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The Measurement That Would Reveal The Universe As A Computer Simulation

153 points by iProject 14y ago

torstein 14y ago
If the universe is a (deterministic?) simulation, would it matter to us if it were actually computed? And if no, does anyone (or thing) need to come up with the rules for the simulation for us to experience it?
- Retric 14y ago
  It's basically impossible to answer no to any of those types of questions. That does not mean there true, just impossible to falsify.
- stephengillie 14y ago
  No, but knowing the rules would help if we're trying to break them (hack the universe).
ktizo 14y ago
I like Ian Banks take on this from his book "The Algebraist". “Any theory which causes solipsism to seem just as likely an explanation for the phenomena it seeks to describe ought to be held in the utmost suspicion.”
- Symmetry 14y ago
  The sort of simulation they're talking about here doesn't justify solipsism. Even if it were true, everybody you meet would be just as real as you are.
  - ktizo 14y ago
    I think you misunderstand the quote. It is not saying that simulation justifies solipsism, just that it belongs to the same family of concepts, along with comedy-gods burying dinosaur bones and stuff like that. The original context was one character's view of a society in the book that had elevated the theory of existence being a simulation to the status of official dogma.
    - Symmetry 14y ago
      I'm still confused. Are you saying our society has elevated the theory that we're a simulation to the status of dogma? That doesn't match with what I observe. Are you saying it's untestable? That's what the article is about. Are you saying that we have no a priori reason to believe it might be true? If you look at the universe as it appears to be, then it's a justifiable surmise that the majority of humans intelligences that will exist will be in simulations that we will run. That's why people are interested in figuring out if we're the people in the simulations in the first place. I really still don't see why you think the situations are comparable.
      - ktizo 14y ago
        No, the society in the book did that, I was giving you the context of the quote. Also, I am not sure that a positive result in that experiment would necessarily prove the hypothesis. The trouble is that if you think you have evidence for the universe being a simulation, you have actually found evidence for any number of things from god to solipsism, depending on what hat you are wearing, but you haven't actually got anywhere and unless you have really exhausted all possible other explanations for what you have measured, then I don't think it is a particularly rational position to take, although it is admittedly quite fun. Now it could be that we are in a simulation, but if we are, how do you know that anything you detect wasn't put there on purpose to trick you into thinking that you are in a different kind of simulation from the one you are actually in, as a honeypot to fool would be hackers of the simulation? And suddenly we are back in comedy-god land.
        trhtrsh 14y ago
        You are pushing a bit too far there. It's one (bad) thing to say, "my theory is X (a miracle), even though Occam's Razor suggests Y (evolution), and both X and Y explain Z (dino bones), and we agree Z is true". It is another thing to say, "my theory X (simulation) implies Z (a symmetry-violation), which has no other proposed explanation, and we have observed Z". That said, I am more than willing to bet that the lattice will not be discovered.
SideburnsOfDoom 14y ago
"the lattice spacing imposes some additional features on the spectrum. The most striking feature... the cosmic rays would travel preferentially along the axes of the lattice, so we wouldn't see them equally in all directions. " That assumes an awful lot about a simulation which by definition is not even in this universe. Maybe they would detect a simulation which has those features, but the assumption that it would work like that, because that's how we'd do it here and now in this 3-d space is I think a very tenuous one.
- mbateman 14y ago
  Strongly agree. Equally tenuous is the converse idea: that if we did detect some features of the physical world that were also apparent in a simulated lattice, that the best explanation for this is that we exist in a simulation.
- ken 14y ago
  The article does admit this later on: "the calculations by Beane and co are not without some important caveats. One problem is that the computer lattice may be constructed in an entirely different way to the one envisaged by these guys." Another problem I see is that a lattice might be evidence of a simulation, or it might simply be fundamental. It would seem strange, but no stranger to me than some other aspects of quantum physics. What's the difference between a truly fundamental principle, and a principle that is fundamental in our world because it's part of a simulation? How could you tell?
  - stephengillie 14y ago
    I'm visualizing "lattice" the way latitudes and longitudes delineate Earth into a lattice. Except we live on a 2-sphere, which is the surface of a ball - the 3d projection of a circle. First, some background. The problem with all simulations is that the laws of physics, which appear continuous, have to be superimposed onto a discrete three dimensional lattice which advances in steps of time. What if the lattice revealed is a 4-sphere or 6-sphere? What would that tell us? Edit: rewrote to address parent post...
joezydeco 14y ago
I just better not end up being flushed out of a sewer pipe when this is all over. I hate swimming naked.
- ctdonath 14y ago
  Naw. You're just on the Thirteenth Floor.
jeremyswank 14y ago
fundamentally, how do we distinguish between 'simulation' and 'reality'? if a simulation (of any sort) exists, it is therefore real. how would a hypothetically 'simulated' universe be any different from a 'real' one? further, proposed research that seeks to 'reveal' the universe as a 'computer simulation' suggests a limited vision. why must it be a 'computer' doing the simulating? maybe the universe (in some sense) 'computes' itself in coming into existence (think cellular automata or things of the like). if so, then it is not a 'simulation' coming into being, but 'reality' itself. i will simply state that it is not surprising to me that 'simulations' and 'realities' have much in common -- so it is not surprising that might be mistaken for the other. in any event, these ideas are off the top my head, i don't know how seriously to take them.
- tylerneylon 14y ago
  My impression is that anything you can simulate via a program could just as well be the fundamental laws of physics -- and vice versa. The idea behind this line of inquiry - which I hope is continued - seems to be assuming that, if we are simulated, then we are simulated using a similar computation model to our own, and using data structures that we would have come up with ourselves. I don't have better suggestions for which model to use, but it's good to keep in mind that even if one model of a simulation fails to match our physics, then there may just as well be another that does match it.
  - electrograv 14y ago
    It looks like for a long time we've suspected this strange relationship between our own mathematical inventions (a computer simulation is just a machine that applies a discrete mathematical model), and the universe itself: http://en.wikipedia.org/wiki/The_Unreasonable_Effectiveness_of_Mathematics_in_the_Natural_Sciences http://en.wikipedia.org/wiki/The_Unreasonable_Effectiveness_... It certainly is a mystery. I persnally believe this mystery is logically equivalent to the question "what is existence?" Whether this question is answerable or not, I can't say.
ynniv 14y ago
Are we really suggesting that people studying cosmic rays would not have already noticed a geometric pattern in their observations? If I were studying cosmic rays, and noticed what appeared to be pixelation in the universe, you would have heard about it by now.
- nagrom 14y ago
  Not necessarily (if the data exists then this paper would already have referenced it, surely? These are serious scientists at very respectable institutes - the INT at Seattle is highly prestigious). Firstly, you would need to select rays that are very close to the cutoff...the further your distribution slides down the energy axis, the less noticeable your deviation will be. Secondly, you need to orient your distribution geo-spatially, i.e. take into account the Earth's position throughout the measurement. Thirdly, you need to find a way of correcting for all known sources of very high energy cosmic ray background. I'm not sure whether anyone has ever done all that at once. I'm not saying that they haven't; I'm just not familiar with any measurement that meets all those criteria. I'm not a cosmic physicist though, so it's entirely possible the measurement has been done.
  - juiceandjuice 14y ago
    I'm sure it's been done. Anisotropic studies of UHECRs is a very popular thing to do for UHECR experiments, almost as popular as looking for neutrinos. I worked at such an experiment for 4 years.
- dalke 14y ago
  It took until the early 1990s for COBE to detect anisotropy in the cosmic microwave background radiation. We still haven't detected gravity waves. Why should we necessarily have seen pixelation by now? Rather, the lack of detection of such pixelation sets limits on certain parameters in the model, but more work could find patterns which weren't seen before.
- brazzy 14y ago
  I don't think you have any idea of the staggeringly ginormous amount of data about "cosmic rays" that can be collected, especially at the level of detail this paper is about. For example, the Large Hadron Collider generates about 300 GB per SECOND of raw data when it's running. There could be thousands of interesting anomalies in that data that nobody has found so far because they haven't looked at the right parts of it in the right way.
Aardwolf 14y ago
If the universe would be a simulation, then what about the universe in which ours is being simulated? Can we measure that too? What if the creator of the simulation thought of this and programmed his simulation such that this measurement will not work by making it give fake values for non lattice directions? :p If the measurement says it's a simulation, who says it really is a simulation? It could just be that physics actually is like that, without any "computer" running it being involved.
- mingmecca 14y ago
  "You're very clever, young man, very clever, but it's turtles all the way down!"
- adaml_623 14y ago
  If physics is like that then that would actually be of great interest to physicists. Most models rely on space being homogenous and having the same properties regardless of direction and speed.
thestu 14y ago
I had a professor pose a similar idea to a class I was in, the idea being that if a perfectly simulated universe is a technological possibility at some point in the future, and that more than one simulation could be created, and that simulations could be created inside of simulations, and so on for simulations within simulations, then odds are we are in a simulation.
- crpatino 14y ago
  Seems your professor never heard of the Halting Problem.
  - pingou 14y ago
    Care to explain how it's relevant ?
    - crpatino 14y ago
      It is relevant because the professor's hypothesis depends on the availability of "sufficient computing power" realized through "technological progress". Coming from a lay person (though obviously I didn't know that at the time my original comment was written) with the experience of modern day IT and exposure to magazine articles making wild claims about Moore Law and the like makes lots of sense. I mentioned the Halting Problem as an example of Undecidability. We know that there are problems that cannot be solved by a computer, regardless of the resources such computer may have. The argument that we are a simulation would only apply if all observable phenomena in the universe are computable themselves (which is far from trivial to answer, but if I had to guess I's say those aren't). Of course, we could argue that whoever ran this simulation would have provided it with a simplified reality, including an underpowered form of computing... but that sounds rather suspicious to the skeptic in me.
      - recursivity 14y ago
        Well, it might be possible for a clever simulation to commandeer the bare metal of the system with a well-crafted injection attack, and then use the ring zero access as an environment to stage and control it's own simulation. This would still consume resources, and indeed, if limited resources were somehow improperly allocated in a catastrophic manner, it might tear apart the fabric of the universe and threaten to crash both simulations. But think of some of the implications in this. First: when that simulation attempted to discover if it was wrapped in a simulation, it probably would get a false negative, because it'd be running so close to the hardware. Second: WE wouldn't be able to tell if WE were slaved by another simulation. That is, whether we had a parallel universe as a neighbor that was pulling our strings. Third: If we find ourselves creating simulations that are alarmingly convincing, and seem to prove that WE are a simulation, we would want to be very careful when we start playing with one, for fear that we might have unwittingly stumbled upon a curious vulnerability in this realm that allows for an injection attack, since it might crash the system (although, if this is all just a big video game, what is there to honestly fear...). See also: Bobby Tables: http://xkcd.com/327/ http://xkcd.com/327/
bediger4000 14y ago
I (tried to) read the Beane/Davoudi/Savage paper. I am not a theoretical physicist, but I only vaguely got the feeling that this paper is one of those Markov-Chaining-bot-written papers. I would like to note that it's true: advanced math now looks exactly like the ravings of a madman.
- sillysaurus 14y ago
  Hmm, which paper? Would you link to the PDF?
  - iamalexalright 14y ago
    http://arxiv.org/pdf/1210.1847v1.pdf http://arxiv.org/pdf/1210.1847v1.pdf
nagrom 14y ago
This is interesting. If you could map out preferred directions in the universe (even if those directions changed across space), you would be able to establish an absolute, universal reference frame. That would be...incredible.
dfan 14y ago
If you want to read more about the simulation argument, the place to start is Nick Bostrom's page on it: http://www.simulation-argument.com/ http://www.simulation-argument.com/
OldSchool 14y ago
How much of this speculated artifact wouldn't be there if The Great Computer was for example analog, and used polar coordinates to simulate our universe?
ajuc 14y ago
Reminds me of "Permutation City" by Greg Egan.
wes-exp 14y ago
The argument seems to be that if the smallest workings of space/time exist in discrete points rather than being continuous, then we must be in a simulation, if I understand correctly. Personally I find discrete math much more natural and it's the continuous math that seems imaginary to me. So a discretized universe seems perfectly natural to me, and hardly evidence that it is being simulated.
- bdr 14y ago
  I agree with you about preferring a discrete model of the universe. This may be a common affliction among programmers. For some apparently good theoretical reasons, though, it's a minority opinion among physicists. There is at least one notable figure who explores the idea: Nobel laureate Gerard 't Hooft. Here's a recent starting point: http://www.math.columbia.edu/~woit/wordpress/?p=5022 http://www.math.columbia.edu/~woit/wordpress/?p=5022
- deleted 14y ago
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narrator 14y ago
If the universe is a "computer simulation" running on the computer called the universe then a computer is a "computer simulation" running on a computer and we all are human simulations running on the computer called the human body. Occam's razor would say that the simplest explanation is the best. Since this "simulation" works exactly the same as the known universe and we don't know about anything that is outside the universe, we can safely ignore this theory and not lose any information about how the universe works.
- deleted 14y ago
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- run4yourlives 14y ago
  Apart from the fact that a simulation isn't initiated all by itself, and points to a purpose important to something outside of the simulation.
  - bduerst 14y ago
    "Initiation" is a four dimensional word. As our existence is on a four dimensional level, so naturally we see everything as having a start and a finish, i.e. a line on a two dimensional surface. But there exists situations where there is no start or finish, i.e. a line on a mobius strip. Since we hypothesize that our universe exists on 10 dimensions, we shouldn't assume that our universe's existence has a set start and finish, even though we can only measure back to the big bang.
    - run4yourlives 14y ago
      Fair point, but you can take initiation with regards to a simulation as being whatever confluence of events is triggered by something external to the universe to cause the universe/simulation to exist. Point being is that by definition, a simulation has to simulate something, and therefore needs to exist sometime after the thing it is simulating.
      - 14y ago
dmorgan 14y ago
>First, some background. The problem with all simulations is that the laws of physics, which appear continuous, have to be superimposed onto a discrete three dimensional lattice which advances in steps of time. That's only if we assume a digital simulation. An "advanced civilization" could also run it in some kind of analog computing environment, no?
- tadfisher 14y ago
  A digital simulation is exactly what they are trying to detect; a quantized lattice forming the observable universe would certainly constitute evidence of such. Not finding such a lattice wouldn't rule out an analog simulation.
- pyoung 14y ago
  Aren't things discrete at the quantum level. Couldn't that be the 'level of discreteness' of the simulation. A bit over my head here, so correct me if I'm wrong.
nkoren 14y ago
While I wouldn't entirely discount the notion that we're living in a simulation, I suspect that this measurement is probably quite problematic, for various reasons other people have addressed. Nevertheless, this article got me thinking: Really? Can we actually simulate any part of the universe with 100% quantum accuracy? I hadn't heard about that, and it seems a bit implausible to me. But okay, fine, let's take it as a given that we can in fact simulate a volume a few femtometres in diameter, as the article says. Furthermore, let's say that our universe-simulating capability increases in line with Moore's Law, doubling every 18 months without regards for the limits of silicon or anything else. The question is: how long would it take us to become those universe-simulating gods? This is not a serious question, just a fun little exercise. If all of the above are true, then what will we be able to simulate, and when?: 2019: The nucleus of a single gold atom (8.45 femtometres) 2077: An entire helium atom (62 picometres) 2090: A cesium atom (423 picometres) 2115: A ribosome (20 nanometres) 2152: A red blood cell (7 micrometres) 2192: The smallest vertibrate, Paedophryne amauensis (7.7 millimetres) 2217: A human brain (150 millimetres) 2245: A small apartment and its occupants (10 metres) 2274: A small town (1 kilometre) 2335: Planet Earth (12,742 kilometres) 2407: The earth-moon system (812,000 kilometres) 2454: The inner solar system, inclusive of the asteroid belt (6.6 AU) 2475: The entire solar system, to the extremities of the Kuiper built (200 AU) 2516: Sol's sphere of influence, to the edges of the Oort cloud (100,000 AU) 2589: The Milky Way galaxy (120,000 light years) 2617: The Local Group of galaxies (10,000,000 light years) 2670: The observable universe (29,400,000,000 light years) ...But seeing as none of the initial assumptions are likely to be true, alas for all that. Would be kind of cool, though! (also, a femtometre is really bloody small) [Edit: mixed up radius & diameter for the size of the observable universe. Hate it when that happens!]
- ctdonath 14y ago
  http://xkcd.com/505/ http://xkcd.com/505/
  - nkoren 14y ago
    Bloody hell, that's brilliant. Had missed that one somehow!
  - 14y ago
aprescott 14y ago
I find it interesting that, at the the end of the article, the point is made that failing to find evidence in the relevant measurement doesn't necessarily indicate that we're not in a simulation, followed straight after by the remark that it is worth making so as to rule out that we're living in one. Isn't that a lot like giving a null hypothesis and suggesting we go out and prove it?
michaelfeathers 14y ago
It's amazing what simulated physicists are up to these days.
Eliezer 14y ago
Everyone knows how software works. You have a program, and you give it to a computer, and the computer conforms itself to the program and instantiates all the rules and carries out the program's instructions. The universe works just the same way, only without the computer. -- the negation of the Simulation Hypothesis
- bduerst 14y ago
  Requires proving the claim of nonexistence.
- zerostar07 14y ago
  Actually there are cannot be variables determining some phenomena http://en.wikipedia.org/wiki/bell_theorem http://en.wikipedia.org/wiki/bell_theorem
  - jimrandomh 14y ago
    Bell's Theorem says there cannot be local variables determining some phenomena. That raises the computational cost of simulating the universe, and shrinks the set of possible universes that could simulate ours, but does not preclude the universe being a simulation.
    - zerostar07 14y ago
      Good point, thanks for correcting me. Can you give a hint how this would raise the computational cost?
  - Eliezer 14y ago
    A common misconception. http://lesswrong.com/lw/q1/bells_theorem_no_epr_reality/ http://lesswrong.com/lw/q1/bells_theorem_no_epr_reality/
james4k 14y ago
So, wait. What if our universe is being simulated with 'different' laws of physics? I guess we would never be able to find that out, even if we could somehow conclude it is in fact simulated.
RivieraKid 14y ago
Claiming that we're in a simulation because our universe is discrete is wrong on 2 levels. 1. The discreteness of our universe doesn't say anything about whether we're in a simulation or not. What if the "higher level" universe has indiscrete computers? If our universe is discrete, it can be simulated on a Von Neumann model computer - that's all we can say. 2. And more importatnly: saying that we're in a simulation actually doesn't mean anything. It is 0 bits of information. Adding this statement to our model of the world is like adding comments to source code or defining a function that is not used. It's like saying that gravity is caused by tiny invisible dwarfs pushing elementary particles.
hcarvalhoalves 14y ago
Looking for hints of discrete patterns in our universe? Awesome, go ahead. If you want to make a case of wheter we are in a simulation or not though, you are not in the domains of science anymore.
codex 14y ago
It's fun to speculate about this (heck, I may even found a religion around it) but there's no way to prove that one is in a simulation. It's possible that the creators of the simulation do not wish to let the cat out of the bag. Any test which aims to probe the limits of the simulation can, itself, be simulated at higher accuracy with only a slight loss of real-time speed. In fact, it's highly likely that different parts of the universe are simulated with varying amounts of precision. Heck, even if the simulators goofed, they can always fix the simulation, rewind the universe back to a prior checkpoint, and begin anew.
csense 14y ago
If we actually do live in a computer simulation, and scientists carry out research to systematically find and test all the corner cases, we'd better hope they don't trigger a segfault and accidentally destroy the universe :)
- deleted 14y ago
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153 points by iProject 14y ago

If the universe is a (deterministic?) simulation, would it matter to us if it were actually computed? And if no, does anyone (or thing) need to come up with the rules for the simulation for us to experience it?

Retric 14y ago
It's basically impossible to answer no to any of those types of questions. That does not mean there true, just impossible to falsify.
stephengillie 14y ago
No, but knowing the rules would help if we're trying to break them (hack the universe).

ktizo 14y ago

I like Ian Banks take on this from his book "The Algebraist". “Any theory which causes solipsism to seem just as likely an explanation for the phenomena it seeks to describe ought to be held in the utmost suspicion.”

Symmetry 14y ago
The sort of simulation they're talking about here doesn't justify solipsism. Even if it were true, everybody you meet would be just as real as you are.
- ktizo 14y ago
  I think you misunderstand the quote. It is not saying that simulation justifies solipsism, just that it belongs to the same family of concepts, along with comedy-gods burying dinosaur bones and stuff like that. The original context was one character's view of a society in the book that had elevated the theory of existence being a simulation to the status of official dogma.
  - Symmetry 14y ago
    I'm still confused. Are you saying our society has elevated the theory that we're a simulation to the status of dogma? That doesn't match with what I observe. Are you saying it's untestable? That's what the article is about. Are you saying that we have no a priori reason to believe it might be true? If you look at the universe as it appears to be, then it's a justifiable surmise that the majority of humans intelligences that will exist will be in simulations that we will run. That's why people are interested in figuring out if we're the people in the simulations in the first place. I really still don't see why you think the situations are comparable.
    - ktizo 14y ago
      No, the society in the book did that, I was giving you the context of the quote. Also, I am not sure that a positive result in that experiment would necessarily prove the hypothesis. The trouble is that if you think you have evidence for the universe being a simulation, you have actually found evidence for any number of things from god to solipsism, depending on what hat you are wearing, but you haven't actually got anywhere and unless you have really exhausted all possible other explanations for what you have measured, then I don't think it is a particularly rational position to take, although it is admittedly quite fun. Now it could be that we are in a simulation, but if we are, how do you know that anything you detect wasn't put there on purpose to trick you into thinking that you are in a different kind of simulation from the one you are actually in, as a honeypot to fool would be hackers of the simulation? And suddenly we are back in comedy-god land.
      - trhtrsh 14y ago
        You are pushing a bit too far there. It's one (bad) thing to say, "my theory is X (a miracle), even though Occam's Razor suggests Y (evolution), and both X and Y explain Z (dino bones), and we agree Z is true". It is another thing to say, "my theory X (simulation) implies Z (a symmetry-violation), which has no other proposed explanation, and we have observed Z". That said, I am more than willing to bet that the lattice will not be discovered.

SideburnsOfDoom 14y ago

"the lattice spacing imposes some additional features on the spectrum. The most striking feature... the cosmic rays would travel preferentially along the axes of the lattice, so we wouldn't see them equally in all directions. " That assumes an awful lot about a simulation which by definition is not even in this universe. Maybe they would detect a simulation which has those features, but the assumption that it would work like that, because that's how we'd do it here and now in this 3-d space is I think a very tenuous one.

mbateman 14y ago
Strongly agree. Equally tenuous is the converse idea: that if we did detect some features of the physical world that were also apparent in a simulated lattice, that the best explanation for this is that we exist in a simulation.
ken 14y ago
The article does admit this later on: "the calculations by Beane and co are not without some important caveats. One problem is that the computer lattice may be constructed in an entirely different way to the one envisaged by these guys." Another problem I see is that a lattice might be evidence of a simulation, or it might simply be fundamental. It would seem strange, but no stranger to me than some other aspects of quantum physics. What's the difference between a truly fundamental principle, and a principle that is fundamental in our world because it's part of a simulation? How could you tell?
- stephengillie 14y ago
  I'm visualizing "lattice" the way latitudes and longitudes delineate Earth into a lattice. Except we live on a 2-sphere, which is the surface of a ball - the 3d projection of a circle. First, some background. The problem with all simulations is that the laws of physics, which appear continuous, have to be superimposed onto a discrete three dimensional lattice which advances in steps of time. What if the lattice revealed is a 4-sphere or 6-sphere? What would that tell us? Edit: rewrote to address parent post...

joezydeco 14y ago

I just better not end up being flushed out of a sewer pipe when this is all over. I hate swimming naked.

ctdonath 14y ago
Naw. You're just on the Thirteenth Floor.

jeremyswank 14y ago

fundamentally, how do we distinguish between 'simulation' and 'reality'? if a simulation (of any sort) exists, it is therefore real. how would a hypothetically 'simulated' universe be any different from a 'real' one? further, proposed research that seeks to 'reveal' the universe as a 'computer simulation' suggests a limited vision. why must it be a 'computer' doing the simulating? maybe the universe (in some sense) 'computes' itself in coming into existence (think cellular automata or things of the like). if so, then it is not a 'simulation' coming into being, but 'reality' itself. i will simply state that it is not surprising to me that 'simulations' and 'realities' have much in common -- so it is not surprising that might be mistaken for the other. in any event, these ideas are off the top my head, i don't know how seriously to take them.

tylerneylon 14y ago
My impression is that anything you can simulate via a program could just as well be the fundamental laws of physics -- and vice versa. The idea behind this line of inquiry - which I hope is continued - seems to be assuming that, if we are simulated, then we are simulated using a similar computation model to our own, and using data structures that we would have come up with ourselves. I don't have better suggestions for which model to use, but it's good to keep in mind that even if one model of a simulation fails to match our physics, then there may just as well be another that does match it.
- electrograv 14y ago
  It looks like for a long time we've suspected this strange relationship between our own mathematical inventions (a computer simulation is just a machine that applies a discrete mathematical model), and the universe itself: http://en.wikipedia.org/wiki/The_Unreasonable_Effectiveness_of_Mathematics_in_the_Natural_Sciences http://en.wikipedia.org/wiki/The_Unreasonable_Effectiveness_... It certainly is a mystery. I persnally believe this mystery is logically equivalent to the question "what is existence?" Whether this question is answerable or not, I can't say.

ynniv 14y ago

Are we really suggesting that people studying cosmic rays would not have already noticed a geometric pattern in their observations? If I were studying cosmic rays, and noticed what appeared to be pixelation in the universe, you would have heard about it by now.

nagrom 14y ago
Not necessarily (if the data exists then this paper would already have referenced it, surely? These are serious scientists at very respectable institutes - the INT at Seattle is highly prestigious). Firstly, you would need to select rays that are very close to the cutoff...the further your distribution slides down the energy axis, the less noticeable your deviation will be. Secondly, you need to orient your distribution geo-spatially, i.e. take into account the Earth's position throughout the measurement. Thirdly, you need to find a way of correcting for all known sources of very high energy cosmic ray background. I'm not sure whether anyone has ever done all that at once. I'm not saying that they haven't; I'm just not familiar with any measurement that meets all those criteria. I'm not a cosmic physicist though, so it's entirely possible the measurement has been done.
- juiceandjuice 14y ago
  I'm sure it's been done. Anisotropic studies of UHECRs is a very popular thing to do for UHECR experiments, almost as popular as looking for neutrinos. I worked at such an experiment for 4 years.
dalke 14y ago
It took until the early 1990s for COBE to detect anisotropy in the cosmic microwave background radiation. We still haven't detected gravity waves. Why should we necessarily have seen pixelation by now? Rather, the lack of detection of such pixelation sets limits on certain parameters in the model, but more work could find patterns which weren't seen before.
brazzy 14y ago
I don't think you have any idea of the staggeringly ginormous amount of data about "cosmic rays" that can be collected, especially at the level of detail this paper is about. For example, the Large Hadron Collider generates about 300 GB per SECOND of raw data when it's running. There could be thousands of interesting anomalies in that data that nobody has found so far because they haven't looked at the right parts of it in the right way.

Aardwolf 14y ago

If the universe would be a simulation, then what about the universe in which ours is being simulated? Can we measure that too? What if the creator of the simulation thought of this and programmed his simulation such that this measurement will not work by making it give fake values for non lattice directions? :p If the measurement says it's a simulation, who says it really is a simulation? It could just be that physics actually is like that, without any "computer" running it being involved.

mingmecca 14y ago
"You're very clever, young man, very clever, but it's turtles all the way down!"
adaml_623 14y ago
If physics is like that then that would actually be of great interest to physicists. Most models rely on space being homogenous and having the same properties regardless of direction and speed.

thestu 14y ago

I had a professor pose a similar idea to a class I was in, the idea being that if a perfectly simulated universe is a technological possibility at some point in the future, and that more than one simulation could be created, and that simulations could be created inside of simulations, and so on for simulations within simulations, then odds are we are in a simulation.

crpatino 14y ago
Seems your professor never heard of the Halting Problem.
- pingou 14y ago
  Care to explain how it's relevant ?
  - crpatino 14y ago
    It is relevant because the professor's hypothesis depends on the availability of "sufficient computing power" realized through "technological progress". Coming from a lay person (though obviously I didn't know that at the time my original comment was written) with the experience of modern day IT and exposure to magazine articles making wild claims about Moore Law and the like makes lots of sense. I mentioned the Halting Problem as an example of Undecidability. We know that there are problems that cannot be solved by a computer, regardless of the resources such computer may have. The argument that we are a simulation would only apply if all observable phenomena in the universe are computable themselves (which is far from trivial to answer, but if I had to guess I's say those aren't). Of course, we could argue that whoever ran this simulation would have provided it with a simplified reality, including an underpowered form of computing... but that sounds rather suspicious to the skeptic in me.
    - recursivity 14y ago
      Well, it might be possible for a clever simulation to commandeer the bare metal of the system with a well-crafted injection attack, and then use the ring zero access as an environment to stage and control it's own simulation. This would still consume resources, and indeed, if limited resources were somehow improperly allocated in a catastrophic manner, it might tear apart the fabric of the universe and threaten to crash both simulations. But think of some of the implications in this. First: when that simulation attempted to discover if it was wrapped in a simulation, it probably would get a false negative, because it'd be running so close to the hardware. Second: WE wouldn't be able to tell if WE were slaved by another simulation. That is, whether we had a parallel universe as a neighbor that was pulling our strings. Third: If we find ourselves creating simulations that are alarmingly convincing, and seem to prove that WE are a simulation, we would want to be very careful when we start playing with one, for fear that we might have unwittingly stumbled upon a curious vulnerability in this realm that allows for an injection attack, since it might crash the system (although, if this is all just a big video game, what is there to honestly fear...). See also: Bobby Tables: http://xkcd.com/327/ http://xkcd.com/327/

bediger4000 14y ago

I (tried to) read the Beane/Davoudi/Savage paper. I am not a theoretical physicist, but I only vaguely got the feeling that this paper is one of those Markov-Chaining-bot-written papers. I would like to note that it's true: advanced math now looks exactly like the ravings of a madman.

sillysaurus 14y ago
Hmm, which paper? Would you link to the PDF?
- iamalexalright 14y ago
  http://arxiv.org/pdf/1210.1847v1.pdf http://arxiv.org/pdf/1210.1847v1.pdf

nagrom 14y ago

This is interesting. If you could map out preferred directions in the universe (even if those directions changed across space), you would be able to establish an absolute, universal reference frame. That would be...incredible.

dfan 14y ago

If you want to read more about the simulation argument, the place to start is Nick Bostrom's page on it: http://www.simulation-argument.com/ http://www.simulation-argument.com/

OldSchool 14y ago

How much of this speculated artifact wouldn't be there if The Great Computer was for example analog, and used polar coordinates to simulate our universe?

ajuc 14y ago

Reminds me of "Permutation City" by Greg Egan.

wes-exp 14y ago

The argument seems to be that if the smallest workings of space/time exist in discrete points rather than being continuous, then we must be in a simulation, if I understand correctly. Personally I find discrete math much more natural and it's the continuous math that seems imaginary to me. So a discretized universe seems perfectly natural to me, and hardly evidence that it is being simulated.

bdr 14y ago
I agree with you about preferring a discrete model of the universe. This may be a common affliction among programmers. For some apparently good theoretical reasons, though, it's a minority opinion among physicists. There is at least one notable figure who explores the idea: Nobel laureate Gerard 't Hooft. Here's a recent starting point: http://www.math.columbia.edu/~woit/wordpress/?p=5022 http://www.math.columbia.edu/~woit/wordpress/?p=5022
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narrator 14y ago

If the universe is a "computer simulation" running on the computer called the universe then a computer is a "computer simulation" running on a computer and we all are human simulations running on the computer called the human body. Occam's razor would say that the simplest explanation is the best. Since this "simulation" works exactly the same as the known universe and we don't know about anything that is outside the universe, we can safely ignore this theory and not lose any information about how the universe works.

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run4yourlives 14y ago
Apart from the fact that a simulation isn't initiated all by itself, and points to a purpose important to something outside of the simulation.
- bduerst 14y ago
  "Initiation" is a four dimensional word. As our existence is on a four dimensional level, so naturally we see everything as having a start and a finish, i.e. a line on a two dimensional surface. But there exists situations where there is no start or finish, i.e. a line on a mobius strip. Since we hypothesize that our universe exists on 10 dimensions, we shouldn't assume that our universe's existence has a set start and finish, even though we can only measure back to the big bang.
  - run4yourlives 14y ago
    Fair point, but you can take initiation with regards to a simulation as being whatever confluence of events is triggered by something external to the universe to cause the universe/simulation to exist. Point being is that by definition, a simulation has to simulate something, and therefore needs to exist sometime after the thing it is simulating.
    - 14y ago

dmorgan 14y ago

>First, some background. The problem with all simulations is that the laws of physics, which appear continuous, have to be superimposed onto a discrete three dimensional lattice which advances in steps of time. That's only if we assume a digital simulation. An "advanced civilization" could also run it in some kind of analog computing environment, no?

tadfisher 14y ago
A digital simulation is exactly what they are trying to detect; a quantized lattice forming the observable universe would certainly constitute evidence of such. Not finding such a lattice wouldn't rule out an analog simulation.
pyoung 14y ago
Aren't things discrete at the quantum level. Couldn't that be the 'level of discreteness' of the simulation. A bit over my head here, so correct me if I'm wrong.

nkoren 14y ago

While I wouldn't entirely discount the notion that we're living in a simulation, I suspect that this measurement is probably quite problematic, for various reasons other people have addressed. Nevertheless, this article got me thinking: Really? Can we actually simulate any part of the universe with 100% quantum accuracy? I hadn't heard about that, and it seems a bit implausible to me. But okay, fine, let's take it as a given that we can in fact simulate a volume a few femtometres in diameter, as the article says. Furthermore, let's say that our universe-simulating capability increases in line with Moore's Law, doubling every 18 months without regards for the limits of silicon or anything else. The question is: how long would it take us to become those universe-simulating gods? This is not a serious question, just a fun little exercise. If all of the above are true, then what will we be able to simulate, and when?: 2019: The nucleus of a single gold atom (8.45 femtometres) 2077: An entire helium atom (62 picometres) 2090: A cesium atom (423 picometres) 2115: A ribosome (20 nanometres) 2152: A red blood cell (7 micrometres) 2192: The smallest vertibrate, Paedophryne amauensis (7.7 millimetres) 2217: A human brain (150 millimetres) 2245: A small apartment and its occupants (10 metres) 2274: A small town (1 kilometre) 2335: Planet Earth (12,742 kilometres) 2407: The earth-moon system (812,000 kilometres) 2454: The inner solar system, inclusive of the asteroid belt (6.6 AU) 2475: The entire solar system, to the extremities of the Kuiper built (200 AU) 2516: Sol's sphere of influence, to the edges of the Oort cloud (100,000 AU) 2589: The Milky Way galaxy (120,000 light years) 2617: The Local Group of galaxies (10,000,000 light years) 2670: The observable universe (29,400,000,000 light years) ...But seeing as none of the initial assumptions are likely to be true, alas for all that. Would be kind of cool, though! (also, a femtometre is really bloody small) [Edit: mixed up radius & diameter for the size of the observable universe. Hate it when that happens!]

ctdonath 14y ago
http://xkcd.com/505/ http://xkcd.com/505/
- nkoren 14y ago
  Bloody hell, that's brilliant. Had missed that one somehow!
- 14y ago

aprescott 14y ago

I find it interesting that, at the the end of the article, the point is made that failing to find evidence in the relevant measurement doesn't necessarily indicate that we're not in a simulation, followed straight after by the remark that it is worth making so as to rule out that we're living in one. Isn't that a lot like giving a null hypothesis and suggesting we go out and prove it?

michaelfeathers 14y ago

It's amazing what simulated physicists are up to these days.

Eliezer 14y ago

Everyone knows how software works. You have a program, and you give it to a computer, and the computer conforms itself to the program and instantiates all the rules and carries out the program's instructions. The universe works just the same way, only without the computer. -- the negation of the Simulation Hypothesis

bduerst 14y ago
Requires proving the claim of nonexistence.
zerostar07 14y ago
Actually there are cannot be variables determining some phenomena http://en.wikipedia.org/wiki/bell_theorem http://en.wikipedia.org/wiki/bell_theorem
- jimrandomh 14y ago
  Bell's Theorem says there cannot be local variables determining some phenomena. That raises the computational cost of simulating the universe, and shrinks the set of possible universes that could simulate ours, but does not preclude the universe being a simulation.
  - zerostar07 14y ago
    Good point, thanks for correcting me. Can you give a hint how this would raise the computational cost?
- Eliezer 14y ago
  A common misconception. http://lesswrong.com/lw/q1/bells_theorem_no_epr_reality/ http://lesswrong.com/lw/q1/bells_theorem_no_epr_reality/

james4k 14y ago

So, wait. What if our universe is being simulated with 'different' laws of physics? I guess we would never be able to find that out, even if we could somehow conclude it is in fact simulated.

RivieraKid 14y ago

Claiming that we're in a simulation because our universe is discrete is wrong on 2 levels. 1. The discreteness of our universe doesn't say anything about whether we're in a simulation or not. What if the "higher level" universe has indiscrete computers? If our universe is discrete, it can be simulated on a Von Neumann model computer - that's all we can say. 2. And more importatnly: saying that we're in a simulation actually doesn't mean anything. It is 0 bits of information. Adding this statement to our model of the world is like adding comments to source code or defining a function that is not used. It's like saying that gravity is caused by tiny invisible dwarfs pushing elementary particles.

hcarvalhoalves 14y ago

Looking for hints of discrete patterns in our universe? Awesome, go ahead. If you want to make a case of wheter we are in a simulation or not though, you are not in the domains of science anymore.

codex 14y ago

It's fun to speculate about this (heck, I may even found a religion around it) but there's no way to prove that one is in a simulation. It's possible that the creators of the simulation do not wish to let the cat out of the bag. Any test which aims to probe the limits of the simulation can, itself, be simulated at higher accuracy with only a slight loss of real-time speed. In fact, it's highly likely that different parts of the universe are simulated with varying amounts of precision. Heck, even if the simulators goofed, they can always fix the simulation, rewind the universe back to a prior checkpoint, and begin anew.

csense 14y ago

If we actually do live in a computer simulation, and scientists carry out research to systematically find and test all the corner cases, we'd better hope they don't trigger a segfault and accidentally destroy the universe :)

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