Brian Cox On The Multiverse And Life On Other Planets | Minutes With | @LADbible

because Mercury is way too hot Venus is horrendously hot and 90 atmospheres pressure and sulfuric acid rain it melts lead on the surface right so you're not going there and the rest of them are made of gas so you're not going there either so so Mars is the only place beyond Earth that we could feasibly ever go a planet [Music] so Brown we're doing this episode of minutes with very different from anything we've done before we put a survey out to the audience ask them to send in all the questions they want to ask you what is the one fact about the universe that blows your mind the most there are a lot of things about the universe that that I find it almost impossible to imagine well actually impossible to imagine one just the size and scale of it I mean in the piece of the universe we can see there are something like roughly two trillion galaxies I think we haven't counted them all but that's a an estimate based on surveys of the local Universe 2 trillion 2 000 billion galaxies and each Galaxy is let's say around the size of the Milky Way some are bigger some are smaller but the Milky Way has 400 billion stars in it it takes light over a hundred thousand years to cross a Galaxy and there are two trillion of them in the piece of the universe we can see and we're very sure that that piece that we can see is a small bit of what may be an infinite universe beyond we don't know actually and I always say you know don't get worried about that because nobody can picture it it is impossible to visualize the Scale of the Universe and so that's the first thing I could I could then list a lot of moral things but we'll stop there for now but just the size and scale of it I think is beyond imagination there's been a lot of references to the Multiverse and parallel universe in popular culture in Italy do you think that something like this is a possibility so there are lots of multiverses actually um in physics one of them is called the inflationary Multiverse which is we have a theory of um essentially what happened before the Big Bang right you have to be careful with the language so if you define the Big Bang really carefully as the time when the universe was very hot and very dense and as I said you can't argue with that because we can see it because we can look out into this guy our best theory of how the universe got into that state is that there was a time before that and it's called inflation so the idea is the universe was he was there in a sense cold and empty and expanded extremely fast and that expansion slowed down and stopped and the energy that was driving that expansion got dumped into space heated it up and made all the particles out of which we're made and that's what we call the big Bank so that's textbook it's a textbook Theory cold inflation it made predictions some of which had been tested some incredible predictions actually about the way that galaxies are distributed across the sky because they're not just random if you look at the galaxies they're in sort of flows and rivers of galaxies that cross the sky in a pattern called The Cosmic web and inflation predicted that before it was seen actually so it's an astonishing idea and that theory has a kind of an extension called Eternal inflation which is that the inflation essentially goes on forever and it just stops in little patches so you imagine this this straight the fabric of the universe Face Time Stretch stretch stretch and then it slows down and stops and little patches and each one of those patches is basically a big bang and a universe of which ours is one so you end up with this sort of picture of a an infinite fractal Universe of of basically an infinite number of big bangs and that's called the inflationary Multiverse and that that there's something it answers some neat questions that because it if you say why is our universe the way that it is what why are the laws of nature such that life can exist for example um well the answer might be that all possible combinations of all the laws of nature exist in the inflationary Multiverse so then it's not surprising there are universes that permits things like us to exist because every possible Universe exists in the inflationary Multiverse and that that's a a well-supported theory it's a theory so this is not the same as saying there was a big bang which we know this is kind of what's the theory it's a guess basically but it is a theory that in its simplest form has made predictions that have subsequently been verified and we could go on then as the the so-called many worlds interpretation of quantum mechanics which is more kind of Marvel film kind of Multiverse where um so quantum mechanics is it's a probabilistic theories imagine a Quantum coin I call it and the quantum coin can be it doesn't have to be heads or tails it can be heads and tails it can be mixed up can be both heads and tails at the same time you may have heard of Schrodinger's cat which is a cat in a box and it's both alive and dead until you observe it or interact with it in some way and then you find out which one it is but before you looked at it or before you interacted with it it was both you've talked about the number of galaxies does any of this ever make you feel insignificant yeah I mean so um I say sometimes in my live shows there's only it's kind of a joke right so I'm not insulting philosophers here but I say there's only one interesting question in philosophy and I don't really mean it but I think it sounds funny and so the interesting question is what does it mean to live a finite fragile life in an infinite Eternal universe so that's not that funny right it's a good question what does it mean to live a finite fragile life in an infinite Eternal universe and um I think the answer is that sort of paradoxically whilst we are definitely physically insignificant I've just said you know that the Earth is one star around one that the Earth is one planet around one star amongst 400 billion stars in one Galaxy amongst two trillion galaxies in a small patch of the universe right so we're definitely small and you can't argue with that we're just effects of dust but if you think about what we are so everybody me and you everybody we're we're just collections of atoms right some of them are as old as time pretty much and some of them were the other ones everything else other than the hydrogen in our bodies was made in Stars right so so we all cooked over billions of years and we're in this pattern that can think so suddenly there's the great Carl Sagan said you have a means by which the universe understands and explores itself which is us and that sounds unlikely when you put it like that that you can have a few things that were cooked in the hearts of stars you stick them together in the pattern and suddenly he has some ideas and starts writing music and an art and things that's that's quite difficult to comprehend right but that what that happened here we know that because we're sat here having a conversation and so the question then becomes well on how many other worlds did that happen and that's where I think the value can come in because it's a reasonable guess and it's just a guess right but it's reasonable you can make the argument that there aren't any other worlds where this happened certainly in our galaxy so it could be this planet notwithstanding its physical insignificance it's the only place where anything thinks right for millions of light years in every direction I'm suddenly therefore you end up considering this planet as being the most valuable place in the local Universe notwithstanding the fact that it's small and that idea it's not just a complete random guess by the way we've had a bit of a look where astronomers have pointed radio telescopes up at the stars for a while 50 years or more now and heard nothing we've seen no evidence of any civilizations out there beyond Earth and that's a surprise there's a reasonably plausible explanation for that which is biology which is that if you look at the history of life on Earth then you see that life began pretty much as soon as it could here on Earth we have evidence there was life 3.8 billion years ago something like that and the Earth four and a half billion years old so pretty much pretty quick in geological time you get life but then if you talk about Advanced like complex life multicellular life then there's no evidence at all Beyond uh back Beyond a billion years actually really in the fossil record 650 million years ago or something you start seeing the first evidence of complex creatures so that means that on he on this planet it took over three billion years to go from single cell life to anything more complex than a single cell and then another half a billion years or so to go from the multicellular things to a civilization so it's three and a half to four billion years it's a third of the age of the universe that is a really long time if you say that's an unbroken chain of life on a little piece of rock in a violent universe and that chain was not cut for four billion years in order to get us and that might be a big ask right we live in a really violent Universe you look at the Milky Way and you look at the Arc of stars across the sky 400 billion Suns although all they will be up there at best is slime it's just slime nothing right and I think that's a reasonable guess that's my that's where I start from I mean I wouldn't be surprised if that's wrong then you go okay good well fine that but at the moment it looks like there isn't anything else other than slime we haven't even discovered Slime by the way yet we're still in the position where we've not seen anything not even a single cell on mars or you know the moons of Jupiter or somewhere like that so at the moment we are alone as far as we can tell do you have a favorite planet star or Galaxy out there the favorite planet well um it's it's a cliche right but I saw I I actually asked this is a name John I asked Jeff Bezos that question so there's a name and he said correctly Earth Earth is the best and that's true so so because of everything I've just said right I just said it's the only place where meaning exists potentially in a galaxy of 400 billion Suns so that would be your favorite planet as a result of that but beyond that it's in the solar system so let's go to to Elon Musk as mentioned the other rocket rocket engineer um so he wants to go to Mars um might well get to Mars um that's the only other planet you could go to actually in our solar system because Mercury is way too hot Venus is horrendously hot and 90 atmospheres pressure and sulfuric acid rain it melts lead on the surface right so you're not going there and there's rest of them are made of gas so you're not going there either so so Mars is the only place beyond Earth that we could feasibly ever go a planet we could imagine perhaps going to some of the moons of Jupiter and Saturn in the far future that's much more difficult what would happen if we traveled into a black hole so the old answer of what happens if you jump into a black hole is you go to the end of time that's this pure Einstein right you just so you get spaghettified on your way to the end of time which means you get stretched infinitely actually and then squashed and you'd say well you get dissociated into a strain of atoms and then everything goes to the end of time now as of 2019 I would say uh we think that if you think of yourself as information so if you think of a let's say I think very 2022 right let's say you burn a book very fashionable today's current political climate so burn a book and and collect everything that comes out of the book all the ashes and all the gas and everything then in principle you can reconstruct the book They're not in practice right but you can imagine if you collect every single thing and measure it in principle you can reconstruct the book information is conserved in all of physics which means that so basically if you can measure everything perfectly you can you can predict what happened in the past and what's going to happen in the future it's called determinism then right so the the old picture of black holes and Stephen Hawking believed this for a long time and that's about it actually is that they seem like they destroy information you can just kind of see it goes to the end of time right it's gone but and then they evaporate away and it seemed that though there was no way even if you gathered all the Hawking radiation that had come off for trillions of years there's no way you could reconstruct or went in so therefore he jumped into a black hole you'd be erased from the universe well that breaks pretty much every law of physics right things don't erase information they scramble it up make it difficult to read but they don't destroy it but now we think actually no even black holes don't destroy information so it turns out that now we think and this is very 2022 papers right if you jumped into a black hole then we do think that if a super being in the far future could collect every bit of Hawking radiation that was event that came off the black hole for trillions and trillions of years and stick it into a giant quantum computer then they Could reconstruct everything that fell in so actually in some sense you come out Stephen Hawking had a bet with John preskell about this so and it was I I can't remember I think it was the 90s when he conceded the bet it might have been late 80s but it so he had a bet and the BET was the black Stevens calculation initially from the 70s said that black holes destroy information so he thought that was true for a long time and he had a bet with John Prescott it turned out that the BET was a set of encyclopedias so whoever lost the vet would have to give the other one a set of encyclopedias and uh John Prescott asked for baseball encyclopedias and uh because of some work by someone called maldicino actually ultimately Stephen said no no they don't destroy information the information comes out it's conserved so he conceded the event and gave John preskull the encyclopedias he said what I should have done is I should have burnt the encyclopedias and giving him the ashes because all the information still right so yeah you described earlier on you described the universe as a dangerous piece of violent place what is the most likely way that the world could end well so the the world the way that the world the Earth will end ultimately is is a cinder right it's because what's going to happen is that the sun in about starting in a few billion years time actually but it's going to start growing it's going to be it'll grow as it gets older and it'll swell up it probably won't engulf the Earth but it'll get close you know the Earth will probably drift out because it's sort of lose some Mass so it probably but it'll toast it basically so the Earth will end up toasted as a cinder probably still orbiting the remains of the sun which shall be what's called a white dwarf star which is just something that basically Fades away so that's what's going to happen in about five billion years I'm laughing because it's you know well that's what's going to happen so um so that's that's how our world ends as a crisp basically it's Cinder um if you even by the end of the world you mean the end of civilization then um long before that we will had to escape because it will become the the conditions on the planet will not be will not support complex life like us it'll be too hot um but uh you know the the possibility is that we discussed we could destroy ourselves which is um you know it would be given that it's quite possible that there is nowhere else um in a galaxy then as we said before that would be a really silly thing to do so I think it's more likely we might not have to wait for the sun to do it because we might do it through our own stupidity and then can you talk a little bit about the dart that's been high there for an asteroid protection how what is that mechanism well yeah so it sounds like science fiction doesn't it you say well you know we've all seen Hollywood films where asteroids come and don't look up right brilliant film I think um where an asteroid comes in we don't even believe it so you see it and people don't even believe that things come in that's real right that you know we know the dinosaurs other than the birds were wiped out by a big asteroid impact 65 million years ago we know that so um so it occasionally big pieces of rock hit the earth and occasionally those big pieces of rock are big enough to cause Mass Devastation that easily take out a city pretty easily take out a country sometimes take out like the one that took out the dinosaurs take out pretty much every big living thing on the planet that's happened before and it will happen again um now the Big Planet Killer so-called Planet Killer asteroids are very rare um I can't remember off top of my head it's something like one every 100 million years or so roughly you'd imagine but and we had one about 60 odd million years ago right um but the little ones that can take cities out there was one in Siberia in uh I think it's 1908 I might be slightly wrong but roughly the first bit of the 20th century that exploded in an air burst over Siberia and flattened an awful lot of forest and if that had happened over a city it would have flattened an awful lot of City so these things happen what we do now is we look for them quite sensibly so we met the orbits of as the big asteroids we've got most of them we think um that cross the Earth orbits and we monitor them all the time and we have a what's called a keyhole system and it says if one of these asteroids goes through this point in space at this time then we're worried about it and we'll be very careful and we'll watch it so we're watching them um and everyone goes through the keyhole then you what you need to do is nudge it a bit so it doesn't hit the Earth and the dark mission was the first mission designed to make sure that if we really want to hit an asteroid with something then we can do it and it's hard and so we did it it's a very clever Mission because it's a double asteroid system so um so what the little one that one of them was hits there's two of them going around each other then we hit one of them and that means that you can measure the orbit afterwards of these two things orbiting around each other to see how much we deflected it so it's a smart thing to do so we're really developing the technology so that if we have to hit a big one and move it away then we can do that and Carl Sagan he said correctly the dinosaurs that had a space program they'd still be around and that's that's basically the dark Mission that's what he's doing and there are bigger I mean there are things we couldn't do anything about comets are really problematic so asteroid's a piece of rock they're in orbit around the Sun and there's the asteroid belt where there are lots of them the Comets are more like often described as icy snowballs and they come from much further out a place called the Kuiper belts or the Oort cloud so way way out actually the old cloud of comets extends probably about a quarter of the way to the next star so you can go out a light year as a this is all this stuff around that we should basically icy snowballs and they because of collisions and interactions in the kaifabelle and the Oort cloud or even passing Stars can distrib disturb just anything can disturb these things and they can come and fall in towards the Sun and we saw one recently Schumacher Levy nine relatively recently which hit Jupiter um and we we didn't see it coming until a few months before it hit I think maybe a year or something I think it was even quicker than that maybe a few months let's say and it it made a a bit of a mark in Jupiter actually when it hit it it was actually the the whole it left was bigger than the earth right in the clouds so these things they're big right and they they come in and they're unpredictable and we'd have a lot of trouble with one of those so we'd have less trouble with the asteroids at the moment we'd have an awful lot of trouble with the comments I don't there's nothing we could do actually well we will end on that note uh but that shows you just shows you there doesn't it we talked earlier about the the how long it takes to get something as complex as a human being on a planet and you've got to avoid that and so we did you know 65 million years ago or so um the dinosaurs were pretty much wiped out and that left a little evolutionary Niche for a little thing shrew-like mammal type thing and and ultimately that's why we're here if that hadn't hit and wiped out cleared the way we wouldn't be here you probably wouldn't have a civilization you can guess and so you know there would be none of the things that we just take for granted in the potentially the Milky Way galaxy so if we're the only civilization in the galaxy then it's I think it's pretty likely that if that Comet hadn't hit 65 million years ago and white dinosaurs there wouldn't be any civilizations in the Galaxy so nobody nothing could know anything you know none of this knowledge would exist so that just shows you how precarious the position of civilization and life is as Yuri was bringing the spacecraft in for the the first manual approach we were just aware that things were not going right we had another failure which meant the computer screen went down so Tim and I were effectively blind and that was the point I realized this approach is is just not good and Yuri actually his hand started trembling on the controllers

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Id: aPOCP4GHJvI

Length: 22min 54sec (1374 seconds)

Published: Sun Oct 30 2022