I don't know what it's like to be an alien.

I would like to know.

Two alien civilizations coexisting on a planet.

What's that look like exactly?

When you see them and they see you, you're assuming they have vision.

They have the ability to construct in 3D and in time.

There's a lot of assumptions we're making.

What human level intelligence has done is quite different.

It's not just that we remember states that the universe has existed in before.

It's that we can imagine ones that have never existed.

And we can actually make them come into existence.

So you can travel back in time sometimes.

Yes.

You travel forward in time to travel back.

Yes.

The following is a conversation with Sarah Walker and Lee Cronin.

They have each been on this podcast once before individually.

And now for their second time, they're here together.

Sarah is an astrobiologist and theoretical physicist.

Lee is a chemist.

And if I may say so, the real life manifestation of Rick from Rick and Morty.

They both are interested in how life originates and develops both life here on

earth and alien life, including intelligent alien civilizations out there in the cosmos.

They are colleagues and friends who love to explore, disagree and debate nuanced

points about alien life.

And so we're calling this an alien debate.

Very few questions to me are as fascinating as what do aliens look like?

How do we recognize them?

How do we talk to them?

And how do we make sense of life here on earth in the context of all possible

life forms that are out there?

Treating these questions with the seriousness and rigor they deserve.

So that I hope to do with this conversation and future ones like it.

Our world is shrouded in mystery.

We must first be humbled to acknowledge this and then be bold and diving in and

trying to figure things out anyway.

This is Alex Friedman podcast to support it.

Please check out our sponsors in the description.

And now, dear friends, here's Sarah Walker and Lee Cronin.

First of all, welcome back, Sarah.

Welcome back, Lee.

You guys, I'm a huge fan of yours.

You're incredible people.

I should say thank you to Sarah for wearing really awesome boots.

We'll probably overlay a picture of what we're wearing.

Sure, later on.

But why the hell didn't you dress up, Lee?

No, this is me dressed up.

You were saying that you're pink, that your thing is pink.

My thing is black and white, the simplicity of it.

Where's the pink?

When did it hit you that pink is your color?

I became pink about, I don't know, actually, maybe 2017?

Did you know me when you first...

I think I met you pre pink.

Yeah, yeah.

So about 2017, I think I just decided I was boring and I needed to make a

statement and red was too bright.

So I went pink, salmon pink.

Well, I think you were always pink.

You just found yourself in 2019.

There's an amazing photo of him where there's like everybody in their black

gown and he's just wearing the pink pants.

Well, that wasn't a wagon in university.

It's totally nuts.

100 year anniversary.

They got me to give the plenary and they didn't find the outfit for me.

So they were all wearing these silly hats and these gowns.

And there was me dressed up in pink, looking like a complete idiot.

We're definitely going to have to find that picture and overlay a big full

screen, slow motion.

All right, let's talk about aliens.

We'll find places we disagree in places we agree.

Life, intelligence, consciousness, universe, all of that.

Let's start with a tweet from Neil deGrasse Tyson, stating his skepticism

about aliens wanting to visit Earth.

Quote, how egocentric of us to think that space aliens who have mastered

interstellar travel across the galaxy would give, pardon the French, would

give a shit about humans on Earth.

So let me ask you, would aliens care about visiting Earth observing, communicating

with humans?

Let's take a perspective of aliens.

Maybe Sarah first, are we interesting in the whole spectrum

of life in the universe?

I'm completely biased, at least as far as I think right now, we're the most

interesting thing in the universe.

So I would expect based on the intrinsic curiosity that we have and how much

I think that's deeply related to the physics of what we are, that other intelligent

aliens would want to seek out examples of the phenomena they are to understand

themselves better.

And I think that's kind of a natural thing to want to do.

And I don't think there's any kind of judgment on it being a lesser

being or not.

It's like saying you have nothing to learn by talking to a baby.

You have lots to learn, probably more than you do talking to somebody

that's 90.

So, yeah, so I think they absolutely would.

So whatever the phenomena is that is human, there would be an inkling of the

same kind of phenomena within alien species and they would be seeking that same.

I think there's got to be some features of us that are universal.

And I think the ones that are most interesting, and I hope I live in an

interesting universe, are the ones that are driven by our curiosity and the fact

that our intelligence allows us to do things that the universe wouldn't be

able to do without things like us existing.

We're going to define a lot of terms.

One of them is interesting.

Yes.

That's a very interesting term to try to define.

Ali, what do you think are humans interesting for aliens?

Well, let's take it from our perspective.

We want to go find aliens as a species quite desperately.

So if we put the shoe on the other foot, of course, we're interesting.

But I'm wondering, and assuming that we're at the right technological

capabilities to go searching for aliens, then that's interesting.

So what I mean is, if there needs to be a massive leap in technology that we

don't have, how will aliens prioritize coming to Earth and other places?

But I do think that they would come and find us, because they'd want to find out

about our culture, what things are universal, what about, I mean, I'm a

chemist, so I would say, well, is the chemistry universal, right?

Are the creatures that we're going to find making all this commotion, are

they made of the same stuff?

What does their science look like?

Are they off planet yet?

I guess there's, so I think that Neil deGrasse Tyson is being slightly

pessimistic and maybe trying to play the tune that the universe is vast.

And it's not worth them coming here.

I don't think that, but I just worry that maybe we, we don't have the

ability to talk to them.

We don't have the universal translator.

We don't have the right physics, but sure, they should come.

We are interesting.

I want to know if they exist.

It would make it easy if they just came.

So again, I'm going to use your tweets like it's Shakespeare and

analyze it.

So Sarah tweeted, thinking about aliens, thinking about aliens.

So how much do you think aliens are thinking about other aliens, including

humans?

So you said we humans want to visit, like we're longing to connect with aliens.

Why is that?

Can you introspect that?

Is that an obvious thing that we should be, like, what are we hoping to

understand by meeting aliens?

Exactly.

Exactly. Asking as an introvert is like, I ask myself this all the time, why, why

go out on a Friday night to meet people?

What are you hoping to find?

I think the curiosity.

So when I saw Sarah put that tweet, I think I answered it actually as well,

which was we are thinking about trying to make contact.

So they almost certainly are, but maybe there's a number of classes.

There are those aliens that have not yet made contact with other aliens like us.

Those aliens have made contact with just one other alien.

And maybe it's an anticlimax and slime, right?

And aliens that have made contact with not just one set of intelligent

species, but several, that must be amazing.

Actually, literally, there is some place in the universe.

There must be one alien civilization.

It's not made contact with not one, but two other intelligent civilizations.

So they must be thinking about it.

There must be entire degree courses on aliens, thinking about aliens

and cultural, universal cultural norms.

Do you think they will survive the meeting?

And by the way, Lee did respond saying that's all the universe wants.

So Sarah said, thinking about aliens, thinking about aliens.

Lee said, that's all the universe wants.

And then Sarah responded, cheeky universe we live in.

So cheeky is a cheeky version of the word interesting, all of which

we'll try to define mathematically.

Cheeky might be harder than interesting.

Because there's humor in that too.

Yes.

I think there's a mathematical definition of humor, but we'll talk about that in a bit.

Oh, interesting.

Yeah, absolutely right, yeah.

So if you're a graduate student alien looking at multiple alien civilizations,

do you think they survive the encounters?

I think there's a tendency to anthropomorphize.

A lot of the discussions about alien life, which is a really big challenge.

So usually when I'm trying to think about these problems, I don't try to think

about us as humans, but us as an example of phenomena.

That exists in the universe that we have yet to explain.

And it doesn't seem to be the case that if I think about the features,

I would argue are most universal about that phenomena, that there's any reason

to think that a first encounter with another lineage or example of life

would be antagonistic.

I think, yeah.

And I think there's this kind of assumption.

I mean, going back to Neil deGrasse Tyson's quote, I mean, it kind of bothers me

because there's a, I mean, I'm a physicist, so I know we have a lot of egos

about how much we can describe the world, but that there's this, like,

because we understand fundamental physics so well, we understand alien life

and we can kind of extrapolate and I just think that we don't.

And the quest there is really, you know, really to understand something totally

new about the universe and that thing just happens to be us.

I agree, I agree.

There's something else more profound.

I think Neil is just being, again, he's just trying to stir the pot.

I would say from a contingency point of view, I want to know how many ways

does the universe build structures, build memories, right?

And then I want to know if those memories can interact with each other.

And if you have two different origins of life and then origins of intelligence

and then these things become conscious, surely you want to go and talk to them

and figure out what commonalities you share.

And it might be that we're just unable to conceive of what they're going to look like.

They're just going to be completely different, you know, infrastructure.

But surely we'll want to go and find out a map.

And surely curiosity is a property that evolution has made on Earth

and I can't see any reason that won't happen elsewhere

because curiosity probably exists because we want to find innovations in the environment.

We want to use that information to help our technology and also curiosity

is like planning for the future.

Are they going to fight us?

Are we going to be able to trade with them?

So I think that Neil's just, I don't know, maybe, you know, I mean, give a shit.

That's really, I think that's really down on Earth, right?

How would aliens categorize humans, do you think?

How would we?

So let's put the other way around.

Slime category?

Maybe, no, no, no.

We, maybe we could, the thing is a bit odd, right?

Look at Instagram, Twitter, all these people taking selfies.

And I mean, does the universe is the ultimate state of consciousness,

thinking beings that take photographs themselves and upload them to an

interweb with other thinking beings looking at each other's photos.

So I think that they will be, I did not say there was anything wrong with it.

It's consciousness manifested at scale.

Yeah.

Southeast Instagram.

It's like the mirror test at scale.

Yeah.

I do think that curiosity is really the driving force of why we have our technology.

Right? If we weren't curious, we wouldn't go out left the cave.

So I think that, so I think that Neil's got it completely wrong, in fact.

Actually, of course, they'd want to come here.

It doesn't mean they are coming here.

We've seen evidence for that.

I guess we can argue about that, right?

But I think that we want, I desperately, and I know that Sarah does too, but I won't

speak for you when you're here.

You can, I desperately want to have missions to look for life in the solar system.

Right now, I want to map life over the solar system.

And then I want to understand how we can go and find life as quickly as possible

at the nearest stars and also at the same time do it in the lab just to compensate.

You know, so sure.

Yeah, I just want to point on this.

If you think about sort of what's driven the most like features of our own evolution

as a species, you could, and try to map that to alien species.

I always think like optimism is what's going to get us furthest.

And so I think a lot of people always think that it's like war and conflict is going to

be the way that alien species will expand out into the cosmos.

But if you just look at how we're doing it and how we talk about it, it's always our

future in space is always, you know, built from narratives of optimism.

And so it seems to me that if intelligence does get out in the universe, that it's going

to be more optimism and curiosity driving it than war and conflict, because those things

end up crushing you.

So there might be some selective filter.

Of course, this is me being an optimist.

I'm a half, half full kind of person, but is it obvious that curiosity?

Not obvious, but what do you think is curiosity a more powerful force in the

universe than violence and the will to power?

So because you said you frame curiosity as a way to also plan on how to avoid violence,

which is an interesting frame of curiosity.

But I could also argue that violence is a pretty productive way to operate in the

world, which is like, that's one way to protect yourself.

The best defense is offense.

Um, I'm not qualified to answer this, but I'll have a go.

I think that's not what, that's the summary of this podcast.

I would, yeah, but maybe I would, let's not call it violence, but I call it erasure.

So if you think about, um, the way evolution works all the way, um, obviously

call it assembly theory, but I won't, so if you say, you, you, you build pro, you

curiosity allows you to open up avenues, new graphs, right?

So new features you can play, what, what, the ability to erase those things allows

you to start again and do some pruning.

So the universe, I think curiosity gets you furthest curiosity gets you rockets

that land, it gets you robots that can make drugs, it gets you poetry and art.

And communication and then, you know, I often think, wouldn't it be great in

bureaucracy to have another world war, not literally a world war now, please.

No world war, but a, the equivalent so we can get, remove all the admin bureaucracy,

right?

All the admin violence, get rid of it and start again.

Do you know what I mean?

Because you get layers and you get redundant systems built.

So actually a reset, let's not call it violence, a reset in some aspects of our,

culture and our, our technology allows us to then build more important things

without the, because how many, you know, how many cookies do I have to click on?

How many things, how many, how many extra clicks I do I have in the future of my

life that I could remove and that a bit of a reset would, would allow us to, to,

to start again.

And maybe that's how I suppose our encounter with aliens will be.

Maybe they will fight with us and say, oh, we're not as excited by the

rules, we thought we'll just get rid of you.

Or they might want to reset earth.

Yeah, why not?

To be like, let's see how the evolution runs again.

This seems like they've, there's nothing new happening here.

They're observing for a while.

This is just not, let's keep it more fun.

Let's start with a fish again.

I like how you equated violence to resetting your cookies.

I suppose that's the kind of violence in this, this modern world where words are

violence, resetting cookies.

I don't know where that came from.

I'm completely, yeah.

That's poetic, really.

Okay.

So let's talk about life.

What is life?

What is non life?

What is the line between life and non life?

And maybe at any point we can pull in ideas of assembly theory.

Like how do we start to try to define life?

And for people listening, so Sarah identifies as a physicist and Lee

identifies as a chemist.

Of course, they are very interdisciplinary in nature in general, but so what is life?

So I'm a little asking that question because it's so absurdly big.

I know, I love it.

It's my absolute favorite question in the whole universe.

So I think I have three ways of describing it right now.

And I like to say all three of them because people latch on to different facets of them.

And so the whole idea of what Lee and I are trying to work on is not to try to define life,

but to try to find a more fundamental theory that explains what the phenomena we call life.

And then it should explain certain attributes.

And you end up having a really different framing than the way people usually talk.

So the way I talk about it, three different ways.

Life is how information structures matter across space and time.

Life is, I don't know, this one's from you actually, simple machines constructing more

complex machines.

And the other one is the physics of existence, so to speak, which is life is the mechanism

the universe has to explore the space of what's possible.

That's my favorite.

So can I, yeah, yeah, can I add on to that?

Okay, can you see the physics one again?

Oh, the physics of existence.

Yeah, the physics of existence, I don't know what to call it.

You know, like if you think of all the things that could exist, only certain things do exist.

And I think life is basically the universe's mechanism.

Of bringing things into physically existing in the moment now.

Yeah.

Yeah, well, what's what's another one?

We were debating this the other day.

So if you think about a universe that has nothing in it, that's kind of hard to conceive

of, right?

Because this is where physicists really go wrong.

They think of a universe with nothing in it.

They can't.

And you think that existence is really hard to think of.

Yeah.

And then you think of universe with everything in it.

That's really hard.

And you just, you just have the universe.

And you just, you just have this white blob, right?

This is everything.

But the fact we have discrete stuff in the universe beyond, say, planets.

So you've got stars, space, planet stuff, right?

The boring stuff.

Well, I would define life or say that life is where there are architectures, any architectures,

and we should stop fixating on what the bill is building the architectures to start with.

And the fact that the universe has discrete things in it is completely mind blowing.

If you think about it for one second, the fact there's any objects at all,

and there's, because for me, the object is a proxy for a machine that built it.

Some information being moved around, actuation, sensing, getting resource,

and building these objects.

So for me, everyone's been obsessing about the machine.

But I'm like, forget the machine.

Let's see the objects.

And I think in a way that assembly theory, we realized maybe a few months ago that assembly

theory actually does account for the soul in the objects, not mystically like, say,

Sheldrecht's morphic resonance or Leibniz's monodology, seeing souls in things.

But when you see an object, and I've said this before, but this object is evidence of thought,

and then there's a lineage of those objects.

So I think what is fascinating is that you put it much more elegantly, but the barrier

between life and nonlife is accruing enough memories to then actuate.

So what that means is there are contingency.

There are things that happen in the universe get trapped.

These memories then have a causal effect on the future.

And then when you get those concentrated in a machine, and you're actually able,

in real time, able to integrate the past, the present with the future, and do stuff.

That's when you are most alive.

You being the machine?

Yes.

Wait a minute.

Why is the object, so one of the ways to define life, as Sarah said,

is simple machines creating complex machines.

So there's a million questions there.

So how the hell does a simple machine create a complex machine?

By mutation.

So this is what we were talking about at the beginning.

You have a minimum replicator, so a molecule.

So this is what I was trying to convince Sarah of the mechanism get there.

Years ago, I think, but then you've been building on it and saying,

you have a molecule that can copy itself, but then there has to be some variability.

Otherwise, it's not going to get more functional.

So you need to add bits on.

So you have a minimum molecule that can copy itself,

but then it can add bits on, and that can be copied as well.

And those add ons can give you additional function

to be able to acquire more stuff to exist.

So existence is weird, but the fact that there is existence is why there is life.

And that's why I realized a few days ago that there must be,

that's why alien life must be everywhere, because there is existence.

Is there like a conservation of cheeky stuff happening?

So like, how can you keep injecting more complex things?

Like, doesn't the machine that creates the object need to be as or more complex,

more powerful than the things it creates?

So how can you get complexity from simplicity?

So the way you get complexity from simplicity is that you,

I would, this, I'm just making this up, but this is kind of my notion that you have a large volume

of stuff, so you're able to get seeds if you like random cues from the environment.

So you just use those objects to basically write on your tape, ones and zeros, whatever.

And that is, that is necessarily rich, complex.

Okay. But it has a low assembliness, but even though it has a high assembly number,

we can talk about that.

But then when you start to then integrate that all into a smaller volume as over time,

and you become more autonomous, you then make the transition.

I don't know what you think about that.

I think the easiest way to think about it is actually, which I know is a concept you hate,

but I also hate it, which is entropy.

But people are more familiar with entropy than what we talk about in assembly theory.

And also the idea that, like, say physics as we know it involves objects that don't exist

across time, or as we would say, low memory objects.

So one of the key distinctions that that is low memory objects.

Yeah. So physics is all.

Physicists are low memory objects.

But physicists are creators of low memory objects or manipulators of low memory objects.

Yeah. Absolutely.

It's a very nice way.

Okay. Sorry, go ahead.

Yeah, I'm sorry.

Sorry to keep interrupting.

No, no, no, it's fine. I like it too. It's very funny.

But I think it's a good way of phrasing it, because I think this kind of idea we have

in assembly theory is that physics as we know it has basically removed time as being

a physical observable of an object.

And the argument I would make is that when you look at things like water bottles or us,

we're actually things that exist that have a large extent in time.

So we actually have a physical size in time.

And we measure that with something called the assembly index in molecules.

But presumably everyone should have sort of a, do you want to explain what assembly?

Yeah, let's, you know what?

Let's step back and start at the beginning.

What is assembly theory?

Please send me some slides. There's a big sexy paper coming out probably.

Maybe, I don't know.

We've almost finished it.

Almost, almost finished it.

That's also a summary of science.

We're almost done.

Yes.

Well, no, no, we're almost done.

It's the history of science.

We are ready to start an interesting discussion with our peers.

Right.

You're the machine that created the object and we'll see what the object takes us.

All right.

So what is assembly theory?

Yeah, well, I think the easiest way for people to understand it is to think about

assembly in molecules, although the theory is very general.

It doesn't just apply to molecules.

And this was really Lee's insight.

So it's kind of funny that I'm explaining it.

But...

On marquee.

Okay. All right.

You ready? I'm ready.

I'm ready.

You can tell me where I get the check mark minus.

It's your theory as well.

Yeah, I know.

But imagine a molecule and then you can break the molecule part into elementary building blocks.

They happen to be bombs.

And then you can think of all the ways for molecular assembly theory.

You can think of all the ways of building up the original molecule.

So there's all these paths that you can assemble it.

And the sort of rules or assembly is you can use pieces that have been generated already.

So it has this kind of recursive property to it.

And so that's where our kind of memory comes into assembly theory.

And then the assembly index is the shortest path in that space.

So it's supposed to be the minimal amount of history that the universe has to undergo

in order to assemble that particular object.

And the reason that this is significant is we figured out how to measure that

with a mass spec in the lab.

And we had this conjecture that if that minimal number of steps was sufficiently large,

it would indicate that you required a machine or a system that had information

about how to assemble that specific object.

Because the combinatorial space of possibilities is getting exponentially large

as the assembly index is increasing.

So it's just, sorry to interrupt, but so that means there's a sufficiently high assembly index

that if observed in an object is an indicator that something life like created it

or is the object itself life like?

Both.

But you might want to make the distinction that a water bottle is not life.

But it would still be a signature that you were in that domain of physics.

And I might be alive.

So there will be potentially a lot of arguments about where the line at which assembly index

does interesting stuff start to happen.

The point is we can make all the arguments, but it should be experimentally observable.

And we can talk more about that part of it.

But the point I want to make about it is there was always this intuition

that I had that there should be some complexity threshold in the universe,

above which you would start to say whatever physics governs life actually becomes operative.

And I think about it a little bit like we have Planck's constant,

and we have the fine structure constant.

And then this sort of assembly threshold is basically another sort of potentially constant

of nature.

It might depend on specific features of the system, which we debate about sometimes.

But then when you're past that, you have to have some other explanation than the current

explanations we have in physics, because now you're in high memory.

The things actually require time for them to exist, and time becomes a physical variable.

So the path to the creation of the object is the memory.

So you need to consider that.

Yeah, but the point is that's a feature of the object.

So when I think of all the things in this room, we see the projection of them as a water bottle,

but assembly theory would say that this is a causal graph of all the ways the universe

can create this thing.

That's what it is as an object.

And we're all interacting a causal graph.

And most of the creativity in the biosphere is because a lot of the objects that exist now

are huge in their structure across time, four billion years of evolution to get to us.

So is it possible to look at me and infer the history that led to me?

If you as an individual might be hard.

You as a representative of a population of objects that have high assembly with similar

causal history and structure that you can communicate with, i.e. other humans,

you can infer a lot probably.

Yeah, also with them.

Which we do genomically even.

I mean, it's not like we have a lot of information in us.

We can reconstruct histories from assembly saying something slightly deeper.

Yeah, one thing to add.

I mean, it's not just about the object, but the objects that occur.

And not just objects with a high assembly number, because you can have random things

that have a high assembly number.

They must have, there must be a number of identical copies.

So you know you're getting away from the random, because you could take a snapshot.

This is why it's not I hate entropy.

I love entropy when used correctly.

But it's about the problem of entropy.

You have to have a labeler.

And so, so you can label the beginning and the end to start on the finish, you know,

where what you can do in assembly is say, oh, I have a number of objects in abundance.

They all have these features.

And then you can infer.

And one of the things that we debated a lot, particularly during lockdown,

because I almost went insane trying to crush the produce the assembly equation.

So we came up with the assembly equation.

I had, just imagine this.

So you have a string where, oh, actually it makes me trying to remember it.

It was so, it did my head in for a long time.

Yeah, because I couldn't size.

If you just have a string of say words, say, you know, a series of words, series of letters.

So you just have a, a, a, b, b, b, c, c, c, d, d, d.

And you find that object and you just have four a's, four b's, four c's, four d's together.

Boom, then, and that really, that you measured that, so you physically measured that string of letters.

Then what you could do is you can infer sub graphs of maybe the four a's, the four b's,

the four c's, and the four c's, but you don't see them in the real world.

You just infer them.

And I really got stuck with that because there's a problem to try and work out

what's the difference between a long, you know, physical object and the assembly space of the

objects that we realized the best way to put that is infer in time.

That, so, although we can't infer your entire history, we know at some point the four a's were

made, the four b's were made, the four c's were made, and the four d's were made,

and they all got added together.

And, and that's one really interesting thing that's come out of the theory.

But the, the killer, when we knew we were going beyond,

and beyond standard complexity theory, it was incredibly successful

is that we realized we could start to measure these things for real across domains.

So the assembly index is actually intrinsic property of all stuff that you can break into

components, particularly molecules are good because you can break them up into smaller

molecules into atoms.

The challenge will be making that more general across all the domains.

But we're working on it right now, and I think the theory will do that.

So components, domains, so you're talking about basically measuring the complexity of an object

in what, biology, chemistry, physics.

That's what you mean by domains.

Complexity of tests.

Sociology.

Computers.

Complexity of memes.

You know.

Memes.

Yep.

What, what is that?

Ideas.

Yeah.

I mean, so one of them.

Ideas are objects in assembly theory, though.

Yeah.

They are.

They're physical things.

They're just pictures of the causal graph.

I mean, the fact that I can talk to you right now is because we're exchanging structure

of our assembly space.

So conversation is the exchanging structures in assembly space.

What is assembly space?

When I started working on Origins of Life, I was writing about something called top down

causation, which a lot of like philosophers are interested in and people that worry about the

mind body problem.

But the whole idea is, you know, if we have, you know, the microscopic world of physics

is causally complete, it seems like there's no room for higher level causes like our thoughts

to actually have any impact on the world.

And that didn't, that seems problematic when you get to studying life in mind because it

does seem that quote unquote emergent properties do matter to matter.

And so, and then there's this other sort of paradoxical situation where information looks

like it's disembodied.

So we talk about information like it can just move from any physical system to any other

physical system, and it doesn't require like you don't have to specify anything about the

substrate to talk about information.

And then there's also the way we talk about mathematics is also disembodied, right, like

the platonic world of forms.

And I think all of those things are hinging that we really don't know how to think about

abstractions as physical things.

And really, I think what assembly theory is pointing to is what we're missing there is the

dimension of time.

And if you actually look at an object being extended across time, what we call information

and the things that look abstract are things that are entangled in the histories of those

objects, their features of the overlapping assembly space.

So they look abstract because they're not, you know, part of the current structure, but

they're part of the structure if you thought about it as like the philosophical concept

of a hyper object, an object that's too big in time for us to actually to resolve.

And so I think information is physical.

It's just physical in time, not in space.

To a hyper object, too difficult for us to resolve.

So what we're supposed to think about of life is this thing that stretches through time

and there's a causation chain that led to that thing.

And then you're trying to measure something with the assembly index about.

The assembly index is the ordering the order, like you could think of it as like a partial

ordering of all the things that can happen.

So in thermodynamics, we coarse grain things by temperature and pressure.

In assembly theory, we coarse grain by the number of copies of an object and the assembly

index, which is basically, if you think of the space of all possible things, it's like

a depth of how far you've gone into that space and how much time was required to get there.

In the shortest possible version.

The shortest possible version.

Not average.

Can't you just read it?

You're going to kill me with that question.

Well, not 3D.

Can't you always 3D print the thing?

It's like it's happening in the heart.

No, because I had such fights.

So Sarah's team and my team are writing this paper at the moment.

It's so funny.

I think we kind of share the, at the beginning, you were like,

no, that's not right. Oh, that's right.

And we're doing this for a bit.

And then the problem is when you build a theory and build the intuition,

there's some certain features of the theory

that almost felt like I was being religious about.

Say, right, you have to do this.

And the assembly theorist does this, does this, does this.

And Sarah's postdoc Daniel and my postdoc Abishek,

and they were both brilliant.

They're brilliant.

But they were like, no, we don't, we don't buy that.

And I was like, it is.

They were like, well, Lee, actually,

I thought you're the first to say that, you know,

you can't, if you can't explain it,

and you can't do an experiment that doesn't exist.

And that saved me.

And I said to Abishek, Abishek's my postdoc in Glasgow,

Daniel is Sarah's postdoc in ASU.

I was like, I have the experimental data.

So when I basically take the molecules

and chop them up in the mass spec,

the assembly number is never the average.

It's always the shortest.

It's an intrinsic property.

And then the penny drop for Abishek said, OK,

because I had these things that we had to believe to start with

or to trust.

And then we've done the math and it comes out.

And they now have the shortest path.

Actually, it's up.

It explains why the shortest path.

Here's why the shortest path is important, not the average.

The shortest path needs you to identify when the universe

has basically got a memory, not an average.

So what you want to be able to do is to say,

what is the minimum number of features

that I want to be able to see in the universe?

When I find those features, I know the universe

has had a coherent memory and is basically alive.

And so that gives you the lower bound.

So that's like, of course, there's going to be other paths.

We can be more ridiculous, right?

We can have other parts, but it's just the minimum.

So probabilistically, at the beginning,

because assembly theory was built as a measure for biosignatures,

I needed to go there.

And then I realized it was intrinsic.

And then Sarah realized it was intrinsic

and these hyperobjects were coming.

And we were kind of fusing that notions together.

And then the team were like, yeah, but if I have enough energy

and I have enough resources, I might not take the shortest path.

I might go a bit longer.

I might take a really long path

because it allows me then to do something else.

So what you do is, let's say I've got two different objects, A and B,

and they both have different shortest paths to get them.

But then if you want to make A and B together,

they will have a compromise.

So in the joint assembly space, that might be an average,

but actually it's the shortest way you can make both A and B

with a minimum amount of resource in time.

So suddenly you then layer these things up.

And so the average becomes not important,

but as you literally overlap those sets, you get a new shortest path.

And so what we realized time and time again when we're doing the math

that shortest path is intrinsic, is fundamental, and is measurable,

which is kind of mind blowing.

So what we're talking about, some basic ingredients,

maybe we'll talk about that, what those basic ingredients could be

and how many steps, when you say shortest path,

how many steps it takes to turn those basic ingredients into the final meal.

So what's the shortest way to make a pizza?

Or a pie, an apple pie.

An apple pie, that's right.

And the pizza and the pie together.

Or a scratch.

So there's a lot of ways.

There's the shortest way and you take the full spectrum of ways

and there's probably an average, like duration for a noob to make an apple pie.

Is the average interesting still?

If you measure the average length of the path to assemble a thing,

does that tell you something about the way nature usually does it?

Versus something fundamental about the object,

which I think is what you're aiming at with the assembly index.

Yeah, I mean, look, we all have to quantify things.

The minimum path gives you the lower bounds,

so you know you're detecting something, you know you're inferring something.

The average tells you about really how the objects are existing

in the ecosystem or the technology.

And there has to be more paths explored

because then you can happen upon other memories

and then condense them down.

I'm not making too much sense.

Let's just say, I mean, maybe we're going to get to alien civilizations later, right?

But I would argue very strongly that alien civilization A and alien civilization B,

they're different assembly spaces.

So they're kind of going to be a bit messed up if they happen to come on another.

Only when they find some joint overlap in their technology,

because if aliens come to us and they don't share any other causal graph,

we've shared it, but hopefully they share the periodic table

and some other and bonds and things.

So we're going to have to really think about the language to talk to us aliens

by inferring, by using assembly theory to infer their language,

their technology, and other bits and bobs.

And the shortest path will help you do that quickly.

All right, so all aliens in the causality graphs have a common ancestor in the...

If the building blocks are the same,

which means they live in the same universe as us.

It depends on how far back in time you go though.

But the universe has all the same building blocks.

And we have to assume that.

So there's not different classes of causality graphs, right?

The universe doesn't just say,

here, you get the red causality graph and you get the blue one.

These basic ingredients and they're geographically constrained

or constrained in space or time or something like that.

They're constrained in time because only by the virtue of the fact

that you need enough time to have passed for some things to exist.

So the universe has to be big enough in time for some things.

So just a one point on the shortest path versus the average path,

which I think we'll get to this, is you had a nice way of saying it's like

the minimal compression is the shortest path for the universe to produce that.

But it's also like the first time in the ordering of events

that you might expect to see that object.

But the average path tells you something about the actual steps

that were realized and that becomes an emergent property

of that object's interaction with other objects.

So it's not an intrinsic feature of that object.

It's a feature of the interactions with other things.

And so one of the nice features of assembly is you basically gotten rid of,

you just look at the things that exist and you've gotten rid of the mechanisms

for constructing them in some sense, like the machines are not as important

in the current construction of the theory, although I would like to bridge it

to some ideas about constructors.

But then you could only communicate with things as Lee was saying

if you have some overlap in the past history.

So if you had an alien species that had absolutely no overlap,

then there would be no means of communication.

But as we become, you know, as we progress further and further in time

and more things become possible because the assembly spaces are larger,

because you can have a larger assembly space in terms of index

and also just the size of the space because it's exponentially growing,

then more things can happen in the future.

And the example I like to give is actually when we made first contact

with gravitational waves, because, you know, that's an alien phenomena

that's been permeating our planet, not alien in life phenomena,

but alien like something we had never knew existed.

It's been, you know, like we're, you know, there's gravitational waves

rippling through this room right now.

But we had to advance to the level of Einstein writing down his theory of relativity

and then 100 years of technological development to even quote, unquote,

see that phenomena.

So the, okay, to see that phenomena, our cause of graph have to start intersecting.

Yeah, we needed the idea to emerge first, the abstraction, right?

And then we had to build the technology that could actually observe features

of that abstraction.

So the nice promising thing is over time the graph can grow,

so we can start overlapping eventually.

Yeah, so the interesting feature of that graph is there was an event, you know,

1.4 billion years away of a black hole merger that we detected on our detector.

And, you know, now suddenly we're connected through this communication channel

with this distant event in our universe that, you know,

if you think about 1.4 billion years ago what was happening on this planet

or even further back in time that, you know, there's common physics underlying all those events,

but even for those two events to communicate with them.

Now I understand what you were going on about the other week.

Yeah, I'm sorry.

This is a really abstract example, but it's sort of...

Your causal graphs are not overlapping.

Yeah, so, well, let's just say now our causal graphs are overlapping in the deep past.

No, I like it.

See, you made it.

I totally missed it.

Oh, the 1.6 billion.

Yeah.

You made a connection with it.

No, I do like that.

No, you can tell me what your epiphany is now.

This is good.

Because I was...

And I should get the jokes before 30 seconds after, so...

Oh, I get it now.

All right?

No, it's all right.

The joke came two minutes ago.

I'm slow on the uptake here.

I wasn't able to comprehend what you were talking about when saying the channel communicating

to the past, but what you're saying is we were able to infer what happened 1.4 billion years ago.

We detected the gravity wave.

I mean, I think it's amazing that, you know, at that time we weren't even...

We were just becoming multicellular, right?

It's like insane.

And then we progressed a multicellularity through to technology and built the detector,

and then we just extrapolate backwards.

So although we didn't do anything back to the graph back in time, we understood there's

existence then overlapped going forward.

Well, that's because our graphs are larger.

Yeah.

But that means that has a consequence.

One of the things I was trying to say is I think, I don't know, Sarah might be, she

might correct me, information first, and I'm an object first kind of guy.

So I mean, as things that get constructed, there has to be this transition in random constructions.

So when the object that's being constructed by the process bakes in that memory and those

memories then add on and add on and add on.

So as it becomes more competent and life is about taking those memories and compressing

them, increasing their autonomy.

And so I think that, you know, like the cell that we have in biology on Earth is our way

of doing that, that really the maximum ability to take memories and to act on the future.

Oh, I think that's mathematics.

No, mathematics doesn't exist.

No, but that's the point.

The point is that abstractions do exist.

They're real physical things.

We call them abstractions.

But the point about mathematics that I think is, so I don't, I don't disagree.

I think you're object first and I'm information first, but I think I'm, I'm only information

first in the sense that I think the thing that we need to explain is why what abstractions

are and what they are as physical things because of all of human history.

We've thought that there were these properties that are disembodied exist outside of the

universe and really they do exist in the universe and we just don't understand what their physics is.

So I think mathematics is a really good example.

We do theoretical physics with math, but imagine doing physics of math and then think about

math as a physical object and math is super interesting.

I think this is why we think it describes reality so well because it's the most copyable

kind of information.

It retains its properties when you move it between physical media, which means that it's

very deep and so it seems to describe the universe really well, but it probably is because

it's information that's very deep in our past.

And it's just, we invented a way of communicating it very effectively between us.

Isn't math more fundamental?

Isn't the assembly of the graph, isn't basically, I'm going to say, I sound completely boring.

It's like math, assembly theory invented math, but it did.

It has to be.

Okay.

So what is math exactly?

It's a nice simplification, a simple description of what?

So we have a computer scientist, a physicist and a chemist here.

Walking to a bar.

I think the chemist is going to define math and you guys can correct me.

Go for it.

Let's lay it honestly.

We're ready.

I think the ability to label objects and place them into classes and then do operations on

the objects is what math is.

So on that point, what does it mean to be object first versus information first?

So what's the difference between object and information when you get to that low fundamental level?

Well, I might change my view.

So I'm stuff first, the stuff, and then when stuff becomes objects, it has to invent information.

And then the information acts on more stuff and becomes more objects.

So I think there is a transition to information that occurs when you go from stuff to objects.

Information is emergent.

Not emergent.

Information is actionable memories from the universe.

So when memories become actionable, that's information.

But there's always memory, but it's not actionable.

Yeah.

And then it's not information.

And actionable is what you can create.

You can use it.

If you can't use it, then it's not information.

If you can't transmit it, if it doesn't have any causal consequence.

I was in the forest.

I don't understand.

Why is that not information?

It's not information.

It's stuff happening, but it's not causal.

Yeah.

Yeah.

This is cool.

It's happening.

The happening requires information.

Can't stuff.

Stuff is always happening.

No.

This is where the physicists and the mathematicians get themselves in a loop, because I think

the universe, I mean, I think, say, Max Tecmark and is very playful and say like the universe,

the universe is just math.

Then we might as well not bother having any conversation because the conversation already

written, we just might as well go to the future and say, can you just give us the conversations

happened already?

So I think the problem is that mathematicians are so successful at labeling stuff and so

successful understanding of stuff through those labels, they forget that actually those

labels had to emerge and that information had to be built on those memories.

So memory in the universe, so constraints, graph, when they become actionable and the

graph can loop back on itself or interact with other graphs and they can intersect, those

memories become actionable and therefore their information.

And I think you just changed my mind on something pretty big, but I don't have a pen.

So I can't write, I'm going to write it down later, but roughly the idea is, is like you've

got these, these two graphs of objects of stuff that you have memories and then when

they intersect and then they can act on each other, that's maybe the mechanism by which

information is then, so then you can then abstract.

So when one graph can then build another graph and say, hey, you don't have to go through

the nonsense we had to go through, here's literally the way to do it.

Stuff always comes first, but then when stuff builds the abstraction, the abstraction can

be then teleported onto other stuff.

And the abstraction is the looping back to power.

Okay.

Am I making, I don't know, I've got stuck.

Yeah, so first a God made stuff.

And after that, when you start to be able to form abstractions, that's when the, the

audition memory week, the universe can remember.

God is the memory, the universe can remember.

Otherwise there's not, wait, did you deciphering that statement hundreds of years from now?

What does that mean?

What does the human being by this?

Hey, look, don't, don't diss my, my one liners.

It took me 15 seconds to come up.

I don't know what it means.

What does it mean?

Okay, wait, we need to, well, how do we get onto this?

We were time causality mathematics.

So what is mathematics in this picture of stuff, objects, memory, and information?

What is that?

It's mathematics.

It's the most efficient labeling scheme that you can apply to lots of different graphs.

Well, the labeling scheme doesn't make it sound useful.

Can I try?

Yep, sure, please.

Have you rejected my definition of mathematics?

I'm shocked.

Yeah, no, I'm sorry.

But it's correct.

Go ahead.

Excellent.

Um, no, I mean, I think, um, I think we have a problem, right?

Cause we, we can't not be us.

Like we're stuck in the shells we are and we're trying to observe the world.

And so mathematics looks like it has certain properties.

And I guess the thought experiment I find is useful is to try to imagine if you were outside

of us looking at us as physical systems using mathematics, what would be the specific features

you associate to the property of understanding mathematics and being able to implement it

in the universe, right?

And, um, and when you do that, mathematics seems to have some really interesting properties

relative to other kinds of abstraction we might talk about, like language or artistic

expression.

Uh, one of those properties is the one I mentioned already that is really easy to copy between

physical media.

So if I give you a mathematical statement, you almost immediately know what I mean.

If I tell you the sky is blue, you might say, is it gold ball blue?

Is it your blue?

What color blue do you mean?

And you have a harder time visualizing what I actually mean.

So mathematics carries a lot of meaning with it when it's copied between physical systems.

It's also the reason we use it to communicate with computers.

Um, and then the second one is it retains its property of actually what it can do in the

universe when it's copied.

So the example I like to give there is, is think about like Newton's law of gravitation.

Um, it's actually, it's a, it's a compressed regularity of a bunch of, uh, phenomena that

we observe in the universe, but then it'll, that information actually is a causal in a

sense that it allows us to do things we wouldn't be able to do without that particular knowledge

and that particular abstraction.

And in this case, like launch satellites to space or send people to Mars or whatever it

is.

Um, so, so if you look at us from the outside and you say, what is it for physical systems

to invent a thing called mathematics and then to use, uh, and, and then, and then it to

become a physical observable mathematics is kind of like the universally copyable information

that allows, uh, new possibilities spaces to be open in the future because it allows this

kind of ability to map one physical system to another and actually understand that the

general principles.

Yeah.

So is it helping the, uh, overlap of causal graphs then by mapping?

Oh, I think that's the explanation for what it is in terms of the physical theory of assembly

would be some feature of the structure of the assembly spaces of causal graphs and their

relationship to each other.

So for example, and I mean, this is things that we're going to have to work out over

the next few years.

I mean, we're in totally uncharted conceptual territory here.

Um, but as is usual, uh, diving off the deep end.

Um, but I would expect that we would be able to come up with a theory of like, why is it

that some physical systems can communicate with each other?

Um, like language language is basically because we're objects extended over time and some

of the history of that assembly space actually overlaps.

And when we communicate, it's because we actually have shared structure in our causal history.

Let me have another quick go at this, right?

So I think we all agree.

So I think, um, we take mathematics for granted because we've gone through this chain, right?

Of, you know, um, we all, we all share a language now.

Okay.

And we can, well, we share, so we have languages that we can, we can make interoperable.

And, and so whether you're speaking, I don't know, all the different dialects of Chinese

or the different dialects of English, French, German, whatever, you can interconvert them.

The interesting thing about mathematics now is that everybody on planet Earth, every human

being and computers, um, share that common language, that language was constructed by

a process in time.

So what I'm trying to say is assembly invented math is those, those pro right from the, you

know, mathematics didn't occur.

It didn't exist before life.

Abstraction was invented by life, right?

That doesn't mean that the universe wasn't capable of mathematical things.

Wait, wait a minute.

Can we just ask that, that old famous question is math invented or discovered?

So when you say, assembly invented or whatever, uh, uh, you, you, you, it means.

Assembly is a mathematical theory, but sorry.

Right.

Are we arguing?

Exactly.

Are we arguing now?

That's what it sounds like.

Are we discovering?

No.

Well, yes and no.

I would say.

You call mathematics a language.

I would say developing.

Like I'm pretty sure that, um, there, there are some very common seeds of mathematics in

the universe, right?

But actually not the mathematics that we are finding now is not discovered.

It's invented.

Um, but even though I think there's two terms are very triggering and I don't think they're

necessarily useful because I think that what people do, the mathematicians that say our

mathematics was discovered because they live in a universe where there is no time and it

just all exists.

But what I'm saying is, and I think in the same way you can create, let's say I'm going

to go and create and make a piece of art.

Did I make that piece of art or did I discover, discover it?

Like inventing the aeroplane.

Did I invent the aeroplane?

Let's stick with the aeroplane.

The aeroplane is a good one.

I, let's say I'm, I did, did I discover the aeroplane?

Well, in a way, the universe discovered the aeroplane because it's just chucked a load

of atoms together and a load of random human beings want to do stuff and they, we, we discovered

the aeroplane in the space of possibilities.

But here's the thing.

When the space of possibilities is so vast, infinite, almost, and you're able to actualize

one of those in an object, then you are inventing it.

So in mathematics, because there are infinite number of theorems, the fact you're actually

pulling, there's no difference between inventing a mathematical structure and inventing the

aeroplane.

They're the same thing.

But that doesn't mean that now the aeroplane exists in the universe.

It's something weird about the universe that, you know, so I think that the more, this is

the thing that you probably, the more memory required for the object, the more invented

it is.

So when a mathematical theorem has a, has a, needs more bytes to store it, the more invented

it is and the less bytes, the more discovered it is.

But everything then is invented.

It's just more or less invented.

Absolutely.

Okay.

The universe has to generate everything as it goes.

Yeah.

And it wasn't there in the beginning.

And the way we're thinking it, when you're thinking about the difference between invented

and discovered is because we're throwing away all the memory.

Yeah.

And if you start to think in terms of causality and time, then those things become the same.

Everything is invented.

And the idea is to make everything intrinsic to the universe.

So I think one of the features of assembly theory is we don't want to have external observers.

There's been this long tradition in physics of trying to describe the universe from the

outside and not the inside.

And the universe has to generate everything itself if you do it from the inside.

Assembly theory describes how the universe builds itself.

They'll take you 15 seconds to say that and do it to come up with that also.

No, I've thought of that before.

Okay.

It's a good line.

Are you making fun again?

No, I'm not making fun.

I'm having fun.

There's a difference.

Oh, that's good.

All right.

She's inventing fun.

I'm not all intimidated.

Yeah.

And there's a causal history to that fun.

You mentioned that there's no way to communicate with aliens until there's overlap in the

cause of graph.

Communication includes being able to see them and like what are we, this is the question

is, is communication any kind of detection?

And if so, what do aliens look like as you get more and more overlap on the cause of

graph?

You're assuming, let's assume that so when you see them and they see you, you're assuming

they have vision, they have the ability to construct in 3D and in time, there's a lot

of assumptions we're making.

What detection?

All right.

Let's step back.

So yes.

Okay.

You're right.

So when in the English language, when we say the word see, we mean visually, they show

up to a party and it's like, oh, wow, that's an alien.

That's visual.

That's 3D.

That's okay.

And that's also assuming scale, spatial scale of something that's visible to you.

So it can't be microscopic or it can't be so big that you don't even realize that's an

entity.

Okay.

But other kinds of detection too.

I would make it more abstract and go down.

I was thinking this morning about how to rewrite the Arecibo message in assembly theory and

also to abandon binary because I don't think aliens necessarily, why should they have binary?

Well they have some basic elements with which to do information exchange.

Let's make it more fundamental or more universal.

So we need to think about what is the universal way of making a memory and then we should

reencode Arecibo in that way.

What's more basic than zeroes and ones?

Well, it's really difficult to get out of that causal chain because we're so, so let's

erase the idea of zero for a moment.

It took human beings a long time to come up with the idea of zero.

Now, now you got the idea of zero.

You can't throw away.

It's so useful.

To discover the idea of zero.

To discover or invent.

I don't know.

But it took a long time, so it was invented.

That's right.

Yeah.

I think zero was invented.

It's exactly.

So it's not given that aliens know what zero is.

It just has the one massive assumption.

It's a useful discovery that you're saying if you break the causal chain, there might

be some other more efficient way of representing.

That's why I want to meet him and ask him for a shortcut, but you won't be able to ask

him until.

Well, so I interrupted you and I think you're making good point.

I was just going to say, well, look, sorry, rather than saying, please internet, tweet

at him for the rude interruptions.

Go ahead.

I'm sorry.

No, it's okay.

Maybe it's change.

How do we say, oh, I don't know what it's like to be an alien.

I would like to know what is the full spectrum of what aliens might look like to us.

Now that we've laid this all on, on the table of like, all right, so there has to be some

overlap and this causal chain that led to them.

What are we, what are we looking for?

What do you think we should be looking for?

So you met, you mentioned mass spec, measuring certain objects that aliens could create or

are aliens themselves.

We show up to a planet or maybe not a planet or maybe what, what, what the, what the hell

is the basic object we're trying to measure the assembly index of?

Let's cut ourselves a break.

Let's assume that they are, they, they're metabolized, they've got an energy source

and they're, they've, they're a size that we can recognize.

Let's give ourselves a break because there could be aliens that are so big, we won't

recognize we're seeing them.

And there might be aliens that are so small, we don't yet have the ability to, you know,

we don't have microscopes that can see, you know, far enough away that just wouldn't be

able to see them.

So what's a good range?

So let's just make a range of, let's just be very anthropocentric and say we're going

to look for aliens roughly our size and technology our size because we, we know it's possible

on earth, right?

I mean, a reasonable thing to do would be to, to find exoplanets that in the same zone

as earth in terms of heat and stuff and then say, Hey, if there's that same kind of gravity,

same type of stuff, we could reasonably assume that the alien life there might use a similar

kind of physical infrastructure and then we're good.

So then, then your, then, then your question becomes really relevant and say, right, let's

use vision, sound, touch.

So, okay, that's really nice.

So that if there's a lot of aliens out there, there's a good likelihood if you match to

the planet that they're going to be in the same spatial and temporal operating in the

same spatial temporal domain as humans.

Okay.

Within that, what, what, what do they look like visually?

What do they sound like?

What are they?

Oh God, this sounds creepy.

It tastes like, what is it?

Oh, it smells like, it smells like that's the smell.

It sounds like our clubhouse.

It was like, can we have sex of aliens?

Which was basically me saying, passionate, passionate love, but it wasn't actually about

sex.

It was about, is our chemistry compatible?

Right.

Is there some?

Yeah.

Yeah.

Can, can we?

Yeah.

Are they edible too?

They could be very edible.

They could be delicious.

That's why I want to see some aliens, right?

Because I think, are there, I think evolution, I mean, evolution exploits symmetry, right?

Because why, why generate memory?

Why generate storage, the need for storage space when you can use symmetry?

So, and symmetry is quite, maybe quite effective in allowing you to mechanically design stuff,

right?

So maybe alien, it could, you could be, would be reasonable to assume that aliens could

have, they could be bipedal, they could be symmetric in the same way, might have a couple

of eyes, or a couple of senses.

I mean, we can make, make them, perhaps there's this whole zoo of different aliens out there

and we'll never get to be able to classify some of the weird aliens we can't interact

with because they have made such weird stuff.

Yeah.

But we are just going to look at, we're going to find aliens that look most like us.

Why not?

Because those are the first ones we're likely to see.

Yeah.

Yeah.

But I think it's really hard to imagine what the space of aliens is because the space is

huge.

Because, you know, like one of the arguments that you can make about wildlife emerges in

chemistry is because chemistry is the first scale in terms of like, you know, building

up objects from elementary objects, that the number of possible things that could exist

is larger than the universe can possibly make all at once, right?

So, so you imagine you have two planets and they're cooking some geochemistry, you know,

our planet invented one kind of biochemistry and presumably as you start building up the

complexity of the molecules, the chances of the overlap in those trajectories, those

causal chains being built up is probably very low.

And it gets lower and lower as it gets further advanced along its evolutionary path.

So I think it's very difficult to imagine predicting the technologies that aliens are

going to have.

I mean, it's, it's so, it's, you're looking at basically planets have kind of convergent

chemistry, but there's some variability.

And then you're looking basically at the outgrowth into the possibility space for chemistry.

So do you think we would detect the, the technology, the objects created by aliens before we detect

the aliens?

Possibly.

So when you're talking about measuring assembly index, don't you think we would detect the

garbage first, like at the outskirts of alien civilizations, isn't this going to be trash?

I think I would come back to Arecibo, the Arecibo message sent from the Arecibo telescope

built by Drake, I think, and, and Sagan.

How's Arecibo spelled?

Arecibo.

Yes.

Thank you.

And there we go.

They got out there.

That's the telescope that sent the message that you're talking about.

So that message was sent where?

It was beamed, it beamed at a star, a specific star, and it was sent out many years ago.

And what they did, so this is why it's pushing on binary, it's a binary message.

I think it's a semi prime length number of characters.

I think 2073 by 23, I think, and it basically represents human bit, proton, binary, human

beings, DNA, male and female.

And it's, it's really cool.

But I'm just wondering if it could be done, not making any, because it made assumptions

that aliens speak binary.

Yeah.

Why make that assumption?

Why not just assume that if the difference between physics, chemistry and biology is

the amount of memory that's recordable by the substrates, then surely the universal thing,

I'm going to make some sacrilegious statement, which I think is pretty awesome for people

to argue with.

So this is, we're looking at an image where it's the entirety of the message encoded in

binary.

And then there's probably interpretation of different parts of that image.

There's a person, there's green parts.

It looks like for people just listening like a Tetris, a game of Tetris.

So it's encoding in minimal ways, a bunch of cool information probably.

Representing all of us.

So the top, it's kind of teaching yourself to count and then it all goes all the way

down teaching you chemistry and then just says, but it makes so many assumptions.

And I think if we can actually, so look, I think, I mean, Sarah's much more eloquent

expressing this, but I'll have a go and you can correct it if you want, which is like,

one of the things that Sarah has had a profound effect on the way I look at the origin of

life.

And this is one of the reasons why we're working together, because we don't really care about

the origin of life.

We want to make life, make aliens and find aliens, make aliens, find aliens.

I think we might have to make aliens in the lab before we find aliens in the universe.

Right.

I think that would be a cool way to do it.

So what is it about the universe that creates aliens?

Well, it's selection through assembly theory, creating memories.

Because when you create memories, you can then command your domain, you can basically

do stuff, you can command matter.

So we need to find a way by understanding what life is of how the minimal way to command

matter, how that would emerge in the universe.

And if we want to communicate, I mean, maybe we don't want to necessarily uniformly communicate.

What I would do, perhaps if I had, is I would send out lots of probes away from Earth to

have this magic way of communicating with aliens, get them quite a far away from Earth,

plausibly deniable, and then send out the message that would then attract all the aliens

and then basically work out if they're a friend or foe and how they want to hang out.

The message is being something has to do with the memories.

Yes.

Like the assembly version of our SIBO, so that everyone in the universe that has been understands

what life is.

So aliens need to work out what they are.

Once they've worked out what they are, they then can work out how to encode what they

are and then they can go out and send messages.

It's like the universal, the Rosetta Stone for life in the universe is working out how

the memories are built.

I don't know, Sarah, you have any, well, whether that, you would agree with that?

No, I wanted to raise a different point, which is about the fact that we can't see the aliens

yet because we haven't gotten the technology.

And presumably we think assembly theory is the right way of doing it, but I don't think

that we know how to go from the kind of data you're describing, Lex, like, you know, visual

data or smell to construct the assembly spaces yet.

And in some ways, I think that the problem of life detection really is the same problem

at the foundations of AI that we don't understand how to get machines to see causal graphs to

see reality in terms of causation.

And so I think assembly and AI are going to intersect in interesting ways, hopefully.

But the sort of key point, and I've been trying to make this argument more recently and might

write an essay on it, is people talk about the great filter, which is, again, this doomsday

thing that people want to say, there's no aliens out there because something terrible

happened to them.

And it matters whether that's in our past or our future as to the longevity of our species,

presumably, which is why people find it interesting.

But I think it's not a physical filter.

It's not like things go extinct.

I think it's literally we don't have the technology to see them.

And you can see that with microscopes.

I mean, we didn't know there were microscopes on this table for our tables for thousands

of years or telescopes.

Like, there's so much of the universe we can't see.

And then basically what we have done as a species is outsource our physical perceptions

to technology, building microscopes based on our eyes, you know, and building seismometers

based on our sense of feelings, like feel earthquakes and things.

And AI is basically we're trying to outsource what's actually happening in our thinking

apparatus into machines now into technological devices.

And maybe that's the key technology that's going to allow us to see things like us and

see the universe in a totally different way.

But you kind of mentioned the great filter.

Do you think there's a way through technology to stop being able to see stuff?

So can you take step backwards?

I think so.

Yeah.

Did you imply that with the great?

Well, no, I mean, I think there's a great perceptual filter in the sense that a example

of life evolving on a planet over billions of years has to acquire a certain amount of

knowledge and technology to actually recognize the phenomena that it is.

Well, that's the sense I have is, when you talk with physicists, engineers in general,

there's this kind of idea that we have most of the tools already to hear the signal.

But to me, it feels like we don't have any of the tools to see the signal.

Yeah, I agree.

Yeah, that's the biggest, like to hear.

We don't have the tools to really hear, to see.

Yeah.

Aliens are everywhere.

We just don't have the...

Exactly.

Yeah.

Well, that's...

I mean, I got this in part, actually, because you were like, you know, last time I was here,

I was like, look at the carpet.

You know, could it be like if you had an alien detector, would the carpet be aliens?

I mean, I think we really don't...

So it would be both aliens would nevertheless have a high assembly index or produce things

of high assembly index.

Yeah.

Yeah, yeah, yeah.

High assembly index, you have to have a detector that can recognize high assembly index in

all its forms.

Yeah.

Yes.

That's it.

That's it.

Take data, construct assembly space.

Yeah.

Those patterns, basically.

So one way to think about high assembly index is interesting patterns, all of basic ingredients.

I can give you an example, because, I mean, in molecules we've been talking about in objects,

but we're also trying to do it in spatial trajectories.

Like imagine you're just like, I always get bothered by the fact that like, when you look

at birds flocking, you can describe that with like a simple boys model or like, you

know, people use spin glass to describe animal behavior, and those are like really simple

physics models.

Yet you're looking at a system that you know has agency and there's intelligence in those

birds.

And I...

And basically, like, you can't help but think there must be some statistical signatures

of the fact that they're...

That's a group of agents versus, you know, like, I don't know, you know, the physics

example, maybe like, I don't know, Brownian motion or something.

And so what we're trying to do is actually apply assembly to trajectory data to try to

say there's a minimal amount of causal history to build up certain trajectories for observed

agents, that's like an agency detector for behavior.

Do you think it's possible to do some like, like Boids or those kinds of things, like

artificial, like cellular automata, play with those ideas with assembly, with assembly theory?

Have you found any useful, really simple mathematical like simulation tools that allow you to play

with these concepts?

Yeah.

So like one, of course, you're doing math spec in this physical space with chemistry,

but it just seems, well, I mean, computer science person, maybe, it seems easier to

just...

I agree with you.

It's easier in terms of tweeting visual information on Twitter or Instagram, more importantly,

to play like, here's an organism of a low assembly index, and here's an organism of

a high assembly index.

And let's watch them create more and more memories and more and more complex objects.

And so like, in mathematics, you get to observe what that looks like, to build up an intuition

what assembly index is like.

We are building a toolkit right now.

So I think it's a really good idea, but what we've got to do is, I'm kind of still obsessed

with the infrastructure required.

And one of the reasons why I was pushing on information in mathematics, when human beings,

when human beings, we take a lot of the infrastructure for granted.

And I think we have to strip that back a bit for going forward.

But you're absolutely right.

I would agree that I think the fact that we exist in the universe is like, I can see

that lots of people would disagree with the statement, but I don't think, I don't think

Sarah will, but I don't know.

The fact that objects exist, I don't think anyone on earth will disagree that objects

can exist elsewhere, right?

But they will disagree that life can exist elsewhere.

But what perhaps I'm trying to say is that the acquisition, the universe's ability to

acquire memory is the very first step for building life.

And that must be, that's so easy to happen.

So therefore, alien life is everywhere, because all alien life is, is those memories being

compressed and minimized and the alien equivalent of the cell working.

So I think that we will build new technologies to find aliens.

But we need to understand what we are first and how we go from physics to chemistry to

biology.

The most interesting thing, as you're saying to these two organisms, different assemblies,

is when you get into biology, biology gets more and more weird, more and more contingent.

Physics is, chemistry is less weird, because the rules of chemistry are smaller than the

rules of biology.

And then going away to physics, where you have a very nicely tangible number of ways

of arranging things.

And I think assembly theory just helps you appreciate that.

And so once we get there, my dream is that we are just going to be able to suddenly are,

I mean, I'm, I mean, I'm maybe just being really arrogant here.

I'm not mean to be arrogant, it's just, again, I've just got this hammer called assembly

and everything's a nail.

But I think that once we crack it, we'll be able to use assembly theory plus telescopes

to find aliens.

Do you have, Sarah, do you have disagreements with Lee on the number of aliens that are

out there?

So, and,

Do you actually, yeah, well.

And what they look like.

So any of the things we've been talking about, is there nuanced, oh, it's always nice to

discover wisdom through nuanced disagreement.

Yeah, I don't, I don't wholly disagree, but I think, but I do think I disagree.

It's kind of, there's nuance there, but, but we disagree, no, it's fine.

It is nuanced, right?

So you made the point earlier that you think, you know, once we discover what alien light,

what life is, we'll see alien life everywhere.

And I think I agree on some levels in the sense that I think the physics that governs

us is universal, but I don't know how far I would go to say, to say that we're a likely

phenomena because we don't understand all of the features of the transition at the origin

of life, which, which we would just say in assembly is you go from the no memory physics

to there's like a critical transition around the assembly index where assembliness starts

to increase.

And that's what we call the evolution of the biosphere and complexification of the biosphere.

So there's a principle of increasing assembliness where that goes back to what I was saying

at the very beginning about the physics of the possible that the universe basically gets

in this mode of trying to make as much possibilities as possible.

Now how often that transition happens that you get the kind of cascading effect that

we get in our biosphere.

I think we don't know if we did, we would know the likelihood of life in the universe.

And a lot of people want to say life is common, but I don't think that we can say that yet.

So we have the empirical data, which I think you would agree with.

But then there's this other kind of thought experiment I have, which I don't like, but

I did have it, which is, you know, if life emerges on one planet and you get this real

high density of things that can exist on that planet, is it sort of dominating the density

of creation that the universe can actually generate?

So like if you're thinking about counting entropy, right, like the universe has a certain

amount of stuff in it, and then, you know, assembly is kind of like an entropic principle.

That's not entropy, but the idea is that now transformations among stuff or the actual

physical histories of things now become things that you have to count as far as saying that

these things exist and we're increasing the number of things that exist.

And if you think about that cosmologically, maybe Earth is sucking up all the life potential

of the whole universe.

I don't know.

But I...

How's that...

Can you explain that a little bit?

Why can anyone geographical region suck up the creative capacity of the universe?

Just like...

No.

I know.

It's a ridiculous thought.

I don't...

I don't actually agree with it, but it was just a thought experiment.

I love that you can have thoughts that you don't like and don't agree with, but you have

to think through them anyway.

Yeah.

The human mind is fascinating.

Yeah.

I think these sort of like counterfactual thought experiments are really good when you're

trying to build new theories because you have to think through all the consequences.

And there are people that want to try to account for, say, the degrees of freedom on our planet

in cosmological inventories of talking about the entropy of the universe and when we're

thinking about cosmological era of time and things like that.

Now, I think those are pretty superficial proposals as they stand now, but assembly

would give you a way of counting it.

And then the question is if there's a certain maximal capacity of the universe's speed

of generating stuff, which Leo always has this argument that assembly is about time,

the universe is generating more states, really what it's generating is more assembly possibilities.

And then dark energy might be one manifestation of that, that the universe is accelerating

its expansion because that makes more physical space.

And what's happening on our planet is it's accelerating in the expansion of possible

things that exist.

And maybe the universe just has a maximal rate of what it can do to generate things.

And then if there is a maximal rate, maybe only a certain number of planets can actually

do that, or there's a trade off about the pace of growth on certain planets versus others.

I have a million questions there.

Do you have thoughts on?

Just a quick, yeah.

I'll just say something very quick.

It's a flat experiment.

No, it's good.

I think I get it.

I think I get it.

So what I want to say is when I mean aliens everywhere, I mean memories are the prerequisite

for aliens via selection and then concentration of selection when selection becomes autonomous.

So what I would love to do is to build, say a magical telescope that was a memory, a magical

one, or a real one that would be a memory detector to see selection.

So you could get to exoplanets and say that exoplanet looks like there's lots of selection

going on there.

Maybe there's evolution and maybe there's going to be life.

So what I'm trying to say is narrow down the regions of space where you say there's

definitely evidence of memory as high assembly there, or not high assembly because that would

be life, but where it's capable of happening.

And then that would also help us frame the search for aliens.

I don't know how likely it is to make the transition to cells and all the other things.

I think you're right, but I think that we just need to get more data.

Well, I didn't like the thought experiment because I don't like the idea that if the

universe has a maximal limit on the amount it can generate per unit time, that our existence

is actually precluding the existence of other things.

I'll just say one thing.

But I think that's probably true anyway because of the resource limitations.

So I don't like your thought experiment because I think it's wrong, but no, no, I do like

the thought experiment.

So what you're trying to say is like there is a chain of events that goes back that's

manifestly combated with life on Earth, and you're not saying that life isn't possible

elsewhere.

You say that there has been these number of contingent things that have happened that

have allowed life to merge here.

That doesn't mean that life can't emerge elsewhere, but you're saying that the intersection of

events may be concentrated here.

Right?

And I think that's not exactly, it's more like, you know, if you look at, say the causal

graphs are fundamental, maybe space is an emergent property, which is consistent with

some proposals in quantum gravity, but also how we talk about things in assembly theory.

Then the universe is causal graphs generating more structure in causal graphs, right?

So this is how the universe is unfolding.

And maybe there's a cap on the rate of generation, like there's only so much stuff that gets

made per update of the universe.

And then if there's a lot of stuff being made in a particular region that happens to look

the same locally, spatially, that's an after effect of the fact that the whole causal graph

is updating.

Like, it's...

Yeah, I don't know that.

I think that that doesn't work.

I don't think it works either, but I don't have a good argument in my mind about.

But I do like the idea of the capacity, the universe, because you've got a number of states.

Yeah, we can come back to it.

Let me ask real quick, like, why does different, like, local pockets of the universe start

remembering stuff?

How does memory emerge exactly?

So at the origin of the universe, it was very forgetful.

That's when the physicists were happiest, those low memory objects, which is like ultra

low memory objects, which is what the definition of stuff, okay?

So how does memory emerge?

How does...

Which is this...

How does the temporal stickiness of objects emerge?

I'm going to take a very chemo centric point of view, because I can't imagine any other