Imagine if Einstein thought something (let's say for the sake of argument that he had access to some real close-to-speed-of-light experiments): "classical mechanics, isn't wrong, but predictions for close-to-the-speed-of-light experiments don't match the reality because we live in a simulation and the resource constraints forced by the computations needed for the simulation computer to do for such cases make it distort things through heuristic approximations ...and because we live in a simulation I can further pursue my other line of work, the genetic theory of Leprechauns and Fairies...".

Now I actually believe the plausability of the simulation theory, unfalsifiable as it may be, and all, but I think such simulations wouldn't be run for "fun" alone: if we're in a simulation, we're either (a) "babies" in nursery that probably involve multiple existences in multiple simulations until we are "prepared" for the "top-level reality" or (b) we and our universes are a very advanced form of... future "bitcoin miners" :| (I sincerely hope for either (a) or the plain ol "reality is real" theory, but one can never now...)

However, if we were unintended by-products, the simulation starters could turn on us - especially if we start interfering in the global state of the simulation. There is an interesting Asimov story along these lines where top scientists would be mysteriously killed in order to prevent humans developing force field tech. The protagonist compared humans to bacteria growing in a petri dish. In order to stop the bacteria spreading out you surround the bacteria with penicillin. The simulation starters did something analogous to humans.

Think of the Deist philosophy of the 18th century: that of God as a "clockmaker," who wound up the universe and then left it to tick. Whatever outcomes emerged were not necessarily the results of his actions or intentions; they were the effects of his original cause. It was a quirky and relatively short-lived philosophy, especially in the Western cannon. But it's eerily applicable here.

If this is all a computer simulation, it's possible the creator(s) of the simulation programmed only the fundamental physics and set up the Big Bang, allowing everything else to unfold and develop as it has.

In effect, this wouldn't be very different (to us) from a non-simultated reality. Hell, it's possible that we're in a simulation that people in the "real" universe set up as a scientific study, to model their own universe's birth and evolution.

Even advanced societies will have crappy programmers.

Found this : http://stackoverflow.com/questions/154163/detect-virtualized...

Whether something like this exists for our virtualized environment, we have to find out.

Think about time-lapse photography and simulated photons. As we get better at doing time-lapse photography (more FPS), we might see movement along the predicted course become step-wise (rather than a smooth function). Barring some weird physical phenomena, this could show we were inside a simulation.

But it's also possible that the simulation's FPS is far higher than what we can ever measure. That doesn't make it any less a simulation, but we also can't assume it's reality.

But the lack of such a finding wouldn't necessarily disprove a simulation. It's possible we're in a very simplified model of the real universe, and that the simulators --whoever or whatever they are -- inhabit a universe of very different physics and phenomena. Broadly and metaphorically speaking, we're trying to probe for the glass walls at the edge of the fish tank. But what if it's not a fish tank?

wrong. there are multiple alternatives; we are the nth civilization in a real universe, we are the nth to the nth civilization in the multiverse, etc. Sloppy sensationalism and bad statistical reasoning in this article.

It's almost like saying "we're probably characters in a novel," since for every universe there are many novels. Or like that old proof that God exists because he has every desirable quality, including existence -- as if a hypothetical entity could be forced into being by sheer burden of how it is described.

When we talk and reason, we call something a universe to invoke all the general properties our universe has -- except existence, of course, because it would be silly if we could only talk about things that exist. Various things like books and simulations are physical representations of universes that don't exist. By virtue of our interpretation, they are universes nonetheless. When reading a book, we fill in assumptions and details from real life if the author gives us no reason to think otherwise. Tautologically, the world of the book is different from the real world in some limited and structured way, but not in any way that keeps it from being a world at all.

Physics seeks to explain the world exhaustively and reductionistically in terms of mechanisms, models, and mathematics -- basically, to boil it all down to the consequences that emerge from laws and equations that we can completely conceptualize. If the universe consisted just of electromagnetism, for example, then Maxwell's equations would be a "complete" description of the universe, and any simulation of them could be considered a universe. Everything about the universe, every general description that's true of it without reference to specific places, times, and things, would be reflected in the simulated universe as well, because science allows us to subsume it all into the more fundamental description given by the equations.

The problem is that a model of the universe is stil a model. Humans invented the notion that a thing and a description of a thing are equivalent.

The bottom line is that we just don't know, and are unlikely ever to know, but if one wants to argue intelligently about it, there's a huge amount of philosophical literature on just this topic.

On the other hand, your position would seem to deny human rights to future intelligent robots, which has serious ethical ramifications should you happen to be wrong.

But the thing is, the exact same thing is true for your brain too! If you zoom in on your brain you will find nothing more than electrical impulses and neurons that strengthen or weaken their connection to other neurons. If the neurons were suddenly replaced with little computers that performed exactly the same, you wouldn't feel any different. You would still experience emotions and feel sensations and have no idea any parts had been swapped under the hood, unless you looked.

I don't know why but this idea is confusing to me. This XKCD http://xkcd.com/505/ is a good example. My consciousness could be a bunch of static rocks and a man placing new rows based on simple rules. I find this thought disturbing, but there isn't anything fundamentally different between that, a computer simulation, and a world of a bunch of atoms hitting each other, following simple physical laws.

Different beings could exist in all three universes. And each would feel emotions and sensations and all that. And each would argue about how beings just like them in the other universes "don't really exist" like they do.

So how is this different from a character in a novel or a variable in a computer set to "happy"? I honestly don't know. The character in a book is completely static. Whatever is written in the pages, it isn't changing, it isn't taking input and producing output. But the rows of rocks are static too after all. They don't take any input from the outside world either. They change over a dimension of space, each new row one foot to the right of the last. As do the characters in a book. Each paragraph moves the characters forward through their own dimension of time. Maybe the process that creates the rows of rocks, the man following simple rules, is what makes it conscious. But the book is created by a writer following a process too, does that make it conscious?

The only thing I can think of is that the character in the book is far simpler than a human. Words that say "john is happy" is similar to setting a variable on your computer equal to "happy". Happiness in a human is far more complex, involving tons of interactions between neurons. But this answer isn't satisfactory to me. Complexity isn't what makes something intelligent or conscious after all.

This is the difference between a running program and a short description of the program. The short description isn't runnable, and isn't running. The reason the program itself is doing what we want it to do is not because it's more complex than the short description (though it is), but because it's actually executing the algorithm. We could imagine more and more detailed descriptions of the program, specifying more and more closely how it works, and eventually it's so detailed that you could run the program from that description. At that point, the description is still not a running program, unless and until you run it. Being conscious is a process -- a running algorithm -- not a static description.

Anyways you can think of time as a dimension. Each moment of time exists, connected to the ones that came before and come after it. You can represent the every state that a turing machine goes through all at once. Just like those rows of rocks. What does "running" even mean in a universe where all points in time can exist at once?

But regardless of that, you can still say the book is "running" when it is being written or when it is being read. The characters don't just exist in the book, but literally in your mind. Though I still wouldn't call them conscious or even intelligent.

If they all exist at once, then in what sense are they connected? Certainly not a causal sense, which I would argue matters quite a lot.

> The characters don't just exist in the book, but literally in your mind. Though I still wouldn't call them conscious or even intelligent.

If your mind was able to simulate the actual process of consciousness in the brain of the character being read about, then I would argue that the character could be conscious. Of course, brains don't have that much additional processing power. :)

That is pure speculation. Just because we can observe similarities between two phenomenons it doesn't mean they are the same thing. You're erroneously assuming that the universe can only work in a way that fits our theories and models.

Why not?

But that's equally true of saying "complexity doesn't make something intelligent and conscious". All right, then what does? "Not complex" is a label just as much as "complex" is. Either way you haven't explained anything. That's what I was trying to get at.

Also, saying "complexity doesn't make something intelligent/conscious" is not the same as saying "something intelligent/conscious doesn't have to be complex", which is what I think the statement I originally responded to, taken in context, was really intended to mean. Do you really think intelligence and consciousness can be present in simple things like rocks? Might there not be a reason that the human brain is three pounds of complex matter, not three pounds of jello?

Anyways in the original context of where I said that, I was trying to come up with a satisfactory way to distinguish consciousness from non-consciousness. Complexity obviously isn't the way since lots of complex things are not conscious. It may be that all conscious things are also complex. But then complexity isn't the reason it's conscious, it just happens to correlate with it.

Setting a variable in a computer equal to "happy" obviously doesn't make the computer experience happiness. But then what possible sequence of commands and state changes would? If you accept that there is no possible sequence that would, then you have to accept that humans can not experience consciousness either. Because for all we know we are running in a computer too. Even if we are not, the process our brain follows easily could. The fact that it runs on atoms bouncing into each other and not electrons flowing through logic gates makes no difference.

Really? Show your work, please.

A lot of neurons may seem complicated, but you only need to understand the programming of a few, than just copy them a billion times.

This assumes that they are all "programmed" the same. Why do you think that must be the case? Also, you're leaving out all the chemical processes that contribute to brain function.

I was trying to come up with a satisfactory way to distinguish consciousness from non-consciousness. Complexity obviously isn't the way since lots of complex things are not conscious.

True.

It may be that all conscious things are also complex. But then complexity isn't the reason it's conscious, it just happens to correlate with it.

The connection might well be stronger than "just happens to correlate". Even if "complexity" by itself isn't the reason it's conscious, it might well be that consciousness requires a complex substrate.

Setting a variable in a computer equal to "happy" obviously doesn't make the computer experience happiness. But then what possible sequence of commands and state changes would?

Um, a much more complex sequence of commands and state changes?

If you accept that there is no possible sequence that would

I don't. I just think there is no simple sequence that would.

If that is too complex, you could create an even simpler algorithm which produces that. Maybe by creating a genetic algorithm which "evolves" human-like intelligence after billions of generations.

In both cases the end result may be complex, but the algorithm that creates it is not. Whether it be a network of billions of interconnected neurons that arise from simple programming of a few neurons, or a complex intelligence optimized by simple random mutation and selection.

This is the idea of emergence. That complex seeming behavior can "emerge" from simple rules and a simple process.

The problem is that both of these terms are really too vague. What do you mean by "consciousness"? Some people claim insects are conscious; some claim bacteria are conscious; some even claim electrons are conscious.

Also, what do you mean by "intelligence"? By some definitions, the process of evolution by natural selection is "intelligent".

If by these terms, you mean "the properties humans have that we call consciousness and intelligence", then why do you think there is no connection between them? Does your own intelligence really have nothing to do with your consciousness? Or vice versa?

It's conceivable you could create something like a human with very simple machinery, just massively scaled up.

Conceivable, yes. Likely, I don't think so. But that's really a matter of opinion; it depends on how much of the complexity in the parts of the human brain (neurons, chemicals, etc.) is necessary for human consciousness or intelligence, and how much you think is just an artifact of the implementation, so to speak. We don't know enough about how the brain works yet to really judge.

the end result may be complex, but the algorithm that creates it is not.

In other words, the complexity is still there.

That complex seeming behavior can "emerge" from simple rules and a simple process.

Wait a minute--complex seeming? Or complex?

If you're trying to argue that the complexity may not be in the algorithm itself, but only in the actual working out of the algorithm in time and space, I'll buy that.

But if you're trying to argue that it isn't "really" complex because the algorithm is simple, I don't buy that. I never said the algorithm had to be complex; I just said there has to be complexity somewhere for there to be (human-level, to avoid all the definitional issues I raised above) consciousness and intelligence. That's perfectly consistent with the complexity ultimately being built out of simple parts--just a lot of them with a lot of interactions, so the complexity is in the interactions, not in the parts themselves.

(I think it's likely that the parts themselves have significant complexity too, as I said above, but even if that's true, there will still be some lower level, possibly much lower, where there are simple parts, just a huge, huge number of them with a lot of interactions.)

>In other words, the complexity is still there.

Well yes in a way. By the definitions used in information theory, complexity is just the amount of bits you need to accurately describe something in some language. By common usage complexity just means the amount of concepts you need to learn to understand something (about the same thing.) But it can also mean the number of moving parts a machine has, so to speak, which could be very large while simple enough to understand or write on paper. Like a computer display which has a few thousand pixels each of which is almost exactly the same.

I don't know if you would call a computer display complicated, at least not much moreso than the invidual pixels that make it up. The same is probably true of humans. Even if humans are fairly complicated, someday a connectionist approach or maybe a rough approximation of a human brain might succeed at creating something arguably conscious.

>If you're trying to argue that the complexity may not be in the algorithm itself, but only in the actual working out of the algorithm in time and space, I'll buy that.

This may be a much better way of describing what I just said above. So yeah.

Consciousness is a property that we ascribe to ourselves and other entities. We don't experience it in others the way we experience it in ourselves, of course, but we infer it from the data available from interacting with them. They produce a pattern of signals that resonates deeply enough with us that we recognize them as like us in having goals, feelings, and access to the "human experience." For example, one of the most convincing things we could observe an AI do would be to make a novel observation about life, derived from current circumstances, that strikes us as deep and insightful, perhaps because it was hovering at the edge of our own awareness, or because it immediately activates mental patterns that we did not activate but are also meaningfully connected to the situation at hand for us.

It makes sense that if we were to copy the workings of the brain in sufficient detail in a machine, the machine would also be ascribed consciousness by human users. Perhaps we could say that it is an "artificial brain" in a literal sense, performing normal brain functions the way an artificial heart pumps blood.

In the case of the universe, it's at issue whether there is such a thing as a "complete description" of the universe, whether a simulation could be done, and then whether this simulation actually is a universe in some sense. Unlike brains, we don't regularly encounter other universes (actual, physical ones), ones which we don't live in and experience from the inside, but which we are forced to conclude are true manifestations that correspond in every important detail to our own nevertheless. A complete description of the universe by a future physicist (say) would start with a short list of all the types of information that go into describing a particular universe, like a list of type of particles and variables such as position and momentum. This list describes universes in general. Then we'd have to describe a particular universe, with a long, long, long list of all the individual particles and so on. Then we have to represent this information physically in some sort of computer, for the purpose of simulation, and perform the ongoing processing involved in running the simulation.

Finally, we must argue that the simulation is a universe. Not just deserving of being called one, or having the properties typically associated with one, but a true instance of some class that previously had the universe we live in as its single member.

One interesting feature of this line of thought is its seemingly infinite ambition. What about smaller goals we could set for mankind -- might we ever engineer an artificial star? How about an artificial galaxy? We can try to beef up the likelihood of this ever happening by considering not just mankind but any other "intelligent beings" the universe might happen to contain, in the past, present, and future. However, we are again on the shaky ground of inventing a class from a singleton. All extraterrestrial "intelligent beings" ever conceived are just stories with small, structured deviations from the human template; beings we identify with because they, too, have intentions and goals and act in their ultimate self-interest for the purpose of self-preservation and just trying to make a go of it in this big ol' universe. Some of them, it's presumed, make detailed copies of natural things at an astronomical scale and then talk about whether the old thing and the new thing are members of the same class of thing or not.

I agree that it's irrelevant to us and our operation if our brains are made of billiard balls or quantum clouds, and the same seems true of the universe.

It is still interesting whether the universe is "computable" or not, that is, whether something meeting the current definition of a computer could simulate it, even in theory. The part I object to from the OP is the implication we could draw conclusions about the origin of the universe from the prospect of being able to simulate one in theory. I think it's silly or meaningless to say we possibly -- or probably! -- live in an "artificial" universe.

I think you've come much closer than I to getting a definition of consciousness, but I still don't find it satisfactory. You could have a computer mimic a human without actually having anything resembling an inner "human experience". For example, a giant look up table with a preprogrammed response to any possible input. We have created extremely simple versions of this that are almost effective enough to pass the turing test. Just by gather a large number of human responses to chatbots. Though you could say the process that creates the giant look up table is intelligent, the table itself obviously is not.

There are AIs like AIXI which could be vastly intelligent without reasonably being considered conscious. They don't actually "think" so much as brute-force every possible solution to a given problem, or every possible explanation for a series of inputs, etc. Given enough computing power this would actually be effective. You could then ask it to mimic a conscious being and it could do so easily (given either a definition of consciousness or a set of observations about other conscious beings.) Maybe doing that requires the intelligence to actually simulate a conscious process somewhere along the line, so I don't know if that counts. It may be able to do so through mere, without having to actually run a full simulation. Providing a "deep insight" about life is nowhere near as complicated as a full human consciousness.

Maybe there is no such thing as consciousness. In the sense that there is no simple way to define it that is fully consistent with everything we want it to mean. That there are always going to be arbitrary seeming exceptions and gray areas. But that has deep and disturbing implications for morality. Maybe it's not relevant to our day to day life, but if we ever want to program a friendly artificial intelligence, we are screwed.

>I think it's silly or meaningless to say we possibly -- or probably! -- live in an "artificial" universe.

Well assuming that there are more simulated beings in all of existence, whatever that means, than there are non-simulated ones, it is very likely we are simulations. Though it's impossible to know what exists beyond our own universe. What is the distribution of universes? Do 50% of universes allow for infinite computing power, for example? What programming language do they use, which would determine how many bits a given universe would take to specify in that language, and therefore how often it gets simulated? How many universes even have anything close to intelligent beings?

An infinitely powerful computer would allow you to simulate every possible universe all at once, instantly (you would also be able to simulate every possible branch of non-deterministic universes, continuous variables, time travelling, and other things that people claim makes the universe "uncomputable.) And you could instantly do it an infinite number of times. If it were possible for such a thing to exist in a universe, that universe would contain every other possible universe. Including copies of itself and others universes with infinite computing power, which would contain more universes, etc.

(Very interesting short story that explains the implications of this http://qntm.org/responsibility)

So what is the top level universe? Why does something exist rather than nothing? Perhaps everything that can exist does exist. Maybe every computable program has been (is being?) run, including one that specifies our universe. That's the simplest possible explanation that explains the existence of the universe. Though I can not wrap my head around why something exists rather than nothing. None of this has any practical implications for our daily life, and the answer is probably unknowable, but it bothers me.

Sorry for going off on such a tangent. I hope this is comprehensible, as I know philosophical writings rarely are.

Simulated universes: I still think this is all meaningless metaphor. It's not easy to articulate why, but I'll try.

Some lines of thought just combine ideas in deep ways, but don't actually tell you anything new. For example, Zeno's paradox -- to get from point A to point B, you have to first go halfway, then halfway again, and so on forever -- doesn't actually teach us that nothing can ever go from point A to point B. It just demonstrates a glitch in the metaphors we use to reason about time and space. Actually, it's a glitch in the metaphor of traversing space as achieving a goal. Normally, if reaching a particular goal involves an infinite to-do list of subgoals, we wouldn't expect to ever get to the end and actually achieve the goal. However, if the goal is traversing some infinitely subdividable interval of space, we are provided with a mechanism to generate an infinite list of subgoals that are presumably all involved in achieving the larger goal. It's all just mental gymnastics and the normal tools of intuition breaking down.

To take a closer example, consider this line of thinking: "If you pick a random marriage proposal, chances are it is an imagined one rather than an actual one, because for every actual marriage proposal there are on average two or more imagined ones that never came to pass." This strange kind of thinking also mashes together diverse intuitive concepts. There's the idea that every class of thing (like "marriage proposal") has an extension set, an ensemble of instances. There's the fiction that an "event" is a discrete thing that we could identify and count if we had to, like counting the number of thoughts I've had today ("a thought" is a singular noun after all). There's the concept from probability theory of picking a member at random from a set (with the presumption that this is a well-defined act). There's the idea that an imagined X is still an X, because we still call it one. Unicorns are still unicorns even if they don't happen to exist.

The most intellectual, abstract part of the brain has a tendency to focus on what could possibly be rather than what is. We can get so wrapped up in generalities that we forget that this is the universe -- what we see around us, not what we imagine or are capable of conceiving of. Statements like, "Perhaps everything that can exist does exist" sound to me like a projection of our own models of reality out onto reality. Similarly, it's fascinating that we can conceptualize and talk about infinite computing power, but that doesn't mean there is any reality to it.

http://www.simulation-argument.com/simulation.pdf

Anyway, your objection here isn't actually relevant as far as I can tell. It's a probabilistic argument about the number of real minds vs. the number of simulated minds, and the bulk of the "proof" is in demonstrating that, under certain assumptions, the number of simulated minds would be so high in comparison to the number of real minds that you'd almost be forced to conclude that you are simulated.

It really doesn't have anything to do with "universes inside universes."

And I'm pretty sure the numbers you mentioned--like the number of real universes, the probability of life arising from non-life--really don't come into it at all. Skimming over the paper, none of that stuff seems to come up at all. Again, this isn't about universes inside universes (the news article phrased the argument poorly).

A provoking question: if we found evidence that convinced us, beyond a reasonable doubt, that we were living in a computer simulation, would you change your behavior?

What 'postulates' would they be calculated from? Does it even make sense to speak of universes following different 'logics'?

> far more universes simulated that have properties that are nothing like the "real" one as technology progresses, i.e. there are more instances of "sonic the hedgehogs" and "super mario brothers 1"

Those seem like perfectly normal universes to me: they're fully describable by short programs executing over discrete binary states like a chunk of RAM. Where's the violation of logic or metaphysical oddities there?

Exactly the point. What game do you know of that follows the laws of logic as we know them in the 'real' universe we habitate? It follows that it's nonsensical that we can reason ourself to reality if we are a simulation.

But the 'real universe' appears discrete on the smallest level, and I don't believe physicists will ultimately settle on a theory in which two completely different sorts of theories take over at different regimes and the macro-scale theory is not reducible, even in principle, to derivations and predictions of the micro-scale theory. The quantum theories will eventually predict the relativity-scale results./

> In addition, a "video-game universe" runs on a programmatic logic with discrete conditionals rather than our universe's equations that don't branch.

How would you know? What governs quantum randomness?

I treat free will as an assumption:

- If we are, in fact, predestined, assuming I have free will doesn't hurt or matter.

- If we do have free will, I'm applying that free will to make decisions based on a correct assumption

- If we do have free will and I had assumed we were predestined, this could have worse results. At the very least, it is unlikely to improve outcomes

Not to mention you were predestined to assume so.

That sounds distinctly like Anselm's ontological proof for the existence of God, and thus likely suffers from the same logical fallacies.

That said, I do often feel that at the literal edges of our universe (in all the senses of that term), our uncertainties simply dominate everything and all of our guesses about the true nature of reality are dominated by that uncertainty. Something (or, depending, multiple somethings) must be true for some value of true, but I'm skeptical if we can discover it. If it popped up and simply flat-out told us what the truth was somehow (the Great Simulator writing the message in the stars [1]), we probably couldn't confirm it.

[1]: http://lesswrong.com/lw/qk/that_alien_message/

My favorite theory was that all the humans were passengers on a generational seed ship traveling to the next star, kept in near stasis to keep them alive and mostly sane during the millennial transit.

That would have played nicely with The Architect's explanation that in the perfect simulated world, humans went insane. So The Architect devised worlds with struggles. But the iteration we observed got out of hand, due to The Oracle's meddling.

Such a wasted opportunity.

Yeah, but there were a lot of explosions.

Pretty sure under our current understanding of physics, it's impossible to simulate a universe like our own within our own.

Impossible to perfectly model a universe, but not impossible to simulate something that looks like a tiny part of a universe.

http://en.wikipedia.org/wiki/Ontological_argument

(no comment, just providing context)

The simulation argument says: if simulating minds is possible, and technologies eventually advance to the point that they can do it, a civilization would make lots of them. Thus, most minds are virtual, so your mind has a high base rate of being one.

Anselm's argument is: the best thing in the world would have to exist, since existence is better than non-existence. I define God as the best thing, so God must exist.

I don't quite see the parallel, but if you see something specific, I'd like to hear it.

Therefore, our universe would be a reasonable facsimile of there's in most respects.

Which has the implication that their may be limitations on their computational substrates which required workarounds or optimizations, or as the lattice QCD case points out - which require representing phenomenoma as discrete computational steps, rather then continuous analytical functions. It's a well known problem in all the computational disciplines, that changing the time-step of your simulation frequently leads to wildly different results then you expect.

Think about the speed of light and tell me how it makes _any_ sense that time slows down due to velocity. Yet that's exactly what EVE Online does to stop nodes crashing during heavy gameplay.

I didn't mean to say that this isn't an interesting line of inquiry, just that I don't think we can possibly consider the result conclusive either way. I think it's reasonable to re-weight one's beliefs to an extent based on the outcome, but not so far as to adopt one possibility as "a belief" and discard the other.

Would you take that as evidence that it does not computate discretely?

https://en.wikipedia.org/wiki/Slartibartfast

As opposed to us simply being some other civilization on one of the other billions of habitable planets in that same "first" universe?

So with no other knowledge, it's slightly more likely that we are the first civilization than the 5 millionth.

Of course it's tricky to talk about the "first" civilization in the face of relativistic time, but I'm assuming that there is some way to have an ordering of all civilizations.

You can't meaningfully speculate about the nature of what (if anything) is dimensionally/physically/extra-universally "outside" of our universe.

We don't even know what that means, much less if it exists or what the number/nature of it would be.

Our universe may be a piece of candy floating on a chocolate river in another universe that flows eternally.

It's all just make believe. Make believe can be fun, but let's not pretend that we're doing anything more substantial than what three year olds do when talking about space robots.

Yes, but if we are in a simulation we can almost answer the Fine-tuned Universe Paradox too, two birds with one stone. That is nice for Occam's rasor reasons.

"Physicists to Test if Universe is Computable"

I think the question is whether the compution is discrete (i.e., cheats) or is everywhere continuous.

Are there no infinitely many natural numbers unless we observe them? And then finally is actually computing a universe described by a set and a step function the only way to make it real? Is it not "real" by simply being possible?

As for discreteness of time, in quantum mechanics changes in state are modeled by square matrices over complex numbers. GL(n, C) is complete - for every matrix M you also have M^1/2, representing half the state chance. It follows that our time, at conceptual level, is at least as "dense" as rational numbers.

http://www.utilitarian-essays.com/lab-universes.html

"Abstract. I think there's a small but non-negligible probability that humans or their descendants will create infinitely many new universes in a laboratory. Under weak assumptions, this would entail the creation of infinitely many sentient organisms. Many of those organisms would be small and short-lived, and their lives in the wild would often involve far more pain than happiness. Given the seriousness of suffering, I conclude that creating infinitely many universes would be infinitely bad."

Time Cube! These stupid idiots still don't understand it.

The problem is that this is human bias. You can describe any theory by information manipulation, and it is as good a description as any other.

- If we're self aware of the simulation, would we be able (or ever want to) reverse engineer the fabric of which makes up our sim?

- Would there be infinite simulations? How far _up_ does the rabbit hole go?

- Another idea, and this is reaching, would be to consider the motivation behind running simulations like these. Are the "controllers" running simulations to try and find solutions to problems they are facing? Of course, this is the stuff right out of Scifi movies.

What is really being researched is whether the universe is computable, because that's something you can prove.

I see what you mean though, it would be impossible (with our current understanding of ... everything) to actually determine is we're in a sim or not.

If you prove the universe is computable, that still doesn't give you any answer whether it's a simulation or not.

As it stands, the theory is a tautology, because that's just proving the universe is something that it is.

Would? If they could, they might, or they might be pleased we figured it out :-P

By the time we are actually able to perform a simulation on such a scale would the numerical method not have evolved as well and possibly produce totally different kinds of 'observables'?

I realise I am totally out of my depth here :).

As the civilisation becomes closer to being capable of creating a perfectly simulated universe, they get less benefit from having one. If we assume the universe we are in is at least similar to 'the first', then the existence of entropy / thermodynamic laws would surely create a significant cost to universe simulation. So I can't see it being done without good reason (eg as a toy), and as the master would have to understand all the factors involved in the universe already to create the simulation, so what would they gain?

Is it right to say that it would be impossible to simulate the universe at full speed? (ie. the computer would need to be powerful enough to simulate itself and more (ie. the rest of the universe)). If so, this would not only make it less useful, but put significant (increasing) limits on the local age of the descendent universes; assuming (fairly, i think) that the master universe does not have an infinite existence with infinite time between shocks. Also, how would it be possible to store all the information for a universe within itself?

Or perhaps we are talking about imperfect simulations, which would make it much more feasible? but then the infinite exponential chain would not be possible as each child would become more crude. Or perhaps only a (diminishing) proportion of space(-time) is simulated.. or maybe the speed of light decreases as simulation levels get deeper?

In writing this I think I have come to the conclusion that it is impossible (in so far as anything is given our imperfect knowledge), at least a complete universe simulation or an endless chain, but I would love for someone to show otherwise.

The Douglas Adams-style answer would be that we're some kid's physics homework. Perhaps, in a sufficiently advanced civilization, building a working computer model of an advanced universe is child's play.

An alternative is that the simulators inhabit a very different universe from our own, and that our simulation is something entirely new. It's not a replica of their universe; it's a completely different creation. They could be studying various scenarios, of which ours is just one.

We need to bear in mind that we're approaching this problem from our own, subjective understanding of our universe. It's not a given that the simulators' universe is anything like ours.

It's interesting to consider if we were a different simulation. But it would still have the same limits (that the sum of the activity ('reality') in each simulation must be less large/complex than it's host), prohibiting the 'infinite simulations' concept.

It surely isn't necessary that we are similar to a host universe, but I wouldn't you say it was a necessary part of this theory?; because it all starts with the vastness of our own space(-time) as the justification for the likelihood of super-advanced civilisations. You could argue that the size of our universe implies simulations must happen, and that if our universe were a simulation the host must be larger, i suppose. If the simulations are not similar to their host, though, the foundation suggestion that a simulation could be our universe seems a little more shaky (as there would be no direct theory ('evidence') that a universe like ours could be simulated).

There is perhaps a semantic issue too.. if somewhere in this universe we are simulating something that works on different rules to our universe, is it in fact a universe, or what makes it so?

I don't think it's a necessary part of the theory, but it's a necessary part of the test we would need to conduct. And given that such a test is simply testing for inconsistencies, artifacts and bugs inherent to our own universe/simulation, it's possible to detect whether we're in a simulation without having to test for the precise nature of it (or the nature of the simulators).

But our tests are inherently being conducted from our own frame of reference, with our own understanding of what should and shouldn't be found. Ergo, we can prove a simulation by finding artifacts of one as recognizable to us, but we can't necessarily disprove a simulation by not finding artifacts.

That being said, the proper way to think about the test wouldn't be "Physicists are testing to determine if we're in a simulation." It would be "Physicists are testing to find evidence that we're in a simulation."

To the first one though, so long as politics and war exist, there would always be reason to attempt to run simulations, regardless of the degree of advancement of a civilization.

By the By, Iain Banks plays around / has a recurring thread of simulations and high powered computers in his culture series, if you enjoy sci fi.

As for the motives, for a simulation to be helpful, it would have to run at greater than real time, no? Which.. is surely impossible, at least for a complete 'perfect' simulation. Right? Imperfections (and the limit of a simulation having to be simpler than its host) would infer a finite chain of simulations, which would vastly reduce the likelihood of us existing in a simulation.

Also if these wars (etc) exist, the simulation is going to be knocked offline at some point, destroying all descendant universes, shrinking the pool of possible existent universes much further still.

So (AFAICT) we have gone from it being almost a certainty we are part of a simulation (only one true universe from infinite similar simulations), to being very unlikely.

I may check out the culture series, but i'm not one for reading much fiction, sadly.. impatient internet world that has formed me and all.

Not for the people in the simulation : ) We'd just be self-conscious byte code. Which actually is the question Iain Banks brings up. They want to run simulations on how a society will respond to a political action, but that would imply creating self-conscious byte-code in the simulation. And wouldn't that be genocide when they turn off the sim? So maybe the only ethical thing is to never turn off the sim...

At some point down the line there must be a purely physical universe though, but we're probably not there, but in one of the branches. So while I am not atheist in a pure sense, I am not a theist either. Nice, isn't it? Science makes almost full circle to religion. The IDers are almost right.

In the 20th century, one could be ignorant and scoff at the idea that Mankind might ever create a universe, and therefore scoff by extension at the idea that anyone or anything else could either... but now we know better. We've got universe prototypes already in production as ongoing commercial concerns (far more than mere theory!), at various stages of incredible primitiveness, but prototypes nonetheless. Rather than a massive leap, it is now merely logical progression that something, somewhere in some reality may actually have the knowledge and the resources to have "created" our universe, for some value of the term "created".

(I speak here of science in the vague philosophical movement sense. As much as it would like to claim total philosophical neutrality, there are certain Opinions that are Had.)

Atheists would rightly consider the evidence, conclude there was a creator, but give it no due reverence because they would conclude (rightly) that none is morally due.

As for the 'correct' conclusion that none is due, that is itself an awfully confident statement about a deity you know little about, even whether it exists. Some might consider the fact that we are left alone, rather than driven like puppets in some manner, to be a positive factor on its own, after all. You may not like that we are not handed a life of total goodness and light and luxury, or whatever your ideal universe looks like, but it could also be a great great deal worse.

Concluding there is a creator, simply transforms one from being an Atheist into something completely separate.

http://en.wikipedia.org/wiki/Anthropic_principle

If we share any form of resources then its going to be possible either through a timing or storage channel attack - this is simplified but here's an example of two vms communicating via the hypervisor:

http://www.idontplaydarts.com/2012/08/data-exfiltration-thro...

can it be that.. we are beings living inside another huge-living-being and working for it under some laws. like the way we have cells in our body working for us, we could be something like cells working in this huge-living-being.

can this explain the multiverse idea i.e a universe inside another universe inside another universe.. and maybe finite in number.

As for simulations within simulations. If we are in a simulation and our "program" is permitted to run long enough by it's creators we will most certainly find out :)

Very curious to see if we are all really living within Simcity or The Matrix.

Who knows? Maybe our universe was created by the lowest bidder and cut corners to improve profits.

There is a theory which states that if ever anyone discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable.

There is another theory which states that this has already happened.

(No, please, do NOT do this.)

I thought current quantum physics determined the universe had 13 dimensions? (two time version of M-theory)

In 1969, Zuse suggested the concept of a computation-based universe in his book Rechnender Raum (Calculating Space).

http://en.wikipedia.org/wiki/Konrad_Zuse

[1] http://en.wikiquote.org/wiki/J._B._S._Haldane

If I wanted to create an AI, I would probably follow a similar strategy to evolution. It would be beneficial to have many iterations occurring and interacting all at once to speed up the process. Having the AI develop it's own complexity would save incredible amounts of programming time. It would also make the intelligence unique and have a different perspective.

Create a system for replication (reproduction) that also introduces an exchange of components (genes) with other iterations of the program. Maybe add a chance for random mutations at this stage. Have a way of transferring knowledge, experience and ideas (memes, mirror neurons, sensory inputs - language will develop evolutionarily). A lot will still be learned through trial and error in each instance, especially at lower complexity levels. Look at how a baby learns. It's similar to current machine learning. Limit the amount of time that any single instance can run, and have earlier more primitive instances have a faster roll over time to work out the negative traits faster. There must be predatory characteristics (in instances as well as the environment) to enforce survival of the fittest.

Why would you want to make an AI? Maybe it's to solve problems that you can't figure out. Maybe it's to do work that you don't want to do. We could be a simulation that's solving the problems of another civilization. Maybe we just create their entertainment for them. How can we solve global warming? If we could simulate a planet just like ours and have time pass at a faster rate, we could eventually run enough iterations to find a solution. Or maybe simulations are used to do research and develop new technologies. Want to develop cold fusion? Let a machine figure it out by running simulations that generate intelligence and introduce the need for sources of efficient power generation (interplanetary travel and survival instinct for example). Solutions would be transferable since you would presumably create a copy of your own environment and rules, and the language used to reach the solution is irrelevant since it all just boils down to math. Or maybe they're just lonely? Who wants to be the only sentient being in existence.

What happens when the AI that was created figures out that the easiest way for it to solve its problems is to create an AI and have it do all the work? Visually I think it would probably be similar to a fractal. Infinite.

Evidence suggests this has happened before.

If you were running a simulation you wouldn't want to have to wait billions of years for the first life to form.

You decide.