Physicists Devise Test For Whether the Universe Is a Simulation 529
olsmeister writes "Ever wonder if the universe is really a simulation? Well, physicists do too. Recently, a group of physicists have devised a way that could conceivably figure out one way or the other whether that is the case. There is a paper describing their work on arXiv. Some other physicists propose that the universe is actually a giant hologram with all the action actually occurring on a two-dimensional boundary region."
Re:What if they are right? (Score:4, Interesting)
What will we do then?
Try to communicate with our creators, duh. Maybe they will even let us out of our high-tech ant colony.
Speed of light (Score:5, Interesting)
Wouldn't one of the interesting consequences of the Universe being a 'hologram mapped on a two-dimensional boundary region' be that we could then postulate the reason for the speed of light? Speed of light could be then some upper boundary on the most primitive matrix transformation, sort of like the maximum GHz that the Universe is running at (assuming that the matrix itself is a memory map and that there is a gigantic number of processors that can access and modify memory simultaneously), or maybe the speed of light is then a manner, in which race conditions and dead locks are prevented? Sort of like in a bad system, where you know an atomic transaction takes 1ms, so you force a wait condition on the memory it access for 2ms, so you know for sure that the transaction committed.
At the same time, if that is the case, then going above and beyond speed of light could cause transactional failure and that could mean some form of memory corruption and destruction of the matrix or space time distortion and destruction :) But then if we didn't care about transactionality we could somehow breach the speed of light, but only by going outside of the memory boundaries of the simulation, crossing into the instruction stack and overwriting that constant!
I just gave myself a mental highfive on the level of crazy.
Re:What if they are right? (Score:5, Interesting)
Headline is a little misleading (Score:5, Interesting)
The test can (maybe) figure out of one of the consequences that would result from our universe being a simulation does, in fact, exist, provided, of course, our theories about how the universe and simulations work are actually accurate. Or in other words, it might show that it is possible that the universe is a simulation. Even if we show that the consequence exists (the consequence is that energy particles have a limit, the theory being that a simulation would have an upper limit on what it is able to simulate, kind of similar to how your computer has an upper limit on what it can fit into it's RAM), we still won't know that it is actually the result of the universe being a simulation, or some other unknown cause, and even if we don't find an upper limit, it could mean either our methods are too limited to find it or that the simulation isn't limited in the way that we think.
Really, while the research is itself fascinating, it isn't some kind of definitive test. Such tests are phenomenally rare in physics, perhaps even non-existent (it's always possible to create another theory that fits the observations).
As a side note, saying the universe isn't "real" is almost self-contradictory, as we define existence and reality precisely by our observations of the universe itself. A holographic universe would be no less real for being holographic, if only because we would literally have no other possible meaning for the word "real" (the simulation that occurs in The Matrix movie is of a completely different nature from the holographic principle). I'd also somewhat object to even using the word "simulation" in the first place, as that implies it is a simulation of something, when we really have absolutely no reason to suspect that is indeed the case (holographic universes can be modeled by simulation cases, hence the use of the term).
Disclaimer: IANAP yet, but I'm studying in the field.
Re:What if they are right? (Score:5, Interesting)
For all we know, we're all criminals and have been sentenced to a new life to give us a second chance at redemption. Maybe "going to heaven for being a good person" means we keep living once unplugged and "going to hell" means a real death sentence at the time we get unplugged from this virtual reality.
And let me add that some people are failing miserably at saving themselves.
I saw this back in the 1960s (Score:5, Interesting)
The Outer Limits - Wolf 359
http://www.youtube.com/watch?v=8uAGABz4R4s [youtube.com]
Re:Headline is a little misleading (Score:4, Interesting)
My favorite test of the universe being a simulation is to run bigger and bigger quantum computer factorizations in the hopes of hitting some sort of processing limit in the simulator. The processing power required to run all the parallel universes for factorization increases exponentially with the key length, and presumably at some point you'd see spontaneous decoherence or some other mechanism which disrupted the process.
Observing some kind of upper limit on quantum computing power would be evidence for a simulator with limited processing power, or of a simulation with some sort of pruning algorithm to keep the number of universes from exceeding some level. Failure to observe such a limit would be evidence against these types of simulations.
Not very strong evidence, of course. But evidence we'll have within a few decades at the current rate of quantum computer development.
-dentin
Re:What if they are right? (Score:4, Interesting)
Or we're all just a simulation for a being/beings who don't have that kind of "sinner's guilt", and want to understand it, so they created our universe to play that out while they observed. It's what we do with our simulations.
The relationship between simulation and simulator isn't necessarily arbitrary, but it's probably not understandable by the simulation. That is in effect (among) what Goedel's incompleteness theorems [wikipedia.org] say.
It seems more likely to me that the entire guilt/redemption pattern is an artifact of our simulation, not the more fundamental reality of the simulator. Because it seems pretty arbitrary on anything but a relatively modern political economics level.
Re:I hate those types of physicists (Score:5, Interesting)
Metafilter recently had a thread discussing an interview (alas, poorly written) with Rich Terrile [vice.com], a NASA scientist who speculates that our universe is a computer simulation.
The article is somewhat thought-provoking, but the discussion at Metafilter is really entertaining [metafilter.com].
In particular, I liked what one user (Malor) had to say [metafilter.com]:
I've been thinking for some time that all the quantum weirdness down at the bottom of things could be, in essence, lazy evaluation. Whatever computational substrate we're running on, to this way of thinking, simply never determines many of the answers, using approximations instead. It's only when a specific answer actually matters that the computation is fully carried out, and, if necessary, any other retroactive adjustments to spacetime are also implemented. That's why quantum measurements taken in the future are always consistent with entangled ones taken in the past -- the simulation goes back, and edits everything that way. [. . .]
Interestingly, simply watching for 'hot spots' in the simulated universe, areas that are taking lots of computation time, should inevitably lead the implementors to interesting things happening in that universe.... our particle accelerators, if we're running on a simulation, would be producing some very, very strange requests for 'CPU time'. That would be a flashing neon light that the entities running the simulation should check out that third planet orbiting that unremarkable sun in that rather plebian spiral galaxy.
[. . .]
Another thought I just had: the fundamental quantum randomness might be very deliberate, a damping effect on perturbations. If the GodComputer has to go back to earlier frames and change the results of computations to match later measurements, the ripples from that change could potentially mean everything within that event's light cone would have to stop, return to an earlier frame, and restart -- a missed branch prediction, in CPU-speak. The random quantum oscillations could function as a field reducing the spread of butterfly-wing effects to a local area, so that scientists doing weird crap in a laboratory, instead of making a huge chunk of a galaxy miss a couple of beats, might just force a recomputation of their local laboratory... eventually, the ripples of difference would be swallowed by quantum noise.
Gotta love this stuff.
Re:Deception (Score:5, Interesting)
This is not a test whether the universe is a simulation.
This is a test about the possibility that one kind of simulation can model the (known) behavior of the universe.
I keep repeating that "the universe is a simulation" vs. "the universe is real" does not make sense as a dichotomy. The question, unanswerable from the inside, is whether the universe is the last level of abstraction or the product of a meta-universe.
Let's take a game of chess as an example. A particular game of chess is an abstraction. A reality on its own. It is not some pieces on a checkerboard, it is something in the minds of those who know what those pieces mean. It depends on our reality for its existence (you gotta keep the moves recorded somewhere) so we say it's one level of recursion below ours. At the same level of dreams, laws, and so on.
Asking whether this universe is a simulation is like showing the transcript of a game of chess (the abstraction called a game of chess has a 1:1 mapping with the transcript of the game) and ask who was playing that game. Impossible question, because it's outside the level of abstraction represented by the game of chess. I need some meta information. But if my reality is constrained by the game of chess itself, like science is constrained by observation and human logic, I cannot perceive nor understand that meta information. If I try to process that meta information, like when we enter the field of religion, I can't tell whether that meta information is true or whether I understood it at all.
Sure, it's good to try, to reason about a game: "this move seems silly so white is probably a pc with some primitive algorhithm". But it could be a human rookie. Dramatic difference in the meta reality, irrelevant for the game.