think it's interesting to talk about a little bit of the human story of the Nobel Prize,

which is, I mean, it's fascinating.

It's a really, first of all, the prize itself.

It's kind of fascinating on the psychological level that prizes, I know we kind of think

that prizes don't matter, but somehow they kind of focus the mind about some of the most

special things we've accomplished.

They do.

It's the recognition, the funding, you know.

And also inspiration for, like I said, when I was a little kid, thinking about the Nobel

Prize, like I didn't, you know, it inspires millions of young scientists.

At the same time, there's a sadness to it a little bit that, especially in the field,

like depending on the field, but experimental fields that involve teams of, I don't know,

sometimes hundreds of brilliant people, the Nobel Prize is only given to just a handful.

That's right.

Is it maxed at three?

Yeah.

Yeah.

And it's not even written in Alfred Nobel's will, it turns out.

One of our teammates looked into it in a museum in Stockholm when we went there for Nobel

Week in 2011.

The leaders who got the prize formally knew that without the rest of us working hard in

the trenches, the result would not have been discovered.

So they invited us to participate in Nobel Week.

And so one of the team members looked in the will and it's not there.

It's just tradition.

That's interesting.

But it's archaic, you know, that's the way science used to be done.

It's not the way a lot of science is done now.

And you look at gravitational wave discovery, which was, you know, recognized with the Nobel

Prize in 2017, Ray Weiss at MIT got it and Kip Thorne and Barry Barish at Caltech.

And Ron Drever, one of the masterminds, had passed away earlier in the year.

So again, one of the rules of Nobel is that it's not given posthumously, or at least the

one exception might be if they've made their decision and they're busy making their press

releases right before October, the first week in October or whatever, and then the person

passes away.

I think they don't change their minds then.

But yeah, you know, it doesn't square with today's reality that a lot of science is done

by big teams, in that case, a team of a thousand people.

In our case, it was two teams consisting of about 50 people.

And we used techniques that were arguably developed in part by people who, astrophysicists

who weren't even on those two papers, I mean, some of them were, but other papers were written

by other people, you know, and so it's like we're standing on the shoulders of giants.

And none of those people was officially recognized.

And to me, it was okay.

You know, again, it was the thrill of doing the work and ultimately the work, the discovery

was recognized with the prize.

And you know, we got to participate in Nobel week and, you know, it's okay with me.