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That makes sense. The whole point of the theory about holographic spacetime is that the 3d universe is completely described by the information densities on its
by WJW 3y ago
That makes sense. The whole point of the theory about holographic spacetime is that the 3d universe is completely described by the information densities on its edge. This implies that if you need to contain a computation involving a certain amount of information, then you need to have at least that amount of information on the edge. Since the amount of information anywhere is not infinite, this also implies that you need a non-zero amount of edge surface for that computation and thus a non-zero volume.
TL;DR: If the volume is too small, you just cannot fit enough information inside and so you cannot do computations which require more information than that.
- PaulHoule 3y agoBut what is the point of computing inside a black hole? You’re not going to get the answer out.
- hoseja 3y agoYou're currently possibly living inside one. Big Bang? - The initial collapse. Universe expansion? - Matter falling in. It may be unfalsifiable from inside though.
- WJW 3y agoFrom the article: While we are ultimately interested in the physical limits of computers in our universe, working within the context of the AdS/CFT correspondence gives us a precise framework for quantum gravity. As well, a fundamental observation in computer science is that the power of computers is robust to “reasonable” changes in the details of the computing model: classical computers can be described in terms of Turing machines, uniform circuits, etc. and the resources needed to solve a given computational problem will change only polynomially. Quantum computers are similarly robust. This robustness suggests understanding the power of computers in AdS is likely to yield insights that apply more broadly. I'm decidedly not an expert in this field but as I understand it there are two points to doing the math in this way: - We know how to describe the inside of a black hole mathematically from an AdS perspective. - IF the AdS/CFT correspondence is true (likely but unproven), then you can generalize from "works inside black hole" to "works inside the normal universe". It's more an exploratory step towards getting a better understanding of complexity theory for quantum computers than it is a practical result intended for doing computations inside black holes.
- tsimionescu 3y agoIt's important to remember that we know very well that we don't live in an AdS space. It's actually not all that likely that many of these theories apply to a de Sitter space-time like our universe, though it remains to be seen. That is, even if the AdS/CFT correspondence is true, it may still turn out that the dS/CFT correspondence is not, and so the results are not applicable to the physical universe.
- bee_rider 3y agoIt turns out it is pointless, we just work in a very fad-driven industry. Once Google started computing in a black hole, it just automatically became popular, and eventually it became common knowledge. “Can’t get fired for computing in a black hole” they’d say. Then the Hackernews guys put their server in a black hole that turned out to be a wormhole, one thing lead to another, and posts were getting sprayed across the timeline. What a mess.
- Nevermark 3y agoGreater understanding is never pointless. Throwing around general accusations of fads doesn’t reduce a paper to part of a fad. Papers stand on their own merits, based on their reasoning, independent if any associations with fads. I expect the properties of a black hole are simply a convenient context to talk about the holographic principle. If the holographic principle holds true, it is true across any border separating one space from another. Likewise, mathematicians prove things about infinities, which we will never encounter directly, but which have useful implications for things in math that can relate to things we might create or encounter.
- thomashop 3y agoI think the comment you are responding to was a joke
- bee_rider 3y agoThe time police insist that I inform everyone that my post about accidentally posting across timelines is, in fact, just a joke, nothing serious, haha.
- KineticLensman 3y agoThis is how you lose the time war...
- 3y ago
- spacecadet 3y agoMaybe.
- Tagbert 3y agoIt's possible that our universe is inside a black hole or a black hole analog.
- nabla9 3y agoThey describe computations that are forbidden despite the inputs to these computations being small, and the description of the computation being easily fit inside the black hole.
- WJW 3y agoSure? That doesn't even matter for normal computers though. Busy beaver algorithms can be described in very few lines of code but can generate incredible complexity. It's not super difficult to devise an algorithm that would need many more bits of information than just its description+inputs to accurately describe all the state required, and that is in fact exactly what the authors of this paper did.
- Nevermark 3y agoLimits on all computational complexity in a given regime are a quite different result from noting particular algorithms have high computational complexity. And if these results and the holographic principle holds, then these limits would apply to all computers. Even “normal” ones.