How Things in the Universe Came About and How They Ended Up Within Us

good evening everybody my name is andrew frak noi i'm the astronomy professor here at foothill college and it's my pleasure to welcome everyone here in the Smithwick auditorium and everyone viewing us from their screens at home to this lecture in the 16th annual silicon valley astronomy lectures at foothill college we're delighted to welcome everyone here and those of you watching from afar this series is co-sponsored by NASA's Ames Research Center the Foothill College astronomy program the Astronomical Society of the Pacific and the SETI the search for extraterrestrial intelligence Institute all of which are organizations devoted to science and education in space science and astronomy so tonight's program is a very exciting one we're delighted to welcome from Stanford University dr. Tom Abel and he's going to talk about how things in the universe came about and ended up within us dr. Abel is a computational astronomer who explores cosmic history using supercomputer calculations a professor of physics at Stanford University and the SLAC National Accelerator Laboratory he is the director of the Kavli Institute for particle astrophysics and cosmology and this is one of the sexiest fields of astronomy looking at the very smallest things in the universe and some of the very largest things in the universe and seeing how they go together and we're delighted he could talk with us today his long-term goal is to build a galaxy one star at a time via computer modeling among his particular research interests are the processes and events of the dark ages the first few hundred million years after the Big Bang his visualizations and simulations of Dark Age events have been featured on public television the Discovery Channel and on the cover of National Geographic among many other places it is a real delight to be able to welcome to this or Torian dr. Tom Abel well thanks so much great to be here the yeah okay let's get into it so what can I have some fun thinking about the universe and so we have to spend a little bit of time of getting our mind sort of ready moving from our earthly domains out into space and I'll sort of talk for a little bit about galaxies we look at some images of get our minds ready of what astronomy is then I want to walk us through its like how we can serve a very quickly estimates how many stars are in the Milky Way that sort of a sort of a duty of being a citizen of the Milky Way we need to figure that one out then we also want to very quickly find out how many galaxies are in the universe in the visible universe that's also being a good citizen of this universe we should know about that and be be able to figure out how to do that ourselves and then I want to talk you through a little bit more of the sort of the grand stories of the big big long 13.8 billion years of history that was full of events and many of them so dear to us in had ended up making us and at the very end note sort of close up with just sort of thinking about what are the aspects actually that this whole history of the universe why should we take this quite so personal and it is very personal okay but it's actually very easy I can start out with what the universe looked like 13.8 billion years ago yeah yep not a lot going on there and that is sort of the amazing thing right sort of this this concept that the universe has an age and you know it really takes a little bit of time to let that sink in you know if you started out with a universe where you really didn't have anything and now you look out and you have all this stuff out there you know there is a time where you've got to make the very first thing in the universe and for me personally that's what sort of set me off in this career it was that sort of question of but wait a minute what was the very first thing in that thing you know that was just such a lovely question and I suppose at the time I first sort of thought about is like gee why didn't I think of this earlier I should have wondered about this before because I already knew that the universe had an age now it's very fortunate timing to get into this field sort of in the early 90s mid 90s because we learned at that particular time very spectacular things about the very early universe there was a particular satellite that studied light left over from the Big Bang it was called Kobe and it was the first time there that we saw light not only did we see the light from the Big Bang that was already found in the late 60s it was amazing amazing feet thin but there we started probing and see that there's very slight variations from place to place in the universe in a modern version of this is from a recent satellite mission called planet which made this image and so walk you just very briefly through it this is false color image there's radiation that looks exactly like a body that's very cold that's three Kelvin cold so three above absolute zero is sort of this radiation that comes to us from from the universe but it was very hot back then but the universe since then expanded a great deal in fact it expanded over a thousandfold and all the radiation there was very hot - very high frequency was sort of stretched in long wavelength we now it looks very cold to us and so when we look out at that it actually looks exactly the same in all directions it's a little bit hotter in one direction that's the direction we're traveling and there's a from our emotion there is a thing that's taken out here okay so we take out that motion then we take out the mean and then we just look for very slight variation one part in a hundred thousand variations from space to space so that's what we did to get this sort of image and now we get these variations some things are colder other things are hotter and you see it as a particular pattern to it there's sort of a certain circle size it looks more prominent than other other sizes sort of a sort of these tiny blobs here that's a from these scales we actually learn something about the geometry of the universe yeah the fascinating thing is this is radiation that for 13.8 billion years was just moving in a straight line you know all we had to do is put a detector in front very sensitive detector right because it was one part in a hundred thousand I'm not in the light okay thank you thank you thank you all right I'll just wave at you over here area so the it's a show that Toby fantastic was just traveling in a straight light we had to only put these detectors there and we get to record information that was imprinted within the first 380,000 years after the Big Bang absolutely brilliant so that's great so okay first there was nothing then the universe that looked like this and from this we can infer okay there was some regions they were slightly denser than others others were slightly under dense and this was a fantastic finding for us because then finally the whole story made sense because if there is a universe that would be completely the same everywhere well everything would be gravitating to every other place and nothing would be happening but however if we have a region there's a little bit denser it realizes oh you know it actually will try to fall together all the denser regions will try to get denser and denser gravity will try to slow it down from this rapid expansion that it's doing and physics saved right so the structure will actually form and it will form in the right time scale to eventually make galaxies and stars and more interesting things and so we'll get to that sort of bigger story mmm but first I want to sort of take us out it was really about the early part now let's just look out at our own Milky Way McNish a magnificent image here in the sort of visible wave think that our eyes can see and you notice all these dense dark regions these are just clouds of dust that block out the light that's behind them and wherever there is not as much dust we see this very milky appearance because we have so many stars that fall within a given pixel of our camera and it just washes out look if it's a hazy band of light across it ah yeah that's nice okay so that's why we live as a part and we're just one one of very many and we have this very particular viewpoint because we're twenty-four thousand light years out from the center of the galaxy and we're going around to takes us 250 million years to get around right so last time we were in this spot the you know the the whole story with the dinosaur it still had to happen you know it's just sort of real different timescales if you think about but there's beautiful galaxies like this some of bigger than the Milky Way but perhaps not so different as a disc that we're now looking on face on and we again see all these dust lanes contained in here and on top of it we see a whole bunch of reddish regions these reddish regions are usually lit up by massive stars that heat the hydrogen gas around them and make this hydrogen gas glow in this particular line that comes out as reddish light for us so we'll see that a lot when we look at optical images like this you'll see lots of little red red regions that's typically where a thousand or ten thousands of new stars have formed recently recently means in the last few million years they have to have changed the gas around it into these stars in stellar explosions really shape how gas within galaxies is distributed and how it gets thrown about it also quite relevant to us without giving things away you know obviously parts of us many of the atoms of us used to be flying around at 10,000 kilometers a second in space fortunately they're not doing that anymore okay okay we try this out with the heads who's ever been to the southern hemisphere oh you are some travelers great I hope you looked up in the night sky two favorite things is totally fascinating thing this is the Large Magellanic Cloud that's a small magellanic cloud that you can see from the southern hemisphere and these are galaxies they orbit within our own Milky Way so there's galaxies within our galaxy okay that's a good thing to remember not everybody knows that okay these two we've known actually for quite some time right too however over the last couple of decades within finding lots and lots more so we know over 50 galaxies now that are orbiting in in our Milky Way but we also had to learn new things of what to call a galaxy because some of them only have a few hundred stars in it that's sort of crazy they'd a thousand over a thousand light-years across and only have a few hundred stars in it all we can call them still now is we call them ultra faint dwarf galaxies that just means they even fainter than the small galaxies we knew before so we used to have you know over ten dwarf galaxies that we knew about it we call them dwarf right now we call them out too faint it's worth galaxies anyhow fascinating story we won't have time for that one so I'll just spend a little bit of time on Large Magellanic Cloud because I like this image here a lot because you know I'm a theorist so when I get a picture like this it's awesome because the names are all on there alright so now you know he's a strong bar in here there's about a billion stars in this Large Magellanic Cloud and you know I'm only partly joking but it's really great fun to sort of go through all the names of the individual nebulae and objects that are cataloged and look up much finer versions of them and that is one of these fun parts of astronomy that you don't have in other fields quite as much look at this I just zoomed in on the image you can see the name is still there looks like we don't see a whole lot but we always have another really awesome telescope and it's let me just flip back for my time because that's that's the really fun part is you can look at the very large parts of the sky like we did when we looked at the Milky Way we saw the whole thing was like wow but then there's so much information hidden on on much smaller scales and that's what we do here typical star forming region again we're blowing out gas forming a very strong shell glowing and hydrogen around it let's do one more so many fascinating things going on here young stars throwing out jets there's a propelled gas out while they have discs going around them there's jet material flying out of it there's another one that's actually right in there this actually came from a single explosion of a star that created what we call a supernova remnant this is now gas that's rushing out still at 10,000 kilometers a second sweeping up material there was outside of it creating this very fine filamentary structures around it as the gas plows into the circumstellar medium really fun so you know just one of these galaxies you can spend a lifetime studying now there was one dimension so we looked at scale so there's a big scale and we looked at smaller scales the beauty of physics is light exists in so many different forms we have very long wavelength light that's what we use for radio that's what we use for our cell phones we've got optical light now we're looking at a very sort of narrow band of a particular parcel in the optical bringing out these regions we have infrared light all the sort of radiation that warm bodies give off same object right so the the galaxy looks completely different in this case when we look at infrared we see all this warm dust glowing and we have a hard time almost seeing any of the stars if we go to even cooler sort of longer wavelengths with another Space Telescope this one's from Herschel looks even more dramatic of the galaxies being filled with gas that's cold some of it will still keep making new stars that's the great fun for us we can study it in the infrared in the optical in gamma rays super-high energy rates in x-rays radio wavelengths of very different kinds we can tune in on particular lines that only certain atoms give off or tune in on vibrations of certain molecules where we can study only the carbon monoxide if it's great and then we can do that for all the galaxies not just that one right so astronomy even just the looking where you don't even try to understand some of the parts yet already that parts enormous fun and so one part of the Large Magellanic Cloud is this tarantula nebula another very massive star forming regions so there's a whole new cluster being born here throws around a lot of the gas in this is by the Hubble Space Telescope now how a Space Telescope obviously it's not the biggest telescope we have but it has a huge advantage being outside of the atmosphere so no nonsense of twinkling stars right you actually get extremely sharp objects and over time now we've had it this long we actually even start to see objects move on the on the sky because it has such a fine resolution it can tell when things just moved laterally you still have to be nearby for really distant things that doesn't work it um but then first locally of course there's amazing things to study is called the Californian nebula and this star here is a bit in the background but one thing to notice is that thing is about 40 times as massive as our Sun but it's 330 thousand times as bright okay so that's just crazy massive stars you know joke about them really like the rock stars you know they they shine bright and die young it's the thing with them because obviously when you give off this much energy you're gonna consume fuel like crazy and so they run through their fuel which is all this hydrogen that they burning up in their Center we create helium they run through that very quickly and they only live a few million years then you cried so that's that would be very bad for the sudden unfortunately there we have about 10 billion years and so that difference of from one to 40 the mass of the Sun already creates a difference of a few hundred times shorter lifetime and so we have to understand the totality of all these stars and obviously ventilated this bright they really can shape gas tides around them in this California Nebula is very heavily formed by that I think we're here are we yeah we're actually usually extremely bad with naming things in astronomy this time kind of make sense actually okay right aunt I am into these spectacular supernova explosions this was literally a single star that exploded and we now started in this image is composed of different wavelengths light put together and we can sort of look out for different types of materials and over the last couple of decades we learn a tremendous amount you know we always hope they like round things that we sort of go perfectly how you could model it well there's nothing like that the real thing of course is a very clumpy distribution some very iron-rich bumps are flying out you've got the neutron stars that can be formed in some of these supernovae explosions some of them get a kick they start running at 200 kilometers a second there must be a symmetries in these explosions very fascinating topic that you know really combines an enormous amount of physics where you're trying to understand well how did all the thermonuclear fusion stopped why did the center of the star then try to contract when it then contracts what are all the things that some of the material gets flung out and the rest ends up in a neutron star in a black hole the model through all those physics has been a huge challenge for us and I'm afraid to say our computer models are not that great yet in fact many of them just don't explode that seemed to be sort of a syrup or the thing we should be trying to get right and we were working very hard on it but it has some something to do with a very subtle physical aspect of neutrinos of this elusive particle would be also a lovely story I would like to dive into but we would run out of time anyhow so here just a quick summary our Milky Way in many different wavelengths and that was sort of I was trying to you know I'm showing you the excitement I have about it from optical here that's with better image then the near-infrared we're going to sort of longer wavelengths there mid we keep seeing different parts and the interesting thing is what used to be all black here where the light was blocked in the visible away of things all of a sudden that stuff is what gets bright that's what has emitted in other way things and that's is just so awesome because this one atomic hydrogen in particular that gives off radiation in a very narrow frequency band and from that if if there's a velocity on top of it if things are moving towards us the frequency appears somewhat higher if it's moving away from us as redshift it's somewhat lower that gives us a perfect tool to measure how fast this gas is going inside the Milky Way if we know how fast it's going in and what distance it is it tells us how much mass there must be that holds it together on a gravitational bound orbit so we can measure the mass of our own Milky Way particularly well with this thing and so it's just one of these examples and you know real strong and we just get totally into that they're always measuring velocities as much as we can because that tells us velocities and distances is our thing because that we usually can turn into masses okay so now I wanna just do a sort of a really quick exercise of estimating how many stars we have and this is gonna be super crude but let's let's just try it out really quick so all I'm saying is okay but the Sun we're sort of out here somewhere looking in and if you from where we are we get a sense of actually what angle on the sky you know we see all the star is in from that angle we can get a rough very rough estimate how high is it how high is that disk and then we just have to know how a distant and so now all I'm doing is I'm taking the radius of us times the height and so I say okay PI R squared okay so that's the area of the circle now that we have times the height that's the volume of this tiny little cylinder it's much narrower than its wide that gives me the volume and now I need to guess how many stars there are per volume and for that I just need to know that the nearest star is a few light years away okay so that gives me a rough estimate a few light years will have one star in it that gives me a density how many stars I have and I calculate as I just put these two numbers together and we'll get a hundred million which is this is a great did I say million oh my god there's another extra three over there all right one hundred billion so that's a great number right and we often talk about this because it's the age of the universe in dog years there's a hundred billion it's a great number to remember so now you can remember two numbers in the same to do the same thing and so perhaps you just get that one really quick but okay now we'll do that a similar number once again and just count how many stars are in the Milky Way and for that one it also helps you know the the Hubble we had a point at one part of the sky for as long as astronomers would allow you know people get very jealous about the time of the telescope and so you can only get so many chunks at a given thing but this program where they said okay let's just stare at some black you know dark sky part patch of the sky for a really long time that's where you could get many astronomers to agree sure let's try that right good and so it's a very small field I mean if you compare it to the size of the moon it's like the tiny little region here and if you wanted to map out the entire Skai we would have to do 32 million of these little patches so that gives you a sense of how little Huckle actually sees it almost sees nothing of this guy is one you know party or one part in 32 million that it can see but one pointing okay that's almost nothing right so you can't we couldn't use Hubble to study the entire sky to forget it however what it can do is study that patch epics wonderfully well write fantastically well and so we have these deepest images it was just a really wonderful thing for us to study of what the universe looked like going back in time right because all for some of these galaxies it took billions of years for the light to get to the eventual camera so now all these little blobs and all the little dips and tiny little things that are small fudges even those are still galaxies there's almost no stars in here and it's all all just galaxies distributed over cosmic time so now let me zoom in we'll do this quickly and I'll just pick one Chris cent of the whole area so I I really it just went in sort of a tenth on one you know sort of a tenth on each side now we have one 1% of the total area and why don't we just everybody just count how many little galaxies you find there's one there's one there's one just sort of go through what you what do you think it might be I only did this half the other one has more anyhow I got two let's see we've got two twenty more right forty fifty sixty seventy okay we're taking it easy right so around there fifty sixty good yeah any magic that was the job of many of my college I mean so you know in particular what we get excited about is we look for the faintest smudges that's the greatest greatest possible thing because that's most likely the farthest away thing because you know the further things are away the faster they're moving away from us in this expanding universe and so when you get some smudge like this this one's a lot more interesting than this one to this subset of astronomers right but through that we found galaxies at earlier times that we've never seen with any other telescope yeah let's put these numbers together so we did fifty roughly in this field but we only counted one percent okay so we'll have to do that times a hundred so okay five thousand and then we have to do that times thirty two million right because we only looked at that spot and wow it's almost again 100 billion it's a little bit much a little bit more 160 more or less same number again so we had a hundred billion stars in the Milky Way and we have a hundred billion Milky Way galaxies in the observable universe and yeah so you should own this number now because you actually figure it out yourself right mmm okay so let's check out a little bit the local parts for us now and so I'm gonna take in a little journey directly from Earth and you one thing you notice right away you know again I'm a theorist but this constellation I actually know okay that's a windsock on winter conservation Orion's belt there's a sword hanging from it that's over the elbow that's the head and there's like some sort of bow over here and he's like hunting beer or something over there very busy very busy guy but the remarkable thing of it is as we fly towards it all the constellations gone already there's only a few things in this case the belt actually there are relatively close to each other those stars but you see even now that's dissolves you see the Orion Nebula alright nebula the Horsehead Nebula constellation is obviously our chance projections on the sky but the crazy thing about this movie is the location the color the luminosity of every single star is correct these are actual measured position now it just goes sort of on a tour and visits a few interesting places around us that's a rosette nebula it's again about 10,000 young stars form there in the last two million years lighting up all this nebula around it we're already a few thousand light years out okay so we're going a crazy speed we're not doing relativity the light would be highly blue shifted to us and it would be very very dangerous actually we could much faster than the speed of light we have other problems and yeah that's the Crab Nebula you see that there was a little blinking in there that's a neutron star that in reality is going at 30 times a second and we sort of slowed it down here then you get that impression so now we come to the only made up part of this movie okay nobody's ever seen the milky way from top right where we're a few hundred thousand light years away depending on your types of camera but now here all these other galaxies was the Large Magellanic small Magellanic Clouds all of those every single dot here again is the correct galaxy at the correct location that's our sister galaxy Andromeda the Triangulum lovely little thing now there was one more thing we had to do in this movie it was again cheating we made the galaxies a few times bigger than they really are because otherwise the movie looks even more boring in the sense that it empty space right so we made them a little bit bigger and that's why this cluster here the Virgo cluster looks quite busy now there's thousands of galaxies growing around each other whole scales here on the hundred million light year scales but again this is all the things we learned all sort of put into this animation and you see galaxies you've got round balls you got to the flat in structures one sort of sheets or filamentary structures and that's what gravity likes to do if you give it time you know you start out with some ellipsoidal thing first it wants to collapse one axis this gives you a sort of a sheet like thing then the other axis collapses you get sort of a long cylinder I'm the variant until you think of sausages okay then the third axis collapses you get something round right and that the that's what these galaxies clusters feeling there's about 1% of all galaxies are in such galaxies cluster the very centre has this total monster galaxy we call it m87 and it's got this funny little thing here there's actually a little elongated thing sticking out which is material being thrown out at almost the speed of light a very good fraction of the speed of light by the central black hole which is three billion times as heavy as the Sun total monster black hole in there oh my poor computer is suffering trying to play backwards okay so well we'll save it from there but that's the part that we're getting all excited about as astronomers because in a few billion years Andromeda will merge with the Milky Way which will be a great time for astronomers all right you would be studying all these stars right in front of us phenomenal time okay it takes a very patient astronomer I think it's a very interesting story for the long-term evolution you know the two galaxies will come together will make one really big one but also Andromeda itself has tens of these dwarf galaxies that we touched upon earlier all of these things will sort of sort out completely new orbits and make it nice a very nice new galaxy okay so I'm having fun with this part so I'm gonna go a little bit quicker on a couple of these things and take us back to that story of you know where it all came from and so studying this radiation left over from the Big Bang provided us incredible insight of how much gas is there so how much hydrogen helium right since we directly see the radiation it tells us okay how much radiation there was you know so that's a great thing to measure but we also learn about how much mass was around because the scale all these little dots those are how big those regions are actually have to do with how much mass there is because gas will fall together and will be held together by that gravity and it's as a compresses gas it'll try to appear warmer right just when we use it of heat or if we sort of pump up you know the classic videos with a bicycle pump you'd have to pump really well but you'd notice it gets warmer and then use of compressed gas the that's where you get some of these warm sports so there is a connection how warm it gets with how much gravity it is and so it's even in this cosmic microwave background radiation have we been certain to find evidence for dark matter some really unknown thing we've our best guesses at some particle you know perhaps not that not that different from the neutrino in the sense that it can go right through earth and us and not interact with anything but probably not moving as fast otherwise we wouldn't get that structure so we have now many different ways of how we found dark matter whether it has to do with how galaxies move themselves how galaxies move internally whether we look at those images we see how dense things get we can only explain that if there's dark matter so we have many different types of evidence but this provides us a great way of measuring how much there is 25 percent or so of the total amount of energy around and then even more mysteriously before it found this crazy thing that you know we didn't have a better name for the dark energy but it's it sort of makes the universe accelerate over the last eight billion years it's very very weird thing but by sort of combining these images and probes of the very early universe with all the things that we can measure here that's where we can put put together the comprehensive picture to make this work okay so yeah in a nutshell we still have measured out you know what the universe is made of that was great because even 20 years ago we used to argue about this stuff how old the university is how fast it's expanding some of this we just argued well factor of two back and forth now we're down to accuracies of a few percent on many of these numbers and that was you know just a phenomenal thing to be so lucky to be around at this time so so if it's been I mean fast what a ride you know and I mean I just started exactly at the best time well everybody would say that I think you know you know the previous years also were so full of so many fun discoveries any answer okay we know what the density structure in the early universe looks like all there is how much stuff we have great then it becomes a homework problem all right this is a physics thing you know what you're starting with if you know how gravity works how gas moves around all these other physically effects well it didn't you know you'd better just work out what happens next in that in a way sort of the story of computational cosmology that we're doing and here's sort of a visualization we did recently for a planetarium show called the dark universe I hope some of you may have seen that the Cal Academy was narrated by Neil deGrasse Tyson and what we did in this animation we just show you the entire history of the universe and how gravity makes dark matter comes together and what we did was a very novel thing for this show is to show the dark matter in black we used to do false-color and then we asked people so where's the dark matter and they're always pointed in the empty regions because that was the darkest one and so I'm talking about it but instead of a key thing is really you get the sense it's everywhere in that stuff yeah it then falls together and makes finest structures but that's what the dark matter does and then all the luminous things here these are just the very densest regions that's where you have stars that's where you'll get galaxies but all the stuff in between is just dominated by the dark matter right and so calling this one cosmic web those are actually pretty good naming better than you know we were in better shape than usual I guess on this one anyhow so all my research then over the last few decades was always about you know taking these initial conditions in evolve it forward figure out what are all the physical things that we need we need gravity the fluids the chemistry actually how you build up molecules how radiation from the star is coming out really changes the gas around it and the key was for us you know that's a little nerdy bit is how to do this over many different length scales because the star is a trillion times smaller than the Milky Way and so you actually have to capture it like all these processes of how does the gas all come together over these very large scales so we've built some crazy long codes and I don't expect you to read all of this but these are hundreds of lines of suarez hundreds of thousands of lines of source code now where we turn these physical equations into algorithms that we then tested very carefully to make sure we awkwardly solving the equations in the coupled fashion and where we make sure that we can do this over this very broad range of scales and that's what we call adaptive mesh refinement act as a way where every time there's an interesting part you add more resolution you had more information element and tracked what happens there and so through that we were able to study many different objects and so the highlight for us was to study the very first object first things first I guess and we had over decades we were arguing yes there will be an object it has a million times the mass of the Sun but then some folks argued well you make a star cluster no there's argued no you make a big black hole you know but they all started with the same arguments they all started with the same temperatures densities evolutions early on but you just can't work it out on a piece of paper what comes out next and that's the another really fascinating thing about using big computers in these types of calculations that we can use it to build intuition of under which physical conditions do you have what outcome and so here is sort of a quick summary which is from a movie we produced for Discovery Channel so ok so about a thousand light years across the light are the color the higher the density of the material it's the hydrogen helium gas that we have at about a hundred million years after the Big Bang what do you notice is gravity is pushing all this stuff together and you get this very you know crazy patterns it just is turbulence that gets in generated by all these gravity driven by all this gravitational motions what we're doing now is flying in towards the center so we're moving to smaller and smaller scales and you notice we go to ever denser regions and then the most central part it's a bit more roundish out here let's see you get the sense already that it's somewhat flattened we now get more of a disk like structure more flattened structure with a dense blob in the middle in these dense blob is a protostar that forms proto just means that it's not a full star yet but it's just getting going it has 10 times the mass of Jupiter and this flattened object around it is falling on top of it at a very rapid rate so we're building up a really massive star very quickly and it was just so much fun to see that because we never had you know the computer code where we could actually zoom in to these small scales and do it all in one go and then we could see oh wow oh yeah here we skipped three million years and there was a supernova thing exploded so a whole bunch of stuff is flying out now at high speeds so now let me try this and we'll see whether the audio works because there we did a version of this for another planetarium show called a journey to the Stars let's see does the audio work see that I can go back then now that we have it we you can see whether you recognize the voice but these stars didn't last long they were massive they burned hot lived fast and died young after they heated the gas nearby and ran out of fuel they blew up in gigantic explosions called supernovas look another one's forming and there it goes the first stars changed everything combining hydrogen and helium into new elements such as oxygen and carbon then supernovas blasted these elements into space supplying ingredients for stars and planets to come and though it may sound incredible your body actually contains about a teaspoons worth of this stuff formed thirteen billion years ago by the very first stars there was only an invisible substance called a dark matter hydrogen and helium gas dark but whatever sort of you know it was great to be able to build those balls you make the star then you follow how the radiation comes out then you follow how it explodes now you see how they have the elements the carbon oxygen goes around that obviously the next thing you want to do is keep going right until we're that sort of the the mater that oddly was hinting at is we'd love to build galaxies one star at a time like literally build up exactly those structures on a computer and there is there's many uncertainties still of exactly how what the masses of the very first stars are how exactly they evolve so we run many different realizations of it to learn about what the very first galaxies might look like into that movie here just flies around a little bit of some of the very small dwarf galaxies that we've made early on okay I had a couple more things that I I want to get us to take it a little bit personal and so there is one aspect now that yep we build up really small galaxies with individual stars but then if they zoom out to be a bit again and to think about the galaxies themselves that are close or to think about how the Milky Way itself may have formed I want to just show you this animation we did which is also in the American Museum for Natural History now but you you see all the build up of the individual stars and every single dot here again is a galaxy formed on a computer there's millions of resolution elements for every single one of them where we track you know how dense Achatz how hot it gets how many stars you have what metal content or heavy element content the stars have and you see all these dust lanes in here just like we have in the Milky Way and you see all of them merging and the young stars are blue or white and there's a short phase where they light up and red that's those aged 2 regions that we saw in the images as well and you will see lots and lots of little galaxies orbiting the bigger ones and it's really here where we we can play through on the computer exactly how they build up of the individual galaxies works this was only about 2 billion years so is the early time off that build up so I took you on this whole journey a bit from you know thinking about individual stars think about our Milky Way think about the whole history now I would often like to see whether you want to take it a little bit personal so a lot of our atoms obviously all the hydrogen that's in water the h2o the H part that's been around since the Big Bang right so that's nothing changed those protons are exactly how they were even 3 minutes after the Big Bang nothing new on that front a lot of the auxin oxygen carbon and many of the things we have they obviously formed in stars later on and we know this but it's old stuff it's all the stuff that was around when the Sun was made it was all this stuff that was around when the earth formed so actually all the atoms in our body are older than 4.5 billion years the tiny exceptions of sort of radioactive element but that means you're very old right your minimum age is four and a half billion years it's actually much bigger over if you average it out the even for these very first stories that were made straight out of the material lifter of the Big Bang roughly about to the pinky size part of atoms had contributed we're part of these very first generation of stars and that's the thing that sort of question here is it like how many stars contributed making the atom I somehow had a very clear answer and it was three and I had no idea how I got to that answer but it was just another gut feeling you know that gotta be right but then I sort of started thinking more about it and you saw this in some of the movies of how much mixing goes on and how much the material gets sort of smushed together I think my best answer now is my best guess informed guess is about a billion stars that there's really I mean we have many more atoms we have a ridiculous amount of atoms at our bodies these are amazing numbers Avogadro's constant that tells you just how much how many atoms you have anagram that's a crazy large number much larger than the number of galaxies in the milk in a much larger yet then the numbers of stars in the visible universe sorry is that the other way how many galaxies is there at the observable universe more that there's stars in the Milky Way there's a ridiculous number compared to this the billion is actually nothing so if we have a billion stars most likely contributing to making us but the other part that sort of part of this is that every single one of us at one point used to be over a million light-years across yeah I'm still thinking of taking a diet though but never never want to expand that far but it is a really interesting sort of as you study all these different aspects we talked about there there's always this very personal connection and very clear thing of you know it's not abstract in that sense it's really right right within us you're probably wondering about this funny image here to me the first realization I'm sure many of you appreciate this already is when you have when you throw something in water and you see the water wave travel out very clear there's information we're having out first a small circle then there's a bigger circle in it you know it goes to a certain distance clearly there's information being transmitted you barbel over there because something happened over there so information but nevertheless water molecules never made it over there they just went up and down right there's just a wobble information goes but the atoms don't and then for us it's kind of the other way round right we are you're who you are and who we think we are but the atoms we have in our body they move through in the sense that you know I don't have the atoms anymore that I had as a baby right you know we eat sand you know we you sort of turn through this but the information is all still here and so that just that was a motivation to have that one and so then I'll just spend ten seconds very quick to do advertising for us before I leave up a summary slide and we'll we'll do questions and the answer is Chi PAC is the scoville Institute for paragraph Services in cosmology is super close we were sort of joint between Stanford University endless Locke National Accelerator Laboratory that's why I'm a professor of both places oh I might cut this off we'll have an open house which is for the public we had it over I think about 1,500 people come last here sort of a blow-up planetarium we'll do some of these movies that you've seen in three dimensions so you put your goggles on at yet another dimension is really fun we started five in the evening there'll be some stargazing and I'll hope you'll come they'll be an event bright page you can sign up for and I think in the local papers you'll you'll see quite a bit of us it'll be its lack in and we're using part of this brand new building which some of you may have seen as you drive down Sand Hill Road first time you can actually tell slack from that road and yeah I hope you'll do that and so just in summary key points we learned about the age of the universe in dog years being a very important number of being a hundred billion stars in the Milky Way a hundred billion galaxies in the observable universe and that is really a very rough number we also learned that there's lots and lots of little galaxies that we didn't even count so the real number is actually larger than that so we got a lower limit on how many galaxies are in the observable universe there's a crazy number of dead stars that helped in making us and everything around us and I hope sort of one thing that you'll take away from this is that supercomputers these this computational modeling is one other way where we can learn and make sense of the universe okay thanks so much

Channel: SVAstronomyLectures

Views: 10,159

Rating: 4.5384617 out of 5

Keywords: astronomy, science, astrophysics, science news, comology, star formation, galaxy formation, Tom Abel, computer simulations, big bang, life in space

Id: K2dUFYzLbJ8

Length: 53min 48sec (3228 seconds)

Published: Wed May 25 2016