- 5/20/2025
In 1543, Nicholas Copernicus proves that the Earth is not the center of the cosmos. The "after-glow" is the Big Bang from 13.7 billion years ago is called the cosmic microwave background (CMB), which is the supporting evidence that the "Big Bang" occurred. But since we can only see as far as light has traveled in that time, we can't actually make out the edge of the universe. After the Big Bang, the universe balloons up at an incredible rate in the process of inflation.
Neil Cornish, a Montana State University professor, is interviewed. Archytas of ancient Greece is the first person known to have ponder the question of whether the universe has an edge. Janna Levin compares the shape of the universe to the 1979 Asteroids game. Jean-Pierre Luminet is interviewed. WMAP of NASA photographs the CMB (cosmic radiation) for five years.
Glenn D. Starkman and Sasha Kashlinsky are interviewed. Dark flow is the attraction of matter in the universe in one direction. Laura Mersini-Houghton advances string theory to explain a multiverse structure from which our universe is born. Mersini-Houghton contends that one universe acts as the Great Attractor of another universe to cause the "dark flow."
Thanks for watching. Follow for more videos.
#cosmosspacescience
#thruougthewormhole
#season2
#episode2
#cosmology
#astronomy
#spcetime
#spacescience
#nasa
#space
#spacedocumentary
#morganfreeman
#edgeofuniverse
#isthereanedgetotheuniverse
Neil Cornish, a Montana State University professor, is interviewed. Archytas of ancient Greece is the first person known to have ponder the question of whether the universe has an edge. Janna Levin compares the shape of the universe to the 1979 Asteroids game. Jean-Pierre Luminet is interviewed. WMAP of NASA photographs the CMB (cosmic radiation) for five years.
Glenn D. Starkman and Sasha Kashlinsky are interviewed. Dark flow is the attraction of matter in the universe in one direction. Laura Mersini-Houghton advances string theory to explain a multiverse structure from which our universe is born. Mersini-Houghton contends that one universe acts as the Great Attractor of another universe to cause the "dark flow."
Thanks for watching. Follow for more videos.
#cosmosspacescience
#thruougthewormhole
#season2
#episode2
#cosmology
#astronomy
#spcetime
#spacescience
#nasa
#space
#spacedocumentary
#morganfreeman
#edgeofuniverse
#isthereanedgetotheuniverse
Category
📚
LearningTranscript
00:00Space.
00:03It seems like it must go on forever.
00:07But does it?
00:09Out there in the farthest depths of the universe, might there be some place where something
00:14turns into absolutely nothing?
00:21Scientists are probing the far-flung reaches of the cosmos, trying to detect that outer
00:25limit, to find the shape of space.
00:32Now, surprising evidence suggests that not only is there a place where the universe ends,
00:42but that there might be something lurking beyond it, something unimaginably alien.
00:51Space, time, life itself, the secrets of the cosmos lie through the wormhole.
01:10Once in a while, a really big idea comes along, one that completely changes our concept of
01:26who we are.
01:28In 1543, Nicolaus Copernicus proved that the Earth was not at the center of the cosmos.
01:35In the 1920s, Edwin Hubble saw that all the galaxies in the universe were rushing away
01:41from one another, sparking the idea that the universe had not been here forever, but was
01:48created in one explosive moment, the Big Bang.
01:54Now another monumental change is upon us.
01:58We've long imagined the universe to be infinite in size, but many cosmologists now think the
02:05universe is finite.
02:09Some believe they even know its shape.
02:13If we do discover an edge to the universe, we'll have to grapple with another very challenging
02:19and unsettling question.
02:22What lies beyond the edge?
02:28Every day on my way home from school, I used to pass a long wall.
02:34It was at least twice my height.
02:37I had no chance of seeing over it, but I could hear strange sounds coming from behind it.
02:44My mind ran wild, imagining what might be back there.
02:51Wild animals, outlaws, or some fearsome monster.
02:57I would press my ear up against it to try and decipher what it could be.
03:03I never did find out, but I never stopped wondering.
03:12Neil Cornish is a cosmologist who lives and works in the Big Sky Country of Montana.
03:19The only walls out here are fences to keep his horses from roaming off.
03:25Neil is the latest in a long line of thinkers to contemplate the size of the universe.
03:31The first we know of was a Greek philosopher king called Archytas.
03:36The Greek philosopher Archytas offered an argument for why the universe must be infinite.
03:41He said, if I was to go out to the edge of the universe and then extend my staff to here,
03:47that would now be the edge of the universe.
03:50And then if I was to extend my staff to here, that would now be the new edge of the universe.
03:55And if I was to extend my staff out to here, that would now be the edge of the universe.
04:00So the universe must be infinite.
04:04Archytas' mental game set the tone for over 2,000 years of scientific dogma.
04:10Our universe must be infinitely large and has existed forever.
04:16But that dogma is now being challenged.
04:19So one problem with an infinite universe that's not just infinite in space, but also infinite
04:24in time, has no beginning.
04:26You have an infinite number of stars.
04:28So the sky would be this completely covered in white, bright, bright, so bright that it
04:33would fry you.
04:35So when we look at it at night, that's not what we see.
04:37We see a star here or there, and then essentially darkness all around.
04:41So this tells us something.
04:42It tells us we don't live in an infinite universe that's infinitely old.
04:47It was our dark sky that inspired a revolutionary idea about the cosmos, that it cannot have
04:54been here forever.
04:57The Big Bang.
04:59A moment where all the space and matter we can see burst into existence, expanding out
05:06from a single point.
05:10But the Big Bang creates a problem for astronomers searching for the edge of the universe.
05:16Because it takes, like, time to travel across the vastness of space, astronomers are always
05:21looking back in time, and eventually, they run out of time.
05:27So when we look out at the stars at night, we're seeing those stars as they were years
05:31ago.
05:32The nearby stars, maybe a few years ago, looking out across the galaxy thousands of years ago.
05:36And going back and back, we see galaxies back billions of years ago.
05:41And then beyond that, where we see no more galaxies, 13 billion years ago, is the next
05:46thing that we've managed to image.
05:48And it is the afterglow of the Big Bang.
05:51It's called the Cosmic Microwave Background, and it's a picture of the way the universe
05:57looked about 400,000 years after the Big Bang.
06:02The universe is filled with this hot gas, this hot plasma.
06:06Light really can't go anywhere.
06:07So we can't see any further back, just as we can't see into the sun.
06:13The Cosmic Microwave Background is a barrier that blocks our vision.
06:19Beyond it, there could be an edge, or perhaps the universe does extend on forever.
06:26But no matter how powerful our telescopes become, that domain will never be visible.
06:38But there might be another way to discover if the universe has an edge.
06:43Jana Levin is a theoretician who uses complex numerical simulations to solve some of science's
06:49most challenging problems.
06:56It might surprise you that a game as old as asteroids can teach us something about the
06:59universe.
07:00But there's a rule in the game to make a world out of the game that makes sense, where if
07:05you exit the top, you re-enter the bottom, or if you exit the left, you re-enter from
07:09the right.
07:10And that rule makes this world in which you're playing the game, this space in which you're
07:15playing the game, a finite space.
07:18And that's kind of like the rules we're imagining for the universe.
07:22If our universe is finite, scientists believe its edges must also be linked, that the entire
07:29cosmos must act like a giant game of asteroids.
07:33If we could bend this space, we would see that it looks like something more intuitive.
07:40For example, if I were to take this menu and apply that rule from the asteroid game, you
07:44know, I exit the top, I enter the bottom, that's exactly the same as taking the menu
07:49and rolling it up and gluing the sides together.
07:52It gives the same effect.
07:54And if I could bend this rather too stiff menu, I would try to bend it so that the two
08:00edges came together and were glued.
08:02And then I'd be making something kind of like, you know, a bagel, a classic New York bagel.
08:07And the bagel is glued together, not just like a cylinder, but also around the other side.
08:14Even though the surface of this bagel is clearly finite, no one living in this space would
08:19ever run into an edge, so it feels boundless and infinite.
08:24When we live inside the universe, we can't step outside of it.
08:27There's no other dimension to look down from onto our three-dimensional universe, so it's
08:32harder to visualize.
08:34But we can use the rules like the rules that are used in the asteroids game.
08:39And then we add one more rule for three rules for three dimensions, go out the back face,
08:44come in the front.
08:47If we do live in a cosmic asteroid cube, there is a way we could discover the edges.
08:53Not by flying a spaceship across them, but by standing still and watching light as it
08:58wraps around the universe.
09:02If the universe were the size of a room, and you stood in the middle of it, holding up
09:07a lantern, light beaming out from your back would zip out one wall and reenter the room
09:13from the other side.
09:15So you'd see an image of your back on the wall in front of you.
09:20Looking out to the right, you'd see light coming from your left side.
09:25The room would appear to be covered in mirrors.
09:28Whichever wall you looked at, you'd see an image of yourself.
09:34When we look at the night sky, we don't see this hall of mirrors.
09:39But space is so vast, light could take billions of years to loop around the universe.
09:45Space and time on this epic scale mean that mirror images would look nothing like one
09:51another.
09:54So imagine this corrals our universe.
09:57There'll be repeats of this corral, ad infinitum, giving an illusion that we live in an infinite
10:02space.
10:03But if this corral were just 30 light years across, when I look out there, I wouldn't
10:10see myself as I am now, I'd see myself as a 10-year-old boy, because I'd be looking
10:1530 years back in time.
10:18Our Milky Way is around 13 billion years old.
10:23It's been around almost as long as the universe itself.
10:27Could a distant image of the Milky Way be hidden somewhere in the night sky, disguised
10:32the way it looked 5 or 10 billion years ago?
10:36If it is, how would we even recognize this youthful twin?
10:46This scientist believes the cosmos is a hall of mirrors, that the universe is finite, and
10:53that he knows its size and shape.
11:02Imagine if the entire universe was just the size of this room, and there's space wrapped
11:09around itself, so each wall was the passageway to the wall opposite.
11:15Looking around, I would see myself fractured as if by a crystal into multiple copies, and
11:22each version would be slipped backward in time, backward in time.
11:27Is our universe a hall of mirrors?
11:34Astronomers have looked for repeating patterns of galaxies for years, looking for evidence
11:39that the universe has an edge.
11:42But they've never found any.
11:49Jean-Pierre Luminet is a senior scientist at the Paris Observatory.
11:54He's been fascinated with the shape of space ever since he was a child.
11:58I was always interested in shapes created by nature, and, well, it's a nice idea to
12:05imagine a typical snail with a spiral, for instance, and, you know, there are spiral
12:10galaxies, for instance, okay?
12:13The question is, why these shapes could not be also in the sky?
12:18Jean-Pierre's passion to discover the shape of the cosmos grew from the groundbreaking
12:22work of the great Albert Einstein.
12:26His theory of relativity showed that space is a flexible fabric whose shape is deformed
12:32by matter and energy.
12:34Einstein imagined the universe as a flat sheet stretching out to infinity.
12:40But there's no reason it can't also be finite and curled up on itself.
12:49Jean-Pierre realized he might be able to tell the difference between a finite and infinite
12:54universe by thinking of the cosmos as a giant musical instrument.
13:01The cosmic microwave background image shows us the universe the way it was 13.7 billion
13:07years ago, a hot liquid vibrating without the shocks of the Big Bang, like water rippling
13:14on a bathtub.
13:16So in some way, the universe vibrated like a piano or like a drum.
13:22So for instance, this is equivalent to the Big Bang.
13:28It's a complicated mixture of many harmonics, okay, and now we have the fundamental harmonics
13:34which gives the pitch, and after the other harmonics are like this, and so on, okay.
13:42So the full sound that we can listen to is a mixture of all these harmonics.
13:50But the number of harmonics you can hear depends on the size of the piano.
13:55The size of any musical instrument is finite, and a string, for instance, cannot vibrate
14:02on wavelengths larger than the size of the string.
14:05So maybe if we observe that the universe did not vibrate on very long wavelengths, maybe
14:10the explanation is that space has a finite size.
14:15When Jean-Pierre analyzed the ripples in the cosmic microwave background, he found that
14:21the longest wavelength ripples were indeed missing.
14:26We are surprised because there was missing wavelengths, missing fluctuation, missing
14:31low tones, you know, like low notes, very low like this, okay.
14:37They are missing from the cosmic score.
14:42Jean-Pierre's passion for music gave him a profound cosmic insight, that the universe
14:48appears to be finite.
14:51But what shape could it be?
14:55Jean-Pierre spends months carefully testing different shapes for his finite universe,
15:01trying to make it fit the vibrations of the cosmic microwave background as closely as
15:06possible, until finally, he finds the perfect fit, a 12-sided dodecahedron.
15:17A soccer ball.
15:24Here in my hands, I have two different kinds of dodecahedra.
15:27The first one is just ordinary dodecahedron, namely 12 pentagonal faces arranged in a symmetrical
15:34manner.
15:35This is a figure known since antiquity.
15:38You see that the pentagon, the pentagons are flat, okay.
15:41Here you have a different tiling of the sphere.
15:45You see that the pentagons are curved, okay, so this is called the spherical dodecahedron.
15:52If Jean-Pierre is right, the shape of the universe is a lot more complex than a six-sided
15:57asteroid's game cube.
15:59The universe has 12 sides, and leaving one face leads you to a matching pentagon on the
16:05opposite side, but with a twist.
16:09This edge is exactly the same as the opposite edge.
16:13So as soon as you get this point, you re-enter your space on the opposite side, and in addition
16:20you have to turn by 36 degrees.
16:23If the universe were a dodecahedron only slightly bigger than Earth, light would zip around
16:29it in minutes, and you would see twisted copies of Earth in a dozen different directions in
16:35the sky.
16:37But if the edges of Jean-Pierre's dodecahedron are billions of light-years apart, the distance
16:42and faint reflections on them could have escaped the notice of the most careful astronomers.
16:48And if the edges lie further than 13.7 billion light-years from Earth, we would never be
16:53able to see them, because our view would be blocked by the hot soup of the cosmic microwave
16:58background.
17:02As soon as Jean-Pierre announced his results, Neil Cornish begins looking for signs of his
17:07colossal soccer ball.
17:10He's a key scientist on a NASA spacecraft called WMAP, which spent five years photographing
17:16the cosmic microwave background in unprecedented detail.
17:23So here's a possible model of the universe based on a dodecahedron.
17:28Inside we have a balloon representing the visible universe, how far we can see.
17:33And if it was like this, where the balloon is much smaller than the space, there would
17:37be no signs that we're living in a finite universe.
17:44But if the visible universe was so large that it actually touched onto the edges of the
17:50dodecahedron, then light would actually be able to travel right around the universe.
17:57So now we would have these matching circles on the microwave sky where these two spheres
18:05intersect to form a circle.
18:07A circle here matching a circle down here.
18:14Now we have looked at the microwave background data from the WMAP satellite, and we haven't
18:19seen this pattern of matching circles.
18:24But Jean-Pierre Laminé is not ready to give up his soccer ball universe.
18:32His ideas have triggered a scientific battle that spans continents and years of meticulous
18:37work.
18:38At stake is nothing less than the truth about where we live, where we came from, and whether
18:45our universe is alone.
18:51Einstein said, only two things are infinite, the universe and human folly.
19:00But he admitted he couldn't be sure about the universe.
19:04In fact, we are now faced with tantalizing hints that our universe may not stretch on
19:10forever, that there is a point out there where the universe as we know it does not exist.
19:20It's an almost frightening thought.
19:23But before we try to grasp just what might lay beyond that final boundary, we need proof.
19:32Glenn Starkman is a Canadian physicist at Case Western University in Cleveland.
19:37He's taken data analysis to new heights in search of that proof.
19:42Call him an information junkie.
19:45The joke about Canadians is that you go to an airport and you put up a sign, free sex
19:50to the right and free information on sex to the left, and the Canadians are all the
19:54ones that go to the left.
19:55I hope I'm not that boring.
19:58Glenn has been poring over cosmic microwave background data from the WMAP probe for most
20:03of the past seven years.
20:05Along with Neil Cornish, he's been trying to test Jean-Pierre Lumine's prediction that
20:11the shape of space is like a 12-sided soccer ball.
20:14I would have been really happy to find the pattern of circles that the dodecahedron told
20:18us would be there if the dodecahedron was small and we looked for it and we didn't find.
20:24But all of their tests assumed that the edges of the soccer ball universe are closer than
20:29the microwave background that blocks our view.
20:33Now Glenn believes he's found a way to detect the edge of the universe even if it lurks
20:38beyond the area we can see.
20:41What you have to understand is what is this actual pattern of hot and cold spots that
20:46we're seeing on the sphere.
20:47And what it really is, is sound waves that were traveling through the universe when it
20:52was very young.
20:53So you can imagine it like stretching the top of a drum.
20:56At the same time as it was stretching it, it was actually making the drum vibrate a
20:59little.
21:01Different shaped universes, like different shaped drums, should leave different patterns
21:06of vibrations on the early universe.
21:10So what we're going to do is we're going to look at some different shaped and different
21:13sized drums.
21:15And what we have over here is a spectrum analyzer.
21:18And Tom has set things up so that when we make some sound, we're going to get some traces
21:23on this computer screen.
21:26So let's start with our nice round little drum.
21:33Now let's go with our heart shaped drum.
21:39It certainly sounds a little bit different.
21:43Finally, we have a star shaped drum.
21:52When we superimpose the patterns of those three small drums, we'll see that they're
21:57not quite exactly the same.
21:59They have different patterns, and so we can tell the difference between one small drum
22:04and another.
22:05And in the same way, what we're planning to do is use a spectrum analyzer to look at the
22:10different sounds that the universe made and to tell what the shape of the universe is.
22:16Glenn's analysis involves such complex mathematics that he imagines it will take years to find
22:22the answer.
22:24I will be incredibly excited if we turn out to find Jean-Pierre's dodecahedron.
22:29It would be like discovering that the Earth is round, but rather than flat.
22:34But this scientist is not waiting for data to answer this monumental question.
22:41Andy Albrecht, a theoretical physicist at UC Davis, is sure the universe is finite.
22:47He even thinks he can calculate its size.
22:51Andy studies the very first moments after the Big Bang when space was nothing more than
22:56a seething, chaotic ball of energy.
22:59Suddenly, a process called inflation takes hold.
23:03It balloons up the universe at an incredible rate, doubling its size 100,000 times.
23:09A fraction of a second later, all space and matter is smoothly spread out.
23:16Most scientists believe inflation is still happening today.
23:21The going way of thinking about inflation is that it gives us a truly infinite universe.
23:26The inflation itself never ends.
23:29The more I thought about what that infinity might really mean, the more I realized it
23:35probably didn't make sense.
23:38So Andy began working on a new theory of inflation, without infinities.
23:44It's dizzying mathematics, dealing with the laws of physics before the universe as we
23:49know it existed.
23:51But at its core, it all boils down to bubbles.
23:56A random process starts the formation of a bubble that is our universe.
24:01I will be the random process and blow the bubble.
24:12The traditional view of inflation imagines this bubble inflates forever.
24:18But Andy now takes the lessons he learned in kindergarten as a serious insight.
24:23A bubble can only grow so big before it pops.
24:28Andy believes inflation must stop when space gets to a certain maximum size.
24:34And his pioneering theory predicts that size.
24:38The universe is actually just about 20% bigger than what we see around us today.
24:44When I first started trying out those ideas, it was really difficult to go all the way
24:50from infinity to such a small thing, just a little bit larger, just 20% larger than
24:55what we see around us today.
24:58I actually felt claustrophobic.
25:01But if Andy's new theory is right, and inflation does not go on forever, our universe could
25:07look something like this.
25:09A large bubble surrounded by a cluster of smaller ones.
25:16Most cosmologists think inflation is the best explanation for the even spread of galaxies
25:21across our visible universe.
25:25But far out in space, there may be regions where inflation never took place.
25:32Find those, and you could be the first to find evidence of the edge of the universe.
25:43The eternal dance of light in the night sky.
25:47It has fascinated humankind for thousands of years, giving birth to gods, myths, and
25:55finally to science.
25:59But now there are hints of strange movements in the heavens.
26:03If they can be verified, they'll be the first hard evidence that there is an edge to the
26:09universe.
26:17Sasha Kashlinsky is a NASA astronomer.
26:20He claims to have detected a pattern of movement in the heavens so bizarre that it could revolutionize
26:26our theory of the universe, just as the Big Bang once did.
26:33We're here at Glendale Golf Course near NASA's Goddard Space Flight Center, and we came here
26:40to simulate the Big Bang.
26:42So let me try and do that.
26:48As you see, the balls just move away from their mutual center.
26:54This even spreading out of galaxies from a central explosive beginning is what astronomers
26:59see when they look at the night sky.
27:03But Sasha wanted to check more precisely how fast and in what direction galaxies are moving
27:08to see if there might be any subtle deviations.
27:12He used an effect that can only be seen when clusters of galaxies are colliding.
27:17The gases around them get heated to millions of degrees.
27:21When light from the cosmic microwave background passes through that hot gas, it gets subtly
27:27altered.
27:28How much it changes depends on exactly how fast the gas and the galaxies it surrounds
27:35are moving.
27:37But the change is tiny and almost completely buried in background noise.
27:42For each individual cluster, this is a very tiny amount and it gets drowned by the noise.
27:51But if you have many clusters, you can beat down the noise, but it's exceedingly difficult.
27:59Sasha methodically worked his way through a catalog of galaxy clusters from an orbiting
28:05X-ray telescope, checked their precise position using ground telescopes, and then carefully
28:10lined them up with the cosmic microwave background.
28:16We were quite shocked when we saw these results at first.
28:21In fact, so much that we didn't know what to do with it.
28:25We kept checking and checking.
28:26We sat on the data for a year plus, just checking everything because it just didn't make sense
28:32to us.
28:34What Sasha's data showed was almost unbelievable.
28:37All the galaxy clusters, no matter where they were in the sky, were all veering off to one
28:44side of the universe.
28:46It was as if they were being pulled toward a mysterious attractor beyond the visible
28:52edge.
28:53He called it dark flow.
28:57We called it dark flow because the observed distribution of matter in the universe cannot
29:02account for this motion.
29:05But if nothing Sasha could see was pulling the galaxies to one side, what could be responsible
29:11for the effect?
29:13The answer could be the edge of the universe.
29:18If you live in this part of the world, then at first you would imagine that the entire
29:24world is as flat as what you see locally.
29:28But if you were to look sufficiently far away, you may discover that the world is very different
29:33from what you see locally.
29:36Cosmologists ever since Einstein have thought of the universe being like a flat putting
29:40green that extends on forever.
29:44But dark flow could be hinting that our universe is a finite space, surrounded by stranger
29:52terrain.
29:54So this was Big Bang on a flat surface.
29:56So now let's go to a different part of the world.
30:08The balls did indeed disperse, but in addition they also have another velocity which is associated
30:16with the tilt of this surface.
30:18They move collectively and systematically from the higher ground to the lower ground.
30:25Sasha's discovery of a collective systematic movement of galaxies to one side of the cosmos
30:31has shaken the field of cosmology.
30:34Some scientists refuse to believe it.
30:40But for this woman, dark flow was entirely expected.
30:45And her ideas about the universe are even more mind-bending than Sasha's.
30:51She believes she's found evidence that another universe is reaching out and touching ours.
31:04Scientists have discovered a mysterious dark flow of galaxies, all veering off to one side
31:11of our universe.
31:13It could be a sign that way out beyond the furthest star lurks a portion of the cosmos
31:19vastly different from the universe we know.
31:24But there's an even more shocking possibility.
31:28Dark flow could be evidence of another universe reaching out to us.
31:35That's what theoretical physicist Laura Mersini-Houghton thinks.
31:39The seed of this idea was planted many years ago when she realized she had a problem with
31:44the universe, a pretty big problem.
31:48According to her calculations, the universe should not exist.
31:54The chances to start the universe with the high-energy Big Bang are one in ten with another
32:01ten zeros behind it and another 123 zeros behind it.
32:06So pretty much zero.
32:10So whenever in science we end up with an answer that this seems very unlikely, this event
32:19is not generic, then it usually indicates that we may have blundered in something very basic.
32:28But Laura had an idea of how to stop the Big Bang from being such an unlikely event.
32:34You might call it a gambler's hunch.
32:40If you're playing a slot machine where the odds of hitting the jackpot are one million
32:43to one, you could play all day and never strike it rich.
32:48But if all six billion people on Earth each play their own slot machine, someone somewhere
32:54is going to get rich about once every few seconds.
33:00Laura realized that one branch of theoretical physics offered a way to turn the Big Bang
33:06into a sure bet.
33:08It was string theory.
33:11This view of reality suggests that alongside the normal three dimensions of space, there
33:17are another seven hidden dimensions wrapped up so tightly we cannot see them.
33:23You start wrapping up those extra dimensions, the extra seven dimensions.
33:28There are so many ways of doing that process.
33:32String theorists ended up with not just one three-dimensional world, but with many, many
33:39possible three-dimensional worlds.
33:43In fact, string theorists realized there were 10 to the power of 500 possible ways
33:49to arrange these dimensions.
33:52That's a one with 500 zeros behind it, a number countless times bigger than the odds against
34:00our Big Bang.
34:01The only way we can ask the question about the origins of the universe is if we have
34:07a multiverse structure from which our universe is born, a landscape of many possible places
34:15in this multiverse where the universe can start from.
34:19If each of these balls of wrapped up dimensions is an energy site where a universe could start,
34:26then the odds of a Big Bang happening in one of them is no longer an enormous long shot.
34:32In fact, the odds are good enough that Laura's willing to bet this landscape should contain
34:38many Big Bangs and many universes.
34:43You can think of this multiverse landscape as the biggest hotel you can imagine, a hotel
34:48with 10 to the power of 500 rooms, each one waiting for a guest to check in.
34:56Every room would represent an energy site of that landscape.
35:00There is an infinite number of people that can try to check in into these hotel rooms.
35:06I try to go into a room and I discover that energy site is taken, someone else is there.
35:15Once a universe is born in that energy site, first that energy site cannot be shared with
35:21another universe, so I try to go to the next room, until I find an empty room.
35:33That room is really boiling hot, so it contains a lot of energy.
35:38Once I am in the room, I cannot get out of it anymore, the door is locked.
35:43That's how the universe is born.
35:54But if our universe is like a hotel room, shouldn't we be able to detect the presence
35:59of guests in the room next door?
36:02That earth-shattering evidence could look as subtle as this small blue patch.
36:09In 2007, data from the WMAP spacecraft confirmed the presence of a strange cold spot in the
36:16cosmic microwave background.
36:22If I have an empty region of space, that would show as a cold temperature region.
36:27In the case of the cold spot, the only way such a part of the sky could just be completely,
36:33entirely empty.
36:34That kind of bizarre behavior of the universe can occur only if there is some other force
36:41at work.
36:43Laura believes the cold spot is evidence of another universe right next to ours, its enormous
36:49mass pulling on matter at the edge of our world.
36:54If there are some very massive objects in the next room, in other words, in the neighboring
37:01universe, then I should be able to feel that gravitational pull, although I cannot directly
37:08see it.
37:09But for a theory as radical as the existence of another universe, the cold spot alone is
37:15not enough.
37:16Laura needs more evidence.
37:22And help is at hand.
37:24Two scientists are about to join forces in a remarkable endeavor to find the size and
37:31shape of our universe and the universe next door.
37:40Is the universe infinite, or does it have an edge?
37:47Or is our universe just one member of a cosmic family of universes, spread across a strange
37:54and uncharted landscape?
37:57Just a few years ago, even asking these questions was unthinkable.
38:03Now we're close to finding the answer.
38:10Sasha Kashlensky is convinced that some mysterious attractor at the edge of our universe is pulling
38:16on galaxies, forcing them to move with what he calls dark flow.
38:23His work is still controversial, and to convince the skeptics, he needs more data.
38:28We hope in a few years to have a catalog of up to 2,000 galaxy clusters in total.
38:37And with the new data, we hope that we'll be able to measure the flow to much larger
38:42scales.
38:45But Sasha now has a powerful ally.
38:48A thousand miles away, in Toronto, Laura Messina Houghton was refining her own calculations
38:54about the edge of the universe, when she got a phone call from her mother.
39:00And she says to me, did you see the news about something called the dark flow or another?
39:06There was a NASA person there?
39:09And I said, no, I haven't.
39:11So I went straight into my computer and found out that the team at NASA, led by Sasha Kashlensky,
39:19had reported they had seen the dark flow of structure in the universe.
39:25That was exactly in perfect agreement with the prediction we had made two years ago.
39:31But what made it spookier was that even the numbers, the speed at which those galaxies
39:36were moving, and the direction in which they were moving, were in absolute perfect agreement,
39:42astronomically, with our predictions.
39:47Now Laura and Sasha are both contemplating just how this exotic landscape outside our
39:53universe might behave.
39:56I can think of this board as the landscape, the energy sites onto which these wave packets
40:03of the universe will eventually settle.
40:05Now, I have to send the wave packets through that landscape, through that board, in order
40:11to populate it.
40:15Think of this marble as the pulse of energy that triggered our Big Bang.
40:20Soon, another pulse of energy comes along.
40:24It falls into a different dip, and a neighboring universe is born.
40:29That universe is not a place we can ever go.
40:33Its arrangement of dimensions will be completely different from ours.
40:36But there is one way we can sense its presence.
40:42If the two universes are close enough together, their gravitational attraction will pull anything
40:47with mass towards their respective edges.
40:52That's why we see the cold spot.
40:54And that's why there's a dark flow of galaxies moving across the cosmos.
40:59This other universe is pulling on ours.
41:04Until about three, four years ago, we knew nothing of the multiverse.
41:10However, things are changing dramatically on the last few years.
41:14Technology is helping us find signatures of the existence of the multiverse.
41:20But across the world of cosmology, the reactions to these scientists' controversial work is
41:26mixed.
41:27If any one of them is right, the implications would be enormous.
41:32Why do we even care about the size and shape of the universe?
41:36That part of the story is critical for our attempts to understand how it all came into
41:42being, why it is the way it is, and why we see what we see around us.
41:47All these questions have very different answers if we're looking at the infinite story or
41:52the finite story.
41:53You'd be able to say, look, here is the universe, this is its shape, and that's where we live.
41:59And that's a revolution in physics, going outside our universe, at least with the power
42:04of our imagination, but then that's what makes human beings special.
42:13Every now and again, our perception of the universe and our place in it undergoes a revolution.
42:21We used to think the Earth was the center of all creation.
42:26For the past century, we've learned to accept that we live in a nondescript region of a
42:32backwater galaxy in a universe that is unimaginably vast.
42:41Now it's time for another change of perspective.
42:47Our universe itself, once assumed to be infinite, might have to shrink down and take its rightful
42:53place, as a humble member of a truly giant multiverse, a multiverse filled with universes
43:01beyond our wildest imaginations.