Parallel Universes

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Hello, on my right, a man who began as a keyboard player and then became a particle physicist, but he will still do a pub sing-along.

Just don't ask him to do by the light of the silvery moon, because in the preamble he then explains why the moon appears to be silvery, shows you a selection of it.

It takes ages, to be quite honest, much longer than the song.

It's Brian Cox.

On my left, a man to whom the word spontaneous symmetry breaking in the electroweak sector means nothing at all.

Robinins.

I have no idea.

This week we are back into physics, which means we don't really need any guests, as Brian obviously will just sit there going, I know that one.

Oh, I know that one as well.

Oh, I've seen that.

I've got my own accelerator.

We are looking at the idea of parallel worlds.

Is it fair for physicists to declare if it exists on paper, then it exists?

Is this empiricism thrown out of the window?

And if so, which window and into what world?

Can it be true that every time we make a decision, we don't just make the decision we know we've made, but in fact, we make every possible permutation of that decision, each one splitting off to another world?

Does that mean that free will is an illusion?

Is it no longer satisfactory to use as an alibi for lateness?

Well, I can't be in two places at once because it turns out you can.

We're joined by the Astronomer Royal, former president of the Royal Society, Master of Trinity College, Cambridge, Baron of Ludlow, so many accolades, there is no time at all to tell you anything more about him.

But those titles should give you the gist.

He knows what he's talking about.

It's Professor Sir Martin Rees.

And our next guest is also a regular guest on Brian's TV show, Stargazing, which he co-hosts with the well-known and popular comedian Dara O'Brien, who will co-host with him when it's on television.

And the money's very, very good.

And because he's very professional, isn't he?

Yeah.

Very professional.

I'll give you the best years of my life.

Anyway, she co-hosts it.

She also appears on Stargazing, where you probably know her for her popular catchphrase, now if we can imagine what the sky would look like behind these clouds.

It's Dr.

Lucy Green.

And finally, the man behind and sometimes in front of many of the last 40 years' finest comedies, from Black Adder to QI to The Hitchhiker's Guide to the Galaxy and Radio 4's own Museum of Curiosity.

He also created Spitting Image, in which grotesque parodies of humanity were paraded across our screens, an idea so potent that we now rarely see any other form of humanity on television.

It's John Lloyd, and this is our panel.

Martin, we'll start off by just getting the basics, I suppose, which is to say, what do we mean by the phrase parallel universes?

Well, we've learned how huge the universe is, that's no news to anyone, but we have learned it's even bigger than we think, because we know that not only is our Sun one of 100 billion stars in the galaxy, our galaxy is one of 100 billion galaxies we can see with our telescopes, but we've learned that even that is just a tiny part of what there might be.

We've learnt that there may be huge numbers of galaxies beyond those we can see.

We've learnt that our Big Bang may not be the only one.

We've learnt also that there could be other universes alongside ours, just a millimeter away.

But if that millimeter is measured in some fourth spatial dimension and we're imprisoned in our three, we wouldn't know about it.

There could be so much space beyond our horizon that there are indeed, as you were saying,

other avatars of ourselves taking all possible decisions.

So there could be other people like us, but if we make a mistake, our avatar may get things right.

So there is a huge possibility.

And that really means the universe does have to be huge.

Is it really possible for the human brain to get an understanding of the idea of infinity?

I mean, it is, again, a very kind of discombobulating idea.

Well, it just means it goes on and on and on and never stops.

In a way, that's a quite easy idea.

And of course, yes, I know it well.

Well, very well.

No way.

See, I think it in one way, when you say it like that, it seems like a very easy idea.

But when you then go, there are, for instance, this, in in an infinite-sized universe, this is happening just this exact version an infinite number of times, as well as an infinite number of permutations of exactly just this one moment here, as well as the fact that if we have in the classical model, first of all, an infinite size universe which is having an infinite number of differences and also the same things happening, at the same time, then if we look at a quantum level, then we've got also all the different universes which are then happening at each different junction.

We have the idea of his cat.

So, though I do realize that is quite simple, in other ways, it's also quite a tricky thing as well, to cows in a skull.

Well, it is, but I think it's amazing that our brains have understood as much as they have because our brains haven't changed much since our ancestors lived on the African savannah and they cope with the everyday world.

And we can at least get some way in understanding the atoms.

At least Brown Cox can understand the atoms.

And some of us can understand the cosmos a bit.

So it's amazing how far we've got.

But I think we do have to accept that maybe some of these mysteries will have to await some post-human intelligence.

That's quite possible.

And we've had a long time to get used to the idea of thinking about an infinite universe as well.

So back in the fifteen hundreds, you had Giodano Bruno, who was probably the person who tried to move us away from the Greek view of the universe as being spherical and finite.

And he proposed that

the stars that are out there are the same as our Sun.

And given the work of Copernicus, planets go around our Sun, so around those stars there could also be planets, and on those planets there could also be life.

And that this was what, several hundred years ago, that we had the first ideas that an infinite universe was out there, infinitely full of life.

John, does that make it clear?

Somebody can explain to me how you can have an infinite universe and the Big Bang theory at the same time.

Because surely, it started as a sort of, you know, an expanding something and

it happened a certain number of billions of years ago and it's going outwards.

So the question is: there must be an edge to it, but it's always

what I've always wondered: what's it expanding into?

What's this thing expanding into?

And I have one other thing to say: is that in the parallel universes thing, if all parallel universes, all possibilities exist because of the infinite thing, then there logically must be a parallel universe without any parallel universes in it.

And I wonder if that might be the one we're in.

Martin,

there's some excellent questions there.

Let's unpick them.

The first one, I get asked this a lot, so it's it's you know, what if if the universe started 13.7 billion years ago, then how can it be infinite?

It there's a boundary in time there, thirteen point seven years ago.

So how can it be infinite now?

Well, there's a boundary to what we can see.

There's a horizon around us, which is really uh delineated by the distance that light's been able to get since the Big Bang.

But that's not the edge of the universe any more than if in the middle of the ocean the horizon that you see around you is the end of the ocean.

And we have strong reason for thinking that there are lots of galaxies beyond our horizon that we can't see.

So even the most conservative astronomers think that there are galaxies we can never see.

And it's only one step beyond that to believe that there may be an almost infinite universe and maybe other Big Bangs.

I mean, and the other point is that if we look so far away, they might indeed be governed by different laws, but it may well be that there are places far beyond the horizon where the strength of gravity is very different,

where electrons have different masses, and all that.

And this leads to the idea that perhaps we are in a part of the universe which is unusual in it allows the chain of complex events that led to us to occur.

We have to have simple atoms combining into complex chemistry and stars that live long enough to allow life to evolve around them.

And that may not be possible if the physical laws are a bit different.

There may be part of the universe where there's just hydrogen, nothing else.

Chemistry, a very dull subject, and

no possibility of anything as complicated as even a single cell, and certainly not us.

And so.

Oh, you don't mean it's dull here in this universe.

Sorry?

There's a statement.

We can edit that.

Right, it can be more dull in dull universities, yes.

It's where we used to get complaints from creationists, but they stopped listening.

So now the main complaints we get are from chemists, again, going, you've run us down again.

Lucy, can I just ask you one very we're talking there about the expanding universe.

I mean, is it right to say that eventually there will be a point where, due to the expanding universe, this galaxy would believe, say there is conscious life at that point, that this was the only galaxy in the universe, that everything has actually got so far away that it would be impossible to get a sense of, as you were saying, the unseen galaxies that

we don't know if they're there or not now.

But that would be the position we would be in in the future.

It could be.

So it it depends on how the expansion of

what we see out in the sky, of our universe, proceeds.

And I hope that it starts to slow down, because I would like to be able to see some of these galaxies that are in another universe.

But if they have the same laws of physics as we do, how do we tell that they're part of another universe?

What what's the distinguishing features?

What you know,

I'm an observer, so I like to test theories.

And to me, it's not clear how you would discriminate between a part of the universe that belongs to our Big Bang and a part of a universe that belongs to a different Big Bang.

But this is slightly predicated on Martin has said before that it's slightly embarrassing in science that 95% of the universe that we're in is unaccounted for.

Only 5% we know something about, and the other 95% is two madey-uppy things called dark matter and dark energy.

So

I mean, it could be anything, could it be?

Ryan?

They're not madey-uppy in the sense that we've observed their influence on the universe.

Well, no, I'm just saying that we have to, we don't know what they do or where they are, and therefore, what other theory, you know, if I if I produced a comedy show that was only 5% funny, I think I probably

wouldn't be sitting here now.

No,

I'm just saying that most things are dark in the universe, just like that.

My point was that I thought that maybe the 95% that we don't know about is where all the parallel universes are.

But that would only allow for 20 of them, which isn't enough.

Very large numbers of plastic.

That's an interesting point, actually, because Martin, I believe there have been theories where the influence of maybe extra dimensions in the universe are causing those deviations from Newtonian gravity.

Well, extra dimensions are, of course, fascinating.

Most people suspect that if we were to divide up space very finely indeed, on a scale much, much smaller than atoms, chop it up very small, then what we think of as empty space becomes very complicated.

What we think of as a point in our space may even be a sort of tightly wrapped origami in five extra dimensions.

This is what string theorists think about.

And so, space may have extra dimensions which in string theory are mainly wound up very tightly, so we can't see them.

But some people think that there may be some of these dimensions which aren't wound up so tightly, and

it may be that we see some evidence for them in accelerators.

But more spectacularly, it could be that there are some that aren't wound up at all.

And if that's the case, then there could indeed be another universe which is alongside ours, but separated by a small distance in the fourth dimension, and we're not aware of it.

Just like if you imagine a whole lot of ants crawling around on a sheet of paper, that's like their two-dimensional universe, they might be unaware of another population of ants

crawling around on a parallel sheet of paper if they were only aware of two dimensions, not three.

One dimension up, this could be our predicament.

It could be that we are in our three-dimensional world and we are in a space-time that's embedded in some extra dimension, and there are other space-times also embedded in it.

This is really fabulous, but it is, you know, it's science fiction and

fun.

Speculative science.

Speculative science.

Somebody said there is speculation, there is wild speculation, and then there's cosmology, isn't that right?

Lucy, John is making a good point there.

So, how could we we ever see experimental evidence, observational evidence, for such a thing?

Well, this is where I'm hoping CERN is going to come in.

Because,

yes, I can't think of any other way.

I haven't read any other way of being able to investigate this other than the conditions that you find in CERN.

And so, could it be that you have an experiment where what goes into your collision isn't what comes out of your collision?

And there might be some way of working out that it has popped over into one of these other dimensions.

Yeah, so we're talking about gravity being the way to observe these extra dimensions.

I mean I suppose, Martin, if if there were no force, none of the four fundamental forces of nature moved between these different sheets of space-time, there would be no way in principle of ever seeing them.

Right, but you shouldn't expect too much of science.

Let's remember that uh scientists can't even tell you what kind of diet is good for you.

So how can

how could you expect them to tell us

all about the chemistry?

But I think if you think of the rate of progress, we're going to be optimistic because fifty years ago we didn't know if there was a Big Bang at all.

We knew nothing about cosmology.

Now we can talk with confidence about back to when the universe was a nanosecond old.

That's huge progress.

And if we think of that progress we made in the last fifty years, then fifty years from now I suspect we will have got back far enough to be able to understand the Big Bang well enough to say whether it was the only one, whether it was one of many, and whether the other Big Bangs cool down to be governed by the same laws as ours or not.

So, I think we will

make some progress.

We won't observe these other big bangs, but we may understand the conditions right at the beginning well enough and be able to test those ideas in other ways.

And therefore, we will believe in these predictions.

You don't have to be able to test all the predictions of a theory.

A theory gains credibility if you can test a lot of its predictions.

And if we had a theory that we could test in lots of ways, and that theory allowed us to describe the very early stage of the Big Bang.

Then we take that description seriously, and if it predicted a so-called multiverse, we take that seriously.

I should mention that there is an idea called eternal inflation, which is the idea that our Big Bang started with some very rapid expansion called inflation,

but that these Big Bangs keep popping off all the time in some infinite substratum that goes on forever.

So it's rather like the old steady-state universe, but on a much grander scale.

And this I love, because I've been saying, I'm going to really step out of line here.

I've been saying for ten years that the Big Bang theory will not stand out.

It will not be here in its current state in 10 years' time.

And you've already mentioned that there might be some other Big Bangs and this eternal expansion thing, and there's a thing called quantum fluctuation, isn't there, as well, which is quite interesting.

And it's starting to come apart at the seams, this Big Bang thing.

Because there are a lot of...

No, that's not true at all.

It's just the.

But you're saying the steady state.

I like the steady state theory.

I like Fred Hoyle.

And I think that...

Well, it was completely wrong in the form that he proposed.

Well, it's coming back to deciding that there's a matter of...

But it's coming back on a quite different scale.

The point is that

in science, what happens is that there are speculative questions, and as they get settled, new issues come into focus,

and new questions which you couldn't have posed before.

So we've settled most of the questions we debated 40 years ago, but we are now addressing questions that couldn't have been posed then.

And 40 years from now, it'd be another set of questions.

That's the nature of science.

New science doesn't sort of overthrow the old, it transcends the old.

John, you worked with Douglas Adams, you produced Hitcher's Guide to the Galaxy, and I think

co-wrote the last two episodes of the first series.

Now, when he was first playing with some of those ideas which he used, probability drives, etc., did you think, oh, this is obviously just made up by an author with a good imagination?

Or did you immediately know that this was actually, these kind of games and these kind of intriguing ideas were actually part of current scientific thinking?

I mean, Douglas used to say, you know, the the two things you need to know about parallel universes is one, they're not really parallel, and secondly, they're not really universes, which is quite a neat thing.

But we used to have some ideas in Hitchhiker about if there are an infinite number of universes, then, you know, nothing can happen.

And that's where the

infinite improbability drive came from.

The idea that you start playing with these massive numbers, and

it gives some sort of scientific sense or credence to think.

I mean,

I'm very interested in in cosmology and and astrophysics I don't know very much about it but it doesn't matter to me whether there was a Big Bang or there wasn't it's not but if there are parallel universes

that that really matters and it's

well because it's a little bit like the concept of block time you know you know that idea that

nobody knows what time is it's like consciousness it's a really really big deal that we have no idea what it is really and and so in the 20s I think this concept of block time came up which is time's a bit like a landscape.

You know, just because you're not in New York, it doesn't go away, it's always there.

And the same is true of last Wednesday, it's just sitting there with all the people in it going on.

And people who don't have any religious faith, for example, find this rather comforting that somebody who's gone is still there in last Thursday or, you know, three years ago, and whatever.

So, it's all existent.

And I find the same about parallel universe, it's the idea that if I fall under a bus, there's another of me that was careful enough to look when crossing the road and is carrying on having a much nicer life.

And I feel there are much happier John Lloyds wandering around in other universes who

I might have a knighthood or a peerage, for example, be a member of the FRS

and be master of Trinity College.

They seem to have passed me over for that one very annoyingly.

So I do find that comforting.

But this is the main problem you have with it.

Philosophically, you can go, this is an intriguing idea, but you can't see this beyond the idea of the philosophy.

You see this as philosophy rather than science.

Is that that your main?

Well, I was of the opinion, perhaps I'm wrong, I missed something, that science is based on evidence, generally, isn't it?

And is there some evidence for parallel universes?

Let's hear it.

Yeah, there was something that came out last year.

There was a really interesting press release that caught my eye.

And it was related to what was just being said about universes popping into existence.

And so we would have our Big Bang, and space is expanding, and maybe another Big Bang happened near next to our universe and sort of bumped it a bit.

But then the expansion of space moved it away from us and faster than the speed of light, so we would have no hope of seeing it itself.

But the way we investigate inflation is by using what's known as the cosmic microwave background, this relic of the Big Bang.

So there was a story that said they'd seen these, I think the Daily Mail called them bruises in the cosmic microwave background.

So where we were bumped by other universes and then they were taken away from us.

And I thought, oh, fantastic.

But Martin's looking at me.

Well,

I mean, you might just explain a little bit more about the cosmic microwave background, because that is one of the key observations, the key experiments, in a sense, that we can do in cosmology.

So, could you explain a little bit more about that?

I mean, absolutely fantastic.

So, when you look out into the universe, you see a very long wavelength radiation, microwave radiation, and it's thought to be the remnant of the heat produced during the Big Bang.

So, as space has been extretching, time has been passing, the radiation has cooled and cooled and is now in the microwave.

But embedded in that microwave background are signatures of how our universe has evolved since the time of the Big Bang.

And so, for me, it's probably

the key observation to study these theories.

I mean, this is a real argument for having better space telescopes to make more precise measurements of this microwave radiation that's out there.

We should be able to test some of these theories about inflation.

I'm interested, John, as well, that we've just seen there the difference difference between arts and science.

You wanted a knighthood and Lucy wanted more big telescopes.

Martin, you you were talking a bit about the idea of you know we we keep coming back to certainty and the fact that obviously that there we're playing around with many different ideas here.

I mean how do you feel?

Sometimes when you're examining these ideas, do you think, well, I've got enough confidence to keep going, but every now and again there is is a moment of doubt.

You were saying that there's a kind of measurement that can be used for for this.

Yes, well I think the main point is that things that we were very uncertain about become we become gradually more certain about, and the idea that there might be a multiverse is still pretty uncertain.

And I was on a panel

two or three years ago with other people where I was asked the question,

How confident are you that there is a multiverse?

And I said, Well,

if you say, Would you bet your goldfish, would you bet your dog, would you bet your life?

I was about at the dog level.

And the next person on the panel was Andre Linde, and he is the inventor of the eternal inflation model.

He'd spent years and years of his life on this.

And he said he was far more confident than I was.

He would almost bet his life on this idea.

And then Steven Weinberg, the great theorist, he said he'd be happy to bet Martin Rees's dog and Andre Linde's life.

Very quickly I'll ask you, Lucy, very quickly.

There's been various different ideas about the idea that a black hole, there is the possibility that that could take you from one universe to another, and there's various different I think there's a the is it the Einstein-Rosenfield bridge there where you have various different forms.

But this idea of various different forms of a black hole linking to other universes, again, the black hole actually, evidence and the idea of that is still very recent, isn't it?

Yeah, I mean, this is a really

mind-boggling, but an intriguing and an exciting idea.

The fact that you could use a black hole and the opposite, a white hole, as some kind of tunnel through which you would go.

And now, black holes, up until not that long ago, we thought were complete science fiction.

And then we found Cygnus X1 and we had X-ray observations, and they matched the theoretical predictions for a black hole.

But still,

how would we get in and through that black hole?

So, whenever I give school talks and we talk about black holes, we talk about the fact that you get spaghettified when you go to them.

The gravitational forces are different at your head than at your feet.

You get drawn out, you get completely pulverized.

So, theoretically,

yes, I think it comes out of the maths, but realistically, no way.

If you had a very big one, it might be easier because then the forces are more gentle.

But, of course, the other reason.

The other reason people invoked this idea of black holes connected to each other is to get a time machine.

Because we know the problems of time machines from science fiction.

But if you had a black hole and you went into it and you came out somewhere else, then you could produce a sort of time machine.

And indeed,

in the Carl Sagan

story Contact, in the movie version of this, then that's how you get to the galactic centre and back quickly, by going through one of these

tunnels connecting two black holes.

But you said earlier, Martin, that scientists, and I think you've been quoted as saying that actually astrophysics isn't as hard as dietetics.

I mean, it's more complicated to know what sort of diet we should eat than it is to understand the universe at large.

Well, that's right.

I mean, it may be string theory is harder than dietetics, but the fact is that we can talk with some confidence about planets around stars and all that stuff.

Whereas you're crazy if you believe what an expert tells you about diet, because

they change their views.

It still goes to the Daily Mail, of course.

But that's because what makes things complicated isn't them being very big or very small, but them being very complicated in their structure.

And living things are much more complicated than either atoms or stars.

And that's why 99% of us scientists are neither astronomers nor particle physicists, but work on very complicated structures on the everyday scale.

But still, I think we have to be open-minded about whether we'll understand these deep problems or not.

This preconceptions, and you know, it probably,

these things are there.

Douglas used to tell this brilliant story about when Captain Cook arrived in Hawaii, the natives were all sitting there, and they had nothing larger than the canoe, and this massive thing, like to them, a five-story skyscraper, arrived in the harbor.

And people looked and thought, no, No, it can't be.

And just went back about their business because it was so obviously an optical illusion.

And it was only when Cook actually arrived on the beach and said, Oi, hello, that they took any notice.

And I think that's what we've got to in cosmology, is it's staring us in the face.

It's really, really obvious.

And somebody really bright will come along and go, No, it's like this.

And then you say, Oh.

I think John today's been fantastically brutish.

I think we should replace this show with Arm Wrestling for Theories, which means we've scientists coming up.

Martin Rees won that round of arm wrestling, therefore, parallel universes go through to next week.

So, here we are.

This is

given that there are an infinite number of universes in which we now ask the audience a question about parallel universes.

We've decided instead to place ourselves in one to the infinite number of universes in which we ask a completely unrelated question to the rest of the show.

John, you wrote The Meaning of Lyft with Douglas Adams, in which you took place names and made definitions for human experience, such as beude, a polite joke reserved for use in the presence of vicars.

That is a beude.

So we then asked the audience for their LIF definitions, and here are a few.

This is one: Phlochton, the annoying bit of hair that just won't stick down.

That's a phlochton.

Honduras, a medical condition caused by overuse of Japanese cars.

Honduras.

Windlesham, the dreamy look on Brian Cox's face while he stares wistfully at the stars.

Windlesham,

hull for when you've hit rock bottom.

So, there we are.

Thank you to our guests, Martin Rees, Dr.

Lucy Green, and John Lloyd.

Next week is the final show of this series, and we'll be coming from the Latitude Festival, where we'll be asking the question, Art versus science.

And so, one of our guests will explain vaccination, and I'll do a painting.

Now, before we go, we'd like to address some more of the complaints we receive here on Monkey Cage from those who value superstition and irrationality above logic.

So, in the interest of balance, Robin has a prepared statement to read out.

From now on, it is our policy to no longer accept complaints from people who say that science is just another belief system and it was better when we were all eating nuts and berries, nude, and stuff, if they are using technology created by science, herewith known as technology.

From now on, we will only accept such complaints via the media of telepathy or patterns in the clouds.

So, to reiterate, no more emails or tweets from the anti-science lobby because you don't believe in electronics.

And remember, the deadline for all complaints is December 21st, 2012, because that's when the world ends.

Goodbye.

Goodbye.

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