The End of the Universe - with Geraint Lewis

[Music] thank you um so it's great to be back at the RI again I spoke here last year and this is such a fantastic auditorium that's I'm a professor of astrophysics at the University of Sydney and as was mentioned there I'm a cosmologists right my job is to try and understand the forces that have shaped the evolution of the universe from a time when the when the universe was basically formless to the rich structure in the universe that we see around us today so what I want to do tonight is basically take us all in a bit of a journey what we want to do is not take a journey through space but a journey through time and we want to look backwards first to see how our universe evolved from its birth in the Big Bang to the universe with stars and planets and galaxies today and then we want to turn around and run the universe forward and ask what fate holds for the universe just what is going to happen as this universe gets older and older so every journey starts with a single step and before we take a step backwards into the past or step forwards into the future I think it's important to understand where we are where we are today just what kind of universe do we live in and of course the starting point for that is where are we now and we find ourselves on the surface of a small rocky planet and it's a very special planet it's an extraordinary planet because out of the thousands of planets we know that we've discovered in the universe and the trillions of planets we think are out there in the observable universe this is the only one where we have complete and utter evidence that there is life on this planet sometimes it's a bit difficult to see intelligent life on this planet but there is life on this planet ok now I'm going to touch upon life in the universe as we go out into the future a little bit so it's important to try and understand what we mean when we say life and it turns out that define in life is incredibly difficult when you get down to you know the details how you define whether what's alive and what's dead and people set up rules so right this is my dividing line this is the living stuff that's the dead stuff all this stuff on the dead side which is looks a bit alive and that happens all the time and there are arguments about whether viruses are alive where the prions are alive these things even smaller than viruses and so define in life that would take another lecture and probably a few more lectures and we would be here until almost the end of the universe trying to define what life is but what I'm going to touch upon is an aspect of life which in my opinion I think is one of the key things that life does if we're going to define something as a living organism and that's to do with energy okay all life processes energy so what we have in this picture here we have a lovely sunflower that sunflower has captured sunlight and that sunlight has been stored as energy in the chemical bonds inside the plant creatures come along and they eat the plant and they can use that energy to run their own chemical processes in their body and similarly we could eat the plants or we could eat the animals that ate the plants and so there's that just a continuous progression whereby we use and process energy and that is one of the defining characteristics of life all life processes energy of some sort and that energy not only drives the chemical reactions in your body but it also drives the sort of mental reactions in your mind when you think right we all know that you know when you have a sugar low it's very hard to think about anything you need energy to run your brain in fact it uses up a very large amount of the energy that you take in so there's actually a very strong link between flows of energy and processing of information and any time you run your computer and your computers doing very difficult calculations or updating Facebook or something it's processing information and you can feel the heat that's generated by that information being processed so if any living creature is going to be sentient and know about its environment and react to that it's going to need to have an energy flow to drive that sort of behavior now the ultimate source of energy on the earth of course is the Sun in the middle of the Sun every second 11 million tons of hydrogen get turned into helium that releases energy which takes a hundred thousand years to percolate through the Sun and then eight minutes to get from the surface of the Sun to the earth where it's absorbed by this sunflower or it lands on the pavement outside in London and makes the place even hotter all right so all life on Earth exists because we have a vast reservoir of energy right next door to us in the universe and we can use that energy and that has driven life and evolution up until the present day take away that source of energy you have no life what we'll be seeing is that energy will come to play a critical role in what life can do when we look at the far future of the universe it becomes the scarce resource it's the thing that any life that exists in the distant future universe is going to need to seek if it's going to continue to live but let's just try and remember our place in the universe as I said we're on the surface of this rocky planet our energy is given to us by the Sun which is a very typical dwarf star and our Sun is not alone in the universe but the Sun actually occupies a small patch of the universe with roughly 300 billion other Suns in an object which is known as the Milky Way when we look out into the universe we see that there are possibly a hundred billion to a trillion other galaxies out there so there's a huge number of stars huge number of galaxies huge number of potential places where there could be life but we have no idea what the frequency of life is in the universe life could be very common or life could be extremely rare and all of our observational evidence is quite consistent with this being the only place in the universe where there is life at the moment so I said this is a special planet so before we play the game of looking into the future let's work out how we understand what happened in the past okay and what we know is that people have looked at the skies 4000 of years and you see patterns of stars on the sky and people generally invented stories of heroes and gods and legends to explain the various patterns that we see for us here at the RI of course the important thing is not just the stories that people told but how they came to apply science to understand in the evolution of the universe and this all happened of course during the time of the birth of modern science and I'll just pop up this guy here this of course is probably Britain's most famous scientist second famous if you consider Stephen Hawking as well but this this is Isaac Newton in my mind should be Britain's most famous scientist Isaac Newton was around at the time when there was a just a changing viewpoint on how we understand the universe and I like this picture this picture was taken off the back of the old pal note there's people in this room who clearly have never seen an old pal no too far too young but in the old days they used to be a note on the back of it was this picture of Isaac Newton and I like this picture because there's a picture of Isaac Newton with this telescope and he observed the universe he used this telescope to see what was going on now he was not the first to look at the heavens it's reported that Galileo was the first to look at the heavens and see when he looked at the planet Jupiter that Jupiter had companions that there were moons orbiting Jupiter and that led to this general idea that there must be some sort of order to the heavens and then people wondering whether the order in the heavens is similar to the order down here on earth and if I understand how things behave here on earth maybe that will tell me how things are behaving in the heavens and so what you start to do is you start to dispel the need for gods and heroes in describing what's going on in the universe but what you want are laws of science that tell you how things behave now the other reason that I like this picture that in Newton's lap there is his book the Principia where essentially he lay down the the key ideas which became classical mechanics how things react to forces but also there he described the law of gravity and the picture that we have in the background there is sort of Newton's description of how gravity works in basically holding the earth in its orbit as it travels around the Sun and of course Newton's great insight was to realize that the force that takes an apple and pulls it from the tree and pulls it to the ground is exactly the same force that holds the moon in its orbit around the earth the earth and its orbit around the Sun and Jupiter's moons in their orbit around Jupiter so you could write down mathematical equations and you could make predictions you could predict where Jupiter's moons are going to be because they are just obeying the laws of science right no need to introduce any gods or mythical beings anywhere because it's all there in the equations now some people don't like that that leads to a very sterile universe of course where everything is just governed by mathematical equations but it at least means it's predictable right we know where things are going to be now in the 400 years or so since we had Newton the only thing that's changed is that we've gotten deeper into our physical laws we understand the physical laws that govern the universe in a lot more detail and we've peered more deeply into the universe and what we've done is developed new telescopes can see further and further out into the distant cosmos and this picture here this is a telescope that's currently being constructed in the southern hemisphere this is the Square Kilometre Array which has been built in South Africa and Australia it will be a radio telescope so it can only see radio waves and it will basically be a collecting area of one square kilometre so we'll be able to see some of the faintest things that are out there in the universe but as well as a square kilometer array we've lots of giant optical telescopes you have telescopes in space the lot look at x-rays and gamma rays and look at microwaves etc and what they've revealed is a universe which is my humble opinion being a cosmologists quite exciting okay so what we've got here we have a picture that was made by the W map consortium W map is just to tell that's in space the Wilkinson and microwave anisotropy probe its job was to look more deeply into the universe than any other telescopes but what we've got here is a picture of our entire universe as we understand it okay both in terms of what we can see and in terms of what we can understand in terms of the physics that's going on in the universe now because light travels at a finite speed when you look at more and more distant objects you're looking further and further back in time and what we have is a picture of our universe from today as far back as we can see and what we can see is that the universe has changed and evolved over its lifetime the first important thing is to realize that our universe hasn't been around forever the universe appears to have been born in an event now known as the Big Bang that occurred roughly fourteen billion years ago so our universe has a finite age but looking back we see the universe in the past was different to the universe today so today around us we see all these stars and galaxies and as we look back in the past we also see stars and galaxies but they're different to the ones today they're less formed and as we push back further and further we get to a point where there were no galaxies at all and we can push back even further and we run into the the very start of the universe so in terms of the universe's evolution you can go from left to right at this side you have the Big Bang the universe was filled with material or smoothly distributed then the laws of physics acted over roughly fourteen billion years to give us the universe that we see today and so there are a number of key features that people like to talk about the very birth itself which is something that we do not understand we do not have yet have the laws of physics to understand the very birth of the universe but after that the evolution of the universe through this rapid expansion known as inflation through the overall evolution of matter into stars and galaxies that all seems to be described very accurately by the laws of six so in fact one of the things that we like to do it's actually a very big part of modern astrophysics is we like to build our own universes okay and I have PhD students working for me that you know they generate universes before breakfast well generally not because none of them were ever up before breakfast right so early afternoon they'll generate a universe so what do I mean by that what do I mean by generate a universe well as I said we think all of the processes underway in the universe are just governed by the laws of science so if I take my laws of science my laws of physics my law of how gravity works how gases work how nuclear physics works etc etc etc and I translate those equations into computer code and I give the equations to a computer and say to the computer solve the equations for me because that's what good computers are good at I can actually generate a synthetic universe and so in the next sort of animation I'm going to show you the results of one of the big simulations of the universe that was done by a group caller Lustrous essentially what you do is you just say I'm gonna take a big volume of the universe this volume is billions of light-years across much bigger than our own galaxy I'm going to put matter in there nice and smoothy distributed like it was after the Big Bang and then I'm gonna hit go and you can solve all of the difficult equations and you can tell me what the universe looks like so when the best things were given as strongly talks you can just put on the movies and you can dip out have a cup of coffee come back when the movie ends and you say wasn't that lovely right so what we're seeing here this is matter moving in the early universe so it was originally smoothly distributed gravity started acting and pulling matter together and the matter just doesn't fall into one big lump they falls into several lumps connected by this structure which is known as the cosmic web inside these lumps gas can pull together and when that gas pools it can form stars so where you get these big lumps that's where you form your galaxies so inside these galaxies we have stars burning away but stars evolve over time and eventually the giant stars they basically run out of fuel and then they explode and hopefully we shouldn't explosion anytime now there we are right on cue okay what you've got there is a giant star that has been burning elements in its core hydrogen to helium helium into carbon carbon into oxygen to add all those elements are caught up in the the heart of the star but for life having those elements in the heart of a star is pretty pointless what you need them is spread out through the rest of the intergalactic medium or interstellar medium I should say and for that material to be recycled into the next generation of stars so that's what happens when massive stars explode the stars explode and they spit out the heavy elements that is needed for life so it's kind of sobering to think about this that you know you look at yourself and you think that this is me I am nine years old all right but I'm made of water right mostly water the hydrogen in that water that hydrogen was formed in the Big Bang that hydrogen is 14 billion years old the oxygen in the water that oxygen was formed in the heart of a big star and in fact the elements that make up me have probably been through the hearts of several stars through several generations of being formed material spat out recycled being spat out and being recycled and the one that I always like to mention is that elements like this I was told by the jeweler it's gold okay might be but gold stars don't create gold when stars burn gold is only created when stars die that's that gives you the conditions that can squeeze atoms together so hard to give you gold so I said if you want to be romantic then you should say that a star had to die to give us this ring right but we're implicitly tied to that evolution of stars there's no way we could have had life in the early universe with just hydrogen helium there's just not the complexity there to have life so what we have got of course is we've got our picture of today this is today this is a lovely picture taken in Chile this is the VLT the Very Large Telescope we're not very imaginative in naming tells the ELT has come in extremely large telescope I kid you not there's also al which is overwhelmingly large telescope we should spend more time on thinking of these names but anyway the VLT exists it's in Chile it's for eight meter telescopes all the good telescopes in the world are now in Chile because they've got some of the clearest skies you can get up very high and this is a beautiful view of the center of our own Milky Way galaxy ok so if we were in Chile your eyes do not see quite as good as this but the view is quite spectacular but we find ourselves on a rocky planet orbiting a fairly typical smallish star in a reasonably big galaxy which is at one of many hundreds of billions or trillions of other galaxies in the universe now one of the issues about when you think about evolution right let's go back to the evolution of humans is that we often make the mistake is that here we are here we are now and therefore we are the pinnacle of evolution this must be the end point how can it get better than this right but of course we're wrong humans are still evolving still changing all the time evolution hasn't stopped because we've suddenly discovered the iPhone all right we are still evolving there and there are different pressures on how things evolve but we are still evolving and it's the same with the universe you might think well hold this planet is quite comfortable and this universe can't looks kind of pretty and photogenic maybe this is the pinnacle of the universe this is the way that it's always going to be from now on how can it get any better unfortunately this is not the pinnacle of the universe and at some level this is the start of a long decline so on that happy note let's now turn the pitch around and start looking at the future now in understanding the future history of the universe we have some limitations that we're going to have to acknowledge studying the universe's evolution from the Big Bang to now you can have a telescope and you can see what's happened in the universe to guide you in what processes were important but unfortunately we don't have any telescopes that can receive light from the future it would be beautiful to see what future universe is going to do because I would help you make a prediction because you can see it right so we don't so we a some level we're working in the dark right we're going to make predictions and there will be some level of uncertainty because we don't know everything about our current state of the universe perfectly but there's a bigger problem and the bigger problem is is that we don't know our laws of physics perfectly we know that we have some very good laws of physics we have quantum mechanics you know if your iphone wants to work it relies on quantum mechanics we know that to a very high degree of accuracy we also have a really good description of gravity given to us by Einstein again GPS works it gets you down to you know a centimeter on the surface of the earth you need to worry about Einstein's theory of gravity to make GPS work the only problem that we have is that when we have conditions where we have to worry about quantum mechanics and gravity together they just do not fit together mathematically so there will be places where we go into the future that this uncertainty of how these sort of mesh together are going to cause problems so as we go out into the far future universe we're going to get a bit more speculative and I'll try and no flashier speculation meter as we go but nearby times pretty good distant times things are going to get a little more ropey so what's the first thing that's going to happen so what we're going to do is we're going to go forward and we'll go forward in steps but the steps will get bigger because the universe will have different epochs where things are important and they tend to be spaced out at larger and larger steps are we going to worry about at the moment are the next few billion years right so as was mentioned brexit might be solved in that timescale or it might not but what's going to happen well the first thing that we need to think about is essentially the end of our Milky Way galaxy now again look at that lovely picture in a few billion years it will be gone so what do I mean well here's our Milky Way galaxy it's a spiral galaxy there's a bulge in the middle stars going around the outside our Sun is one of those stars going around outside the Sun takes 250 million do one orbit around the center of the Milky Way the problem is the Milky Way is not alone in the universe it inhabits this patch of the universe with two other big galaxies one of them is called m33 or Triangulum it's 1/10 the mass of the Milky Way we don't care the other one m31 is andromeda which is about the same size as the Milky Way and Andromeda is approaching us at half a million kilometers per hour which we do the maths quickly which says in about 4 billion years it will be here so what's going to happen is that Andromeda and the Milky Way are going to collide okay so we saw there that was the initial collision stars started to get ripped off so gravity pulls the Stars starts to fling them outwards now the Sun might be one of those stars that ends up being thrown out of the Milky Way galaxy so the collision has just started now before I proceed I should point out I've got a little timescale up there and I've tried to use words to describe the the time so a billion years that makes sense we all know what a billion is we all know what the national debt is etc etc etc so we can understand trillions but we're gonna have to go to bigger numbers so there's scientific notation 5 times 10 to the 9 years all that means is 5 followed by 9 zeros that's five billion okay so you will see numbers ^ something just add that many zeros on to the end and just say wow that's a lot of time okay so we had this initial collision so if you saw that collision the two galaxies approached each other some stars got thrown off but then they separated so it's gonna get kind of exciting why because in the collision the Milky Way galaxy gets shaken okay it gets vigorously shaken by the Andromeda galaxy coming close and what that shaking does is it causes gas clouds inside the Milky Way to collapse now that gas is the stuff that gives you lots of stars but if you shake it and make it all collapse at the same time then what happens is you produce lots of very massive stars very giant stars so massive stars are hot big glow Lu and so for a little while our universe our local patch of the universe is going to look like a Christmas tree our sky will be completely filled with these hot blue stars glow in a way but the collision isn't over right gravity started doing its thing galaxies will come back together and they will smack each other again and notice that as they smack they get closer and closer they're losing energy because stars are being thrown out but they're now merging together the other thing that happens is that some of that gas instead of getting turned into stars swirls down into the center of the resultant galaxy that's formed from the Milky Way merging with Andromeda I'm gonna have to apologize in advance this object is known as milk Amida I hate the name with a passion I have to use it sorry it's part of my union card I think so there's going to be a big black hole in the center of this remnant galaxy gas is going to go and fall in towards that black hole and that gas as it falls in starts to swirl around and crash into other bits of gas and get very hot so the center of this milk or medium algometer galaxy will start to glow it will glow very very brightly okay so we will not only have this Christmas tree of bright blue stars across the sky we will also have this very active region around the black hole glow in brightly and shoot in that matter here you can see if it's a big jet of matter coming out so that's all very excited so that would be nice to see I'd like to hang around for a few billion years to see this collision but there's a problem and the problem is is that it's all gonna be over way too quickly what do I mean by that well the the massive stars that we have in the Milky Way they are there James Dean stars some people know who James nee was live fast die young Amy Whitehouse other than that my cultural references are out the window I'm afraid so giant stars live fast die young so they burn for 10 million years and then bang they're gone so that Christmas tree effect will go away similarly that gas which - swishing around in the middle of well that eventually gets eaten up by the black hole so the active galaxies the part which glows really brightly that goes away and what we're left with is the rest of the crash is really boring the two beautiful spiral galaxies Andromeda and the Milky Way which were they at the start are now completely gone we are left with this amorphous blob with a rather horrible name okay so that's kind of sad all right one of the nice things about being astronomer is looking up at the sky and see in the structure of the Milky Way in this future galaxy after the collision either we will be inside and we just have a uniform spread of stars all over the sky or we'll be outside I've been been spat out and we looking back at an amorphous blob but there's more things to worry about all right so now we've moved on we're now routed to roughly seven billion years into the future as I mentioned these galaxies collide but one thing is kind of interested in is that stars are actually very small compared to the separation between them so you're going to take two hundred billion stars two hundred billion stars smash them together and not one star will collide with another star okay so our Sun will survive the collision right the Sun will sail past all the other stars I said it might end up somewhere interesting and it might end up somewhere not so interesting but we're now seven getting towards seven billion years into the future the problem the problem is is that the Sun is currently 5 billion years old form 5 billion years ago and what I mean by the Sun is 5 billion years I mean for 5 billion years the Sun has been turned in hydrogen into helium at the core of the Sun and we know how much hydrogen there is in the Sun and so we can estimate how long the Sun has got until it exhausts all of its hydrogen and it's roughly 5 to 6 billion years so while the Sun might survive this collision it's going to run out of its hydrogen fuel now that's I've said the death of the Sun it's not quite the death the Sun doesn't die nice and quietly when the Sun runs out of hydrogen it sort of rearranges his internal pieces and tries to start burning helium into heavier elements rather than hydrogen that causes the Sun to swell it swells and cools so it goes from being a typical yellow star into being a red giant but it continues to swell and swell and swell it eats mercury it eats Venus it gets brighter and brighter and by this point the energy flow from the Sun strips the atmosphere off the earth boils away the ocean and completely sterilizes the surface this is reasonably unavoidable ok this this is what's going to happen when the Sun runs out of hydrogen so eventually we're not quite sure how big the Sun is going to get there are some that think that the Sun is actually to get larger than the orbit of the earth and completely swallow the earth so the earth will be completely and utterly obliterated and the Sun might even swell out towards the orbit of Mars after that point the Sun then goes through a rather sort of middle-age crisis whereby sort of shrinks and grows and shrinks think we all know what happened to get to the middle age right shrinks and growth but and then eventually the Sun becomes unstable and it blows off its outer layers and the Sun is gone now if this is the only planet in the universe where there is life and we haven't gotten off the surface by then then that the end of life in the universe at the earth will not survive now it's there's 7 billion years to go so we sort of hope on that time scale that we can put our differences between us and work together and think maybe it would be a good idea to get off the planet before the Sun completely evaporates it all right may take a few billion years of arguing to get to that point but this is going to be necessary if life is is going to continue it cannot hang around a single star right because the stars just don't live for long enough life is gonna have to move from one star to the other and so what we're going to have hopefully fingers crossed is that life will soar descendants of humans or maybe the cockroaches will develop technology that allows them to travel to other stars ok that's the only way that life is going to be able to protect itself as the universe evolves now the technology required for traveling to stars is hard we know we can't do it at the moment okay we just do not have the technology but as I said there's a lot of time between now and a few billion years so hopefully that kind of thing can be developed but you might sort of think well if I'm going to travel between the individual stars in our own Milky Way galaxy then how about I go large how about sort of just roam in the stars around here I think of jumping between galaxies okay so you know I've got billions of galaxies in the universe they're quite a large distance away but again as technology involves it might become possible that we travel from one galaxy to the next Galaxy and the more life spreads of course the more chance it has are surviving into the future universe the big problem is is that if you're going to do that you better start relatively now-ish why well because it's not going to be possible when we get up to the next step so now we're out to about a hundred billion years why is that well as I mentioned at the start what we've realized is that our universe today is dominated by this strange stuff that we don't really know what it is dark energy okay we know it exists because we see the expansion of the universe accelerating so something is there that's causing the University of that but we don't know what it is but it's dominating seventy percent of all energy in the universe appears to be in this dark energy and as time goes on that percentage increases it's still very close to I don't not too far into the future it's gonna be effectively a hundred percent what that does is drive the expansion faster and faster and faster which means the distant objects move away from us faster and faster until eventually they're moving so fast that any light signals that they try to set let's end us never reach here right because the universe is expanding so quickly in between the distant object and us and that means that basically by the time we get to roughly a hundred billion years then what's going to happen is that our distant universe is going to start to fade from view so firstly the most distant galaxies we see will basically freeze and then become invisible and then the more nearby galaxies until at one hundred billion years the only thing we can see are stars near us in our leftover galaxies everything else is now accelerating away from us so fast that we will never see it again so any species or civilization that arises in this time in the universe will never come to the conclusion that we live in an expanding universe why we all they take their telescopes they look at the sky and they said what do we see or we just see stars in the nearby universe and everything else is inky blackness no evidence that there's expansion no there will be no future Edwin Hubble who measures the redshift of galaxies because there will be no galaxies to see that also mean that life then is isolated it's now stuck here on this galaxy millimetre all right or on the other galaxies but now they are separated that they will never ever have contact ever again so life is going to have to deal with what's going on here if it's going to survive into the longer distant future of the universe so what's next so we're going to now take another big jump we're going to move from a hundred billion years out to roughly ten trillion years okay so the universe sits there evolved in what we're going to see now is we're going to see that remnant galaxies of the Milky Way and Andromeda as they merged and as I said when they they merge they create lots of hot blue stars that live for a very short time before exploding so all the blue stars live for ten million years and then explode and they're gone then stars like our Sun reach the end of their lives right so they store getting older and older and they die now unlike the Milky Way which has lots of gas and can produce new stars this leftover object that used up all its gas in that one burst during the interaction so there's no new stars born and all you have is this continuous death of stars as they get older and older and older and in fact there's an interesting relationship with stars is that the bigger the star the shorter it lives so the big stars live for a few million years stars the size of the Sun live for a few billion years and tiny stars these little red dwarf stars they live for trillions of years so what we're going to have is the stars continuously dying and our patch of the universe is going to become redder and redder as these little faint red dwarf stars are the only things left okay they - of course we'll be getting older and the galaxies will continuously fade over time now you might say okay like this this object that collided it produced many hundreds of billions of stars all moving around you've still got lots of these dreadful off you think that's not so bad for life but there's red dwarfs are not friendly stars what we've come to realize quite recently that red dwarf stars even though they look nice and quiet and sedate actually quite violent and active places these stars instead of just sitting there and nicely put in our energy over their trillions of years what they do is they often have big solar flares they have big bursts of energy and it's thought that those bursts of energy continuously sterilize any planets that are orbiting that star so it's going to be very hard for life to evolve afresh on planets orbiting red dwarf stars but if life has survived from our period into this distant part of the universe they're gonna have to rely on the energy that's generated by these red dwarf stars to keep them going now as I mentioned these stars are small these stars are faint and so they don't put out a lot of energy compared to a star like the Sun so any life in the future part of the universe is gonna have to work very hard to become very efficient at collecting energy and using that energy and there's been a number of suggestions on what you would do I'll just put up this picture because I think it's pretty this is a Dyson Sphere now a Dyson Sphere is a simple idea you have a future civilization that can do lots of difficult things we won't talk about how they do it we'll just pretend that they can and they find a star and they want to be very efficient and using the energy of the star so instead of sitting on a planet you build a big sort of enclosure around the star that way you capture all of the star light you can use that star light to run your life and you can expend waste heat out into the universe so that's essentially what you would probably want to do with a red dwarf star right you have a red dwarf star it's got a very little amount of energy but if you can try and capture all of that energy in one of these Dyson spheres then maybe you can continue to power life into the future the next thing that you might need to do is possibly a little more radical and the big problem is is that this is highly inefficient I don't mean just me okay I mean all of us right human living biological life is highly inefficient right given the thought processes that we generate that all the energy we need to take in and all the various things we need to do to keep us alive is its wasteful in terms of energy so energy is now becoming the rare commodity in the universe and you might decide that essentially that you may want to do away with biological forms of life and move into a more efficient form of life which effectively is a computational electronic form of life now of course there's a few problems with all of that number one we don't know what consciousness is so how you could take consciousness and plunk it on a computer and say there I am is an unsolved problem but people think that this is you know a possibility once computers get smart enough and fast enough that maybe you could have the equivalent of consciousness on a computer and that consciousness compared to the amount of energy we need to keep going would be highly energy efficient okay you would need a lot less energy to run a computer with you on it rather than having you so there might be a move away from the actual physical life into more electronic life they this see the realm loved by philosophers okay they love talking about this stuff pointed at the point out that if this is the case that in the future we move on to an electronic form of life which is much more energy efficient then it would be very easy to generate a huge number of individual conscious life forms on your computer because they're so cheap compared to having biological life forms and they say that over the entire history of the universe then the most numerous life form might be computational life somewhere near the time when we're talking about here where the universe is now dominated by red dwarfs and that we effectively are just at the start of life and most life is yet to come other people counter and say well maybe we are the computational life running on a computer around a red dwarf star which makes you think that if if this is a synthetic reality what was real reality be like let's not worry about that too much now anyway so life will have to do something kind of radical if it's going to be able to efficiently use energy and survive into the future but again there's a problem we're going to go on a factor of ten out to ten trillion years and there will come a time when there will be the last star in the observable universe there will be one star left okay and that one star once it gets to around 100 trillion years old okay it will run out of hydrogen in its core and it will again go through this solid internal sort of reach again and try to burn helium but these stars are small so they settle down for a very brief period and they become a blue dwarf star for a very very short period of time until if essentially they just go this is too hard and give up okay so the nuclear reactions the power the star basically stop and what happens then is that the star shrinks because gravity wins there's no radiation pushing outwards so the star shrinks down and down and down and what you're left with is a white dwarf and a white dwarf is a dead star it's not generating new energy all it does is sit there and cool okay so cool through from white through visible into the infrared into the radio and then effectively disappears so what we've got is that we will get to a period where our universe will just have these dead hearts of stars floating around and there will be billions of them but there will be no more star light the only energy that we get will be from these dead star hearts life is going to struggle right even a Dyson Sphere around a dead star is going to pick up very little energy and here we run into realms of rampant speculation if you're going to have life in this universe it's gonna have to seek out energy wherever it can find it and maybe instead of having life concentrated into single Dyson spheres you spread it out into something that looks like a cloud now this is actually an interstellar cloud in our own Milky Way this is not a depiction of a cloud of life in the future but this is an idea people have had is that maybe life is distributed and grabs bits of energy where it can and it uses that to power itself and it's not a new idea right there's a book by Fred Hoyle who was one of the greatest astronomers of the last century British astronomer called the black cloud where he had this idea that these clouds of interstellar gas think they could be thinking beans they have very slow processes where they somehow send information back and forth and they power themselves in our time by going close to stars which is how the problem started the book this black cloud comes to our Sun to get some more energy but it might be that in the future our life could be spread out and grab all the little bits of energy spread around and continue to drive itself so maybe that's it right we get to a point now where all our stars are dead what's left for the universe well now we have to worry about something kind of fundamental and that's the stability of matter right this table seems pretty solid I think we would all be rather amazed if this table suddenly evaporated it to nothing less in front of our eyes all right we we think of matter has been a solid long-lived object now we know that matter isn't purely stable because we have radioactivity and you can have one element change into another element so uranium can decay into other elements through radioactive decay but what are the bits that make up atoms are they stable on very long timescales so what we're going to do now is we're going to take a really big jump right so here we are at 100 trillion years we're going to jump out to 100 non million years which apparently is a word okay so we're jumping out to ten to the thirty two years and what we're going to do is think about an atom so what we're gonna do is we're just going to zoom in on a single atom here okay so everyone remembers their high school chemistry in high school physics yes that was not very enthusiastic anyway let's try and recap right what we've got in an atom we have electrons moving around the outside sort of clouds of electrons zipping around at very high speeds electrons are tiny things they weigh almost nothing but if we keep going down deeper and deeper and deeper and deeper into the heart of an atom what we eventually find is the atomic nucleus okay now the scales here are incredible the scale of an atom to the scale of a nucleus is the same as a scale of a cathedral to the scale of a fly all right that's how big the nucleus of each of your atoms are and the rest of your atoms are empty space so most of you is just empty space your mass is in all of the nuclei in your eye in your atoms when we look at an atom we see that it's made up of a few particles we have two of them we have the neutron colored blue so named because it's neutral and the proton colored red which carries a positive charge and it's the protons and the electrons interacting which hold the atom together what holds the nucleus together is that yellow stuff that's the strong force and so the strong force holds the all those protons in this very tight bundle at the center of your atom now if I take a neutron and I put it to the side and I wait after about 15 minutes the neutron decays the neutron will turn into a proton and electron and a neutrino so it will decay and it can do that through Einsteins equals mc-squared neutrons are more massive than protons so there's enough energy there for the neutron to turn into the proton plus a few other things now if we take a proton and put it to the side protons have less mass and if we do the calculations worried about quantum mechanics it looks like protons should be stay if I put a proton there it should stay there forever except again there's a problem with that and the problem is is that there is matter in the universe why is that a problem well when we use our laws of physics to predict the early universe when the universe was born there should have been equal amounts of matter and antimatter as the universe cooled down the mantle matter and antimatter annihilate leaving no matter in the universe today yet when I look around this room I see lots of matter what I looked through a telescope I see lots of matter I don't see lots of antimatter so something happened in the early universe which meant there was more matter than antimatter and so what we think is that there was an additional force one that we don't quite understand that sort of treated matter different antimatter which made more matter in the universe than antimatter okay that's all well and good the big thing is is that if that force still exists then it has a consequence and that consequences is that protons should eventually decay and we've tried to look for proton decay and we don't look at it by taking one proton and looking because that would take a long time you take lots of protons and you stare at them and look for any of them decaying we haven't seen it yet but it's thought that on this timescale of ten to thirty two years protons will decay I'll just give you a little illustration alright so this is what a proton looks like it's not fundamental particle it's got quarks buzzing around inside but after around ten to thirty two years two of those quarks will interact by this unknown force okay so to wait a long time eventually this force kicks in to the quarks will interact the proton it goes into a state that it's never been in before and it decays decays into two photons which fly off in one direction and a positron which flies off in another what that means is that on this timescale of 10 to the 32 years matter will melt okay all of the atoms in here will just steadily disintegrate away so if I waited long enough this desk would have evaporated I'd have to wait 10 - for 32 years and that's quite a long time but that's ultimately the fate of what's going to happen to the matter in the universe now life could try and grab on to that energy and continue going but things are now starting to get difficult right you can pick up these teeny bits of energy and you can use it to drive your life but then you realize that your own protons are also decaying so then you're going to come up with a way to make new protons because they will last a long time but to make new protons you need more energy so where do you get the energy so there's one source left we haven't really mentioned them very much but that's black holes I mentioned that there was a big black hole at the center of the Milky Way and that other black holes are formed when stars die so you create these black holes he's completely collapsed massive objects down into points they've got very strong gravitational fields and so you can extract energy from them okay you could drop things into them think about it this way right if you've got a black hole I've got a fishing rod I've got a rock on the end of the fish line I drop that rock in in it falls the spindle spins around I could extract that energy and run the TV and watch the cricket or something like that right but there are lots of ways of extracting energy from black holes and they will still be there in the dark so you might be able to come up with a method to use that extra energy to keep life going except of course there's a problem and the problem is the ghost of Stephen Hawking why well what Stephen Hawking famous for in terms of his scientific work he's famous for looking at black holes and linking black holes with quantum mechanics and what he showed is that black holes aren't really black if you take quantum mechanics into account at the edge of the black hole they emit teeny bits of energy okay tiny amounts but over time that energy which is emitted takes away some of the mass from the center of the black hole now over immense timescales 10 to the 100 years a big black hole like the one in the centre of the Milky Way galaxy will start to lose enough energy that it actually starts to shrink very rapidly and what you get is that if you have black holes in the universe they undergo what's known as Hawking radiation as they shrink they emit more energy and as they emit more energy they shrink even more so they get this runner back run run away feedback which essentially drives them down to a point and then they explode on all of their final masses released to the burst and this will happen to all the black holes right all the black holes will be emitting this this Hawking radiation so there will be these continuous random bursts of energy in the universe now if you're a if you are a creature and you are living in this distant part of the universe maybe you can harness this energy as black holes wink out of existence but I think it's going to be very very hard work all right very very hard work and effectively what you're doing is you're only putting off the inevitable because once these black holes have evaporated right and they're gone once all the stars are dead and their stellar hearts have dissolved there is nothing left all right there's no matter in the form of stars except there's only electrons and positrons buzzing around there are no sources of energy only this soup of photons bubbling through the universe so the universe reaches this rather lovely named state known as the heat death of the universe and what that means is we've got to a point where there's no usable energy left for life this is probably it since probably as far as life is going to be able to push it into the universe now we don't want to finish on a sad note doing we have also entered the realm of speculation and speculative physics so let's be speculative on the positive side shall we we can't really be positive about life in this universe but we can be positive about the universe itself and there are a lot of ideas that if we really stretch the age of the universe out 10 to the 2,000 plus years but the universe might actually manage to change its spots I mentioned there's this dark energy the universe that this material is there and this energy associated with space but there are lots of ideas that that energy might be able to decay and go from one energy state down to another energy state and if it does that then that release of energy as the universe essentially changes this energy state will give a new burst to the expansion of the universe okay so it will be like when you open you know a bottle of a fizzy water you get all these sites where the bubbles form nucleation sites that's where they think will happen to the universe that individual places of the universe there will be this change of energy and you'd get these rapidly expanding patches of the universe and these rapidly expanding patches would effectively be new universes now again speculation runs free we don't know what kind of universes are going to be created they might be universe is completely different to our own in terms of the laws of physics and how the universe is composed of matter and radiation or they could be just like our own and the cycle could start again you could get matter forming from this reborn universe falling together giving us stars the Stars evolving and giving us new bursts of life in whatever universe follows this one which is a reasonably happy end in his name anyway I'm gonna finish essentially with a quote from one of my favorite authors so this is this is Douglas Adams right and there is a theory which states that if ever anyone discovers exactly what the universe is for and why it is here it will instantly disappear and be replaced by something even more bizarre and inexplicable we may never actually answer the deep philosophical questions but we may live in a universe which is replaced by something bizarre and even more inexplicable but the line that really got me when I read this was the next one there is another theory that this has already happened and that this universe itself could have been born from the death of a previous universe and we may have this endless cycles of unit in life going on from infinity in the past to infinity in the future so it's almost Sonic of Buddhists finishing there but that was a that was the same positive note I finished though by putting up a picture of what the Earth's gonna look like in roughly seven billion years time and finish there so thank you you

Channel: The Royal Institution

Views: 267,601

Rating: 4.6185851 out of 5

Keywords: Ri, Royal Institution, universe, futurism, cosmology, cosmos, geraint lewis

Id: IF4UhElRUFg

Length: 57min 48sec (3468 seconds)

Published: Wed Oct 03 2018

Reddit Comments

[u/Buffalo__Buffalo]

*Gerisn't Lewis

[u/andrewcooke]

damn! geraint. you've got an australian accent. wow, it's been years. if you ever see this, hi...