The First Fraction of a Second | Crash Course Pods: The Universe #1

so we live in a universe yes how big is it uh that's a great question it depends on what you mean by universe so already already it's complicated oh no oh no a few years ago I came across a book by the astrophysicist Katie Mack called the end of everything astrophysically speaking the book tells the story of our universe how we understand its beginning its expansion and what we know about its future including well the end of everything we are only here for a little while of course and the universe will be here for much longer but everything we've seen so far in our universe will inevitably die and it seems the universe itself will as well in short there will be no season 2 I was so moved by this book that I wrote Dr Mack an email to thank her for writing it she replied and we struck up a friendship we make a bit of an Odd Couple I'm a novelist by trade who barely passed High School physics largely by being the kind of student my teacher did not want to have in class for a second consecutive year Dr Mack meanwhile holds the Hawking chair in cosmology and science communication at the renowned perimeter Institute but she is a patient teacher and I am curious about the vast and strange Universe in which I find myself so we decided to make a podcast together about the history of the entire universe including the parts of its history that haven't yet been written and more broadly about why we seek to understand what's keeping the Stars apart as EE Cummings once wrote here in the first episode Dr Mack helped me understand the Big Bang which initially caused me a lot of anxiety but then by the end of our conversation I learned something so phenomenally beautiful about the universe that I've been clinging with hope to it ever since which is that we are not just made of Stardust we are also made of big bang stuff with pieces of us directly born in the vast first cacophony here's our conversation okay I already have a lot of questions okay great I would like to ask you why there is a universe oh why there is a universe and then I want to follow that up by saying that in my line of work there's a famously boring question that is the question that everyone asks which is where do you get your ideas and in my wife's line of work she's a curator of Contemporary Art there is a famously boring question which is what is art right is the question of why there is a universe the astrophysicist version of those questions I think that it's just a question that really has no answer and there are very few people in astrophysics or physics or cosmology any of those areas who are thinking really about that question in the sense that there are some people working on like how did the universe begin what started it we kind of step away from that kind of question because that suggests purpose or intent or meaning in some way that that there's there's no empirical approach to that to establishing purpose yeah yeah do we know why there's stuff in the universe we we don't we really that's that's a really am I again asking a why question and you don't want me to ask a why question no it's not that's not a why question that's an embarrassing question because because um our current understanding of of the theories kind of suggests there shouldn't be stuff like oh there shouldn't be stuff that's discouraging yeah there's this um concept of matter antimatter asymmetry so antimatter is it's kind of like a mirror image of matter in in some sense there's an electron an electron is a particle that's part of the the atom there's an antim version of electron called a positron has the opposite charge and there's some technical mathematical sense in which they're kind of reversed in some way and if you take an electron and a positron and you put them together they will annihilate with each other and create gamma rays this is why you know spaceships in science fiction often use antimatter as propulsion because if you Collide matter and antimatter you get a big big boom right like if you if you started the universe with just a bunch of radiation and that radiation then turned into matter it should turn into like an equal amount of matter and antimatter so if you just had sort of radiation turned into matter and all that and and in the way that our equations kind of suggest it should work you should get the same amount of both and then they would just annihilate against each other like they would just and then you would just have radiation again you wouldn't you wouldn't have a whole bunch of matter and almost no antimatter which is what we see so if you if you got into the universe everything we observe is matter unless there's been some kind of big high energy event like a pulsar or a supernova or you know a some kind of high energy beam of of gamas that that splits into electrons and positrons then you can get antimatter in those high energy events and you get a little tiny bit of it and then it annihilates against the matter but all the stuff in the universe is matter like all the stars and planets and all that that's made of matter so there's way more matter than there is antimatter which means at some point there had to have been something that like changed the balance that created an asymmetry between matter and antimatter so that all of the antimatter would be annihilated away and there should be matter left over okay so I know we're only a few minutes in here but this point is really really important so I want to emphasize what Dr Mack is saying here matter is everything you see in the universe it's you it's me it's planets it's stars and galaxies and antimatter is essentially the the opposite of matter and when matter and antimatter meet they basically cancel each other out so nothing but energy remains based on everything we know about the universe there should be equal parts matter and antimatter but that's clearly not the case because you're listening to this and I'm here trying to explain antimatter to you so there is more matter than antimatter in our universe and that is the reason our universe exists and we don't know why and we we don't know why that happened so we don't we don't know the mechanism for that there are theories but we don't have an answer to that question but it had to have happened at the at the beginning right CU we know there's been stuff for a long time yeah yeah I mean our best guess is that it happened like sometime within the first like fraction of a nanc basically what really yeah yeah so it happened it happened very early on like before uh whoa whoa whoa we know what happened in the first second oh yeah yeah we can go down way earlier than that we have we have a lot of information about the beginning we know what happened in the first second of the universe yes the first nanc of the universe the first fraction of a nanc of the univ we can we can go down with reasonable confidence to a microsc well actually let's see um maybe like a fraction of a nanc something like that we're pretty sure we have good like theoretical and experimental evidence for what happened in that time before that things get fuzzy we have a really really good theory but we're not certain okay so that's great that's great we know what happened in the first fraction of a nanc yeah what was that take me back okay okay to the very beginning of the universe and then after you tell me the story of what the first second the first nanc I'll get i'll get into the first minute or so yeah how the heck do we know what happened in the first minute of the universe 13.8 billion years [Music] ago okay okay so I'll start with the Big Bang Theory when people talk about about the Big Bang Theory usually what they mean is like they they're like oh yeah I heard you know the universe was a singularity is a tiny infimal point then exploded in all directions and that's not that's not really what we as astronomers mean when we say the Big Bang Theory when astronomers say The Big Bang Theory we actually mean something a lot closer to the theme song of the TV show The Big Bang Theory because I use this example because it's actually pretty good um in that theme song that says the whole universe was in a hot dense State then nearly 14 billion years ago expansion started then the song goes on to other things right but that's that's it the so the Big Bang Theory is just the idea that the Universe was hot and dense in the beginning in 13.8 billion years ago it was it was hot and dense and it's been expanding and cooling since then the origin of that theory is the idea that currently the universe is expanding right so we observe that because we see all the distant galaxies are moving away from us essentially what's happening is that we see the light from all these very very distant galaxies that light is being kind of stretched out by the expansion of the universe so what that does is it moves it from sort of visible light to infrared light as the the wavelength is kind of stretched out and it's a similar effect to like if a siren goes past your house and it goes into lower pitch you know like that the same kind of thing happens with light when things are moving away from you they get redder or or to longer wavelengths when they're moving toward you they get Bluer to shorter wavelengths and this happens at all the different wavelengths of light you know from Radio to gamma rays and so on so anyway we see we see that distant galaxies are moving away from us they're moving away from each other there's more and more empty space happening all the time the universe is expanding it it's doesn't mean that like objects are expanding it just means that there's like empty space in between objects that it's expanding and we've known that the expansion is happening we've known that for a long time since like the I guess 20s 1920s it's not that long well I mean since we started be able to know that like there are other galaxies essentially we started to see that that that the ones that are far enough away are moving away from us right the conclusion you get from that is that if the universe is expanding now it must have been smaller in the past like if all those galaxies are getting farther away now they must have been closer together and you know if you push things closer together it it makes them hotter you know it makes them denser like you can squeeze things and they get hot and dense and so you you can just kind of extrapolate and say well the beginning of the universe things must have been hot and dense and really close together right and then you you kind of keep going with that extrapolation you you arrive at the idea that the Universe was this kind of hot dense soup of energy in the very beginning and that idea has been around for a long time it's been kind of floated in different ways and the kind of confirmation of that came in the 1960s when we started to actually see the light of that hot dense soup so we know that the universe is expanding both because we can tell that galaxies are getting further away from us but also because we can Glimpse this hot dense soup that the Universe was at the very beginning so we have two independent ways of knowing that the Universe used to be a hot dense Place yeah essentially I mean one is kind of indirect evidence in the sense that you know you just kind of extrapolate the expansion backward and and you get that everything was close together but the seeing seeing the light of the hot dense early universe is very direct yeah what's what's happening there is that you know if you look at at distant objects you're looking at farther into the past because light takes time to travel and so you look at the sun it's 8 minutes ago you look at nearby Stars it's years ago different galaxies millions of years ago you can keep going with that and one would expect that eventually you stop being able to see galaxies because you're looking at so far away that you're looking so far back in time the galaxies haven't formed yet and if you look far enough away you should be able to see that hot dense bright shining universe and it's it's counterintuitive because people think like oh if the universe was small like there should be some direction that the Big Bang was and you look toward that direction but it's not what what it is is that the whole universe was hot and dense so imagine like a large Universe a large space and the whole thing is filled with this like hot dense plasma and then the whole thing is expanding and cooling down and if you're in one spot and you look far enough away you can look far out into a part of the universe where from your perspective it's still in that early hot dense State it's very hard to picture I'm going to imagine incorrectly that we can either look to the left or the right okay if we look to the left far enough we will see that evidence of of what the universe was like when it was hot and dense because we can if if we see all the way out and then we can also see that in any direction is that right yeah I mean what we're seeing is we're actually seeing the universe as it was when it was hot and dense because we're you know we're looking at it as it was 13.8 billion years ago and if we look at a part of the universe that's so far away that the light took 13.8 billion years to get to us then that means the light that's getting to us is the light from The Big Bang the light from that hot dense primordial soup and so yeah we see this like wall of fire around us this like shell of fire yes yes so is this wall of fire which is a very helpful way of imagining it for me is it equally far away in every direction we look yeah yeah just cuz like you know the time that the light took to travel is the same in any direction we are in the center of our observable universe exactly and so this wall of fire is the same distance from us in every direction but if we were in a different galaxy the wall of fire would also be the same distance in every direction because that would be the center of of the observable universe yeah yeah it's it's very much like if you're standing on the earth and you look out in all directions The Horizon is the same distance from you assuming you're on a flat like let's say you're in the middle of the ocean so we're not getting complicated with mountains and stuff yeah um the the Horizon is the same distance in every direction and it depends on where you are if you're in a different part of the ocean The Horizon is the same distance in every direction but it's not the same part of the ocean that you see so there's your observable ocean which is the part within the Horizon and we have an observable universe which is the part within our Horizon which goes out to this this distance the light could could have traveled in 13.8 billion years okay okay yeah and and so it's kind of this weird thing where when we look out into the universe we're like flipping back in time we're like looking at this sort of scrapbook of the universe because the farther away we look the farther back we're looking so we're kind of we're kind of seeing the cosmic timeline very directly when we look out into space and so we we can't see you know the Andromeda galaxy as it is today we can see it as it was you know millions of years ago we can't see the Sun as it is right now we can see the Sun as it was eight minutes ago however far away you're looking you see it at a different time because of the way that the light has been traveling so when we look at something you know billions of light years away we're seeing it as it was billions of years ago and and that hot primordial soup that wall of fire is actually 46 billion light years away because the light has been traveling through 13.8 billion years but the universe has been expanding so it's been carried away from us in that time wow it was actually a lot closer when the light left it so as Katie just explained to me everything is getting further away from everything else and if you look far enough into space you will see the beginning of time when everything was vastly closer together it's so very wondrous and strange to be hurdling not just through space but also through time in a universe that is not only expanding but is expanding faster than it did yesterday like I'm astonished that's happening but I'm even more astonished that we know it's happening but maybe the weirdest part of this whole shebang for me is that it started and will also end like for each of us how weird to be finite within a plausibly infinite Universe anyway that's why there's life insurance a way to make things a little easier for those we'll all leave behind policy genius is the country's leading online insurance Marketplace and with policy genius you can find life insurance policies that start at just $292 per year for $1 million of coverage some options offer same day approval and avoid unnecessary medical exams and policy genius has thousands of five-star 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just like there's a horizon on the Earth but there's no Edge to the Earth in that sense like it kind of like you can keep walking around the earth and you just keep going forever it might be that the universe is like that that maybe it wraps around itself maybe it doesn't maybe it's just infinitely large in all directions and just you can just keep going in One Direction Forever we don't know we don't have any reason to hypothesize either it's infinite or finite because we don't have EV any evidence for it to have a boundary and it would be hard to find that evidence since we know that we can't see past the beginning yeah exactly so so we can't see past our observable universe which is defined by you know how far lights traveled since the beginning and since in our observable univers we see no evidence for an edge if there is an edge beond that we wouldn't know and we never could know yeah so the whole universe could be infinite and it could be just growing anyway which is like a thing that because you can have different sizes of Infinities in mathematics so it's possible that the early Universe was an infinitely large hot dense place and the current universe is an infinitely large less hot less dense place it's just that those are Infinities of different sizes yeah yeah essentially yeah okay that makes me nervous I feel anxious I'm sorry personally I would prefer I liked the image I had when we started out that it was just a singularity that all the matter was just inside of an infinitely small point that made me less anxious than an in infinitely large hot dense space that led to an infinitely large less hot less dense space I mean it it it probably isn't going to help but you can also have a singularity that is spatially extended and still infinitely dense yikes no that made it worse you're right that made it worse [Music] Okay so we've been talking about the mysterious existence of matter and the expansion of our observable universe but before getting too much further I just want to zoom in on the idea of the singularity The Singularity is the idea that the Universe was once an infinitely small point and then it started to expand and has been expanding ever since that's a story about the beginning of the universe you may have heard before but it turns out it may be too neat of a story to actually be true I'll let Katie [Music] explain okay but we don't we don't know if there was a singularity at all CU when we when we do this timeline of the very early Universe it turns out that that just saying there was a singularity and it was everything was super super hot and and like infinitely hot and then it's expanded and cooled just following that timeline doesn't doesn't work let me just kind of tell the story as we think it went and then we can talk about why why we think that okay so maybe there was a singularity we don't know if there was or not the reason that people talk about a singularity the reason that that idea comes into play is that if you write down sort of the equations of how a universe can evolve how SpaceTime can evolve then there's a solution to those equations there's a there's a mathematical picture that works where the universe evolves from a singularity expands and then either keeps expanding forever or evolves back into a singularity in a big crunch so they're kind of different ways that that can go but those are consistent with equations of general relativity the the gravitational theory of the universe but if you actually work out like what the consequences of coming from a singularity and just expanding in a sort of in in that normal way if you work out those consequences you you get a universe that doesn't look like what our early Universe looks like so when we look at the the background light of the early Universe the the light that's at the sort of wall of fire in every direction the properties of that light the essentially essentially it's like it's too uniform it looks to be basically the same in every direction in a way that wouldn't make sense if the universe really started from a single point and then uh expanded and it's a complex story why that why that's a problem um it has to do with the idea that you know there should have been kind of quantum fluctuations that changed the the properties of the universe when it was very very small and then you'd see big changes in the pattern of of the background light so as in the 1980s there was a suggestion that maybe maybe didn't we didn't go just straight from Singularity to expansion maybe there was a period of very very rapid expansion in the beginning called Cosmic inflation that kind of smoothed out the universe kind of like if you if you smooth out like a fabric or something and and or or yeah I guess that's one way to think about it like you kind of like stretch something out and make it really really smooth and then there was regular expansion from there so that our expansion came from a universe that was already made very very uniform by some really really rapid expansion in the beginning okay so we're we're kind of zooming in on a on one part so when we look at the wall of fire the wall of fire looks far more uniform than we would expect if the universe began with Singularity because of certain rules around Quantum fluctuation that should have yeah essentially I well believe me Katie I am going to be oversimplifying that's fine we would expect it to be less uniform this wall of fire than it appears when we look at it and that tells us that maybe what actually happened was that in the very very beginning of the universe there was an extraordinarily rapid expansion much much faster was it faster than the speed of light that's oh no I'm sorry I'm sorry I keep doing this um uh so you expansion you're like that's not that's not an interesting question it's no it's it's an interesting question it's a hard question okay because expansion um you can you can Define the speed that two points are moving away from each other but it you can't Define a speed of expansion because let's say you the fingers in on your in your hands very quickly right when you do that over the course of like 1 second or something you're your the two fingers that were closest together at the beginning they're still kind of close together they've moved maybe like 2 centimeters in those two seconds but the ones on either side of your hand have moved maybe like 10 cenm in those two seconds and so the speed the speed of expansion of the you know the speed that the the two farthest ones have traveled is faster in terms of moving away from each other than the speed of the two closest ones so my thumb and my pinky have moved faster because they've moved further yeah they've moved like like 5 cenm a second whereas your your first finger and your and your middle finger May moved like 2 centimet a second right right so the farther away things start the faster they've moved apart if the UN if the expansion is uniform so if you if your hands were like infinitely large and you did the same kind of like you just make them twice as big in one second then there's going to be there's going to be some distance where the there's going to be variations in the experienced speed of it or the actual speed of it the the recession the like separation speed right so the separation speed of of you know the close by fingers is going to be small the separation speed of the really far away ones is going to be really fast you can always find a distance in a uniformly expanding space where the expansion is faster than the speed of light because there's always going to be two points that are being separated from each other at faster than the speed of light if the whole Space is expanding is this related in some way to what you mentioned earlier that the universe is 13.8 billion years old but the cosmic background radiation light that we see is like over 40 billion light years away from us um it's well that's related to the fact that the Universe has been expanding the whole time that that light has been traveling okay and and that Those Distant places have been moving has been moving away from us faster than any other part of the universe because they're they're the farthest part so yeah essentially so so the part the part of the universe that's that's moving away from us faster than light right now is like most of what we see in the universe which is weird like we see lots of galaxies that are so far away from us that they are currently moving away from us faster than light but it's because the light left them a long time ago and has been traveling toward us while they've been sort of rushing away that we still see that light that light was able to catch up to us but if they put out light now you know it's moving away from us faster than light if they put out light now we would never see it um so it depends on that that also gets complicated because because the light can be moving like the space can be moving can be pulling the light away from us but then different parts of the space are moving are sort of moving at different speeds there so there are some some things that are so far away now that even though they're moving FAS than the speed of light from us now as their light spreads out through the universe it'll reach a part of the universe that is not spread leaving at faster than speed of light and then it'll start to move toward us again and then eventually it'll reach us in the future that gets really complicated I that's like a that that's like we need graphs for that yeah at that point at that point it's like uh train leaves Boston going 80 M an hour another train leaves I'm out this get this gets into the stuff where like I tried to explain this to my general relativity students and everybody looked at me with blank faces like it it that get this gets really complicated um but uh but essentially essentially the point is that that um you know the speed at which things are moving away from us can very easily be faster than light just because space is is expanding in between nothing's moving through space faster than light but the space in between us and other things is is spread spring out so fast that our our relative distan is getting faster you know getting larger very fast so during Cosmic inflation yeah everything was moving faster than the speed of light away from everything else but like in a much more extreme way than is happening now I guess so yeah that it's there there's technical sense in which uh you can explain it through that but it gets it gets too complicated like you again need graphs but the effect of it is like if you know if you think of the universe starting as a singularity now this this is something that always bothered me when I first learned about this whole question was that the problem with the cosm microwave background being really uniform the the background light being really uniform is that it suggests that like the universe was very uniform in the in the early times when the light was produced in a way that that we wouldn't expect unless you have sort of special a special setup now people would say like well but if it was a singularity then of course that it was it was all the same it came from all the same thing but the problem with that is that if you had that sort of infinitely dense infinitely small thing that that kind of expanding like because of quantum mechanics it can't all stay perfectly uniform like there there would be sort of fluctuations and so you shouldn't be able to go from a singularity to you know a perfectly smooth perfectly balanced everything is exactly the same temperature ball of fire it just that just isn't how that would work you should have some kind of fluctuations and so what inflation does is it it's like it zooms in on one one tiny part of that ball of fire where the the temperature is all the same and it it zooms into that and then uses that as the starting point of the whole universe now the whole observable universe now so that's that's the sense in which inflation like Smooth sinks out is it it kind of Zooms in on on a particular part of of this complicated picture [Music] so rather than thinking of the beginning of the universe as an infinitely small point we might think of it more like this in the beginning there were these different parts that were super close together and were sort of in communication and in balance with each other and then during a period of intense inflation like the inflating of a balloon all of these parts moved rapidly farther away from each other as the universe first started to expand and this inflation Works kind of like a cosmic microscope to help us see the quantum fluctuations that existed in the very early universe but it also helps us to understand why at least in terms of background light super spread out parts of the universe are actually shockingly uniform like whichever direction we look it looks about the [Music] same and just to State the obvious we don't know what came before this because we can't know what came before this because it invented the idea of before well yeah I mean so there are two senses in which it's hard to know things before one is that if there was a singularity then that Singularity would have you know you can't see through that that that would have been the starting point for space and time in some sense um the other sense in which you it's we can't see B on that is if there was if there was this Cosmic inflation then by its very virtue it takes most of the information of that early time and just pushes it way outside of our Cosmic Horizon and so we only would ever get to see a tiny piece of that early picture because of cosmic inflation if that's what's happened and so it makes it really hard to know if anything happened before that like what what it was so Cosmic inflation like pushes like takes the whole Singularity problem and says that's not even an issue we don't know if that happened or not we can't have any information from before inflation in this picture like there there might be ways to to gather some information about like the setup of the universe before that but it's observationally it's basically impossible because of that zooming in on this tiny piece right so the first thing we can know is that the Universe was very hot and very dense and then it began to expand through this process that we think was Cosmic inflation well yeah we don't even know for sure if Cosmic inflation happened okay but the hot dense stuff that we see when we look out into the universe is after inflation ended so it's after the inflation stretched out the whole universe made it uniform oh then there was like a hot dense soup oh and then regular expansion okay so the the the sequence is singularity maybe we don't know then Cosmic inflation and then hot dense universe and so when you say we know what happened in the first second of the universe the universe as we're defining it begins after this period of inflation yes yeah yeah and do we know how long this period of inflation lasted well so we think maybe about 10 to Theus 34 seconds shut up so that's what uh real real early yeah yeah I was thinking like a few billion years I was thinking like two to three billion years it's no it was real fast 10 to the - 34 seconds is um I mean there's nothing there's nothing that's that fast right like I can't even there's I can't think of anything that would be that fast no it's it was just a tiny tiny fraction of a tiny tiny fraction of a tiny tiny fraction of a second we we think it was very very quick but the universe expanded by a factor of 100 trillion trillion over that time time at least oh my yeah so it was it was a very very rapid expansion so after that we have a pretty good picture and we can we can talk through the SE sequence of events after inflation ended [Music] yeah so when inflation ended let me I mean there's still some controversy about whether inflation happened were most astronomers think it did when inflation ended it created like this big dump of energy into the universe that caus that that hot dense state to to exist so from there we have a really good idea of of what happened and the reason for that is that we can calculate the temperature and density of the universe at that time and we can study that in a few ways and one of them is by Smashing particles together in particle colliders to try to mimic those temperatures and densities and just see what it looks like and so that's how we have this amazing story of the first like second because we can actually like simulate that in Laboratories by just creating those conditions so for example we know that uh there was something called the cork era where the universe was this Quark gluon plasma so quarks are these tiny particles that make up protons and neutrons and gluons are the the force carrying particles that kind of stick everything together inside and Atomic nucleus so there was like this plasma of quarks and gluons that lasted until about a um a microsc in the in the early universe and during that time there was a sort of reshuffling of the laws of physics um that separated the electromagnetic force from the weak nuclear force and all this kind of stuff was happening but we have a a really good picture of of technically exactly what was happening during that time where we know that there were Corks And gluons we know that this electromagnetism a weak nuclear force separated and we're going to get into the fundamental forces in our next episode but for now we know that there was this quk soup and that these fundamental forces were beginning to happen yeah so the these the sort of laws of physics are being kind of set up by this changing fluid of high energy matter and we know that because we can create a quk gluon plasma in a laboratory by Smashing like gold or lead particles together in like the large haton collider can smash these particles together and create material that dense and that hot that we see that Quirk glue on plasma we can actually like sample it basically and we can see how the laws of physics are starting to change as you get to those really high energies and then we know that at about 2 minutes uh it all sort of cooled down enough for protons and neutrons and electrons to form so before that you couldn't have those particles because it was just too too hot everything was kind of souping around and then at some point it cooled down down just enough so that we have these nuclear particles forming and then then you start to get atoms and that that starts at around 2 minutes and we'll we can get into that a little bit more later so in the first second there's this Quark soup and then those quarks cool off enough that we have protons and neutrons and then that cools off enough that those protons and neutrons start to form atoms yeah yeah and so 2 minutes into the universe we have some version of stuff that is analogous to the stuff that we see today okay so this part is really fun for me so the the at this point this sort of two-minute mark this is when you get big bang nucleosynthesis so what Big Bang nucleosynthesis is is it's when it's the time when the whole universe was essentially like the center of a star it was the same kind of temperatures and pressures at the center of the star and in the centers of stars what's happening is that uh hydrogen nuclei are coming together to form helium nuclei you have this this process called nucleosynthesis where you're creating these heavier atoms you can make uh you know in hotter in certain kinds of SARS you make carbon and oxygen all that kind of stuff so there was there was this time when the whole universe was as hot as the center of a star and when that happened you got this n these nuclear reactions happening so hydrogen turned into a little bit of helium and there was just a little bit of lithium and Brilliant like there were a couple of Trace elements of other things but it's mostly hydrogen turning into helium like the whole universe was a nuclear furnace just like the center of our sun doing basically the same thing as what the center of our sun is doing turning hydrogen into helium and so at that point you get you know about a quarter of the nuclear or whatever become helium and so the cool thing about this is like so people talk about like we're all star stuff because you know stars turn atoms into carbon and oxygen and all these things that that we're made of right we're made of of carbon oxygen nitrogen and so on but most of the atoms in our body are hydrogen just by number just if you count up the number of like the atoms in our body most of them are hydrogen and that means they were formed in that two minutes in that first two minutes of the universe so most of the stuff that we're made of is actually Big Bang stuff it's actually this this primordial nucleo synthesis soup from the beginning of the universe so I was uh part of me was there yeah yeah like literally part of me was there yeah the hydrogen in your body those atoms first formed in that first two minutes of the universe so part of me not in a figurative sense was present 2 minutes in yeah yeah whoa yeah and and and most and as far as I know most of your atams haven't even been through a star they just they coales from the stuff of the early Universe gas clouds and so on and then you sort of fell onto the Earth and then you know you grew out of stuff that was on the Earth but yeah wow so earlier you made me feel very anxious okay I'm Sorry by telling me that the Universe was maybe used to be small and infinite and is now bigger and infinite but now you made me feel very calm and connected to this universe by thinking that I'm not just made of star stuff I might actually primarily be made of big bang stuff so I may have been around albeit not in a sentient form for that whole time yeah yeah exactly which makes me think that that those parts of me will also be around for a while right yeah I mean the hydogen nucleus is just a proton and and we don't have any evidence that protons Decay so your protons will be around for billions and billions and billions and billions and trillions of years and there there may be a Decay time for a proton we the best limit we've got is like it's got to be more than 10 to the 40 seconds or something like that but it's it's a long long time so your your hydrogen atoms are going to carry on I don't know that I need to be around that long you know like well you know the scenery will change the scenery will change the vibe the vibe will be very different I think later those hydrogen atoms will probably combine to make something that's a little less anxious yeah maybe and and a little less self-aware it'll be like both better and worse mhm is there a chance that some of the hydrogen atoms inside of me this may not be an astrophysicist question but is there a chance that some of the hydrogen atoms inside of me will later be inside of another living thing oh yeah yeah uh almost certainly I mean I mean I don't know I don't know what your your plans are in the long term but uh at some point something will probably eat part of you yeah Crown Hill Cemetery um right here in Indianapolis home to more dead American vice presidents than any other location on earth oh great yeah well good company people say Indianapolis isn't a cool town but you know we got some stuff going for us there we go I mean you're also like you know your your atoms are kind of cycling around quite a bit anyway right like you're you're you're losing skin uh particles and and you know things are eating those dust mites and so on and you know so it's it's kind of a constant process yeah yeah this is a reminder for me that the main character on Earth is not any individual or even our species but sort of the overall utter strangeness of life that you know we're part of a much larger earthweb that's part of a much larger universe web yeah yeah what's amazing to me is that that we have so much of this story that we can tell so much of the story that we can that we can look into the sky and see the time when the universe was just beginning I mean we'll I guess we'll talk about the cosmic microwave background more but when we look at that background light like what we see is just a universe that's glowing because it's hot like we see that the properties of that light just show us that this is this is thermal radiation this is just the glow that happens when things are hot and we can see that the early Universe was just this hot place and we can look at it like we can directly look at it there's there's no sense in which it's not just directly looking at it when we pick up that radiation so we're just looking at the beginning of the universe right and is there a sense in which [Music] everything like I don't want to make it too much of a sphere but is there a sense in which everything that we see and observe and are part of is kind of inside of that Cosmic microwave background radiation yeah yeah like can I think of it as a as a sort of a second extremely large Earth yeah I mean it's it's a sphere it's it's a shell it's a bright shell of radiation that we are encased in right and and not just that we're encased in but like everything that we can see in the universe is encased in it's the backlight for everything we see in the universe yeah that again makes me very happy I like that I feel its warmth okay good [Music] yeah thanks for listening to this first episode of the universe listen even though I'm not a scientist and Dr ma kicked us off by saying that astrophysics can't answer questions of meaning there is this huge sense to me that unpacking the wild strangeness of life and the universe in which life happens is a profound way to make meaning like the more I understand myself as part of the Big Bang the more both anxious and relieved I become about everything else in human experience I don't know just can't really get enough of this stuff and I hope you'll join me through this season as we stare into the void which it turns out is not a void because for some reason we can't explain there's more matter than antimatter and my goodness that is Meaningful even if I'm the one making the meaning this show is hosted by me John Green and Dr Katie Mack this episode was produced by Hannah West edited by L openhouse and mixed by Joseph tuna medish our editorial directors are Dr Darcy Shapiro and Megan moery and our executive producers are Heather D Diego and Seth Radley this show is a production of complexly if you want to help keep crash course free for everyone forever you can join our community on patreon at patreon.com/crashcourse [Music]

Channel: CrashCourse

Views: 155,941

Keywords: vlogbrothers, Crash Course, crashcourse, education, podcast, john green, katie mack, crash course podcast, hank green, complexly, cosmos, universe, perimeter institute, physics, science, green, science podcast, dear hank and john, secrets of the universe, astrophysics, astrophysicist, understanding the universe, science communication, physics teaching, timeline of the universe, the future of the universe, physics podcast, education podcast, john green podcast, dftba, dark matter

Id: mqRF8jTF74c

Length: 48min 38sec (2918 seconds)

Published: Wed Apr 24 2024