Putting Together the Pieces of the Universe
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00:00
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GalaxyCalendar dateCamel (cigarette)Digital televisionSkySuperheterodyne receiverDayEinstein, AlbertScanning probe microscopyOrder and disorder (physics)MultimeterYearUniverseAlcohol proofTemperatureCosmic distance ladderGalaxyDark matterBig CrunchBahnelementGasSunlightOrbitElectric currentObservatoryHubble's lawOptischer HalbleiterverstärkerMinuteExtremely high frequencyNut (hardware)IonStarMattressEffects unitTemperatureMercury switchPlane (tool)ParticleOrbitPerturbation theoryDual in-line packageFinger protocolSizingOrbital periodPlanetLightYearBallpoint penJet (brand)ElectricitySchwellenspannungTransmission (mechanics)Alcohol proofGalaxyElectronMaterialCrystal structureAM-Herculis-SternUniverseSummer (George Winston album)Spare partOrder and disorder (physics)Hubble's lawGalaxyMassCosmic distance ladderProzessleittechnikBig CrunchGround (electricity)Gas turbineDark matterSunlightCosmic microwave background radiationExpansionsturbineMeasurementDayGaussian beamSpin (physics)PencilSpeckle imagingAccelerationConstellationForceGravitational lensGasRotationSkyElectric power distributionQuantum fluctuationForgingFACTS (newspaper)StagecoachHose couplingRadiationAtmosphere of EarthWatchAtomismSunriseQuantumWedge (mechanical device)PaperSwitchUninterruptible power supplyShip breakingScale (map)String theoryBohr, NielsGenerationMoonHot workingParticle physicsBlack holePhase (matter)Marble sculptureParticle acceleratorSensorEinstein, AlbertGamma rayBicycle pumpFeldnebelAmmeterSpray paintingSource (album)Bird vocalizationVolkswagen GolfWeather frontWoodturningBestrahlungsstärkeTurningAstronomerMaskStarter (engine)Power (physics)Nissan SunnyVideoOpticsFirearmClub (weapon)Roll formingPlant (control theory)Synoptic scale meteorologyMagnetizationCluster (physics)Series and parallel circuitsFlashtubeField-effect transistorAngeregter ZustandMinerBlackBig BangSpace observatoryRolling (metalworking)LastCardinal directionMechanicFlatcarNew YearFood storageChemical substanceFundamental frequencyFlightSatelliteMagnetspuleRing strainField strengthModel buildingStrahldivergenzBombMondayRailroad carBand gapHourCellular manufacturingVehicle armourWind farmSolidCar seatWeightContactorSoundCatadioptric systemSpieltisch <Möbel>BicycleWeekEnergy levelShutter (photography)Lecture/Conference
Transcript: English(auto-generated)
00:00
is James Bullock and we're very proud to have him. He's a man who is asking those big questions. Has the universe always existed? Did time have a beginning? What makes us think that the earth goes around the sun? What is a black hole? How fast is light? So we're about to hear from someone who asks the big, big questions.
00:21
Would you please give a warm Inside Edge welcome to James Bullock. Well, thanks very much. It's a pleasure to be here. I thought, so what I'm going to do today is talk about some of the things we're trying to understand in the field of cosmology.
00:40
I actually work in that building right over there. That's the physics and astronomy department. We have a center for cosmology there that was started about four years ago. And the center is all about trying to answer the kinds of big questions that we were just hearing about. And so that's what we're doing. And I thought what I would do today is just sort of give you a little bit of an overview of what we're trying to do, some of the big questions
01:01
that we have. And I'm going to do my best to leave some time at the end for questions. Normally when I give these kinds of talks, I like to keep it very free form and open. So if anyone has any comments or questions at any time, I'm happy to address them. Now, I understand that since we're recording this, that might make it a little bit logistically difficult to have people running around with microphones.
01:22
So what I'm going to do then is do my best to make sure I don't talk too much and leave some time at the end just for general questions. If you have an urgent question at any time and you just need to ask it, we can do that. So let's just keep it open there. So I just thought I would start with this. And one of the things I like to do when I talk about cosmology is to show this picture.
01:40
This is a picture that was taken by a photographer named Art Roche. And I thought it was really beautiful. But one of the things that I find very attractive about it is he was telling me when he took this picture, he was in this canyon in the southwest. And he noticed that there were petroglyphs, sort of ancient petroglyphs left on the canyon walls.
02:04
And this reminds me, I think, of really what we're trying to do in cosmology, which is it's a scientific exploration of the kinds of questions that you ask when you look up at the night sky. So you can imagine the people who made these petroglyphs, these ancient peoples who were drawing
02:22
into the canyon walls. And when they looked up at the night sky, they probably had similar questions to the kind of questions that we have when we look up the night sky. So how old is the universe? Was it always there? What's the universe made of? How did structure like us come to be? So these are the kind of questions
02:41
that a lot of us has asked ourselves. And in many ways, cosmology is the oldest science, because you could imagine people have always asked themselves these kinds of questions. What we're trying to do is to answer these questions in a scientific context. So we're trying to make testable predictions and see if they come true. And use that to build up a theory for how the universe
03:02
began and emerged, and for the first time trying to build one that's in a scientifically tested context. And that's what we're trying to do. So what I'd like to do is tell you a little bit about what we believe about the universe, so how we think the universe came to be, and some basic facts. And then I'm going to go on and tell a story of how we began to shape these ideas.
03:24
So this is kind of a cartoon picture of the overview of modern scientific cosmology, our present understanding of what the universe is and how it began. So the first order picture here is that time and space, time and space itself began in something that we call
03:42
the Big Bang, which is just a word, about 14 billion years ago. The universe was very, very hot at early times. The universe has been expanding. So today the universe is quite big, and in early times the universe was smaller and smaller. It's expanding. So if you go back in time like a movie, it's hot at very early times.
04:03
And in fact, it was so hot at early times that, you know, as you crank up the temperature, things start to melt. And if you keep cranking up the temperature, even molecules can't hang together anymore. And if you keep cranking up the temperature, even atoms, it becomes so hot that even atoms can't hang together anymore,
04:20
and electrons will fly off of protons. In the very, very early universe, it was so hot that even elementary particles couldn't exist, and we were down to the most fundamental constituents of nature. So in that sense, it was a very smooth, in some sense, simple beginning. And from this elegant beginning, this very, very simple beginning,
04:40
emerged as the universe cools and cools over time, more complicated structures can begin to form, and then you can start making planets, etc. And so we have a situation where we have really the real primordial soup, OK? The early universe's primordial soup. And then from this, structure grew. And eventually, we end up with galaxies like ours,
05:02
the galaxy that we live in, the Milky Way. And in these galaxies, there are stars, in our galaxy, there are billions of stars. And around one of these stars orbits a planet that's very low mass, that's mostly rock, and that's the Earth. And so what we'd like to understand is how this picture emerges.
05:22
Another thing, oh, one thing I did want to mention is this, you know, numbers like 14 billion don't seem that big anymore. We're hearing about, you know, the national debt and the ... But 14 billion is a big word, is still a big number. So 14 billion years is a very long time. If you took the entire age of the universe
05:40
and scrunched it down into one year, a scale of reference for that is that Shakespeare, OK, living in the 17th century, wrote his plays about a second ago. So you take the whole expanse of time and scrunch it into one year, Shakespeare was walking around about a second ago.
06:00
So that's, these are the time frames we're talking about. So, true cosmological time frames. Now another thing we would like to understand is, in addition to sort of the size of the universe, the age of the universe, we'd like to understand what the fundamental constituents of the universe are, OK? And this represents a pie chart of our current understanding of the composition of the cosmos.
06:21
And I'll talk a little bit about these different pieces here, it's just words, but I thought I would just give you an overview now. The thing you notice here is this area right here, this little yellow sliver in this pie chart, is supposed to be representative of heavy elements. And that heavy elements just means any kind of atom that's heavier than hydrogen or helium.
06:42
So basically us and the Earth. And in terms of a global sort of composition of the universe, that represents only about 0.03% of the composition. So a tiny, tiny sliver of what we believe is out there. About, only about 5% of the universe is made out of things
07:03
that we have a really good understanding of what they are. OK, so the entire periodic table of elements. Everything you learn in chemistry class. In fact, everything that they study in every department on this campus, except for ours, is in this piece of the pie right here.
07:22
OK, I put neutrinos there purposefully, this is a kind of elementary particle that was discovered by Fred Reines, who's our Nobel Laureate over there. So I have to put that on the chart, even though it's 0.3%. But the rest of this chart is all stuff that we really don't understand.
07:40
And I'll talk a bit about this. About 25% of the universe consists of something we call dark matter. Dark matter is some weird stuff that I'll talk about later, and there's some even weirder stuff called dark energy, and that makes up 70% of the universe. So this is really a statement of our ignorance, this pie chart. We have a pretty good idea of what we don't understand,
08:02
but as we all know, that's how you start. You have to understand what you don't understand first. OK, so this is our ignorance chart here. These are the big questions we're trying to answer. Now, sorry. So as I mentioned, cosmology is in many ways the oldest science.
08:23
And as far as I know, every culture on Earth has had their own story of cosmology. So how does the Earth begin? How old is the Earth? How did we emerge? One of the oldest pictures, one of the oldest cosmological models was actually that of Aristotle, and then later on refined by Ptolemy.
08:41
And in Aristotle's model, the Earth sits at the center of the universe, and all the planets and the sun orbit the Earth, and the stars extend out in a celestial sphere. And this was the picture they had. And you know, Aristotle was not a dumb guy, right? When you look up out the sky,
09:00
it looks like the sun is going around the Earth, OK? So, and in fact, this is the longest lasting scientific cosmological model in history. It lasted 1400 years, but eventually this idea was broken by Copernicus and Galileo and Newton and people like that. What Copernicus said is,
09:21
he said, well, you know, if you actually put the sun at the center and let the planets go around the sun, I can also explain all the observations, and to me that seems just prettier. It just seems a little bit more elegant. But that was kind of the end of it, OK? And there was sort of this, it wasn't clear whether that was really true or what. The thing that really changed the way people saw the universe
09:43
was when Galileo turned a telescope to the heavens and he actually started testing some of these ideas. And he showed that there were moons going around Jupiter and that the moon itself was corrupt. That is, it had mountains and things and it wasn't this perfect celestial sphere kind of thing that Aristotle thought was going on.
10:02
And from this piece of technology and the application of this technology in direct observation, it sort of shattered this idea that people had for a very long time. A lot of very smart people had for a very long time. So it was really the tools that Galileo had that allowed us to sort of extend this idea. So this began, this begins sort of the sort of modern theory of cosmology,
10:23
where, you know, at that time, cosmology was the solar system. This is everything. Now, one of the things that's remarkable about this is not only does this move the position of the Earth relative to the sun, but it transforms sort of how,
10:40
it's sort of, it's representative of how bizarre the universe had to be if this was true. It wasn't that no one had ever conceived of the idea that the Earth might be going around the sun before. There were ancient Greeks who proposed that idea. But people decided that was crazy. And the reason why they decided that was crazy is, if you have something that's going around the sun, let's say us, we're going around the sun. Okay, we're moving a big distance
11:00
from one time of the year to the next. So if that's true and you're moving a lot and you look at something and you're moving like this, the position of that thing on the horizon will shift a bit. Right? When you're in a train, you see stuff go by and you have to turn your head. The only way you don't have to turn your head on a train is when you're looking at, say, a mountain peak
11:20
that's really, really far away. So what this meant is, if this is true, this meant the universe, the stars that were really far away, which we never see shift from one time of the year to the next, must be really, really far away. And so by putting the sun at the center
11:40
and having the earth go around the sun, it was actually bizarre in many ways because it meant the universe was much, much bigger than anyone had ever imagined before. So one of the things that's kind of interesting about scientific cosmology is, I think almost every step of the way, the data tell us something that's much crazier than anyone had ever thought of before.
12:01
And I think it's true every step of the way. If you look how cosmology proceeds, it's a crazier universe than anyone had ever imagined, even very creative people. So today, cosmology at the end of the 20th century, it progressed significantly, and people had finally figured out how to measure the tiny wiggles and the distances to stars on the horizon,
12:23
and that allowed them to figure out how far away the stars were. It was realized that the sun, our sun, was just one among billions of stars in this galaxy. And the galaxy is huge. Okay, the galaxy, it takes light 100,000 years to cross our galaxy.
12:41
So just to explain what I'm trying to say here is that if I have a flashlight and I turn the flashlight on, light travels from my flashlight at 186,000 miles a second. So if I turn a flashlight on, a light beam could go around the Earth 10 times in one second. It moves really fast,
13:01
but it's moving at finite speed. Light that leaves the sun takes eight minutes to get here. So, which isn't that long a time, but it's still, you know, it's a delay. Light takes 100,000 years to cross the galaxy, to give you an idea of size. Okay, it's big, very big.
13:23
And in fact, if you take the sun, okay, the sun is big, we really don't have a concept of how big it is, but the Earth, we have some rough idea of how big it is, even though it's hard to conceptualize. You can place 100 Earths across the face of the sun. The sun is big. If you took the sun and shrank it down to the size of a grain of sand, okay, our galaxy would be the size of the Earth.
13:46
So the size of our sun compared to the size of the galaxy is like the size of a grain of sand to the Earth. So these are the distances that we're trying to deal with, okay. Now the thing is, at the end of the 20th century, pretty soon, Edwin Hubble would realize,
14:02
Edwin Hubble looking through his telescope, he would soon prove that actually there are blobs of stuff in the sky that we call nebulae, that at the time people didn't know what they were, he would eventually figure out that these were actually distant galaxies of their own, so that the universe is actually filled with billions of galaxies like ours.
14:21
So yes, billions and billions, just like Carl Sagan, he was right, okay. So this is our current picture of the Milky Way. The Milky Way, our galaxy is a disk of stars. It's got a bright thing in the middle we call the bulge. It's about a hundred thousand light years across, and we live kind of at the edge here,
14:41
sort of in the middle, kind of out, sort of outer outskirts. Here's the sort of blow up of the sun and its circular planets going around it, and like I said, it takes eight minutes from light to get to the sun to the Earth, but it takes a hundred thousand years for light to go across the galaxy. So it's a pretty big place, but this is nothing.
15:03
A hundred thousand years of travel time for light is small potatoes compared to the size of the universe. This is the nearest big galaxy to us called the Andromeda Galaxy. You can see this with your eyes sometimes when it's dark. It takes light two and a half million years to reach us from this galaxy, and so just think about this.
15:22
This picture is what Andromeda looked like two and a half million years ago. So before there were Homo sapiens to look up at the sky, that's when this light left, okay. So we are looking back in time, and the farther things are away, the further back in time you look.
15:42
And that's one of the techniques that we try to use when we try to understand how the universe is assembled over time. Because as we look at stuff that's further away, we're looking at what the universe was like long ago, and from this you can imagine trying to build a movie, sort of how stuff is assembled over time. So you use this fact that light can't travel infinitely fast
16:01
to your advantage, and use it to actually look at what the universe looked like in the past. So we can make maps of what our local environment looks like, and a lot of astronomers like to do this. Here is our galaxy, the Milky Way, and here is Andromeda, the one I was just showing you, two and a half million light years away, and there's lots of other little galaxies all around.
16:22
We are the two big boys on the block, but there are these little things that float around our own things and orbit us, they're satellites. They're galaxies that are satellites of our galaxy, just like there are planets that are satellites of the sun that are orbiting around us. And gravity is doing all this attraction. And you can zoom out again, so this is three million light years, this arrow.
16:42
And if we zoom out again, this is 30 million light years. And we can make maps there too. And they're still naming things, but eventually you stop naming things, so there's so many things. But all these guys have names, you know, they're named after the constellations, a lot of them are named after the constellations, you have to look through to see them, right? You have to look through the Fornax constellation
17:01
to see the Fornax galaxy or whatever. And that's where the naming convention comes from. So this is 30 million light years. Every dot on this point, every dot on this picture is a galaxy. And we can keep zooming out, so this is 300 million light years.
17:20
This is where we kind of stop naming stuff, it gets kind of ridiculous. It keeps going, okay? It's sort of arbitrarily cut off in a circle, but it keeps going. So galaxies like to live around other galaxies. They cluster together in clusters of galaxies and what we call super clusters, and there's giant structures in the sky. And one of the things we like to understand is why.
17:42
How many, these kinds of things. And in fact, so all of these things I had just shown you were cartoon pictures, but this is actually a picture of real data. This is the largest continuous map of the universe that's ever been made by a survey called the Sloan Digital Sky Survey. You've heard of the Alfred P. Sloan Foundation.
18:01
They funded this sky survey to take a huge section of the sky and just look very deeply and try to map continuously all the galaxies. This is a beautiful survey. The total amount of data is 15 terabytes, which is equivalent to about the Library of Congress. So that's the kind of data that they've taken for this one picture.
18:22
So these are the kind of maps that we're trying to make. We want to know what the universe looks like. Now there's another technique. Rather than looking at sort of broadly at everything, we could point at one point on the sky and go very, very deep. And the way you do that is the same way you'd open up a shutter on a camera and you can take a really faint image. You do that with a telescope, okay?
18:40
So let me back up, sorry. So that's what I'm going to show you. I just want to explain it first. So you know when you overexpose your camera, it's not good, but you can take pictures of things that are very, very faint by keeping your shutter open for a long time. That's what we can do with the telescope. So with the telescope, the lens is sort of eight meters across.
19:03
Eight meters across. Okay, these are the biggest telescopes in the world and you can point them at one point on the sky and leave the shutter open. So you can see stuff that's really far away. The Hubble Space Telescope is a big telescope like this. It's not quite that big, but you've heard of the Hubble Space Telescope. So one thing that the Hubble folks did
19:21
is they picked a place on the sky that was completely dark. Nothing there. And they pointed the Hubble Space Telescope there for 12 days straight. And so the point they pointed is somewhere in here. Here's a constellation you might be familiar with. And what I'm going to show you now is a movie that zooms in to this point. Notice that it's complete blackness that they're going to zoom into.
19:42
And what they're doing is they're showing you progressively deeper and deeper images of the same part of the sky. And what we're looking at now is we're seeing nothing but galaxies. We're way past the stars. So we're going deeper and deeper into a sort of a deep pencil beam into the universe. And this is it.
20:01
This is called the Hubble Ultra Deep Field. It's a deep region of space that Hubble just sat on for 12 days. And the light from these galaxies left these galaxies about 12 billion years ago. So this is actually a movie, a snapshot of what the universe looked like something like 12 billion years ago.
20:20
And notice that the galaxies look kind of messed up. They look like they're not fully formed yet. So these are the kind of movies that we try to make and then interpret. We want to understand how from this kind of stuff emerge the galaxies like we see.
20:42
So yeah. So we'd like to ask, where did all this stuff come from? How did we get here? So one of the things you do when you have a question, one thing sometimes people do is you ask the smartest person you know. So the smartest person I know is Albert Einstein.
21:03
So how do we begin to sort of take measure of these kinds of observations? It turns out, especially in the context of a theory that seems to be, we seem to have a universe that's expanding. You want to understand the nature of space and time. It's sort of all grounds there. And really the beginning of modern cosmology was really what this guy here,
21:22
when he had a short haircut. In 1905, he proposed this theory that's called the special theory of relativity. And as part of this theory, he had this famous equation E equals mc squared. But lying at the backbone of this derivation of this equation was that there was some kind of interrelationship between space and time.
21:42
What Einstein realized is, the actual way in which time ticks along is linked in some way with space and how fast people move through it. This was an earth-shattering conclusion that he made. And what it meant was, our previous concepts of space and time were wrong.
22:01
And that in fact, the ideas that Newton had about how gravity operates on earth and why apples fall from trees had to be revised. Now he realized this in 1905 and then for the next 10 years, he said, oh, I need to fix gravity. I need to figure out how gravity really works because E equals doesn't equal mc square according to Newton's gravity, the first order.
22:23
So now we're talking about 10 years of Einstein time. Okay. I don't know how many years of my time that would be. So it's like 600 years of my time. Then in 1915, he comes upon what's called the general theory of relativity.
22:41
And in this theory, by the way, it's largely regarded by most professional physicists as the single greatest achievement ever by anyone, period. I mean, this is a very impressive thing. What he realized is that you can understand gravity as actually a warping of space. So that if you took, I mean, the way of sort of characterizing it
23:01
is if you took a bowling ball and set it on a mattress and there's like a dip in the mattress, you can imagine taking a marble and flicking it on the mattress and the marble would roll and bend as it approached that dip in the mattress. It's in a similar way that Einstein understood how planets go around the sun and that there's a dip in space time around the sun
23:23
and the planets go around on circles because that seems to them to be a straight line in that curved space. He described all gravity that way. Now the thing, the sort of backup ramification of this is that space is not something that's fixed that you just travel through. It can warp and evolve and twist.
23:44
So if you think about this a little bit, you're now kind of in this weird position where you can have space itself not being static, not always being the same. So soon after this paper came out, a guy named Friedman read it and he realized that, hey, you know,
24:01
if I look at your equations, I realize that the universe should be expanding. According to your equations of gravity. Now Einstein said, uh-oh, that sounds crazy. Even to me, that's crazy.
24:21
Okay, even this great creative genius that Einstein was couldn't accept that, even though it was his own theory. And so he changed his equations. He changed his theory to account for it. And he added basically a fudge factor that we call lambda, which is now called the cosmological constant. It sort of like put a wedge in the door
24:41
and kept the door from closing. He just stuck it in. He could do it. It was his theory. He did it. But of course, this is widely regarded now and it's claimed that he said it was his greatest blunder. You know, he could have predicted that the universe is expanding, but he didn't. But then in 1929, the same guy Edwin Hubble,
25:01
using the 100-inch Hooker telescope, which is not too far from here, saw that as he looked at galaxies that were more distant to us, they were moving away from us faster. And this implies that the universe is expanding. So in some level, it fit in with the theory that Einstein had proposed, but he didn't quite have the guts to stick with the prediction.
25:22
Now, what this gives rise to an idea is that we're leaving a... And then a lot of data came after that. People studied this for a long time. And now we're up to this idea where because the universe is expanding, if you just run the movie backwards, it was smaller in the past. And if you take something and you scrunch it down, smaller and smaller and smaller,
25:42
the atoms in it or the gas in it will get hotter. You might notice this sometime if you're holding a bicycle pump and pumping it. It'll get hot. So as you scrunch air together, it tends to get hotter as it's compressed. Same kind of thing with the universe. The universe is scrunched, it's smaller, it's hotter. Earlier than that, it was smaller and even hotter.
26:01
So it's now about 14 billion years since the Big Bang, and now it's very cool. It's about three degrees above absolute zero in empty space. But the universe at early times was very, very hot. And it turns out it was so hot in the early universe, there's radiation that's left over from that. And it was realized that that should be observed. And in fact, in 1965,
26:22
Tenzience and Wilson discovered the glow from the Big Bang, which is called the cosmic microwave background radiation. And from that, they were given a Nobel Prize. And it sort of solidified this idea that in the past the universe was hot. So what we have now is a picture of the universe where not only does it have this map, but it's moving away.
26:45
So I thought I would mention just a couple more words, and then I'll stop and open it up for questions. But when you look at one of these galaxies in particular, it turns out now we don't have to just, we can't just, we don't just sort of take pictures of them and see where they are. We can actually study them in detail and understand things like
27:00
how fast are they spinning around on edge, because it's a disk. It turns out that us, in our own galaxy, we're spinning around or orbiting around the center, spinning like a disk. And in fact, if you look at the stars in the galaxies, you expect them to spin around, but as you go out toward the edge of the galaxy, you expect it to go around more slowly, because there's less gravity out there.
27:22
And in fact, Pluto, if you want to call it a planet, is going around more slowly around the Sun than the Earth. Because it's further away, there's less gravity from the Sun. And this is expected, this is well understood physics. And so when people looked at these galaxies, what they expect to see is that they rotate really fast in the center and then the speed rolls off quickly at large distances.
27:45
But in the 70s, there was a woman named Vera Rubin who went out to actually measure how fast they were spinning around. And what Vera discovered is that's not what's happening. In fact, they're still going really fast way out here. And the way we eventually came to understand this is
28:01
that there are big extended distributions of matter all around these galaxies. And this matter is called dark matter, because we can't see it. That's why it's dark. Okay? Vera Rubin is credited with this observation, although there are a lot of other people who found evidence for it, even before Vera Rubin. Just an interesting tidbit,
28:20
her son is a professor of mathematics in the math department here. There's a lot more evidence for dark matter by studying galaxy clusters of these galaxies. We can measure how fast stuff's moving in those galaxy clusters, and I guess all I want to say is there's a lot of evidence that it's there. It's not just this rotation group.
28:41
There's tremendous amounts of evidence. Another question that people had, and they were specifically going after this issue in the 80s, was, is the universe ever going to stop expanding and re-collapse and have a big crunch? In order for us to know what's going to happen, it kind of goes something like this.
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Imagine that I took this pointer and I threw it up in the air. Eventually, it's going to come back down. It's going to come back down because gravity's tugging on it. But if I lived on a planet that was really, really light that didn't have much gravity, the force of gravity would be less, it'd be like on the moon. And you can imagine me throwing this up and this escaping the moon and never coming back down. So the question with the universe is,
29:21
it's going up now, will it come back down? And the crucial question is, how much mass is there? If there's a lot of mass, it will slow down but never come back down. Sorry, if there's not much mass, it might slow down but not come back down. If there's a lot of mass, it will slow down and then re-collapse.
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So people in the 80s were looking to see if this is what's going to happen. So imagine this is distance and this is time, and you throw a ball up, you might expect it to come back down, or it might keep going up, depending on how much mass the planet has or how much mass the universe has. So a very heavy universe, we expect this. In a very light universe, we just expect that ball to just keep going up.
30:03
The universe is expanding. So a bunch of astronomers, one part of the team was led by a team at Berkeley, was looking at this in the late, actually turned in the late 90s when they actually got the result. So this is a big crunch picture and this is a not big crunch picture. The universe keeps expanding and this is what they wanted to know.
30:22
So they did the observation and this is what they found. So what they found is, you throw the ball up and rather than it coming back down or slowing down, it speeds up as it goes up. That's weird. It's that weird. It's exactly that weird. That's called dark energy.
30:41
So there's some force in the universe that's making the universe expand at accelerated rate. We do not understand what this is. The thing that's kind of fun about it is, our ideas for this, well, let me tell you a little bit about our ideas. This is the dark energy piece.
31:02
This is the thing that makes the universe accelerate. This is the dark matter piece. This is the thing that makes galaxies spin around fast. And this is the piece that we understand. Chemistry, that's easy, right? No, it's actually much harder than this. Our questions are so simple,
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that's actually much easier than chemistry. So here's the big questions. What's the dark matter? What's the dark energy? How did galaxies like ours emerge from this early universe? What was going on in the early universe anyway? So these are the kind of questions we're trying to answer. What is the dark matter? I'll tell you what we know. It's dark.
31:40
It doesn't shine, okay? What that really means is, it doesn't interact with light. It doesn't interact with things electromagnetically. So if I had a ball of dark matter, and it was traveling through the wall, it would go right through the wall. Because the only reason balls bounce off walls is because the electrons hit each other and make it bounce. It's electrical repulsion.
32:01
There's no electrical repulsion with dark matter. It doesn't interact with electricity. It doesn't interact with light. But it does attract to other matter via gravity. And most cosmologists believe that the dark matter is a fundamental particle of nature that we just haven't discovered yet. And there are big programs to look for it. There's a big particle accelerator in Switzerland called the Large Hadron Collider,
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where they're taking particles and zooming them around a 17-mile loop. They're gonna slam them together, recreate the hot temperatures of the universe, and try to make dark matter, and try to observe it. That's going on now. There are also satellite projects. They're looking for glows of high-energy gamma rays, which might be evidence of this dark matter.
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And also, we're looking for it directly. We think there are dark matter particles streaming through the Earth all the time. We don't feel them. But we're trying to build detectors that will feel them. And by detecting them, it would be really interesting. So this is the ways we're looking for it. The dark energy is much harder. It's dark. It doesn't shine.
33:00
It's energy. It causes the universe to accelerate. But it does not attract stuff together like normal matter. In fact, it's a lot like the cosmological constant that Einstein proposed. In fact, it's possible that the dark energy is this cosmological constant that Einstein thought was his greatest mistake. It might have been his greatest prediction.
33:21
The guy's always right. Quintessence. It's some- another idea. So there are other ideas. And these are just words. Another possibility is that Einstein's theory of gravity is wrong. And our whole interpretation of why the universe is slowing down or speeding up is just wrong because it's based on Einstein gravity. So all the young physicists hope that this is true
33:41
because they want to be the one to- don't want the right number, the right answer. Let me just- let me just flash on the future and then I'll take a few questions. So how are we going to try to answer some of these questions? UC Irvine is involved in a survey called the Large Synoptic Survey Telescope.
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This is that little Sloan diagram which is the largest continuous map of the universe that's ever been made, shown on the scale of what we want to do. So we want to make- we want to map about a quarter of the visible universe with this project. This is going to be a telescope in Chile. We're also involved in something called the 30 meter telescope.
34:21
The 30 meter telescope will be the largest optical telescope that's ever been built. And there's something else that's coming online called the Hubble Space Telescope which- sorry, called the James Webb Space Telescope which is the successor of the Hubble Space Telescope. It's 10 times more powerful than Hubble. So these things are coming online. Let me- let me show you, just give you some perspective about what we're getting ready to do.
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The Hooker telescope was 100 inches across which is big. This is the telescope that Edwin Hubble used to discover that the universe was expanding. At the time, he didn't know he was going to discover that and the Palomar 200 inch telescope, this was the biggest telescope in the world in 1949, it was this telescope, of course when it was built no one had any idea
35:02
that eventually they would be able to measure galaxies spinning around and discover dark matter. It was with the Keck telescope which was built in 1993 which is currently the largest telescope in the world that we used to discover that the universe is accelerating its expansion. But when this telescope was built,
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that- if you said that to somebody they would have thought you were crazy. Okay. So now, this is the 30 meter telescope. So who knows what we're going to find. Okay. Now, I will close then with saying, this is the real future. Okay. We're over there across the- the building over there
35:41
and the people who really do the work are the graduate students and all these young people. And so, I- you know, they- I was asked if- if I was- had anything to sell. I don't have anything to sell. But what I do kind of have to sell is this center and really these people. There are people over there who are doing really great work. And if you're interested in that work,
36:00
you can contact me. If you're interested in supporting that work, you can contact me. Specifically supporting maybe one of these people to go to one of these telescopes and do some observations. That would really help us. But anyway. So let's leave- let's leave with this picture. That's it. I can take a couple questions. I'm sorry I went kind of long. This hand was up first.
36:21
Thank you very much. Is this on? Okay. If I can- if we can look into the far reaches in order to see back in time and see a very primitive part of the-
36:42
Yes. Of the universe. Yes. If I were able to stand in that primitive part Yes. At that far away time Yes. Would I eventually see back to where we are now and did that exist? Okay. So if you were in that far away place of the universe and you looked towards us Yeah. You would see us as we were
37:01
10 billion years ago. So there would be no sun. Was there a Milky Way? The Milky Way was- yes. So that's a good question. The Milky Way we think basically came into existence about 11 to 12 billion years ago and the sun was born in a sort of second generation of stars about 5 billion years ago.
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Sure. As you know the- in the sub- subatomic world gravity has no effect. Yes. And so that's why I actually respect Niels Bohr and those guys a lot more than Einstein. But that's me. Einstein contributed to quantum mechanics too.
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The point I'm making is have you- have you guys gleaned into the subatomic world to try to figure out what happened? That's a great question. So one thing I skipped over really fast is in fact that's a lot of what particle physics tries to do. So in the very early universe it was very very hot. So that there really was nothing but some of atomic particles.
38:01
There was nothing on the big scale. The universe was tiny and very very hot at this time. And what particle accelerators do- what particle physicists do is they take particles and slam them together at very high energies to create very high temperatures and see what flies out to figure out what the subatomic world is made of. Okay. Richard Feynman said it's like taking a switch- switch watch
38:21
throwing it against the wall and watching what flies out to figure out what it's made of. Okay. That's what- that's what's done. And that has deep ties to cosmology because cosmology unites these fields. Subatomic physics governs what's going on in the very early universe which sets the stage for all that emerges. And in fact all the structure in the universe we believe originated in tiny fluctuations
38:41
that were originally quantum mechanical processes that were developed some 14 billion years ago in a process known as cosmic inflation that eventually grew to be the galaxies we are today. So without quantum mechanics there would be nothing according to that. Earlier we were talking about Aspen and the wonderful research institute there.
39:02
Last summer I heard a lecture again on the universe and they were talking about- what I want to say is energy polarization when you have a galaxy that is flat and there are these energy spears if you will one going up and one going down if you will.
39:23
And how that creates the energy kind of like the ying and yang. And I was wondering if you could fold that into what you're talking about. A little bit. So the jets you're talking about in galaxies is that a lot of galaxies are observed to have polar jets of material streaming out of them like this.
39:40
What that actually is fueled by is a black hole at their center. A very massive black hole that creates a very strong gravitational field and that heats up matter makes it very hot and at the same time it creates a magnetic field that twists and that's what drives those columns out. And so that's a very interesting subject and that's what people- people are using that to study black holes and black holes are really fundamental objects
40:02
because they sort of sit at the cusp, the threshold of us understanding gravity in the extreme. And so another way we're trying to test our theories of gravity is by studying these black holes that create these kind of jets. I have a rather pedestrian question. I was noticing that when you're showing a galaxy
40:20
that it all seems to be rotating on one plane rather than all these others. Now within that plane does the- do the planets around the sun rotate on that same plane? That's a great question. How about the the moon around the earth? So would you just comment on that, what they do and why? So the planets do not orbit the sun in the same plane
40:43
that the galaxy is going around. It's tilted by about 60 degrees and it turns out that the stars are so far away from each other that they don't really- that kind of effect is small. If our sun was the size of a basketball, the nearest star would be in Hawaii. So the size scales are very big. They don't really interact with each other very strongly.
41:01
And so there's really not a strong correlation. It has to do with smaller scale processes, almost like weather, we believe, in the early galaxy, told our alignment- told the planets what plane to align on basically. And the moon similarly. The moon is sort of orbiting in a slightly different plane as well. That's why we have phases of the moon
41:21
because it's not exactly lined up with the earth and the sun. I have one more. Thank you. Could you tell us about string theory and how does that relate to any of this, please? I know it's the last question. You have 30 seconds. I have 30 seconds to explain to you string theory. Okay. So the basic idea of string theory is
41:41
that there's this idea in particle physics that all the elementary things are single points. Okay. An electron is a single point and you model it that way. String theory says no, no, maybe they're strings. And it turns out if they're strings, a lot of ugliness goes away. A lot of divergences, there are a lot of infinities that pop up everywhere. Remember when you're doing basic math and there are infinities everywhere and that's bad,
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does not exist. It turns out particle physicists get that all the time. But if you do string theory, a lot of that stuff goes away. String theory is an idea that the subatomic world is really based on these one-dimensional loops and that in fact on very, very small scales, the universe is multi-dimensional, has many more dimensions than just four.
42:20
But the fundamental reason for that is if you don't do that, theories break. Trying to unify gravity and quantum mechanics, this issue that was brought up here, cannot happen. So you can't understand gravity in a modern sense unless you do something like string theory. We really don't know where it's going. There are no testable predictions of string theory right now,
42:40
but a lot of extremely smart people work on the problem. So we'll see. Okay. Oh, thanks.