For instance, figure 3 shows how you can't hide a black hole behind another black hole, which has implications for how a 3D universe can be completely encoded in a 2D region.
The breathless tone of this article obscures rather than illuminates its subject. It sounds as if the author describes a box with some particles bouncing around inside, and every time a particle bounces off the wall of the box the outside glows briefly indicating the location and intensity of the collision. The author is amazed that by repeatedly measuring this, you can draw inferences about what's going on in the box.
I can't see what's 'outrageous' about this. You need a lower surface which registers information about activity inside a higher-dimensional volume, some way to accurately read that information, and the time/patience to repeat the measurement many times. Isn't this how radar works, or feeling your way around a pitch-dark room using only the 2-dimensional surface of your hands (or shins)? We know from computer science that you can mathematically encode any structure of arbitrary dimension into a binary tree. One might as well ask how it's possible that our complex 3 dimensional world can be contained in the flat surface of a mirror, film strip, or camera sensor.
If you can convert back and forth between a 2D representation and a 3D representation, and different phenomena are more easily modeled in each, does it matter which is "real"? Unless of course you can come up with a specific prediction and experiment to test it.
Maybe fifth time's the charm. ;-)
Could you keep going, fully describing systems of higher order in less and less dimensions?
There's not necessarily any breakthrough right around the corner and we shouldn't rush to coronation preemptively, but there's a lot of physics "voting with their feet" for holography as the article says, and I think it's officially time to start getting hyped. It could have sanity-restoring answers to questions of quantum weirdness, albeit at the rather expensive cost of giving up even more on our day to day intuitions about space and time in favor of an apparently informational substrate.
String theory had a generation of great science communicators writing its books and singing its praises, but holography doesn't yet have equivalent public champions, and I hope that's something that changes sooner than later.
Consider time itself: one beginning, and many endings. Why many endings? And who even asks the question in the first place? Many intelligent observers, with many endings, but the same beginnings. Perhaps the black holes are a hint to our own ending?
We're born and blink into existence. And then we die and fade into the void, carrying our varied stories with us.
Logically, it doesn't make sense, and we can't possibly know the answer. But what if all those ends wrapped around to the same beginning?
Would you look at the world differently?
That sounds a little like the sophons in the novel Three Body Problem. IIRC, aliens took a photon, unfolded it to a flat surface to etch circuitry on, then folded it back up and fired the photon at earth where it unfolded again and did the bidding of the aliens.
> you can decipher the entire contents of the box just by repeatedly measuring points on the surface
So if the box is both inside and outside of a black hole, is that a path for information to leave a black hole?
But I had the same question few months back. Asking Claude is fruitful in this case.
So if anything moves, the interactions don't change their speed, they stay constant, but the delta to the movement changes, and thus time dilates.
Would be interesting to know if there is some absolute/fundamental global time that has nothing to do with the time we perceive.
* https://www.youtube.com/watch?v=DoCYY9sa2kU
* https://www.youtube.com/watch?v=klpDHn8viX8
Would this imply that time is the third dimension?
"Having space" is just a consequence of black holes. If you have more information in a volume than can be encoded on its surface in theory, you have enough mass inside the volume to make it a black hole and the event horizon then has enough space to encode the information even if the original surface did not.
The correspondence between information, thermodynamics, and mass that causes black holes to 'make it possible' to holographically encode all the information inside is what makes this theory so tempting. What if everything is information, and black holes aren't an expression of 'too much mass', but rather just a result of 'too much information to store'. This theory, if it existed, would demonstrate a key result of both relativity and quantum theory based on a very simple premise, and suggests it might then be possible to base both General Relativity and Quantum Theory on top of a simpler theory.
> That’s a violation of logic and geometry. It asks us to erase the categorical difference between square meters and cubic meters.
No, that's sheer nonsense.
> There is no negative mass, so you can always infer the one real arrangement of stuff inside from the warping of space-time at the surface of your box.
Positive mass does not make this argument work. Two bodies in GR can have different distributions of mass but identical exterior geometry. A counterexample is two spherically symmetric, uncharged bodies with the same total gravitational mass but different radial density profiles. By Birkhoff’s theorem, their exterior vacuum geometries are identical.
Just as acceleration through space causes [the same effect as] gravity, could regular gravity be the movement through TIME?
Could gravity be a facet of time as electricity is to magnetism and vice versa? and the reason we cannot "isolate" gravity is because it's interwoven with time?
But then it would be weird that photos who don't experience time are affected by gravity..
Or maybe space, time and gravity are a trinity?
(no I'm not high, but maybe I should be)
But then Hawking argued back the opposite case, which in simple terms means that some things can, indeed, escape an event horizon. In fact, name dropping Hawking just to mention his views as they stood before his 1973 work, and his 1974 model of Hawking radiation seems dangerously incomplete journalistic reporting.
In 1974 Hawking formulated what we now know as Hawking Radiation, which is the *exact opposite* of what was previously believed about the impossibility of anything coming back from a black hole. Whilst still not conclusively proven as a physical fact, this did win him the Special Fundamental Physics Prize in 2013. specifically for his discovery of Hawking radiation from black holes and his deep contributions to quantum gravity and quantum aspects of the early universe.
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Gah I am not a fan of pop-sci simplifications like this for the sake of a soundbite. The author goes onto explain how no, a picture is not enough, you need to actually measure the distortion of spacetime at the surface. Somebody is going to walk away thinking this stuff is possible, that maybe psychics really can detect something wrong with them.
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There are other dimensionality!
The dimensions are like origami, not parallel universes, however the relationships are as though such (all origami pieces then hyperdimensionality relate.)
If we call the underlying “universal potential” and whatever we think our universe as, is a plane for hyperdimensional coordinates, much of this will begin to make sense.
Gravity (and space time) is a “universal field” that “falls” Around the distributed mass (vector torsions of mass particles) and mass particles are universal potential (same stuff as measured energy in a photon) is half spin vector locked discrete amounts.
Sub-atomic particles may then be discrete spin lock configurations and not distinct in any other way.
This would make the Higgs particle a lie, and the Higgs field this deformation of gravitational surface area.
Just what I’ve come up with. Existential reality (universal potential distributing) is holographic and gravity is half spin vector torsion on a plane of universal existence.
space is an illusion...The only thing that is absolute is consciousness, on top of which all illusions stand.
This is a simplification to the point of just being wrong. Gauss’s law works for gravity; if you put a shell around Earth you have no way of knowing whether it’s a planet or an Earth-mass black hole inside. Assuming spherical symmetry of density, anyway.
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All the extra states you would assume the 3d volume can contain are actually a single state called Black Hole.
There is a limit to how much you can fill a 3d volume before it's a Black Hole basically.
Does it? Isn't this basically the same as how cellular companies can figure out exactly where someone is calling from as long as their phone is pinging 3+ towers? Just connect the towers into a box and you have the same result.
"Put a box around any region of space (space-time, really, but I’m going to drop time throughout this essay for ease of visualization, as physicists often do). The holographic principle asserts that no matter what’s going on inside — from gas molecules pinging around to black holes colliding — you can decipher the entire contents of the box just by repeatedly measuring points on the surface."
Well, if we're bounding a region of space-time then, in a purely classical universe governed by deterministic ODEs or PDEs, the statement reduces to a triviality: having information about the boundary amounts to knowing all boundary conditions. Of course I understand that this isn't really the statement of the holographic principle, but the article's formulation is rather underwhelming.
https://www.youtube.com/watch?v=GHgi6E1ECgo
HIGHLY recommend it for lay folks interested in this stuff. Which reminds me, I should yt-dl this so it's not lost, and I have a copy...
My favorite quote and a point where something really clicked was when he said "If you tried smaller you would instead be making a Planck-size black hole".
What AdS/CFT implies is the opposite: That all the information needed to describe a 3D space can fit in a 2D space, like a hologram. This is astounding and extremely counterintuitive.
The hitch is that our universe is (probably) not AdS; it's dS. And the astounding math doesn't work for the de Sitter space we live in.
The actual dimensionality is 4D to 3D once you add in time. But the math basically says an nD hyperbolic conformal manifold (AdS) can be completely described by its nD-1 boundary (CFT).* So I think it works in any number of dimensions.
*Oversimplified and probably wrong, but probably close enough for this discussion.
I'm not totally certain about this but I think you skipped over something important.
It's not that 3D space can be described by 2D space, it's that _our_ "3D" space appears to fit in 2D space because every time the universe puts too much information in the 3D space we get a black hole and a black hole is a 2D surface in 3D space.
The tiny black holes that are suggested by non renormalizability are one of the mysteries that make AdS/CFT an attractive direction in which to explore our own universe, partially because Susskind has already shown that black holes in our universe can be described by their surfaces.
I would argue that has done more harm than good. Strong media personalities shouting "the next big breakthrough is here!" followed by 25 years of zero practical results have not done good things for public perception of field of physics. A layperson could be mistaken for assuming the field is literally regressing.
Could be forgiven?
Damnit, I rewrote that sentence twice and still got it wrong.
It's more a difference of emphasis (holography in particular) than something that's outside the scope of string theory.
string theory, 11 dimensions, is bonkers though, it's what happens when people are too smart for their own good imho lol
There’s holography in string theory: AdS/CFT but this rather maps 4d super Yang mills (on the boundary of AdS5) in an AdS5xS5 background: which is one holography correspondence we know works.
Holography is much more common, but we only really understand it on hyperbolic spaces.
Also since it has a theory at strong coupling on one side we cannot really do calculation on that side and verify it.
You can use it tho to make calculations.
Holographic gravity is no less fanciful if there’s no practical experiment to prove it.
what does this mean?
I'm of course, oversimplifying things for a fun thought experiment. Everyone wonders about reincarnation, death, and the 'end of time'.
Just a thought experiment that's not grounded in anything. We all believe what we want and act accordingly.
- Time is strictly perceptual. The Universe as a whole (including changes in the fourth dimension) has always existed and will always exist. There is no 'end of time'.
- When your portion of the universe runs out (death) you just rerun it again. Because linear time is an illusion that helps us make sense of it (and not fear the future) and in reality we're skipping all over the place constantly. Forever. So hope your life isn't terrible. You're going to be reliving it infinitely. Enjoy.
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Regarding unitarity, an initial state does not need to contain a record of a history preceding it; unitarity only requires that subsequent evolution preserve the information encoded in the quantum state. Later states may contain enormously complicated correlations that simply did not yet exist in the initial state.
And there is no general principle saying that a large amount of quantum information requires a large classical spatial volume. A Hilbert space can support an enormous number of possible states even when its geometric description is extremely compact.
More importantly, the universe didn't emerge from a dimensionless point. The (t=0) singularity is the limit where classical general relativity breaks down and stops being a useful description, so the ordinary picture of information as some number of independent "bits" packed into a 3D space is no longer obviously applicable. A coherent theory of quantum gravity would probably be needed to really break further ground.
In recent years, they’ve started to get more creative. Susskind and other teams have made progress [link] on holographic de Sitter models [link] that differ radically from AdS/CFT. Instead of squashing a volume into an area, these universes seem to cram all the dimensions into a lone quantum point.
The radiation never originates from within the event horizon. Furthermore the radiation itself does not encode any information about what fell into the black hole apart from the electric charge, angular momentum, and mass (all of which must remain conserved).
I think that with Hawking radiation you have quantum entanglement of two pairs. You have a matter-antimatter pair production near the horizon. When the antimatter falls into the blackhole without being destroyed via mutual annihilation, the matter particle at the boundary now "radiates" away. HOWEVER.
The matter inside boundary which the anti-matter DOES interact with is destroyed, and the information of that interaction is is "passed" to the outside via the the anti-matter's entanglement with its co-created pair.
Something like that, isn't it? Please any physicists clarify :)
That's not how Hawking radiation actually works. It's just a "lies-to-the-children" explanation. Antiparticles have positive mass, so the black hole would be _growing_ as a result. This mechanism also violates the equivalency principle, as you shouldn't be able to detect the event horizon with only local observations.
Reality is more interesting. In flat space, the ground state of quantum fields is actually non-zero. But black holes "bias" the fields in such a way that their ground state becomes _negative_ from the viewpoint of a remote observer.
This in turn permits it to create new particles from just nothing. This in turn adds _negative_ energy to that space, resulting in the black hole decreasing in mass.
But crucially, the event horizon itself is NOT involved. Particle creation can happen anywhere in the vicinity of the black hole, not just on the event horizon.
The current age of the Universe is way small compared to the time needed for evaporation, so observing anything like that happening (or not) is hardly possible.
>> The radiation never originates from within the event horizon. Furthermore the radiation itself does not encode any information about what fell into the black hole apart from the electric charge, angular momentum, and mass (all of which must remain conserved).
> I don't know the slightest about this but... That list looks like it is supposed to be limited but that sounds like infinitely more information than zero?
I don't know about electric charge, but can't you observe mass and angular momentum of a black hole from outside? I think the "no information" thing means the Hawking radiation won't let you tell you if the black hole was made from a dead star or just a really big pile of meat or what's going on inside of it.
IIRC, all Hawking radiation does is provide a mechanism for a black hole to eventually decay.
Hawking found that energy/mass can escape but the information remains destroyed. You can't run a black hole backwards in time and reconstruct the matter that created it and hawking radiation bears no resemblance to anything that was ever beyond the horizon.
1. a particle/anti-particle pair is created at the event horizon;
2. the particle is on the outside edge of the event horizon, so "escapes" the black hole;
3. the anti-particle is on the inside edge of the horizon, so decreases the size of the black hole due to particle/anti-particle annihilation (with a corresponding particle on the inside of the black hole).
For example, Hawking radiation is always photons, with the wavelength corresponding to the size of the black hole. That isn't explained purely by virtual particles.
Also, for that explanation to work, it would always have to be an anti-matter particle that is selected to cross the event horizon, and I don't see how that would be the case.
> Consider a video game sun passing behind a video game tree. The sun pixels touch the tree pixels directly, yet the tree does not burst into flames. This is because the sun pixels are independent of the tree pixels.
With apologies to Babbage, I am not able rightly to apprehend the kind of confusion of ideas that could provoke such an explanation.
Because if we litigate the imperfections of analogies all day long, then you're going to react to videos titled "black holes described at five levels of difficulty" by saying the first four levels were all wrong, which may in a sense be technically true but not in the spirit of the exercise.
If anit-matter had shown anti-gravity effects then gravity may have been just some imbalance of forces in the universe, but it doesn't appear to be that way.
A torsion to the right, a torsion to the left mate in circular momentum.
Sounds like complementary spins.
Using a spin lock is wasteful and not the best move in times of rising energy prices. Use a mutex to put the waiting thread to sleep.
That trapped potential in time and space is mass rather than radial propagation.
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Tell me again how Consciousness is an illusion..
Ours. Or every ones..We can easily accept that we inhabit the same spacetime. Why is it hard to imagine the same for consciousness?
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Is it? If you project a "3D" singularity onto a surface, it's still a point. If you project a roughly spherical object, it's roughly circular.
Gauss' law in this case would apply to the total force of gravity exerted by the mass within the shell, not its distribution across the surface of the shell.
I really think we live on the 3D event horizon of a 4D black hole, folks.
I'm not claiming TBP is hard scifi btw. But the reveal which OP has spoiled already makes for a sick scene and pivotal point in the book.