- 5/22/2025
We move and live in three dimensions: length, width, and height. However, Einstein revealed what was once unimaginable: time is actually a dimension and linked with space itself. To reconcile the massive cosmic and minuscule quantum worlds, physicists are realizing four dimensions may not be enough. Tim Tait believes that a fourth dimension may explain the mystery of dark matter. Others are unraveling up to eleven dimensions.
A hypercube can have 4 dimensions.
Dark matter affects the way stars rotate around galaxies. In 2008, NASA launched the Fermi Space Telescope to pick up intense radiation known as gamma rays [gamma rays are much more energetic than X rays ] emitted by exploding stars.[20] In addition, the Fermi Space Telescope is supposed to detect from the gamma rays from the photons of dark matter.
As of 2011, no physicist has found any physical evidence of strings (which supposedly are vibrating strings that make up sub-atomic particles) at the Large Hadron Collider. However, torturous mathematical evidence has emerged of objects that make up the unseen strings; these strings interact with spacial planes knows as D-branes. Strings and their complementary D-branes are only shown to exist in complex mathematical exercises.
Gravity is associated with closed strings. Within the paradigm of string theory, a graviton is not an elementary particle but a closed-loop string.
Renate Loll believes that string theory "itself is wrong," Freeman narrates.
Thanks for watching. Follow for more videos.
#cosmosspacescience
#throughthewormhole
#season2
#episode4
#cosmology
#astronomy
#spacetime
#spacescience
#space
#nasa
#morganfreeman
#spacedocumentry
#dimensions
#aretheremorethanthreedimension
#threedimensions
A hypercube can have 4 dimensions.
Dark matter affects the way stars rotate around galaxies. In 2008, NASA launched the Fermi Space Telescope to pick up intense radiation known as gamma rays [gamma rays are much more energetic than X rays ] emitted by exploding stars.[20] In addition, the Fermi Space Telescope is supposed to detect from the gamma rays from the photons of dark matter.
As of 2011, no physicist has found any physical evidence of strings (which supposedly are vibrating strings that make up sub-atomic particles) at the Large Hadron Collider. However, torturous mathematical evidence has emerged of objects that make up the unseen strings; these strings interact with spacial planes knows as D-branes. Strings and their complementary D-branes are only shown to exist in complex mathematical exercises.
Gravity is associated with closed strings. Within the paradigm of string theory, a graviton is not an elementary particle but a closed-loop string.
Renate Loll believes that string theory "itself is wrong," Freeman narrates.
Thanks for watching. Follow for more videos.
#cosmosspacescience
#throughthewormhole
#season2
#episode4
#cosmology
#astronomy
#spacetime
#spacescience
#space
#nasa
#morganfreeman
#spacedocumentry
#dimensions
#aretheremorethanthreedimension
#threedimensions
Category
📚
LearningTranscript
00:00There's never been a stranger idea in the entire history of science.
00:10Down at the smallest scale, smaller than ourselves, smaller than atoms, could the world suddenly
00:18get bigger, branching out in new and totally unexpected ways?
00:25A quest to understand the ultimate nature of reality has gripped the greatest living
00:31minds and is forcing us to consider a truly shocking possibility.
00:37Are there more than three dimensions?
00:45Space, time, life itself.
00:51The secrets of the cosmos lie through the wormhole.
01:08Up, down, backward, forward, side to side.
01:15If you want to get anywhere on Earth, these three dimensions are the only ways you can go.
01:21They describe any place in our reality.
01:26Or do they?
01:28Many scientists now believe our world is not three dimensional, that somehow there are
01:35other ways to move.
01:38Discovering those hidden dimensions is the biggest prize in physics and would forever
01:44change the way we see the universe.
01:50When I was a boy down in the Mississippi Delta, bugs swarmed all summer long.
01:58Some of them could even walk on water.
02:01But down below, there were creatures who would occasionally dart up and grab an unsuspecting
02:07bug.
02:10The water bugs never seemed to see it coming.
02:15Why not?
02:17Was it because to them the pool had no depth, no third dimension?
02:26Could we be like water bugs, unable to see the full extent of reality?
02:34Susan Barry knows all too well the limits of human perception.
02:38She was born with her eyes severely crossed.
02:42As a baby, her brain's attempts to fuse the separate two-dimensional images from each
02:48eye into one 3D image ran into serious trouble.
02:53Now, when I was little, being cross-eyed, if I, let's say, looked at the apple with
02:58my right eye, my left eye would be turned in and looking at something else, let's say
03:04this clock.
03:06So that would mean one eye is seeing the clock and one eye is seeing the apple.
03:11And the brain might interpret that to think that that clock and the apple were in the
03:16same place in space.
03:18Now, if you think about that, that's an untenable situation.
03:22Because how would you be able to know how to move and interact with things if you don't
03:26know where they are in space?
03:29So if your eyes are crossed like that, you have to find a way to adapt.
03:33And one way to adapt, the way that I used, was I simply threw out the information from
03:37one eye, the eye that was turned.
03:40Susan had eye surgeries when she was a child, but they only changed her outward appearance.
03:46She could only see two dimensions.
03:49Nothing had any depth.
03:51Everything, even her own reflection, looked entirely flat.
03:56And it seemed she would live that way forever.
04:00For the past half century, there has been a belief that if you did not develop the ability
04:08to see in 3D within the first years of life, in early childhood, you could not develop
04:13it as an adult.
04:16But in her late 40s, Susan began a rigorous vision retraining program to try to teach
04:22her eyes to lock onto the same target and give her brain the chance to discover an extra
04:28dimension of space.
04:31One day, after her 48th birthday, something incredible happened.
04:37I went out to my car, and I sat down in the driver's seat, and I went to look at the steering
04:42wheel, and it had popped out.
04:45It was popped out in space with this palpable pocket of space between the steering wheel
04:50and the dashboard.
04:52And I had never seen anything like that.
04:55And all that day, my stereo vision would emerge, like, intermittently, unexpectedly.
05:01And it would be amazing.
05:03The sink faucets were really jutting out toward me, and I can remember just admiring the sink
05:10faucets and thinking that I had never seen an arc as beautiful as the arc of those sink
05:16faucets.
05:18The sudden appearance of this extra dimension was a revelation to Susan Barry.
05:24But the idea that another dimension beyond the three we know might be hiding from all
05:30of us is now at the center of the world's most important scientific investigations.
05:38Harvard professor of physics, Lisa Randall, is at the forefront of this hunt.
05:43She sees the world differently from you and me.
05:47It was just one day I was walking to work, and I realized I really did think that extra
05:51dimensions could be out there.
05:53The main reason for her conviction that there must be more than three dimensions?
05:58This paperclip.
06:01It's really strange.
06:03If I take this tiny magnet, I can pick up this paperclip.
06:08Even though the entire Earth is pulling down on this paperclip, if you think about it,
06:13the force of magnetism that is exerted on this paperclip is enough to compete and actually
06:18overwhelm the force of gravity that's acting on it.
06:21So there's a mystery there.
06:23Because why is electromagnetism so much stronger than the force of gravity?
06:29Physicists have discovered that we live in a world governed by four primal forces.
06:35There's electromagnetism, the force that affects objects with electric charge, the strong nuclear
06:42force, whose power is unleashed in nuclear weapons, and the weak nuclear force that triggers
06:48radioactive decay.
06:50These first three forces are all roughly equal in strength.
06:54But the fourth force, gravity, is much weaker.
06:58In fact, it's around a trillion, trillion, trillion times weaker than the other three.
07:05So we're trying to understand what can explain why gravity is so much weaker than the other
07:11elementary forces.
07:13And one of the possibilities that we've started to think about quite seriously in the last
07:17decade or two is that there could actually be additional dimensions of space.
07:22If that's true, it could be that gravity is weak because it's actually concentrated somewhere
07:27else in another dimension.
07:29The idea that extra dimensions might be a hidden part of our reality is as old as Plato.
07:35He imagined the world we live in to be like the wall of a cave lit by firelight.
07:41Shadows dance across our two-dimensional world, cast by objects in the body of the
07:46cave, in a third dimension that's hidden from us.
07:50A three-dimensional geometrical shape, like the tetrahedron, which has four equal sides,
07:56could cast a distorted shadow on the wall so that one side looks much shorter than the
08:02others.
08:03Just as an extra dimension can hide the true length of one of the sides, so too it might
08:10be hiding the true strength of gravity.
08:13And Lisa Randall's efforts to learn about extra dimensions begins, like Plato's, with
08:19studying shadows.
08:21So here I have a three-dimensional cube.
08:23Now, if I had a single projection, I might actually confuse that, for example, of just
08:28being a square, which is two-dimensional.
08:30However, by rotating the object and looking from different angles at different projections,
08:35you can tell that what you have is a three-dimensional object.
08:38By putting together the information, you can deduce what's there.
08:41Just as a two-dimensional shadow can help us learn the true shape of a three-dimensional
08:46cube, we can explore a four-dimensional cube, a hypercube, by looking at its three-dimensional
08:53shadows.
08:54Or we can look at different projections of a hypercube.
08:57What we would see are things that, from one angle, might look like a cube.
09:00From other angles, it might look like a cube inside a cube.
09:03It might look like it's turning itself inside out, because we're not really in the fourth
09:07dimension.
09:08So it does things that we're not familiar with, because it has this whole other dimension
09:12of space that it can play with.
09:14But if a fourth dimension does exist, shouldn't we see objects changing shapes like this,
09:20even turning themselves inside out?
09:23Could it be that whatever exists in the fourth dimension is somehow blocked from entering
09:28our world?
09:30Or could there be hidden some other way?
09:32So if there are extra dimensions, they have to be pretty well hidden for us not to have
09:36seen them.
09:37So why would that be?
09:38It could be these other dimensions are just so tiny, we just don't notice them.
09:42But this scientist thinks he's discovered a new way to detect them, and that dimensions
09:47we can't see control the way everything in the universe moves.
09:53What would it look like if we were to travel into a fourth dimension of space?
10:01It's not easy to imagine.
10:03But here's one way to get an idea.
10:06Think of the palm of my hand as a world of only two dimensions.
10:11If a three-dimensional ball were to pass through it, what would the inhabitants of my palm
10:16see?
10:18A circle that grew and then shrunk down to a dot before disappearing.
10:24So, if I could move into the fourth dimension, my three-dimensional projection would distort,
10:31shrink, and finally flicker out of this world, becoming totally dark.
10:41UC Irvine physicist Tim Tate has discovered a new way to detect objects.
10:47The physicist Tim Tate thinks most of the matter in the universe may have moved into
10:52the fourth dimension and gone dark.
10:56He too spends most of his time trying to escape the dimensions that normally confine us.
11:12When you scuba dive, you become immediately aware of the fact that you have to control
11:16how high you are, how deep you are in the water, how close you are to the surface.
11:21And so, you instantly become aware of the fact that there's another dimension in a way
11:26that you can't really feel when you're on the ground.
11:29Tim believes that yet another dimension, a fourth dimension, might be the key to explaining
11:34one of the deepest mysteries of the universe, the mystery of dark matter.
11:40In the recent years, we've become really aware of the fact that when we account for all the
11:44stuff in our universe, there's stuff that's missing.
11:47We can see it pulling on other things gravitationally, but other than that,
11:51it doesn't leave any trace that it's there.
11:54Scientists are convinced dark matter exists because it's affecting the way stars rotate
11:59around galaxies.
12:01The gravitational pull of it is so strong that they estimate dark matter outweighs normal
12:07matter by five to one.
12:10We really don't know what dark matter is, but there have been many ideas that have been
12:14proposed to try to explain it.
12:16And my own personal take on dark matter is a theory with extra dimensions.
12:23Tim's idea is that dark matter could be evidence that a fourth dimension exists,
12:29a dimension that is almost impossible for us to see.
12:33So an analogy for the extra dimension would be looking at the anchor line of a boat.
12:37When you look at the line from far away, you see a line.
12:40You see a long, thin object, and you don't realize that it actually has width,
12:44that it has an extra direction that you can move if you were sitting on the surface of it.
12:48Close up, it's actually a cylinder.
12:50It's big and fat, and you can move around the periphery of it.
12:54If particles were moving around this cylinder, and if it was small enough,
12:59they would look to us like they were not moving at all.
13:03So this is our model for an extra dimension.
13:05We have the bob, which represents a particle.
13:08As I spin the particle around, it goes in a circle with a string holding it in place,
13:13and that represents it moving in the extra dimension.
13:15So let's see how that works.
13:17So here we have it spinning around in the extra dimension.
13:20As it gets closer and closer, it speeds up, it moves faster and faster,
13:23and it has more energy.
13:25Even though this particle looks like it's standing still,
13:28it can actually be moving very, very fast just in a very, very small circle.
13:32Any particle that is moving must have energy,
13:35and according to the most famous equation in all physics,
13:39if you have energy, you have mass.
13:43That gave Tim a flash of inspiration about what dark matter particles might actually be
13:49and how they might lead us to discovering the fourth dimension.
13:53So photons are particles of light, but if there's another direction that photons can travel in,
13:59we can actually get a dark matter particle by just taking these massless photons
14:03and letting them move around in a circle in the extra dimension.
14:06If Tim is right, dark matter is actually made of light,
14:11massless particles that appear to have mass because they are racing around
14:15a tiny fourth-dimensional loop that's too small for us to see.
14:20But how and when did these photons leave our three-dimensional world
14:25and enter the fourth dimension?
14:28One way you can try to understand this is if you think about a roundabout in a playground.
14:33It's spinning around really fast.
14:36To actually get onto the roundabout, a child is going to have to run around it
14:39at the same speed that it's spinning.
14:42But if it's spinning faster than the child can actually run,
14:45then there's no way to get onto it safely.
14:49Most particles we have today just don't have that much energy,
14:52but when the universe was very young, it was very small and it was very hot.
14:57And at that time, particles had a lot more energy,
14:59and they were able to actually get into the extra dimension.
15:03Right after the Big Bang, super high energy particles of light
15:07may have blasted their way into the fourth dimension.
15:11They've been stuck there ever since and appear to us today as dark matter.
15:17But Tim thinks there might be a way for them to get out.
15:21And when they do, they could bring us proof that the fourth dimension really exists.
15:29If two photons are moving around this curled up dimension in opposite directions,
15:34they might occasionally bump into one another.
15:38When they collide, they annihilate and burst out as an intense shower of energy
15:43into our 3D universe.
15:47Even though this event is rare, these collisions in the fourth dimension
15:51should create a telltale signal.
15:54Engine start. Lift off.
15:57In 2008, NASA launched the Fermi Space Telescope,
16:01a probe designed to pick up the intense radiation, gamma rays,
16:06created by cosmic cataclysms like exploding stars.
16:10But it should also detect gamma rays from dark matter photons
16:15as they annihilate one another.
16:18So as it collects data, we understand the gamma ray sky
16:21and we start to look for where the dark matter might be.
16:24Fermi has already discovered a sea of gamma rays emanating from the center of our galaxy.
16:29But much more work is needed to prove this signal is coming from the fourth dimension.
16:35So obviously I hope that tomorrow we declare victory and explore the extra dimension.
16:39On the other hand, I don't know exactly when we're going to discover it.
16:42I think though that the prospects today are much better than they have been in the past.
16:49The Fermi Telescope will continue gathering evidence from the depths of space until around 2015.
16:59But proof that there are more than three dimensions may not come from so far away.
17:04Right now, the biggest experiment mankind has ever built
17:08is trying to find them under the Swiss Alps.
17:18The goal of science is to reveal to us the deepest workings of nature.
17:24And nothing in science attempts to go deeper than string theory.
17:30String theory says that every single particle of matter and energy in the universe
17:36is actually a tiny vibrating string.
17:41A string that vibrates not in three dimensions, but in nine.
17:48If string theory is right, at every point in space there are six extra dimensions
17:55curled up incredibly tight.
17:58These hidden dimensions could solve all the mysteries of physics.
18:03But there's a problem.
18:05Since string theory was first proposed over 40 years ago,
18:10there's not a single shred of evidence to support it.
18:17Thousands of scientists are on the hunt for that evidence.
18:21Under the foothills of the Alps in Geneva lies the Large Hadron Collider, the LHC.
18:29It's a 17-mile-long circular racetrack designed to smash
18:33subatomic particles together at phenomenal energies.
18:38Caltech physics professor Maria Spiriopoulou has been working
18:42at the atom smashers in Geneva since she was an undergraduate.
18:47She has seen trillions of particles fly like subatomic shrapnel through the detectors.
18:53The LHC, I think it is the most ambitious and technologically complex
18:58scientific project that humanity has ever attempted.
19:02We got a billion collisions per second and this is a daunting task to record this data.
19:09Maria and her colleagues have sifted through this immense pile of data
19:13and identified dozens of tiny subatomic particles.
19:17The basic building blocks of matter.
19:20But they've never seen the strings that lie at the heart of each of these particles.
19:25String theory predicts that they must be a trillion, trillion times smaller than an atom.
19:32Put that another way, if an atom were the size of the solar system,
19:37a string would be the size of a light bulb.
19:40And the smaller an object is, the more energy it takes to see it.
19:45The energy of the subatomic particles racing around the LHC is staggeringly large.
19:52Protons zip around this ring so fast that a beam of light
19:56only outruns them by about 8 miles an hour.
20:00But to see fundamental strings, you have to travel a long way.
20:04A beam of light only outruns them by about 8 miles an hour.
20:08But to see fundamental strings and their six curled up dimensions
20:13requires levels of energy almost beyond comprehension.
20:19If you want to make a collider that will actually produce something like strings,
20:26it would take an accelerator much bigger than the LHC,
20:29much bigger than the Earth, the circumference of the Earth,
20:32possibly much bigger than the Milky Way.
20:49But there may be a way to prove that string theory
20:51and the six extra dimensions of space that come with it is correct.
20:56A way that does not require seeing tiny strings directly.
20:59Joe Polchinski is one of the world's leading string theorists.
21:04Like many physicists, he draws inspiration from being close to nature.
21:09It's great to get out here in nature, in the mountains, to think about things a bit.
21:14When you get to the top of a climb, you really get a much bigger picture.
21:22Joe has probably delved deeper into the workings of string theory than anyone else,
21:26and in doing so, he realized something crucial was missing from the man.
21:32So we know that the basic building blocks of nature have to be really small.
21:36Smaller than anything we've ever seen, probably a whole lot smaller.
21:40So if these building blocks are strings, you know, they're very elusive.
21:44How do we know that they're there?
21:46And so it's challenging, and there was this one calculation we would do,
21:51and the answer that the math was giving us was that
21:54the answer that the math was giving us wouldn't match up with the physical picture we thought we had.
22:00It turned out that the problem was the strings themselves were not enough.
22:04What the math was telling us was there was another kind of thing,
22:08another sort of object in the picture.
22:10In 1995, after many years of work,
22:14Joe made his way through the tortuous math and discovered the source of strings.
22:20He called these objects D-branes.
22:25So we're out here on this nice hike out here in nature,
22:28and we've got this beautiful spiderweb, which is a nice model for some of these ideas.
22:34So D-branes are these higher-dimensional objects.
22:37They can be two-dimensional, three-dimensional, or even more.
22:40And this spiderweb is two-dimensional, a nice sheet,
22:42and like a sheet, it can flex and bend the way D-branes can flex and bend.
22:46Now, it's not a perfect model because this web is stuck between these two branches,
22:50but the D-branes can go on forever.
22:52They could be of cosmic size, stretching from one side of the universe to another.
22:56And if you look close, you see that there are these little bugs stuck to it,
23:01the way strings get stuck to a D-brane.
23:04In Joe's theory, D-branes could take on any of the nine dimensions
23:09that exist in the mathematics of string theory.
23:12Our entire universe could be a three-dimensional brane.
23:16A block of space to which all the strings, all the matter in our universe, is stuck.
23:24Now you have the brains doing what they do,
23:27and you find that very possibly the dimensions could be much larger than we thought about.
23:33Large enough to see particle accelerators,
23:36large enough to maybe have effects on what we see in astrophysics,
23:41in some of the physics we see from space.
23:47Thanks to Joe's discovery, scientists around the world are fueled with fresh hope
23:53that they may soon detect extra dimensions.
23:57If you, me, every star, every galaxy in the cosmos is stuck on a three-dimensional brane,
24:06then a fourth dimension wouldn't have to be a tiny fraction of an atom.
24:11It could be much bigger.
24:12The discovery of extra dimensions would be one of the biggest breakthroughs in the history of science.
24:18But it might also spell disaster.
24:21Because the experiment that proves they exist might also create a black hole here on Earth.
24:31In 1609, Galileo peered through his telescope and spied the moon's orbit.
24:39He peered through his telescope and spied the moons of Jupiter.
24:45His discovery of those four tiny points of light, invisible to the naked eye,
24:51changed our understanding of our world.
24:55Extra dimensions of space would be much harder to see than Galileo's moons.
25:00But if we discover them, it would change our understanding of the entire universe.
25:07This piece of delicately balanced equipment could be the device that discovers the fourth dimension.
25:14It sits in a basement at the University of Washington and belongs to this man.
25:20Eric Adelberger, along with a small team, has spent the last decade watching this torsion balance twist back and forth,
25:28hoping it reveals evidence that there are more than three dimensions.
25:33Gravity is really an amazing story.
25:37It was the first of the fundamental forces that the physicists learned about.
25:41Isaac Newton had his theory of gravity, which has been tested very well in the solar system,
25:47but it's not really been tested very well at all at very short distances.
25:51And these short distances are now where all the theoretical action is, so to speak.
25:56The forces Eric needs to measure are incredibly weak.
26:00Even though the lab is underground, his data is frequently marred by trains, rush hour traffic,
26:07even airplanes flying miles overhead.
26:10The forces we're measuring are really extraordinarily tiny.
26:14To get some idea, if you could cut a postage stamp into a trillion little pieces somehow,
26:20and could weigh one of those little pieces somehow, that's the kind of forces that we're measuring.
26:26If the force of gravity deviates from Newton's laws at very small distances,
26:31it would be a telltale sign that an extra-microscopic dimension exists.
26:37It's a principle Eric knows firsthand from his passion outside the lab,
26:42tending another set of delicate objects.
26:45A nice way to understand this is this analogy between the way gravity spreads out in varying number of dimensions
26:51and the way flow of water spreads out in varying number of dimensions.
26:56We've got a steady stream of water that flows out of these two outlets at the top,
27:01falls into a channel, and is confined in one dimension, and it runs down along in one dimension.
27:07And we've made one channel twice as long as the other channel.
27:11And we're going to see, measure the flow of water,
27:14by watching how much the level of the water in this bucket changes compared to this bucket,
27:21where the water's had to travel twice as far in that one dimension.
27:25Music
27:31The amount of water that's flowed through the longer one-dimensional channel
27:36is just the same as the amount of water that's flowed through the shorter one-dimensional channel.
27:40So what this tells us about gravity is that if gravity were operating in a one-dimensional world,
27:46this would be the same if objects are close together or if they're very far apart.
27:51So now we're going to see what happens when the water flows in two dimensions.
27:55Music
28:10In our two-dimensional experiment, the beaker that was closer to the water source
28:16got twice as much water as the beaker that was farther from the source.
28:20If these two beakers here were our measure of gravity,
28:23we would know that we were in a two-dimensional world
28:26because we got twice as much water over here.
28:29Music
28:32Okay, now we're going to see what happens when the water spreads in three dimensions.
28:36Music
28:38When water spreads out in a three-dimensional world,
28:42when you place the bucket twice as close to the source,
28:45you get four times as much water.
28:48Music
28:51So if we lined up the beakers from the three experiments,
28:54we'd see that the 1D beakers, the water was the same height.
28:572D, the nearer beaker had twice the water,
29:00and in the case of 3D, it had four times the water.
29:03Now if we could imagine that we were living in four dimensions, what would we see?
29:08We would expect to see that the nearer beaker had eight times the amount of water
29:12that the more distant one had.
29:14The more dimensions there are,
29:17the faster the force of gravity changes with distance.
29:20Music
29:22Well, we've measured gravity down to roughly 50 microns.
29:27That's about half the diameter of a hair on your head, okay?
29:30So far, Mr. Isaac Newton is still correct.
29:35If Eric can get even closer,
29:38the hidden world of extra dimensions could suddenly pop into view.
29:43There are reasons to think that, you know, the region between 50 and 10
29:47might contain some real surprises,
29:48and of course that's stimulating our enthusiasm for doing the experiments.
29:54Music
29:56On the other side of the planet, at the Large Hadron Collider,
30:00particle physicist Maria Speriopoulou is also looking for unexpected changes
30:05in the force of gravity.
30:07But if her experiment is successful,
30:09she'll create something never before seen on Earth,
30:12a black hole.
30:14Music
30:16It is quite possible the LHC experiment can produce
30:21the so-called microscopic black holes.
30:24This is not the type of black hole that is born from a collapsing star,
30:29where the core gets so compacted that nothing can escape its gravitational pull.
30:34What Maria is looking for is evidence of a microscopic black hole.
30:39If the LHC can force two particles sufficiently close together,
30:43and the extra dimensions are large enough,
30:47gravity could start growing much stronger than expected,
30:51eventually compacting the two particles enough to form a tiny subatomic black hole.
30:57But don't worry about moving to Mars just yet.
31:01The black holes Maria and her colleagues expect to create are tiny,
31:07so tiny that they will evaporate in a fraction of a second.
31:10The microscopic black holes, as soon as they are produced,
31:15they immediately decay with a very, very short lifespan.
31:19There is a spray of these particles,
31:22and that is the clue that such an object might have been created.
31:27The LHC has been looking for these black holes for over a year.
31:33So far, they've found no hint of even a single black hole being created.
31:37Extra dimensions remain elusive.
31:41But Lisa Randall thinks that might be because they're different from what most scientists expect.
31:48She believes extra dimensions are warped,
31:52and that they are passageways to a parallel universe.
31:59Extra dimensions are not easy to see.
32:03If they were, we'd have found them.
32:05If they were, we'd have found them long ago.
32:09Many scientists now believe we'll never have the technology to find them.
32:14But extra dimensions might still reveal themselves,
32:18because they might be separating us from a parallel universe.
32:24An entire cosmos could be lurking less than a trillionth of an inch away.
32:31Harvard professor Lisa Randall has a radical new idea about extra dimensions,
32:37one that will change the way we see our entire universe.
32:42She began with string theory,
32:45the idea that all the fundamental particles are just vibrations of tiny nine-dimensional strings.
32:52Then she added in Joe Polchinski's ideas
32:56that strings making up all the stuff in our universe
32:59had to be stuck to a giant three-dimensional object called a brain.
33:05There are two types of strings.
33:07Strings with ends and strings that are closed loops like rubber bands.
33:11And the strings with ends, those ends have to be somewhere.
33:15They can't just be anywhere in higher dimensional space.
33:17They have to be on the surface of a brain.
33:20And if that's true, the particles associated with that string will also be on the brain.
33:25And it turns out that all the matter we know about
33:27and also the forces through which they interact
33:30might all be stuck in a brain through this mechanism.
33:33Except for gravity.
33:35Because gravity is never associated with open string.
33:38Gravity is associated with a closed string.
33:41And closed strings have no ends.
33:43There's no mechanism that makes it stick to a brain.
33:45A closed string can be anywhere.
33:47Lisa's math suggested that gravity might be so weak
33:51because the closed loop strings that carry this force, gravitons,
33:55are being pulled away from our brain
33:58and concentrated instead in a parallel universe
34:01that's separated from us by a fourth dimension.
34:05You can imagine that these two buildings behind me
34:08represent two different brains.
34:10And we may be in a parallel universe,
34:12but these two buildings behind me represent two different brains.
34:15And we may be living only in that building or that brain.
34:19If gravity is concentrated at the other building,
34:22we might only get a tail end of gravity.
34:24It might be that that could explain why gravity is so weak for us.
34:28Gravitons flow freely between our brain
34:31and the one that's across the fourth dimension.
34:34But the gravity in that parallel world is so strong
34:37it compresses space trillions upon trillions of times
34:40smaller than ours.
34:42The space between these two brain worlds is warped.
34:46As gravitons move from the dense gravity brain to our brain,
34:50they spread out and that force gets far weaker.
35:00Things get rescaled as you go from one place in an extra dimension to the other.
35:05So whereas things might be extremely heavy here,
35:07they could be exponentially lighter here,
35:10which would naturally explain why gravity is so weak.
35:14Lisa Randall's idea of a warped fourth dimension
35:18separating us from a parallel universe
35:21where gravity is just as strong as the other forces of nature
35:24has set the world of physics alight.
35:28Back at the Large Hadron Collider in Geneva,
35:31the beams will soon be smashing together
35:34with enough force to produce particles
35:37that could prove this warped dimension really exists.
35:42Well, if this idea is right,
35:45you would actually be able to make particles
35:48that essentially have momentum in another dimension.
35:51And that's what we're trying to do here.
35:53We would actually be able to make particles
35:56that essentially have momentum in another dimension.
35:59Now, we don't see that other dimension.
36:01What we see is the effect as if the particle had mass
36:04and the mass turns out to be the right mass
36:07that it can be produced at the energies of the Large Hadron Collider, we hope.
36:14Any day now, news may come from the Swiss Alps
36:17that the world is fundamentally different
36:20from the way we've always imagined it.
36:23Is there a twist to this epic hunt
36:26for warped or curled up extra dimensions?
36:29One scientist thinks our search is doomed to failure.
36:34She does not believe there are more than three dimensions.
36:37She thinks there is only one.
36:44How do you build a universe?
36:47Do you need three dimensions?
36:50Or do you need four?
36:51Nine?
36:53Or more?
36:55These are the most fundamental questions
36:58scientists can ask about our reality.
37:01But the simplest questions are often the hardest to answer.
37:08Swarms of scientists at the Large Hadron Collider
37:11and labs around the world are hunting for evidence of extra dimensions,
37:15be they warped or curled up in tiny loops.
37:18They hope to make a major breakthrough within the next few years.
37:23But Renate Loll, a physicist at the University of Utrecht,
37:28isn't holding her breath.
37:31Of course, one of the problems you have in string theory
37:34is that there are all these many dimensions.
37:37Then you have to explain why you only see a few of them.
37:41So that would be wonderful if you could do that.
37:44But currently, that's too difficult.
37:46Or no one has managed to show that.
37:49Renate believes that the extra dimensions predicted by string theory
37:53are merely a mathematical quirk.
37:56And the theory itself is likely to be wrong.
38:00Of course, it raises the question of, well,
38:03can we maybe do without these extra dimensions whatsoever?
38:07Renate Loll's dislike for the extra dimensions of string theory
38:11is matched only by her passion to attack the same puzzle
38:14it was created to solve,
38:17the mystery of gravity.
38:20Einstein realized that gravity could be seen
38:24as simply a bending of space by massive objects.
38:28His theory of general relativity was a masterpiece of modern physics.
38:33But it left a serious problem unsolved.
38:36How does gravity affect space on the microscopic level?
38:41So if you ask questions that have to do, say, with the very, very small,
38:45and that involves anything that has to do with gravity,
38:48so how do objects interact gravitationally on very, very short scales,
38:53then you need an extension of Einstein's theory
38:56because it doesn't cover that range.
38:59Renate has taken on that challenge.
39:03She's trying to develop new laws of gravity
39:06that apply even at the smallest distances.
39:08And she's testing them in computer simulations.
39:13She begins with a collection of microscopic points of space
39:17and attempts to stick them together with gravity.
39:21In other words, she is growing space.
39:24The last time this happened outside a computer
39:27was about 13.7 billion years ago.
39:30It was part of an event you've probably heard of,
39:33the Big Bang.
39:35Renate is working on a much smaller scale.
39:39But the microscopic universes she is cultivating
39:42have some very unexpected properties.
39:45Imagine you're given a space, or just a piece of space,
39:48and you want to learn about what it is.
39:51And in particular, you may want to learn about what its dimension is.
39:55So one experiment that you can actually do
39:59to find out what the dimension is,
40:02is to let an ink drop fall in it
40:05and see what happens, see how the ink spreads in the space.
40:09In water, ink spreads into three dimensions.
40:14On a piece of blotting paper, it spreads into two.
40:18But when Renate tested how things spread out
40:21inside her computer-simulated universes,
40:24the results looked something like this.
40:29Watch what happens now.
40:33It filled out much less volume than we expected on small scales,
40:38and that's a sure indication that the dimension
40:42is actually smaller than what we expected.
40:44It's smaller than three.
40:46Renate's simulations look like they have three dimensions.
40:50But at root, they only have one.
40:53If her theories of gravity are right,
40:56it suggests that solid space is not solid at all.
41:00Down at the smallest scales,
41:03it might be built from a mesh of one-dimensional lines.
41:14Is this the fundamental truth about how space is formed?
41:19Is one dimension all there really is?
41:23So in the old days,
41:25one would think of the dimension of a space as fixed.
41:28I mean, just God-given, it's just there.
41:31But what happens then on very, very small scales?
41:34And there, the story we find is totally different.
41:37The space appears to have a smaller and smaller dimension
41:42as you explore it on smaller and smaller scales.
41:46Other scientists are not convinced
41:48that Renate's one-dimensional universe is correct.
41:51Their bets are headed on a universe with many extra dimensions.
41:55The truth is still elusive, but it's not out of reach.
42:01It's a problem that we really want to solve.
42:03We really think there has to be an answer.
42:05It really tells us that something has to be there.
42:07And it could tell us that there's some really exotic
42:10underlying matter or physics or forces
42:13that we haven't thought about yet.
42:15In the end, there is, you know, some theory.
42:18There is some simple, elegant theory out there
42:20that accounts for all of nature, for everything we see.
42:22And we feel like we could be very, very close to it.
42:25So when you have shocking questions,
42:29it takes sometimes shocking ideas and answers
42:33to try to put your arms around this.
42:36Are there nine dimensions, or only one?
42:41Is this hidden space warped or curled up in tiny loops?
42:47We don't know yet.
42:49But we can be ever more sure of one thing.
42:52The three-dimensional world we thought we lived in
42:56is only what we see.
42:58Reality is almost certainly a lot stranger.
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