Simulations Back Up Theory That Universe Is a Hologram 433
ananyo writes "A team of physicists has provided some of the clearest evidence yet that our Universe could be just one big projection. In 1997, theoretical physicist Juan Maldacena proposed that an audacious model of the Universe in which gravity arises from infinitesimally thin, vibrating strings could be reinterpreted in terms of well-established physics. The mathematically intricate world of strings, which exist in nine dimensions of space plus one of time, would be merely a hologram: the real action would play out in a simpler, flatter cosmos where there is no gravity. Maldacena's idea thrilled physicists because it offered a way to put the popular but still unproven theory of strings on solid footing — and because it solved apparent inconsistencies between quantum physics and Einstein's theory of gravity. It provided physicists with a mathematical Rosetta stone, a 'duality', that allowed them to translate back and forth between the two languages, and solve problems in one model that seemed intractable in the other and vice versa. But although the validity of Maldacena's ideas has pretty much been taken for granted ever since, a rigorous proof has been elusive. In two papers posted on the arXiv repository, Yoshifumi Hyakutake of Ibaraki University in Japan and his colleagues now provide, if not an actual proof, at least compelling evidence that Maldacena's conjecture is true."
Re:so does this mean.... (Score:2, Interesting)
It changes nothing since it's always been more probable that we're in a simulation than not. If there is only one real world and we can create a complete simulation of it, then we can run a second simulation of it. If there's two simulations and one real world, it's more likely you're in one of the simulations than in the real world.
Personally, I'd rather be living on the event horizon of a 4D black hole instead of someone's hologram. Are these two theories mutually exclusive?
Oh, it's a lot older than that. (Score:4, Interesting)
Quite a lot older. [wikipedia.org]
3 Previous Articles on /. (Score:2, Interesting)
http://science.slashdot.org/story/12/10/13/1434223/physicists-devise-test-for-whether-the-universe-is-a-simulation [slashdot.org]
http://science.slashdot.org/story/10/10/21/0326216/fermilab-to-test-holographic-universe-theory [slashdot.org]
http://science.slashdot.org/story/09/01/16/1446238/the-universe-as-hologram [slashdot.org]
Re:No idea what that means (Score:3, Interesting)
Ampletuhedrons? (Score:4, Interesting)
Is this related to the work that Arkani Hamed and Trnka are doing with Ampletuhedrons? They have discovered a geometry that simplifies calculations and that suggests space and time might not be fundamental to physics.
I don't have the language to explain it... (Score:5, Interesting)
The way I think of the universe, is like a 11 dimensional sphere of putty, that got hit with a hammer. (aka the big bang).
So, the sphere got deformed spraying outward in 3 dimensions (space) while flying off into a 4th (time) and the other 7 dimensions got compressed.
A Particle is a bit of energy caught in a loop around some number of those 7 dimensions, each combination of possible wrapping gives a different fundamental particle, with antiparticles having the same wrap, but opposing spin.
Light/radio 'waves' are caused by the photons looping around one of the higher dimensions, not one of our 3 spatial dimensions, which is how it is travelling in a straight line space, yet still taking a wavering path; like a piece of string wrapped around an infinitesimally small cylinder.
But that's just my mental model, it work well enough to keep me from going mad (I think)
Re:A projection of what? (Score:4, Interesting)
If I understand this wikipedia article correctly [wikipedia.org], it's a projection of the universe's cosmological event horizon. So think of it as being caused by turbulence the "blast wave" produced by the big bang.
Re:so does this mean.... (Score:4, Interesting)
Any simulation of the world will be as complex as the original. So if you build a full simulation of the real world, you'd double the information complexity of the world. So that wouldn't work.
One thing that might work is if you simulate regions of the "world" just in time -ie the things you see are being simulated as you look for them. That ties that simulation to a Matrix like world - each person effectively has his own world and they can be independent of each other.
Another possibility is that we are in a limited simulation - some have said that quantum theory shows the graininess of the simulation and that relativistic speed limits limit the size of the canvas on which the world is being painted (ie you only have to simulate as far as the edge of the canvas, nothing outside it affects whatever is inside).
In either of these cases, you cannot (be guaranteed to be able to) run a simulation within a simulation.
Re:so does this mean.... (Score:5, Interesting)
The physicists have figured out how to simplify the maths. This transformation also has a physical interpretation which is best explained as a hologram. A hologram has information from 3 dimensions scrunched into 2 dimensions, ie when you look at a hologram, it appears to have depth. In a common hologram sticker, that information is encoded in polarization. In the same manner, they seem to say information in a 11 Dimensional world can be scrunched into lesser number of dimensions. Hence the analogy.
Re:A projection of what? (Score:1, Interesting)
Mathematics, especially in this context, is just a language for expressing ideas. So I think that in some sense it is possible that some particular string theory really does describe what's going on. I don't know if it's very likely, but the idea of a "final theory" is that it is, in some sense, a complete and accurate description of our universe's mechanics. (The holographic principle is nice because it states that two seemingly very different theories can actually be equivalent.)
I think there are two main caveats here. One is that you never really know when you're "done", and have a theory that is indeed final. We know now that we are not done today because of inconsistencies, but science also does not have even the capability of perfect validation. The other is that a microscopic, reductionist description of physics is not useful or even the correct language for describing more macroscopic effects since basically "more is different." Chemists don't use quantum field theory because it's just not helpful.
And while it's great (even important) to consider philosophical ramifications of theoretical work like this, we have to remember that it's all still conjecture and it will probably always be conjecture. The philosophical spin-offs, so to speak, should never be taken as a way of either supporting or condemning the theory.
I think I'm basically summarizing some of what Wienberg describes in his book Dreams of a Final Theory (1993). That seems old but I highly recommend it!
Re:A projection of what? (Score:5, Interesting)
One can manipulate math to to describe or answer pretty much anything you want. Just because the equations match what's happening does not mean they describe what's going on.
Who cares? As long as the equations match what's happening (and what's going to happen), does it matter what's "really" going on? We've been doing quantum mechanics for almost a century now, and still no one actually knows what it all means - but we're perfectly happy to take advantage of QM in our technology.
Yes, it really matters. In the middle ages, there were mathematical formulas which described the planets and sun revolving around the earth. The math worked very well even though the theory was proven to be very wrong.
Math, particularly when used as a language, can be used to describe all sorts of things. As with the spoken language, one can create a sentence that is technically and grammatically correct, but still is nonsense. The whole purpose of langauge, any language, even mathematics is to convey ideas. So, yes, it really does matter what's going on. That's the whole point of using a precision language, like math, in the first place.
Projection =/= Simulation (Score:5, Interesting)
I got into this discussion too late to be noticed, but I feel the need to help people understand that this theory is *NOT* stating the universe is a simulation. Projections are not simulations.
What the theory suggests is that of all the dimensions we know about (the article mentions 6, which is how many dimensions you get with one flavor of string theory), some of them are illusion. Like a hologram -- a 2D plastic or glass toy that displays a 3D image. The universe does not contain 6 dimensions; it contains a smaller number, and the rest of the dimensions only appear to be there.
It's likely that the universe contains at least three dimensions, because we would have noticed non-isomorphic behavior in space. But the jury is still out on whether the fourth dimension -- Time -- is an illusion. The same goes for the fifth and sixth dimensions.
None of this says anything about the universe being simulated. That's a philosophical question that physics will probably never be able to answer.
Re:A projection of what? (Score:1, Interesting)
Instrumentalism [wikipedia.org] won. Get over it.
Re:A projection of what? (Score:5, Interesting)
What do you mean it was proven wrong? It never was, and it hasn't been yet. It probably can't be. (Well, except in the sense that Newtonian Mechanics was wrong.)
What was proven was that the heliocentric theory was a lot easier to calculate. And you didn't need to keep adding on as many special correction factors each time the instruments improved. So now we're doing relativity and quantum mechanics, and they are just means of calculation. Relativity doesn't really define an interpretation, and Quantum Mechanics is consistent with multiple different interpretations. The different interpretations seem quite different when described in English, but the math is exactly the same. You can't chose between the multi-world interpretation and Solipsism on the basis of evidence, you need to choose on the basis of philosophical biases.
Just consider, Relativity talks about bent spaces, but in what direction is space bent? Well, that's not clear. Perhaps saying bent is just something to enable you to understand that what we're really talking about is lengths being longer in one direction than in another, but that's just gibberish. You CAN'T translate Relativity into English and have it really make sense, any more than quantum mechanics. The last one you could "pretty much" do that with was Newtonian Mechanics, and if you really think carefully about that, you also find places where you must follow the math rather than reason. Just try to think carefully about what an infinitesimal means, or an imaginary number. You can't. You're just used to them, so you slide over the places where they are incomprehensible.
FWIW, I don't understand pre-Newtonian mechanics well enough, but I'm rather certain that they had equally incomprehensible places. Think of Cantor's proofs, and then try to imagine what it means to paint one copy of the interval of real number red and another blue. Or Zeno's paradoxes.
everything you can't disprove is true (Score:5, Interesting)
The fixation on "best" accepted theory is more about hubris than insight.
The Kolmogorov/Chaitin view is that you should believe every statement about the universe that you can't formally disprove—all at the same time— using an exponentially weighted average based on the minimum description length of each viable description (baroque theories with billions of epicycles are down-weighted by k^-1e9, where k is the mean entropy of your typical epicycle). I don't really know the math, so take that with a grain of salt, but it's at least the general idea.
The standard model is extremely cogent and concise. It will exponentially outweigh practically everything else.
The only reason this isn't used is that we pretty much never know the minimum description length for anything (there's a result where something akin to minimum description is length is formally proven to be the hardest computation definable), and we can't take the exponentially-weighted integral of all as-yet undisproven theories by any convenient method.
Any undisproven theory that comes along with the potential to be formulated as cogently (or nearly so) as the standard model should be regarded as valid until proven otherwise (either false, or irredeemably baroque).
There's no sane reason to impose incumbency politics on theory. Theory is not a vote.
Re:Oh, it's a lot older than that. (Score:4, Interesting)
There WERE a lot of REALLY STUPID ideas and health practices. But the worst ones didn't adversely affect the practitioners. There was a lot of "evolution" going on before there were reasonable models, where people would come up with ideas almost at random, and the ones that killed (or adversely affected) their practitioners didn't tend to get transmitted on. But high status people could adopt practices that were frequently lethal to low status people with very little adverse affect, and because they were high status the ideas would tend to persist.
Consider, e.g., the doctors who used to pride themselves on not washing their hands. For that matter, Aristotle decided that women had fewer teeth than men, and this was accepted as truth up through, I think, the 1500's. It didn't have much bad effect, but it's an example of high status individual and a totally arbitrary idea.
Re:so does this mean.... (Score:4, Interesting)
Then again, all that really has to be simulated is each person's sensory perception.
Who is to say that the water in the oceans is actually made of H2O and NaCL and all kinds of microbes and other chemicals? One just needs to be convinced that any personal measurement is consistent within their universe (such as "seeing" light through a microscope, or "seeing" data on a screen connected to a spectrometer or other analysis device).
Playing Halo doesn't require that every tree leaf on the map is rendered always, but when at least one player zooms in through their scope they should see those leaves.
Re:A projection of what? (Score:4, Interesting)
As for science having a "belief system", I strongly suggest you not attempt to "disbelieve" in gravity while near the edge of a high building or in electromagnetism while sticking an uninsulated conductor into a live socket.
That's an absolutly miserable analogy. Gravity and Electricity in themselves aren't the same as the Scientific Laws describing Gravity or Electricity. People still died from falling off cliffs before Newton ever put some math to Gravity. Disbelieving that Newton has correctly described Gravity with the inverse square equations may mean you will screw up your Moon-shot, but it never made anybody jump off a cliff and hope to fly, and a lot of people built heavier than air craft that failed to fly before anyone got it right, even though they did believe in Newton's laws.
Scientific axioms are ideas such as Naturalism (meaning simply "the rejection of the Supernatural as a possible explanation for a given phenomenon", not the whole, complex philosophy we would properly call Naturalism). The principle that a theory must make testable predictions to be a part of Science is one of those Axioms of Science, as you yourself point out. You just cited a big part of Science's belief system as proof it doesn't have a belief system. A given theorem, i.e. Alfred Wegener's continental drift hypothesis, Darwin and Wallace's Natural Selection, or even Einstein's General Relativity is NOT part of the belief systems of Science - such things are the results of applying the Scientific Method, and it's the things that make up the method itself that count as belief systems. Again, the results of the method are not, and can NEVER be, themselves part of the method, in just the way Korzibski said "The map is not the territory".
I, you, or anyone else can certainly build theories that are not scientific, in that they can't be tested. Does that mean they have negative value, (in a way analogous to your "falling off a high building" analogy)?. Not at all. I can devise an idea that can't currently be tested but might be testable later (Ideas can become scientific with time, as new technologies make it possible to test things we once couldn't, but there is no Axiom of Science that explains, for all hypothesi, how to judge in advance whether a hypothesis can ever become scientific or not), I can speculate about subjects that don't fall under Strict Naturalism at all, such as what another person was thinking when they did the action I observed. I can judge various matters by a different standard than in Science (such as applying a legalstandard instead of a scientific one in determining whether someone is guilty of a crime.
None of that deserves to analogized to various forms of painful death inflicted on people for not 'believing'. Acknowledging that Science has a belief system may not count as making it into a religion, but when you conflate specific theories with the method, and then use that to threaten non-believers with painful consequences for their non-belief, you've definitely started treating Science as a religion.
Read some Kurt Gödel, Thomas S. Kuhn, and Karl Popper, please.