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2022-10-26: Why Did Quantum Entanglement Win the Nobel Prize in Physics?

  • 18:49: ... spurious spaces that appear when you choose a coordinate system whose dimensions extend  beyond the physical ...

2022-10-19: The Equation That Explains (Nearly) Everything!

  • 07:51: ... whatever was written has to be repeated several times depending on the dimensions of spacetime, the number of charges, the number of different particles, ...

2022-09-28: Why Is 1/137 One of the Greatest Unsolved Problems In Physics?

  • 09:15: The weirdest thing is that it’s dimensionless.
  • 11:20: ... example, the speed of light is the translation  factor between the dimensions of space and time in relativity; it’s also the relationship  ...

2022-08-03: What Happens Inside a Proton?

  • 11:28: ... ingenious yet. We’re going to pretend that time is just another dimension of space.   This operation is called the Wick rotation and ...

2022-07-20: What If We Live in a Superdeterministic Universe?

  • 08:18: Let’s play out the Bell test on something called a space-time diagram - with one dimension of space only on the x axis and time on the y.

2022-06-15: Can Wormholes Solve The Black Hole Information Paradox?

  • 06:01: ... that a   particular type of universe with three spatial  dimensions is encoded on its own 2-D surface.   The power of AdS/CFT ...

2022-05-04: Space DOES NOT Expand Everywhere

  • 02:24: ... coordinate system of a chunk of spacetime with 3 spatial and 1 temporal dimensions. ...
  • 03:48: ... points is the sum of the squares of x, y & z, but here adding the dimension of time. And this thing is the scale factor, which represents the ...
  • 07:12: ... try something else. Lose another dimension of space so the universe becomes an expanding ring instead of a ,sphere, ...

2022-03-23: Where Is The Center of The Universe?

  • 04:43: In order to do that we need to lose a dimension.
  • 04:54: But for a 2-D being living on that surface, those two dimensions are all that exists.
  • 05:37: So could it be that there’s a higher dimensional space in which our 4-D hypersphere lives?
  • 05:43: Could there be an equivalent of “down” in that space that we are just too dimensionally-challenged to point to?
  • 06:02: Those three spatial dimensions just loop back on themselves.
  • 06:16: So far we’ve ignored the dimension of time.
  • 06:29: So, very crudely, we can think of the radial direction as the dimension of time.
  • 06:34: ... would be more accurate to say that the radial dimension of this expanding hypersphere is represented in the math by the scale ...
  • 08:20: In both of these cases there is no geometrical center, even in a fictional higher dimension.

2022-03-08: Is the Proxima System Our Best Hope For Another Earth?

  • 17:58: ... framework, upon which all the quantum weirdness can play - those are the dimensions of space and ...

2022-02-10: The Nature of Space and Time AMA

  • 00:03: ... start in this description with newtonian physics in which they're the dimensions that form the stage on which the play of the universe takes place in ...

2022-01-12: How To Simulate The Universe With DFT

  • 02:46: Our Schrodinger equation just dealt with one dimension of space, x.
  • 03:05: Of course the real universe has 3 spatial dimensions, so for most real applications we’d want Psi(x,y,z).
  • 03:50: Every new electron adds 3 new entire dimensions.
  • 03:53: So 26 electrons means 78 dimensions, which for our 10-point grid is 10^78 numbers.
  • 04:52: ... adding dice to this system- every time we add a particle we increase the dimensionality of the ...
  • 06:14: We don’t need a 3-cubed or 9 dimensional equation.
  • 07:25: An equation is separable if the solution along one axis - in one dimension - doesn’t depend on the solutions on any other axis.
  • 07:33: ... we can take an equation for N particles in 3D and reduce it from a 3^N dimensional equation to simply N coupled equations each in ...
  • 08:15: And we can’t reduce the dimensionality by treating particles separately because the Schrodinger equation can’t be made “separable”.
  • 08:49: ... and it’s perhaps the most successful approach to tackling the extreme dimensionality problem when solving realistic quantum ...
  • 13:35: ... by understanding how the universal wavefunction with its insane hyper dimensionality is connected to the narrow sliver of that wavefunction that represents ...
  • 13:51: Our computationally tractable reality, due to its very few dimensions of spacetime.
  • 14:25: Peter, the infinite dimensional universal wavefunction barely contains enough information to describe your generosity.

2021-12-20: What Happens If A Black Hole Hits Earth?

  • 00:00: ... everything. They're not really like that. I imagined wormholes to other dimensions. ...
  • 16:33: ... of the string vibrations. It’s holographically projected into 2 spatial dimensions, and in its experience it keeps falling. Meanwhile from the perspective ...

2021-12-10: 2021 End of Year AMA!

  • 00:02: ... it as many times where branching is just movement in a second time dimension has there been any thought on interpreting it that way and would it ...

2021-11-17: Are Black Holes Actually Fuzzballs?

  • 07:13: ... for the somewhat unrealistic case of a black hole horizon with 4 spatial dimensions, but it was a decisive step and it gave us a compelling reason to think ...
  • 11:46: This last thing is the weirdest and coolest thing about fuzzballs, so let’s explore a bit further by dropping a few dimensions.
  • 11:54: Instead of the 4 spatial dimensions of a Strominger-Vafa or the 3 dimensions of regular black holes, let’s think about a 1-D black hole.
  • 12:04: One dimension means a line, so a 1-D black hole is just a segment of a line with a point of infinite density on it.
  • 12:20: In string theory we have extra compact dimensions - spatial dimensions that are coiled up on the Planck scale so we can’t see them.
  • 12:29: Adding a single coiled dimension to our 1-D black hole turns our line into a drinking straw.
  • 12:35: The extra dimension is the distance around the straw.
  • 12:43: The extra compact dimensions contract and pinch off, so all spatial dimensions end in that direction.

2021-07-13: Where Are The Worlds In Many Worlds?

  • 02:25: The weirdness of this is clearer if we watch two waves cross each other in one dimension.

2021-05-19: Breaking The Heisenberg Uncertainty Principle

  • 08:03: ... phase space, this amounts to a shrinking of the uncertainty in one dimension, and a corresponding stretching in the opposite dimension, so that the ...

2021-05-11: How To Know If It's Aliens

  • 16:32: ... particles as gravitational singularities - wormholes between adjacent dimensions threaded by electromagnetic fields. Turns out particles aren’t that, but ...

2021-03-16: The NEW Crisis in Cosmology

  • 13:38: ... asks how can we be traveling at the light speed in the time dimension? I'm glad you   asked, because this notion gets stated ...
  • 14:47: ... matter - or whether they're really   the same type of thing - dimensionally speaking. We would also need to justify why the c in ...

2021-02-24: Does Time Cause Gravity?

  • 00:04: If even a tiny bit of your breakneck temporal velocity leaks into one of the dimensions of space.
  • 02:02: At least, it stays motionless with respect to the three dimensions of space.
  • 02:07: Everything is moving through the dimension of time.
  • 02:13: Let’s have just two dimensions of space and so we have space … for time.
  • 05:31: But if we interpret time as a dimension like space, then a stationary mass really is moving at the fastest possible speed in the temporal direction.

2021-02-10: How Does Gravity Warp the Flow of Time?

  • 07:56: Now 2 dimensions of space instead of one.
  • 08:07: It’s easier to see if we just take a slice out of this - one dimension of space again.

2021-01-19: Can We Break the Universe?

  • 04:12: We have time on the y-axis and just one dimension of space on the x.
  • 06:24: We’re still just doing one dimension of space, but now that dimension loops back on itself.

2020-11-18: The Arrow of Time and How to Reverse It

  • 01:58: ... block universe picture, where we have 2-dimensions of space and one dimension of time, with time flowing ...
  • 02:53: ... And those laws don’t even require time to “flow” - it’s just another dimension like ...
  • 09:39: ... of time to space, but it’s timely to spend time on that fascinating dimension that deserves more space: ...

2020-11-11: Can Free Will be Saved in a Deterministic Universe?

  • 03:05: Two dimensions of space and one of time, the slices of the block universe represent the causal ordering of the universe.

2020-10-13: Do the Past and Future Exist?

  • 02:31: Let’s cut out one dimension of space - space then becomes a 2-D slice at a given instant in time.
  • 02:38: Now let’s stack successive instants so that time becomes the 3rd dimension.
  • 03:17: Time is just a dimension like space, and we only observe a flow of time if we play the slices in sequence like a flip-book.

2020-08-10: Theory of Everything Controversies: Livestream

  • 00:00: ... where it was only about strings because they had reasons why higher dimensional objects didn't exist to brain theory it went from a finite number of ...

2020-07-28: What is a Theory of Everything: Livestream

  • 00:00: ... equations out of that equation gravity quote unquote albeit and 10 dimensions and supersymmetric pops out general relativity in that guys pops out ...

2020-06-30: Dissolving an Event Horizon

  • 11:42: Is it, for example, some extra dimension that the black hole leads into?
  • 11:46: ... in those representations take a 3-dimensional space and take a two dimensional slice out of it, so the black hole or wormhole ends are circular instead ...
  • 12:00: Then the third dimension is just a way to represent the strength of the spatial curvature and the connections between different regions.
  • 13:46: Inyobill asks if we’re assuming that the lightest particles are without dimension, so they have an undefined size relative to the universe.

2020-06-15: What Happens After the Universe Ends?

  • 02:01: This is perhaps the simplest conformal transformation - just multiplying or dividing all dimensions by the same scaling factor.
  • 04:15: ... simplify things by gridding up an imaginary universe with only one dimension of space on the x-axis and one dimension of time on the y, and we choose ...
  • 09:56: That’s for one dimension of space and one dimension of time.

2020-06-08: Can Viruses Travel Between Planets?

  • 13:42: ... time we explored the possibility that the existence of hidden extra dimensions might change the law of gravity on the smallest scales, and we saw how ...

2020-05-27: Does Gravity Require Extra Dimensions?

  • 00:16: That steampunk contraption may even reveal the existence of extra dimensions of space.
  • 03:09: ... if our universe had more dimensions, say 4, then gravity would spread out over the “surface” of a 4-D ...
  • 03:24: In general, gravity drops off as 1/r to some power - and that power is the number of spatial dimensions minus one.
  • 03:32: Cool - so we have a way to test how many dimensions there are.
  • 03:36: Newton’s inverse square law for gravity tells us there are 2+1 = 3 spatial dimensions.
  • 03:46: ... with the other forces actually propose that there are MORE than 3 dimensions of space, and that these additional dimensions may explain the hierarchy ...
  • 04:03: So let’s talk about dimensions a bit more.
  • 04:20: Now we perceive the 3rd dimension, but perhaps our 3 spatial dimensions are similarly embedded in a higher dimensional space that we can’t perceive.
  • 04:32: ... detection from LIGO seemed to rule out the possibility of extra spatial dimensions. ...
  • 04:42: But there’s a caveat - that experiment only ruled out extra large dimensions.
  • 04:48: And by large I mean they stretch out over astronomical scales like the familiar 3 spatial dimensions.
  • 04:54: But there’s another possibility - the extra dimensions could be compactified - in other words, wound up very small.
  • 05:03: In that case, gravity would only deviate from the inverse square law on the tiny scales of these compactified dimensions.
  • 05:37: It looks 1-dimensional from a distance, but up close you see that it’s really a 2-D surface - extended in one dimension, but looped in the other.
  • 05:45: And that’s the sense in which there may be more than 3 spatial dimensions in this universe.
  • 05:50: 3 extended dimension, but others that are looped - or “compactified” as we say in physics.
  • 05:57: ... most famous example of compactified extra dimensions is in string theory, and in modern superstring theory there are 6 ...
  • 06:10: ... the idea of compact extra dimensions is much older than string theory - first proposed by Oscar Klein in the ...
  • 06:25: ... we’ve never detected these extra dimensions, they seem a promising potential solution to unifying gravity with the ...
  • 06:36: There are different ways of thinking about how compactified extra dimensions can effect the strength of gravity.
  • 06:42: One is that you can imagine the gravity trying to propagate through multiple dimensions, which would dilute it more quickly.
  • 06:48: We can also think about it as gravity producing excitations within those extra dimensions that sap its energy.
  • 06:55: ... the inverse square law, but would be diluted due to the hidden extra dimensions - and that could explain its relative weakness compared compared to ...
  • 07:06: ... on small scales these extra dimensions would actually change the way gravity falls off with distance - but to ...
  • 07:21: So, to search for these hidden dimensions, we need a way to test gravity on very small length scales.
  • 10:53: ... that’s still quite a bit larger than any likely compactified extra dimensions, but we’d still expect a tiny and perhaps detectable deviation from the ...
  • 11:14: So, how many dimensions are there?
  • 11:32: ... are still nowhere near being able to probe the size-scale of the extra dimensions from string theory though, and so string theorists can keep on ...

2020-05-18: Mapping the Multiverse

  • 03:11: Time flows up - for the most part - and one dimension of space is left or right.

2020-05-04: How We Know The Universe is Ancient

  • 15:09: ... It's really a 2-D slice out of 4-D spacetime, with time and one dimension of space discarded. But the diagram has 3 dimensions, so what is that ...

2020-04-28: Space Time Livestream: Ask Matt Anything

  • 00:00: ... but but you know physicists like to set the speed of light as being dimensionless and set it equal to one which is totally reasonable if for the right ...

2020-04-22: Will Wormholes Allow Fast Interstellar Travel?

  • 03:33: ... represents the fabric of only 2 dimensions of space at a single instant in time. The technical name is an embedding ...
  • 03:45: ... keep time frozen for the moment and add back the 3rd spatial dimension. The ring of the wormhole is actually a sphere the size of the ...
  • 04:08: ... if we unfreeze the wormhole - if we add back the dimension of time - that journey becomes impossible. Fuller and Wheeler proved ...

2020-03-31: What’s On The Other Side Of A Black Hole?

  • 01:38: ... map the universe we need 3 dimensions of space instead of two, plus the dimension of time. And maps of the ...
  • 07:57: ... in one direction - to your crushing demise. These lines are the old time dimension, but now traversable in both ...

2019-12-17: Do Black Holes Create New Universes?

  • 04:27: Perhaps the configuration of the geometry string theory’s extra dimensions gets shifted - this would do the job.

2019-12-09: The Doomsday Argument

  • 15:37: ... - for example the 3-torus embedded which is like a donut, but with more dimensions. ...

2019-11-11: Does Life Need a Multiverse to Exist?

  • 11:24: ... energy, are set by the particular configuration of the extra coiled dimensions of that ...

2019-11-04: Why We Might Be Alone in the Universe

  • 14:32: Some One asks if a circle in 2 spatial dimensions would allow for closed time like curves.

2019-10-21: Is Time Travel Impossible?

  • 12:21: We remain firmly in the grip of that one dimension that we can never halt nor reverse it's pace: time.

2019-10-15: Loop Quantum Gravity Explained

  • 00:47: ... of conceptual baggage like tiny wiggling strings made of coiled up extra dimensions. ...
  • 05:00: This is completely at odds with general relativity, in which time is treated as just another dimension.
  • 11:13: And without adding big assumptions – like the existence of strings or extra dimensions or supersymmetry.

2019-10-07: Black Hole Harmonics

  • 08:50: ... also get a spin for the final black hole – a so-called dimensionless spin magnitude of .69 – where the spin magnitude can vary between 0– not ...

2019-09-30: How Many Universes Are There?

  • 05:43: ... on standard ideas, they probably have the same number of dimensions as ours – 3 space, 1 time – but their contents and physics could be very ...
  • 07:27: ... are countless possible minimum-energy configurations of its 6 curled up dimensions. ...
  • 07:46: The vast space of possible configurations of these compact dimensions is referred to as the string landscape.

2019-07-18: Did Time Start at the Big Bang?

  • 05:15: ... points become the same point and three-dimensional space becomes zero dimensional That's the singularity We say that it didn't happen in any one place ...
  • 09:52: ... the Steinhardt-Turok model suggests that our universe floats in a higher dimensional space living on geometric objects called brains collisions between those ...

2019-04-24: No Dark Matter = Proof of Dark Matter?

  • 00:03: ... for 20 informs is that while we may feel that we live in a three spatial dimension universe serve up down left right forward back we're actually in a ...

2019-04-10: The Holographic Universe Explained

  • 00:00: We live in a universe with 3 dimensions of space and one of time.
  • 00:08: 3+1 dimensions.
  • 00:24: ... of the most startling possibilities is that our 3+1 dimensional universe may better described as resulting from a spacetime one ...
  • 03:55: How does the 2-D surface store information about that extra dimension?
  • 04:26: Let’s ignore string theory for the moment and just think about how to create an extra dimension.
  • 06:51: If objects at different scales don’t tend to interact with each other then this new degree of freedom behaves just like another dimension.
  • 07:05: You might say it’s not a real 3-D volume because the 3rd dimension is fake.
  • 07:15: ... is a dimension but a number-line of possible values which a) exists alongside the other ...
  • 07:36: Crudely, this is how an extra dimension can be coded in a holographic universe.
  • 07:47: Even from the beginning string theory had hints of this scale invariance and dimensional weirdness.
  • 08:15: That means you can pretend string length-slash-energy is a separate dimension as a calculation trick.
  • 08:23: ... wave equation for the gluon strand with length expressed as a separate dimension you get the wave equation for a graviton – the quantum particle of ...
  • 10:23: ... resulting braney structure looked just like a Minkowski spacetime of 3+1 dimensions on which their lived a field theory that arose from interactions between ...
  • 11:04: In good string-theorist style, Maldacena defined incorporated that scale factor into be a new spatial dimension.
  • 11:46: ... interactions in the lower dimensional field theory are extremely strong – we would say the fields are strongly ...
  • 11:58: ... strong gravitational fields in the higher dimensional space – like in black holes – look like a solvable configuration of ...
  • 12:37: The lower dimensional CFT space is the surface of the AdS space because the field theory exists where the new dimension becomes infinite.
  • 13:41: ... appear to be negatively curved AdS space, nor does it have 4 spatial dimensions as in Maldecena’s ...
  • 13:58: ... may be holographic – or at least have a dual representation in a lower dimension. ...
  • 15:10: A few of you asked whether our percieved universe is just the surface of a higher dimensional space.
  • 15:16: ... our percieved universe is the volume, but it can be encoded on its lower dimensional ...
  • 15:41: Part of the confusion comes from the fact that Maldacena's derivation is for a volume with 4 spatial dimensions, which would have a 3-D surface.
  • 16:12: So first - the "surface" in current AdS/CFT spacetime is 3+1. 3 spatial, one temporal dimensions.
  • 16:27: ... AdS/CFT is that gravity arises naturally when you add an extra spatial dimension, which ends up looking like the volume contained by the "3-D" ...

2019-04-03: The Edge of an Infinite Universe

  • 05:49: ... the vertical-ish lines are set locations in space in only one spatial dimension. ...
  • 09:38: But this time we’re not mapping space versus time – we’ll just map two dimensions of hyperbolic space.
  • 11:40: So this disk can represent an infinite anti-de Sitter universe with 2 spatial dimensions at a single instant in time.
  • 12:16: ... is itself a conformally-compactified Minkowski space with one fewer dimension. ...
  • 12:34: In fact let’s add the dimension of time to our hyperbolic projection.
  • 12:43: They give you a cylinder and representing an AdS spacetime with 2 spatial and one temporal dimensions – let’s call that 2+1 dimension.
  • 12:53: On the other hand the surface of the disk has only one dimension of space – the circumference – and the same one-D of time – 1+1.
  • 13:17: You can extrapolate to any number of extra dimensions – say a 3+1 dimensional - Poincare ball.
  • 14:31: Quantum mechanics in the form of a conformal field theory in one space is a theory of quantum gravity in a space with one higher dimension.
  • 14:40: The hologram part is because the lower dimensional space can be thought of as the infinitely distant boundary of the higher dimensional space.

2019-03-06: The Impossibility of Perpetual Motion Machines

  • 15:39: Fourier analysis represents functions in one dimension with a series of sine curves.

2018-12-20: Why String Theory is Wrong

  • 01:35: ... string theory into a single picture with a very specific number of extra dimensions. I'll talk more about that ...
  • 02:14: ... with, to a precursor to string theory and the origin of all this extra dimension ...
  • 02:35: He was playing around with the newfangled general relativity in five dimensions, 4 space and 1 time, because why not.
  • 02:43: ... in our universe, plus an extra bit of math from the extra special dimension. ...
  • 03:08: It appeared that gravity acting in this fifth dimension looks like electromagnetism to being trapped in our 4-D space-time.
  • 03:27: The mild inconvenience of their very clearly being no extra special dimension was solved by Oskar Klein in the late 1920's.
  • 03:37: Klein realized that you can get a sensible quantum theory if you compactify that extra dimension.
  • 03:52: In the resulting in Kaluza–Klein theory, the fifth dimension is looped into a tiny circle.
  • 04:07: Momentum in that loop dimension has the exact behavior of electric charge, with the direction of rotation determining the sign of the charge.
  • 05:07: For example, adding more compact dimensions of various shapes and, of course, strings.
  • 05:18: So, start with Kaluza-Klein, add vibrating strings and exactly the right extra special dimensions, and you have string theory.
  • 05:47: ... along with the discovery of the right symmetries for the extra dimensions sparked the first superstring revolution of the mid 80s, roughly ...
  • 06:20: Five different approaches to getting all of the desired particles out of the basic premise of strings wiggling in ten dimensions.
  • 06:28: All required six compactified extra dimensions of space.
  • 07:25: ... theory, or at least at the simplicity of just one extra circular spatial dimension. ...
  • 07:41: Imagine only one extended and one compactified spatial dimension.
  • 07:50: Our tiny quantum strings can roam that small dimension.
  • 08:01: ... number of times a string winds around this compactified dimension is called its winding number. The energy of such a string depends on the ...
  • 09:07: ... a theory in which momentum increases with the size of the compact dimension, or where momentum decreases with that size and both give the same ...
  • 10:51: ... real detail, but the important thing here is that it adds a single extra dimension, to connect all of the five super string theory types via ...
  • 11:08: So whereas the original superstring theories were ten dimensional with six compactified, M-theory is 11D, with seven hidden dimensions.
  • 11:24: Whoa Well, that all sounds a bit arbitrary. Your theory not working? Just add an extra dimension.
  • 11:32: Actually, the realization that superstring theory could be 11 dimensional was a revolution. It sparked the second superstring revolution.
  • 11:49: ... have time to get into, 11 is also the magic number for super gravity dimensions. Super gravity should be the low energy, large-scale limit to super ...
  • 12:43: In all superstring theories the extra spatial dimensions are wrapped, not in simple loops, but in complicated geometries called Calabi-Yau manifolds.
  • 12:53: The behavior of strings in these hyper dimensional surfaces is only understood in idealized cases.
  • 13:08: ... higher. This is the string landscape. Each geometry for the compactified dimensions implies a different set of porperties for vibrating strings, and so a ...
  • 13:44: ... in the string landscape, but without knowing the geometry of the extra dimensions, this can't be verified nor can we make testable predictions beyond the ...

2018-11-14: Supersymmetric Particle Found?

  • 14:17: To quote, "I thought one of the fundamental properties of the strings was that the maths only works if they are one dimensional.
  • 14:24: So how can you get world sheets?" Yes, it is a pain keeping the number of dimensions straight in string theory.
  • 14:32: ... invariance only works for the 2D world sheet, which has one dimension of space and one of time, this is the shape traced out by a string ...
  • 14:54: Some of you recalled a recent episode in which we talked about a study of gravitational waves that appears to refute the idea of extra dimensions.
  • 15:04: Actually, this study was specifically evidence against the idea of extra extended dimensions.
  • 15:11: ... weakness of the gravitational force is that there's an extra special dimension that has the same scale as the familiar three, so a 4d space in which we ...
  • 15:27: Gravity then leaks into the extra fourth dimension, causing it to weaken.
  • 15:32: But this has no bearing on the compactified extra dimensions of string theory.
  • 15:36: Those dimensions are tiny in extent and they're coiled on themselves so there is nowhere for gravity to escape into.
  • 15:43: It may have implications for the single extra extended spatial dimension of M-theory, but I need to research that more.

2018-11-07: Why String Theory is Right

  • 01:14: And, by the way, these strings exist in six compact spatial dimensions on top of the familiar three.
  • 03:34: On a spacetime diagram, time versus one dimension of space, this is called its world line.
  • 10:25: That's on the 2D dimensional world sheet of a quantum string.
  • 10:41: ... but only for 1D strings making a 2D world sheet, not for any other dimensional ...
  • 11:57: ... the photon, out of string theory for a very specific number of spatial dimensions, nine to be ...
  • 12:11: In fact, if string theory makes any predictions, it's the existence of exactly this number of extra dimensions.
  • 12:23: Our universe has three spatial dimensions.
  • 12:25: ... theorists hypothesize that the extra dimensions are coiled on themselves so they can't be seen, but that seems like a ...
  • 12:37: There's also no experimental evidence of the existence of these dimensions.

2018-10-25: Will We Ever Find Alien Life?

  • 13:24: Sam Pollard asks, how does adding more particles require fewer dimensions?
  • 13:42: Adding the symmetry gives you fermions but it also shaves off dimensions.
  • 14:04: ... need to search through to find the geometry of our universe's extra dimensions. ...

2018-10-18: What are the Strings in String Theory?

  • 00:24: And what's all this nonsense of extra dimensions?
  • 04:15: Oh, and we needed to add 22 dimensions to the familiar four.
  • 04:58: As an added bonus, this ambition also shaved off a bunch of dimensions.
  • 05:05: ... framework of m-theory, all for the low price of adding only one spatial dimension for an 11-dimensional ...
  • 10:01: ... of known particles, they need to vibrate in more than just the three dimensions of ...
  • 10:13: In fact, the theory only works in precisely nine spatial dimensions, plus one for time, plus one for M theory, which we'll come back to.
  • 10:23: In short, without exactly this number of dimensions, you don't get gravitons or any other massless particle.
  • 10:34: It's a theory that works in a universe that is clearly not our own with its measly three dimensions of space.
  • 10:44: There's a way to add extra special dimensions that is still consistent with our perceived 3D universe.
  • 11:08: This is a Pac-Man dimension.
  • 11:11: Travel the tiny width of this dimension and you'll find yourself back where you started.
  • 11:16: Very tiny objects like quantum strings could explore that extra dimension, and importantly, oscillate in it.
  • 11:30: Three large dimensions of space and six tiny Pac-Man dimensions that only strings experience.
  • 11:40: Modern M theory proposes an additional large spatial dimension.
  • 11:54: ... fascinating dualities between different ways of thinking about the dimensions. ...
  • 12:13: The exact behavior of strings depends on the shape of their compact dimensions.
  • 12:19: In fact, the single free parameter in string theory becomes the configuration of the extra dimensions.

2018-10-10: Computing a Universe Simulation

  • 12:07: ... were used to search for and rule out the existence of an extra spatial dimension beyond our familiar ...
  • 14:29: Squirrel Bacon is bothered when people use the term dimension to refer to parallel universe.
  • 14:39: An extra dimension would add infinite layers to the current universe, while a parallel universe would just add a single separate 3D universe.

2018-10-03: How to Detect Extra Dimensions

  • 00:07: The hunt for extra dimensions sounds like science fiction.
  • 00:16: So how many dimensions are there?
  • 00:43: ... particular described in a new paper, "Limits on the Number of Spacetime Dimensions from GW170817," by Pardoa, Fishbachb, Holzb, and ...
  • 02:05: In the case of today's paper, it allows us to measure how many dimensions that space actually has.
  • 02:17: Add one dimension of time to give us 4D space-time, which we'll also refer to as 3-plus-1-dimensional space-time.
  • 02:26: ... adding the extra spatial dimensions beyond the usual three could actually explain a lot, from the difference ...
  • 03:45: ... way pulses fade in brightness depends on the number of dimensions, typically proportional to 1 over the distance to the power of the number ...
  • 04:21: But even there, Einstein's general relativity describes gravity perfectly with three spatial dimensions.
  • 05:36: One fun way to do that is to throw in an extra spatial dimension.
  • 05:40: If you recall, intensity drops off more quickly the more dimensions you have.
  • 05:44: So you drain gravity into an extra dimension.
  • 05:48: But you restrict all the other stuff in the universe-- matter, radiation, astronomers-- to only three spatial dimensions.
  • 06:07: ... can think of them as geometrical structures of potentially any number of dimensions on which the quantum field and their corresponding particles can ...
  • 06:15: They're used in string theory, where they typically have a large number of dimensions.
  • 06:20: But in string theory, all but three spatial dimensions of the brane are inaccessible.
  • 06:25: They're finite and coiled up on themselves, compactified, allowing us to cram them into three spatial dimensions.
  • 06:35: ... brane, a 3-brane, embedded in a space-time with four spatial dimensions, where the extra dimension of space is extended rather than ...
  • 06:55: ... and you get normal physics for matter and radiation in three spatial dimensions-- for example, the usual inverse square law for ...
  • 07:14: If gravity spreads out in four dimensions rather than three, then it should become much weaker.
  • 07:48: In our hypothetical universe with four spatial dimensions, gravity is already weak on the scale of the solar system and the galaxy.
  • 07:59: ... law on galactic scales, where it's sort of coupled to the three spatial dimensions of the ...
  • 08:14: ... universe exists, can actually expand into the extra fourth spatial dimension. ...
  • 08:41: ... the gravitational field can extend into this hypothetical extra spatial dimension, then gravitational waves should lose energy to that extra dimension as ...
  • 09:11: If space has four or more dimensions, then gravitational waves should drop off in intensity faster than you'd expect in three dimensions.
  • 09:29: Does that match what you expect in a universe with three spatial dimensions?
  • 09:34: If the dropping intensity was too much, then you have evidence for extra dimensions-- basic stuff, right?
  • 10:36: How many extra dimensions did we discover?
  • 10:49: There was no observable leakage of gravity into extra spatial dimensions, pretty much ruling this out as an explanation for dark energy.
  • 10:59: There still might be compactified extra dimensions.
  • 11:25: I mean, how cool would it have been to discover extra dimensions?

2018-08-01: How Close To The Sun Can Humanity Get?

  • 14:03: Did you think metaphorical physics demons are limited to our paltry three dimensions?
  • 14:08: That their writing is one dimensional?

2018-05-16: Noether's Theorem and The Symmetries of Reality

  • 04:35: See, Einstein's description of gravity reveals the dimensions of space and time to be dynamic and changeable.
  • 07:22: ... of the theorem means we can apply it to not just the symmetries in the dimensions of space and time, but also to more abstract ...
  • 11:44: Yet, it pixels are only 60 milliarcseconds on their shortest dimension.

2017-09-28: Are the Fundamental Constants Changing?

  • 02:54: ... meaningful to talk about it changing independently to its underlying dimensions? ...
  • 03:11: The dimensions behind, say, Newton's gravitational constant-- or the mass of the electron-- all have arbitrary human definitions.
  • 03:20: ... though we've seen a change in a fundamental constant, way to study a dimensionless constant-- one that has no units, and therefore, isn't dependent on our ...
  • 03:37: It's a dimensionless description of the strength of the electromagnetic force.
  • 04:08: It's a dimensionless number.
  • 10:38: ... are also looking into the variation of other dimensionless constants, such as the proton electron mass ratio, and the more obscure ...

2017-08-30: White Holes

  • 05:50: There the dimensions of space and time switch roles.

2017-07-07: Feynman's Infinite Quantum Paths

  • 15:24: These, in turn, may exist in a space of 11 or even 26 dimensions, most of which are compactified.

2017-06-28: The First Quantum Field Theory

  • 02:38: Guitar strings are one-dimensional, but we can expand the analogy to any number of dimensions.
  • 02:59: Every point in space has some displacement in some imaginary extra direction-- analogous to but not the same as a fourth dimension.

2017-06-21: Anti-Matter and Quantum Relativity

  • 01:47: In relativity, the dimensions of space and time are intrinsically connected and they float into each other as frames of reference change.

2017-03-29: How Time Becomes Space Inside a Black Hole

  • 09:53: However the old radial dimension isn't space-like, it's time-like.
  • 10:47: ... this mysterious dimensional flip does give us some fascinating insight into how time and space blend ...

2017-02-15: Telescopes of Tomorrow

  • 08:15: In a way, LSST focuses more on the dimension of time rather than space.
  • 11:57: The hyperbolic geometry is just what you did when you map the space-time interval to a third dimension.

2017-02-02: The Geometry of Causality

  • 02:49: To preserve our sanity, we represent this on a spacetime diagram plotting time and only one dimension of space.
  • 11:56: ... of the core of a black hole an artifact of the limitations of three dimensional mathematics?" Well, maybe, sort ...
  • 12:07: ... in regular 4D spacetime result from oscillations within many more coiled dimensions, so-called ...

2016-12-14: Escape The Kugelblitz Challenge

  • 00:14: ... compactifies our representation of the dimensions of space and time, allowing us to fit onto the one diagram the ...

2016-12-08: What Happens at the Event Horizon?

  • 02:19: ... graphing time versus just one dimension in space, we can look at the limits of our access to the universe due to ...
  • 04:48: ... diagram, blue verticalish lines represent fixed locations in one dimension of space and red horizontalish lines are fixed moments in ...
  • 05:44: And because we only have one dimension of space, and any motion to the left brings us closer to the black hole.

2016-11-16: Strange Stars

  • 12:37: That arc occurs in an imaginary fourth dimension that is analogous to the radial dimension of the 3D sphere.

2016-09-21: Quantum Entanglement and the Great Bohr-Einstein Debate

  • 10:41: ... example, entangled particles may be dimensionally connected by Einstein-Rosen bridges, wormholes that allows instantaneous ...

2016-06-15: The Strange Universe of Gravitational Lensing

  • 01:27: ... theory of relativity describes the real universe as a flexible, dynamic dimensional grid that only resembles our mind's eye Euclidean lattice in the absence ...

2016-05-18: Anti-gravity and the True Nature of Dark Energy

  • 11:35: This law is a property of a Newtonian universe, in which space and time are fixed static dimensions.

2016-05-11: The Cosmic Conspiracy of Dark Energy Challenge Question

  • 04:30: That's 100 doublings of its scale factor-- so its linear dimension, not its volume.

2016-04-20: Why the Universe Needs Dark Energy

  • 04:16: Geometry works just as you learned in school, and a flat universe is still infinite-- open-- in all three spatial dimensions.

2016-04-06: We Are Star Stuff

  • 01:30: So the tapestry of our universe is woven across the dimensions of space and time and complexity.
  • 11:34: Space is still three dimensional, and perhaps infinite in all three dimensions.

2016-03-16: Why is the Earth Round and the Milky Way Flat?

  • 01:43: ... and stars have spherical symmetry, meaning you can rotate them in three dimensions and the basic shape stays the ...
  • 02:48: Gravity exerts itself equally along the three spatial dimensions.
  • 02:53: And this type of dimensional egalitarianism is also shared by another effect, ultimately leading to the ball shapes of stars, planets, and moons.

2016-01-27: The Origin of Matter and Time

  • 01:17: It's just a graph of position in space-- just one special dimension for simplicity-- versus position in time.
  • 01:31: In fact, thinking in four dimensional space time, a thing is its world line.

2016-01-13: When Time Breaks Down

  • 07:47: Is time even a real dimension?

2015-12-09: How to Build a Black Hole

  • 02:51: ... think not in regular 3D space or even 4D space time but, rather, in six dimensional quantum phase ...

2015-11-25: 100 Years of Relativity + Challenge Winners!

  • 02:43: We're also just going to figure this out in one dimension.

2015-10-28: Is The Alcubierre Warp Drive Possible?

  • 05:33: ... warp field, and you hypothetically soften the fabric of space via higher dimensional effects-- literally, a hyper space warp ...

2015-10-07: The Speed of Light is NOT About Light

  • 06:52: Essentially, we're just requiring basic consistency in how the dimensions work.

2015-09-30: What Happens At The Edge Of The Universe?

  • 07:31: Are the laws of physics, or even the number of dimensions, the same?

2015-07-29: General Relativity & Curved Spacetime Explained!

  • 02:21: ... to explain if I first set up an analogy using our old friend the two dimensional ant on the surface of the ...
  • 08:32: ... just a lot easier to say the word gravity than say curvature of four dimensional ...

2015-07-08: Curvature Demonstrated + Comments

  • 04:19: ... Shi and SamBskate were both asking how the dimensionality of the ambient space in which the surface of the sphere is embedded-- ...
  • 05:18: ... the video, the Earth it was shown was supposed to be the physical, three dimensional Earth, and we were taking a vector and moving along a circle in orbit ...
  • 05:27: ... you wanted to know if the three dimensional space around Earth is curved, you would follow the procedure of using ...

2015-07-02: Can a Circle Be a Straight Line?

  • 03:39: From the ant's two dimensional confined perspective, curve one between A and B is straight.
  • 03:55: ... from the ambient three dimensional perspective, you could say that those tangent vectors aren't really ...
  • 04:08: ... parallel, tangent, and straight that it can apply solely within that two dimensional ...
  • 04:47: By the same process you can find geodesics on a saddle or a hillside or in three dimensional spaces.
  • 06:57: Now in a three dimensional space you can test curvature the same way we've been describing.
  • 07:17: So is the three dimensional space around Earth curved?
  • 07:24: And 3D curved space isn't what explains away gravity, it's four dimensional curved spacetime.

2015-04-22: Are Space and Time An Illusion?

  • 04:25: So he proposed the following radical idea-- maybe reality is not a three dimensional space that evolves in time.
  • 04:33: Instead, it's a four dimensional non-Euclidean mathematical space that's just there.

2015-04-15: Could NASA Start the Zombie Apocalypse?

  • 03:35: ... because the bottom line is that infectious disease takes on a whole new dimension in ...
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