The End of the Universe

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Welcome to the Infinite Monkey Cage lockdown podcast.

And this is the first one of the new series, and this is the first time that we've attempted to do a podcast in four different time zones where our guests were across the world.

And we have, and it is, it's a fantastic.

I'm not going to tell you.

You wait till you hear the podcast, but it is probably one of the most joyous shows about the end of the universe you're going to hear in the next couple of months anyway.

Here it is.

Hello, I'm Robin Ince.

And I'm Brian Cox.

Welcome to the Infinite Monkey Cage, which due to the current situation is now considerably more finite than usual.

So our four guests are broadcasting about 5,000 miles apart from their lofts and basements, except Brian, of course, who is usually broadcasting from an ethereal plane in a dimension that, according to our current understanding of physics, may exist theoretically, but is not yet falsifiable.

But that won't stop him.

Robin, if my location is not verifiable by experiment, then how are you receiving the sound of my voice?

I don't know.

You're probably some kind of ghost or something.

There's a block universe issue.

I don't know.

To be honest, I haven't understood you for many years and i continue not to understand you now physics as we know is sometimes voodoo anyway this has been a time of confusion and existential anxiety for many people so it was suggested that we look at the science of the end of the world but then we thought no that is way too parochial in its melancholy and we've gone the whole hog today we're going to milli waves because we're going to be looking at the end of the universe and other conjectures on the extinction of space-time.

According to Douglas Adams's The Restaurant at the End of the Universe, the skies begin to boil, nature collapses into the screaming void, the hideous fury of destruction blazes, and a small trumpet sounds as if from an infinite distance.

And you see, I don't understand that because if the trumpets at an infinite distance, then I don't think you'll hear it.

And also, it's probably a vacuum as well.

The sound doesn't travel through the vacuum because there's no...

Oh, you know what?

I was so hopeful when we weren't going to be doing this in the radio theatre that he wouldn't get distracted yet again by his evidence-based thinking, which has continually stymied this show.

Anyway, 40 years on from this book, what do we actually know about the end of the universe?

Tonight, we're going to look at the current ideas of how the universe is likely to end, and then in a nod to popular culture and the current disastrous penchant for asking everyone their opinion, we're going to put it to an audience vote.

How do you want the universe to end?

Anyway, we are today joined by four quantum fluctuations who made it to sentience and they are.

Hello, my name is Katie Mack.

I'm a theoretical astrophysicist at North Carolina State University and the author of The End of Everything, Astrophysically Speaking, which comes out in August, but is available for pre-order now.

The thing I'd most like to achieve by the time the universe ends is to divide by zero just once to see what happens.

My name is Brian Greene, professor of physics and mathematics at Columbia University, author of a new book called Until the End of Time, sort of relevant to the topic that we're talking about here today.

And the thing that I would like to know before the universe ends is whether Einstein was right when he said that there are only two things that might be infinite, space and human stupidity.

And with that, here's Eric Eidel.

Hello, my name is Eric Eidel, and I'm a writer and comedian.

And the thing I'd most like to achieve by the time the universe ends is to prove that the opposite of gravity is levity.

Hi, I'm Steve Martin.

I've lost any idea of what I am or what I do anymore.

I did think that the universe ended in 1964

when I got my first stand-up comedy review.

However, one thing I'd like to accomplish before the end of the universe is learn the trumpet

and play it from infinity.

And play it from an infinite distance.

We should play it.

And play it be that last sound, the last sound.

I also think it's going to be very warm at the end of the universe.

Am I wrong on that?

I think, yes, completely wrong.

I think it'll be pretty darn cold.

We'll find out.

Well, anyway, what I will say now, we've had the introductions, and so that means, as usual, we say, and this is our panel.

And the reason we always say, and this is our panel, is it creates a Pavlovian response in our studio audience, which of course doesn't exist.

So, what we'd like to ask all of you at home is please whoop and holler until your pet looks at you quizzically.

And I would also like to very quickly say, by the way, if you see the quality of our panel, you will see one of the advantages of lockdown is no one had a good enough alibi to get out of doing this show.

So we're very glad to be enjoyed by them all.

Eric, I'd like to ask you, first of all, from a quantum cosmological point of view, if you wish, how would you like the universe to end?

I like the big sneeze because I think that's how the universe began.

If you look at the big bang, it's like a

and there's a big fast form which they call inflation, which I think we should call influenza because it's very similar.

And I think the big end should be like that.

In what time period was your intake of breath?

Is that before the beginning or?

It's a metaphor, Brian.

It's not literally an intake of breath, but I think if one was faced by the end of the universe, one might worry or go, ah!

Eric, could you do us a favour?

When you have a metaphor, just say metaphor coming.

To avoid confusion.

But I think the end of the universe is very good news, actually, because it is actually the one thing we can't possibly have to worry about.

It's a long way away.

Yeah, of all the things to worry about, sometimes once it gets to trillions of years, I put that on the back burner of my existential anxiety.

Steve, what about you?

Do you have, in terms of your hopes of how the universe might end, is there any favorite?

Hopes.

You know, I just feel that all human life will be completely gone by the time the universe ends.

We'll go first.

And so I don't think, I mean, I'd like to kind of know what it is.

You scientists are going to fill me in on what will actually happen.

But I just figure we're here until the sun blows up or goes quiet or something.

Or even if the Earth temperatures increase by 20 degrees, then we could all be dead too.

So I don't have a favorite way.

I guess burning to a crisp would have to be right up there at the top.

Yeah, because initially you're kind of enjoying the smell until you realize it's you, don't you?

Initially you think snack time, and then you realize it's self-cannibalism.

As Richard Pryor said, what's that fucking smell?

Katie, can we start with discussing the theoretical framework we use to analyze these ideas?

Because it seems at first sight that we're talking about the end of the universe.

As Steve said, it's a long way away.

How can it be that we can talk about this concept in a scientific sense?

Well, the main thing that we can do is we can look at what's happened to the universe until now, and we can extrapolate to the future to get an idea of where it's going.

One thing that we can be pretty sure of is that it will end.

We know it began.

We know there was a beginning of the universe.

We see very clear evidence of the Big Bang.

And we know that it's changing over time.

It's evolving.

It's expanding.

And the components of the universe, the balance of the different components of the universe are changing, and the nature of everything in the universe is changing.

And so we can see kind of where it's headed.

And so we can get an idea of what the end of the universe will look like.

You said quite a few things there in terms of we can see that it's changed over time.

So

how do we know just very simply?

Because it would seem that what you're saying is we can look into the past and we can look into the future.

Yeah, well, we can look into the past.

We can look directly into the past.

We can see the past very, very clearly because every time we look at anything, we're looking at it as it was when the light left that thing.

So even if I'm looking just across the room, I'm looking at a few nanoseconds ago.

And when we look at something as far away from the sun, we're looking at eight minutes ago, and so on.

And so we can look at galaxies that are so far away that their light takes billions of years to get to us.

And so we see them as they were in a universe that was younger than our universe is today.

And so we can see directly the past of the cosmos, and we can go farther and farther back by looking farther and farther away until we see parts of the universe that are so far away that they're still experiencing the final stages of the Big Bang.

We can see parts of the universe that, from our perspective, are at a time so early in the universe that the space that they're in is still on fire from that initial conflagration of the Big Bang.

It's kind of astounding what we can actually see, but we do see the past very, very clearly and very directly.

How does that explain when I look into a mirror, I feel like I'm looking 10 years into the future?

That's beyond the laws of physics.

We haven't figured that one out yet.

But let me point out the following.

When we talk about the universe ending, we have to be really careful what you mean by the word end or ending, right?

The stuff inside the universe that we see, the stars, the planets, we can argue pretty convincingly that it will all disintegrate.

It will all go away.

As Steve said, at some point, you know, the sun is going to get big.

We're all going to fry if we stay here on planet Earth.

That we understand.

But that is stuff inside the universe.

If we're talking about the universe as a whole, say space and time, Even in our current understanding, it could be that the universe is eternal in the sense that space itself will continue to exist arbitrarily far into the future.

So the stuff may go away.

The universe as we know it may end, but the substrate, space and time, may be here for an eternity.

Well, that's the best news I've heard all day.

Thank you.

I'd like to ask Brian Green a question because I actually read his book.

Well, I read 200 pages.

That's nice.

And I understood all two of them,

the dedication and the foreword.

No, but seriously, what I found the most fascinating is that towards the end of the universe, if we were in it, we couldn't see the rest of the universe because it would have expanded beyond our sight.

And that is fascinating.

So we're actually in a very fortunate part of the universe to exist in because we can actually see something.

You're absolutely right.

So right.

I mean, they're all...

Completely right.

So in 1998, there was a shocking realization that not only is space expanding, which we've known since Hubble back in 1929, but it's expanding ever more quickly.

It's accelerating.

It's speeding up.

And that means, just as Eric is saying, that in the future, it isn't even that far in the future by the time scales that we're talking about, roughly 100 billion or a trillion years into the future, the distant galaxies will be rushing away at a speed that's faster than the speed of light.

So distant galaxies riding the swelling space can move away from us at a speed that's greater than the speed of light, and that means the light that they emit will fight a losing battle as it tries to traverse the ever-widening gap between us.

So yeah, exactly as Eric says, we will not be able to see the rest of the universe.

It will be as off those distant galaxies fell off a cliff at the edge of space.

And it'll be kind of a lonely, a lonely time.

The galaxies that are nearby will still be able to see them, but that's it.

We will be a little island oasis floating in a sea of apparently eternal darkness.

And that's

maybe that takes away the good news that I said before.

Could follow up on that?

Would we be able to intuit that there was a universe beyond that?

It's a very good question, and it's a hard one.

Not everybody agrees on this.

I think it would be very difficult for future astronomers to intuit that there was in the past distant galaxies that now have disappeared.

So I think it's quite likely that our descendants, if they're still around, they will come to the conclusion that the universe is static, eternal, and unchanging because the very diagnostic tool that we use to figure out that it is expanding, the motion of the distant galaxies, that data will be gone.

That tool will no longer be available to us.

So, you know, you might say, well, look, we just need to, you know, write a letter to our distant descendants.

Tell them, hey, when you look out, you're not going to see any galaxies, but don't be fooled.

There used to be a universe full of galaxies.

They all just rushed away.

But I think those distant future astronomers are likely to not pay much attention to mythology handed down from an earlier age, billions or trillions of years earlier.

I think they're going to believe their own observations and come to this erroneous conclusion, the very conclusion that Einstein thought, that the universe is fixed and unchanging, even though we know that that's not correct.

Steve, I was wondering, you've studied philosophy, and one of the great philosophical questions is why is the something rather than nothing?

And now, the worrying thing seems to be that when philosophers finally work out, it might just be when it's about to be nothing again.

Do you find any kind of succor from philosophy in these kind of conversations?

Huh?

That is the greatest pracy of Kant I've ever heard.

Well, you know, I did study philosophy

in college,

and I loved it, but you know, 99% of that is completely gone.

But it helped me in many ways, especially studying logic and fallacies and the way people think and being what it means to exist to have influence on something.

Astrophysics was not a part of philosophy.

Philosophy was more metaphysics and the precision of astrophysics.

You know, it lost me.

And you have, you know, Astronomy 101, and I'm loving it.

And then suddenly, there's math.

I once asked Steve a question.

I said, I can understand the physical universe banging away, but why was it necessary, or how did it become to evolve us, an intelligent creature that can see where we are?

And Steve said, so that the universe can experience itself.

That's how Carl Sagan put it.

We are aware of it.

I think it's for the universe to know itself.

You were stealing that line, you mean?

Well, I think it was the other way around, but.

Brian,

we've talked about this idea that we can see that the galaxies, distant galaxies, are receding from us faster and faster.

And that allows us to infer this time in the distant future when there'll only be one galaxy visible, which will be ours or a merger of ours with the closest neighbors.

But that's not an end to the universe.

But what else happens?

Does that imply that we will always have this galaxy even though we can't see the rest of the sky?

Or are there other physical processes at work?

No, there are all sorts of other physical processes that, if you wait long enough, will radically transform

everything.

So if you wait, for instance, about 10 to the 20 years from now, if the Earth wasn't swallowed up by the Sun when it expands, the Earth itself is going to spiral into the dead Sun.

The Sun itself will have used up its nuclear fuel, it will be dark, and the Earth will spiral into it.

That's about 10 to the 20 years from now.

About 10 to the 30 years from now.

So just to say that's the 100 million million million.

Yeah, it's huge, right?

By any, right?

We're now roughly 10 to the 10 years from the Big Bang.

When you say 10 to the 20, it's not like a factor of 10, right?

We're talking in the exponent that 10 is up there.

So you're right.

It's 100 billion billion years into the future.

If you go 10 to the 30 years, which is 1,000 billion, billion, billion years, then stars will spiral into the black hole that's in the center of most galaxies.

If you wait to 10 to the 38 years, our refined theories suggest that protons, the very heart of all matter, will disintegrate.

They'll fall apart.

So all of the complex matter that we know about will simply disintegrate into finer spray of particles.

If you go to 10 to the 68 years, up to 10 to the 100 years into the future, even black holes, the one remaining macroscopic structure, they radiate in a manner that Stephen Hawking taught us back in 1974.

and those black holes will radiate away all of the material and they will as well be gone.

So by 10 to the hundred years from now, I don't know even, it's a Google years from now if you want to put a word to it, the universe will be a bath of elementary particles wafting through an ever larger, ever colder, continually expanding cosmos.

You can go even further from there, but I think you probably want to stop me.

But there are things, even more weird things that can happen after that.

Please do.

Ordinarily, we got nothing but time.

Yeah, we got time here, no doubt.

So if you wait between roughly 10 to the 150 to 10 to the 300 years, it's possible that the Higgs field, remember the big announcement in 2012 that the Large Hadron Collider, Brian, you were there, they discovered the Higgs particle that showed us that there's this field permeating space that gives particles mass, it may disintegrate.

And that would radically change absolutely everything about the physical universe.

And if you keep on going even beyond that, if you allow yourself to think about those particles wafting through the void, if you wait 10 to the 10 to the 68 years, all right, now we've got a double exponential.

10 to the 68 is in the exponent, 10 to the 10 to the 68.

It's possible that particles wafting through the void will just, by their random motions, recreate a brain.

Thought itself may be resurrected in the far future through the random motion of particles.

In fact, those motion, those particles could recreate, say, my brain, the exact particulate arrangement of the ingredients inside my head right now, which means I actually could be hallucinating this conversation, and I'm just a brain floating in the void with memories and experiences that never happened.

They are just mocked up by the particle arrangement of those randomly moving elementary constituents of matter.

So, yeah, there are some strange things that can happen.

And this is a major problem for this theory as well that people have talked about quite a lot.

This is called the Boltzmann brain problem.

And the problem is that if you hypothesize a universe that is eternally expanding in this way, dominated by this dark energy which causes this accelerated expansion, then you can calculate

under certain assumptions that it's much more likely that you are a brain hallucinating the entire history of the universe than that the universe actually exists in any meaningful way, that the evolution of the cosmos that you are observing actually is real.

And so this you have to kind of

tie yourself in knots to convince yourself that there's evidence that the universe is real and not evidence that, you know, much more likely would be that

we're just in this infinitely expanding space that occasionally comes together to create a brain that imagines that the universe is actually happening.

Aaron Powell, but Eric, I wanted to know whether you are, Eric,

are you more comfortable with the idea of a solid physical reality in LA or being this hallucination in a sea of particles?

Which would you see in LA?

Go on.

I think we are a hallucination.

Yes, I think we are.

I'll go for that.

I'll settle for a hallucination.

And, Steve, what do you reckon?

I'm just going to say, is this similar to the

infinite number of monkeys typing Shakespeare?

It's just a kind of a random thing that will come together if there's enough infinity.

Yeah, it's exactly

the same kind of calculation.

Yeah, when you put quantum mechanics and infinite time together, you get some strange possibilities.

Because if something has a non-zero quantum chance of happening, however small that chance might be, if you wait long enough, it's virtually certain that it will happen.

But as Katie says, we really view this as a diagnostic tool for our theories.

We don't like this possibility of Boltzmann brains.

To the the theme of the show, one way to avoid Boltzmann brains is to envision that the universe comes to an end in the sense that the space itself may collapse in on itself well before the time scale necessary for a Boltzmann brain or some other ending to the conventional structure and the conventional ingredients that will avoid the possibility of brains randomly floating in the void.

Katie, we've covered one possibility in some detail, which is the universe just continues to expand forever and, as Brian said, ends up as a sea of radiation, essentially, no structure left at all.

What are the other possibilities?

Well, one of the ones that was much more popular in the 1960s and is very unlikely now, but we can't completely rule it out, is called the Big Crunch.

And this might be one that people are most familiar with from science fiction and popular culture.

The idea that the expansion of the universe, as it's happening now, could at some point stop, turn around, and reverse, and that would bring all of of these distant galaxies rushing back toward us.

And eventually,

when you are compressing the universe in that way, not only are you compressing all of the matter, you're also compressing all of the radiation.

And so you end up with space being much hotter than it is now.

Right now, as the universe expands, space is cooling.

There's a background radiation from the Big Bang.

It's cooling over time.

If you reverse the expansion, that heats up and you get harder and harder radiation at higher densities.

And so in the Big Crunch scenario, the thing that really kills you is not galaxies colliding or stars colliding.

It's the background light of all of the stars that have ever been shining in the universe, cooking the stars and planets from the outside in.

And so, you end up in this horrific inferno compressed.

So, that was Steve's wish, wasn't it?

To be burnt to a crisp.

So, this is still possible.

Yeah.

Well,

you still get that with the sun burning up the earth.

So, you have that stage either way.

But

the reason we think it probably won't happen to the universe is because as the universe is now accelerating in its expansion, it seems very unlikely that that expansion would stop and turn around.

And there's another possibility that happens, which is called the Big Rip.

And this is one where dark energy doesn't just move galaxies apart from each other, but actually becomes more powerful over time, in a sense, and pulls galaxies apart themselves and sort of rips stars away from galaxies and planets away from stars and eventually rips apart the fabric of space itself.

That one is the one that you can almost imagine that that moment you're having a lovely walk, and then you look up at the night sky and you go, think there's just a, oh no,

the big rips happen.

Yeah, I mean, both of them are terrifying in the sense you'd see them coming.

I just want to say that for all you listening on the radio, on the podcast, you can't see, we can see each other.

So we've got a video conference going.

And I always get by Robin and Eric often accused of smiling when I say these things.

The more that I discuss the end of everything and the end of time, the bigger my grin gets.

But Katie and Brian Green also were smiling in describing these scenarios.

I want to ask Stephen Eric what you make of the physicists relishing this discussion of the obliteration of all that we hold dear.

It's because you're so pleased with yourselves.

You know something we don't.

You know something we don't, and you're so proud.

Also, comedians are never pleased with themselves, are they?

Yeah.

Also, I think for the comedian that, you know, we're not worried about the death of the universe.

We're worried about, you know, Saturday night.

Are we going to die on our ass at the comic strip?

You know, that's a, you know, I'm not bothered about our narcissism, our ego is such that to help with the big rip, I'll tell you what, I was doing great for 10 minutes and then I just lost them.

Katie, obviously, there are a lot of survivalists listening to this, making their shopping lists so they can survive the end of the universe.

So I think

we've had the big crunch.

We've dealt with the big rip.

We haven't, now one of the ones that I particularly knew nothing about at all until I read your book, vacuum decay.

Now that that sounds

particularly intriguing.

Yeah, yeah.

Vacuum decay is a possibility where the Higgs field, so this energy field that pervades all of space, could have a different kind of value that it would like to have.

So right now you can measure sort of the energy in the Higgs field, and you can say, what if it had a different energy?

What if it were in a different kind of place in its evolution?

And if that happened, then it would create a bubble around itself at the point of that transition.

And this bubble of this new kind of space, called a true vacuum, would expand out through the universe at roughly the speed of light and destroy everything in its path.

And this new kind of space inside, this true vacuum, would be one in which not only can we not survive as

physical objects, but also that space would be in some sense gravitationally unstable and everything inside would also be crushed into a black hole.

Which means that at any moment, technically, some part of the Higgs field right next to us right now could do this, and you could have this bubble of the true vacuum expand through the universe at the speed of light.

You'd never see it coming.

You wouldn't feel it when it hit you because your nerve impulses don't travel that fast, and it would just sort of erase the entire universe.

I was going to say, Steve, and there, Casey was smiling again.

And I just wanted to explore this.

Which is your favorite so far?

I really think that it is the joy of knowledge.

You're expressing something that, you know, very few people, you know, some people obviously in the world understand this and know it, but you're expressing esoteric knowledge that is known to you and a few others who can understand you.

And it's a real joy to do that.

And you're communicating it to other people.

That's the joy.

I see that joy when Brian talks to people.

You're actually enlightening them.

So that is a delightful thing to do, and it feels good to you, I think.

Well, I think it is worth reflecting on the fact that we're talking about with some, not with confidence, but with some authority, given what we know, about events that will happen.

As you just said, perhaps 10 to the power 500.

It's a very glorious thing to talk about.

You're talking about the apocalypse,

and an internal apocalypse of the universe.

And

it's a very big deal and a very very exciting thing.

And we know that we'll die before all this happens anyway.

And there probably won't be any living creatures at that point unless this dang vacuum thing happens.

Yeah, well, that way.

Uh-oh, here it comes.

Have a word with Dyson.

I think it is a remarkable thing,

but this is to both Brian and Katie, that we have much confidence, and there'll be people listening to this who say, you know, we can't predict what the weather's going to be like next Thursday.

But yet, with some confidence, we've outlined a series of scenarios.

I think we've covered all the main ones.

One of those, given what we know at the moment, is likely to happen, we are saying, even though we're talking about time periods that are unimaginable.

How is that possible?

Well, I mean, I think humility suggests that we have to allow for the possibility that future discoveries may radically change our understanding, and maybe none of these scenarios are the correct scenario for the far future.

However, the mathematical laws have done such a great job of explaining the evolution of the universe from a split second after the beginning all through the formation of stars and planets and galaxies and black holes.

And time and time again, we've been able to confirm the predictions of these mathematical laws.

And that gives us some confidence to say if these laws continue to hold in the manner that they have in the past, then here is what will transpire.

We're not making stuff up.

We are following the mathematical analysis, allowing for the possibilities that are seen within the equations, and just reading off the future that that math predicts.

And we do, I think we do maintain a reasonable amount of humility in this, because there are big parts of this picture that we still very much do not understand.

So there could be something beyond our observable universe that could affect it.

There are ideas about higher dimensions of space where there could be something separated from us by a higher dimension of space that could change the future evolution of the universe.

There are ideas about evolutions of the universe that involve collisions between regions of space that are so disconnected we would call them separate universes.

So

there are clear limits to our knowledge.

There are limits to our understanding of physics, and there are limits to what we can see and observe about the universe.

And those all are very clearly delineated, I think, in our current thinking and understanding.

And we have to always stay aware of those limits and realize that

there could be something beyond those limits that change our whole picture.

I think there is, you know, watching the smile as well, again, there is something wonderful about the brilliant absurdity of it all.

I think that's, you know, here we are where we have this small life on this incredible planet.

And yet we're thinking about, let's just check what's going to happen in 300 trillion years.

Let's just start.

And that is a wonderfully absurd thing.

And I think for both, you know, I know both Steve and Eric, you like surrealism and absurdity, and that's been, you know, part of your work.

And

there are the joys of what you create.

I was thinking, Steve, you, for instance, are someone who is a great art lover.

You know, Schopenhauer, who thought that life was a preposterous thing.

But the joy that you could find in those moments, one moment you'll think about the end of the universe, but the next moment you might be looking at something fantastic by Monet as well.

And I just wonder about that sensation, that balance between the two worlds of humanity.

The question is, why why do we even have joy?

I mean,

how did this come along?

Why did the mind outgrow its own evolution?

Why are these things added on to the mind and love and joy?

I understand sex, that's procreation, something, but why do we even have this appreciation?

It's like somebody should have put the brakes on, you know.

And why do we have all this anger and hate?

It's too complicated.

To me, the thing I'm looking at in 300 trillion years is finally my investments will have matured.

So I'm looking forward to that moment.

Eric.

I was about to launch a cheap joke.

I'm sorry.

It was just a comment on that.

I think that that was the end of the world.

Moment was going to be called the last Trump.

These scenarios we've discussed are all a very long time in the future.

So even if there is something we could call an end, which would be the evaporation and destruction and elimination of all structure in the universe, all these things are a very long time in the future.

So, it seems that we live in a universe today where the things we've been talking about, that thoughts, right, and love and art and understanding, can only exist for a very short space of time in a universe that exists for a very long period of time.

Would that be a reasonable characterization of where we are?

Oh, absolutely.

The universe in the far past didn't have life, and life emerged for a brief moment on the cosmological timeline.

It stood up, it looked around, it enjoyed it for a moment, and then it disappeared.

And that's it, as far as the most conventional interpretation of the physical laws tell us.

In fact, you know, Steve has mentioned a couple times, you know, is there a point when there'll be no life, no humans, and so forth?

Well, there's one moment in the cosmological unfolding that we haven't discussed, which likely happens around 10 to the 50 years from the Big Bang, a far time from now, which is this.

Thought itself is a physical process.

And according to the second law of thermodynamics, all physical processes yield an increase in entropy.

They create waste heat.

And you can do a calculation to show that about 10 to the 50 years in the future, even the process of thought, the heat that it generates, the universe will be unable to absorb that heat, which means that any thinking being at that point, which thinks one more thought will die.

It will fry in the heat generated by the very process of thought itself.

So yeah, it seems quite likely, as Brian is saying, that not only will all matter disintegrate, not only will life as we know it go away, but any possibility of conscious awareness is likely to have an end.

too.

And in an infinite universe, the window of a finite duration is infinitesimal.

We're here for just a blink of an eye and that's it.

Can you give me that date again?

10 to the 50 years.

Mark it on your calendar.

It's

a little after your stocks mature, so

you can still be aware of that happening.

Well that's what I'm worried about.

After Brian Green was just saying, Brian was saying about the danger of thought at a certain point in the universe.

And I wonder if some world leaders are just ahead of the curve in terms of evolutionary survival.

You know, they're thinking, don't have a thought.

I heard that physicist, he was talking on Radio 4, and he he said, thinking is dangerous.

It is true that the heat death is unevenly distributed.

There are regions of the universe now that are in giant voids where there's very little matter, and

there's these large regions of space where they're dominated by just the expansion of the cosmos, and there's very little matter and energy in those.

And those will get there before everywhere else.

So, if you want to extend the possibility of thinking, you want to be in a certain very crowded

center of a galaxy cluster or something.

But

it's just as different people have different responses to thought, the universe itself has

different regions where the evolution goes differently.

So I think we should say the main message of the show is no, do not stop thinking.

It is safe to think on this planet.

We are in the right conditions to have curiosity and thought.

Eric, I wanted to ask you, as we said, we're going to demand that cosmology is democratic by the end of this show and put it to a vote how the audience would like the universe to end.

Of all the versions that you've heard so far today, are there any in particular that you find most appealing?

I think

I'd like my universe to end with a nice bath, you know, because that's the best thing you can have, really.

Is that what was the question?

Was that the question?

That'll do.

Don't worry about the question.

We like the answer.

For me,

I think hugs are overrated, but still,

a nice hug and a very sincere apology for the end of the universe.

Which one comes first, the hug or the apology?

Yeah, maybe the sincere apology comes first, and then the hug that's a little bit too tight and keeps on going.

That terrifying moment where right at the end of the universe, we suddenly see in the small print, oh, terms and conditions apply.

Now I understand.

Yeah, yeah.

Thank you so much, everyone, for joining us.

Thank you very much, Katie Mack, Brian Green, Eric Idle, and Steve Martin.

But before we go to that, we have a few of our audience questions as well.

We asked the audience some questions, or we asked them one question, and they gave us one answer.

We did this, by the way, via social media, if anyone is wondering.

Out social media, we asked, how would you like to see the universe end?

And these are the choices.

Chris goes for, I think, the most English answer.

Not fussed.

As long as it doesn't end in the same bitter disappointment as the TV series Lost.

Because that's the worrying thing.

What if it turns out, you know, the creation of the universe, no one had imagined what the Denoumond might be?

That could be one of the problems there for the creatives.

So, Ard Grunevelt, I hope that's pronounced that right, said, with a celestial voice asking, Have you tried turning it off and on again?

Edge Crusher, possibly not real name.

Having perfected the lifesteel technology, Brian Cox leeches the entire universe into non-existence.

Diane Marky Martin said, I would most like the universe to end in an instant sequel in the vein of Godfather Part 2, Paddington Bear 2, or Star Wars 5 or 2, i.e., bigger and better than the original.

Bigger and better than the original.

We've gone into controversial.

Finally, this is the most controversial thing in the whole show, isn't it?

Star Wars 4, 5, or 2, bigger and better than the original.

Star Wars 2?

No, Star Wars 5.

Oh, yeah.

No, you're right.

Oh, I think that must be a typo.

Ollie Needham says, my friend Lily thinks a massive Hollywood musical number would be the best way to send it off.

So a bit of a Busby Berkeley.

Eric, there you go.

Yeah.

I actually did write once.

I read a song called Einstein in Hollywood.

And it was a big dance number because Einstein visited Hollywood in 1954.

And he was shown round the studio and they were singing and dancing.

He said, what is this all about?

And somebody said, nothing at all.

This is a very good answer, I think.

I think the last one,

this is it.

John Wilkinson, simply, will the last one out turn out the light?

Next week, we should be back, though, in these unsure times, I cannot say that with any certainty.

And if science is about one thing, it's about uncertainty.

You've just seen Heisenberg trying to decide whether he was going to have the soup or salad.

Ugh, ages.

Uncertainty in quantum mechanics doesn't mean that you can't make your mind up.

It just comes from the fact that in quantum mechanics we accept any normalized vector as a possible state of the system and any operator who's either

a normal basis as a potentially observable physical quantity.

I'm being very specific.

Honestly, Heisenberg, you just sit there for like three hours.

Mulligatorney, prawn salad.

Mulligatorney, prawn salad.

It goes on forever.

Anyway, well, it doesn't go on forever.

It goes on till the big rip or one of the other ones.

Anyway, thanks very much, everyone, for listening.

Bye-bye.

Thank you.

Thank you.

In the infinite monkey cage.

Till now, nice again.

You've been listening to the Infinite Monkey Cage podcast, thanks to our studio manager, Jars Aspen, who's, I have to say, in his bedroom.

He's not in a studio.

And our producer, Alexandra Feacham, who I have to say is in her bedroom, she's not in a studio.

And also thank you to Robin Inns, who I have to say is actually I can see him on the video conference and he's not in a bedroom, he's in a loft.

He's not in a studio, but he's in the loft.

He looks like he's been locked in there for many, many weeks.

It's not actually very pretty.

No, I'm transmogrifying into the pigeon in the rafters.

Anyway, we'll be back with some more amazing guests guests who fortunately have found no alibi whatsoever and no way of saying no to us.

So enjoy the next episode.

I hope you enjoyed that one.

And as we said at the beginning, I hope that was an upbeat end to the world and the universe for you.

As someone said, what it should have actually had, the end of the universe, should just end with a Perry and Croft production saying, you have been watching everything.

Hello, I'm Greg Jenner.

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