# How do we tell if we're living in a virtual reality world?

Since I haven't found anything like this yet. I was reading a novel and it talked about how some people created a 'Artificial Virtual Reality World' where the denizens were Human Artificial intelligence. Which to put simply, they reproduced earth in virtual reality with all the humans who can think for their own and have their own thoughts. Now the only way those Artificial Humans found out they were living in Virtual reality was due to Real humans from Real life entering that world and actually telling them that they were living in a Virtual reality.

Now how would someone find out that they are living in a virtual reality if every condition, sense and Fauna on earth and the galaxy and the universe itself were reproduced perfectly? Which means there is literally no difference living in the real world and virtual reality. Would he/she be able to find out that they are in virtual reality?

The kind of Virtual reality I'm talking about is like the VR in this, where they wear a helmet and 'dive' into the VR.

• Your question seems self-contradictory. To perfectly fool "every sense", you need direct neural stimulation. And if you have it, why exactly helmet? Unless the helmet is neural stimulator? Could you please explain this in a way that does not require anyone to read manga to understand your setting? – Mołot Aug 3 '16 at 13:12
• You won't know until you get offered the red pull. Woah. – kingledion Aug 3 '16 at 13:14
• The only sane thing is to assume the world is real, or to assume it does not make a difference. So suppress any twinge about seeking the exit. – Bookeater Aug 3 '16 at 15:46
• I recall a scifi story where the inhabitants discovered they were in VR because they invented a form of file compression that should have worked, but didn't. They came to the conclusion that in a holographic world, there are always going to be issues with perfectly simulating compression since you can't compress something that's already subject to compression. – Richard Aug 3 '16 at 17:47
• If our simulation's creators are reading this thread then, er, hi! And thanks for all the fish. – gcampbell Aug 3 '16 at 20:29

So Descartes's Meditations on First Philosophy speaks on this.

How would you determine that a perfect deception is a perfect deception? If all of your senses are lies and constructs, perfectly flawless, how do you figure out that you are in this deception?

Simply by the very definition, the deception is perfect; so no flaw can be found, and a flaw is what you're looking for.

More to the point if this perfect deception is all you ever knew, everything you're basing your reasoning on to find a deception was learned as part of a deception, so it can't be trusted; if you were taught that '2 does not have consistent value', your conclusion would be that '2 + 2' does not have a consistent value. In other words your attempt to find flaws will be hopeless if based upon flawed assumptions.

Take the computer simulation. If the simulation depicted computers fundamentally working different than they do in the real, non-simulated world, what hope would you have of figuring out that you were in a computer simulation?

To get a better idea of this let's take a different example. Let's say that you, as in the one reading this text right now, are in a perfect deception, and have been all your life. The deception's mechanic? Specifically a magic spell.

"Well that's a silly notion, magic doesn't exist!" you think.

Doesn't it?

What makes you think that?

Are you drawing from your past experiences? If you are in a perfect deception, as we are assuming, could the deception not have lead you to believe that of course magic isn't real? In fact, wouldn't that be an ideal mental trap, to make you refute the very idea of what has you imprisoned?

Kind of a scary concept. And there's no way you can--with every scientific tool at your disposal--say that you aren't under the influence of a magic spell or a computer simulation. There's no way you can say that your whole life hasn't been a perfect deception.

But we have to live our lives assuming it not to be the case, and treat the possibility that it is the case like a simple thought experiment.

I mean we all know that magic doesn't exist, nor does the Matrix.

Because that'd be silly, right?

...Right?

• Kudos to you, this has been disturbing – Skye Aug 3 '16 at 13:54
• Just to add more potentially disturbing thoughts: If you're religious (as I am), and abstract away the names and ideas, you basically believe humanity exists in a simulation inside an unseen true "reality" with entities in that reality occasionally pulling the strings. – SethWhite Aug 3 '16 at 20:47
• +1, and for extra context, I really recommend reading that Meditation I (it starts on Page 6, no need to read the preface/introduction). It’s much more readable than most philosophy — if he’d been writing in the 20th century, one could easily imagine it being framed as a sci-fi short story. It leads up to the famous I think, therefore I am by asking: once you start wondering if you’re in a simulation, is there anything you can be certain of? — and taking your consciousness as just about the only solid spot to start from. – Peter LeFanu Lumsdaine Aug 3 '16 at 21:40
• @FlorianPeschka And you provided a link. Great! – Algo Aug 4 '16 at 11:01
• @Algo All in the service of our s̡i̸̡͟m̡u̢̧ĺ̀͢àt͞ì̛o̡ǹ͘ ov͝e̛r͏̀l̛͢o̢rd̛ş́́ – Florian Peschka Aug 4 '16 at 11:04

# We cannot know this

What you have there is a modern version of Plato's Allegory of the Cave.

So your question has had its answer for a very long time: unless the simulation is in any way flawed and/or giving out hints of its existence, we cannot figure out that we are in a simulated reality.

• Nick Bostrom is a philosopher who has done a lot with this idea in recent years. Reading up on him may help @Sky understand the nuances of the problem. – John Dallman Aug 3 '16 at 13:25
• @Sky as a slightly off topic note, the egg came first, but it came from an animal that would have been just off the criteria for the ability to be called a "Chicken". – Trotski94 Aug 3 '16 at 15:32
• @JamesTrotter - well, chicken egg perhaps. But eggs came millions, if not even billions of years (I'm too lazy too google) before the chickens :) – Davor Aug 3 '16 at 15:34
• If we are in a virtual environment, then we would need to be programmed to know we are virtual. The Sims only wave to the camera when they need something because that's how they were designed. – David Starkey Aug 3 '16 at 17:05
• @Durakken You have to use context. Descartes was writing it as something of a peace offering to the Catholic Church. He was trying to show that logic (on the absolute level he wanted to deal in) could co-exist with the church, and needed to write it so it wouldn't be branded as evil by those who might not follow his logic. He wasn't writing this in 2016, and the text itself's core argument has yet to be actually countered over the hundreds of years since. – Nex Terren Aug 3 '16 at 19:11

This is an actual scientific debate. It is called Simulation Hypothesis. Some physicists suggests us not living in a simulation is unlikely. Obviously, most plausible (in my opinion) of these theories suggests that the simulation runs at quantum level. Here is a website with links to scientific papers about the topic.

• Thanks! I actually just found the blue pill red pill thing and am now currently reading up on these – Skye Aug 3 '16 at 14:01
• Do you know what is worst, most probably simulators has no idea that there are sentient beings inside their simulation. This universe could easily be screen saver of a computer. – Cem Kalyoncu Aug 3 '16 at 17:00
• Very useful and interesting links, thank you. I had long ago come to the same conclusion, but was unaware there were papers on the subject. – Dewi Morgan Aug 3 '16 at 20:33
• @CemKalyoncu Hopefully one that saves its state when the mouse is wiggled... – wizzwizz4 Aug 4 '16 at 7:33
• I can’t believe you’re the only one even mentioning the relevant key term (simulation hypothesis) in this tread. It might help if you could flesh out your answer a bit: of course OP can just read up on the Wikipedia article but the salient features could be briefly mentioned here as well: for instance, current ideas about how to find evidence for or against this hypothesis. – Konrad Rudolph Aug 4 '16 at 11:05

If we define perfect simulation as one that appears to operate with the same rules as our universe rather than one that replicates every particle then we can have a few things that we can point to...

1. Mass causing time to slow may in fact be an indicator that we live in a simulation. Mass = Data. Time = Processing. The more data in an area the more time it takes to process that data. The data is more causally linked to each other and thus increases the amount of operations that are needed in a particular spot, ultimately slowing the simulation in that area while the rest of the simulation continues on at its normal speed.

2. A digital universe is an indicator of a simulated universe as well. If we can only resolve down to a given limit, such as planck scale, and can go no further because it is unresolvable, that there is no meaningful way to divide the scale further, then that means we are likely looking at a universe that is simulated, because a simulated universe requires that it be digital.

3. Likewise, things that happen in Quantum Mechanics would indicate a simulated universe. Those things being things like, I think it's called Quantum Tunneling. Basically any time you have an event where it makes no sense logically that the event happened. For example, it makes no sense that a particle can pass through a solid wall, or have its vector changed by nothing, but it does happen and the math completely supports it. If the universe is a simulation these things become reasonable by fact that what's happening is not that an object is doing things that make no sense, but rather an object is simply following an equation that says this should be like this without any regard to past or future, and in some cases, present, conditions.

I'm sure I could think of more, but one solid thing that seems to land us not in a simulated universe is Quantum Computing which seems to indicate infinite resources which I don't think could be used in a simulation of an universe because of the type of programming required, but I'm not sure.

Of course we could also talk about what IS a "simulated" universe when more than likely an infinitely larger amount of universes are simulated than those that are not.

• As time within the simulation can go faster or slower than real time, more processing would not need to cause a slowdown from the inside as we would be slowed down too. This effect is a consequence of the equivalence principle of gravity and acceleration. – Donald Hobson Aug 5 '16 at 20:45
• @DonaldHobson Are you saying that because you the processing time doesn't have to take place in real time, but rather an entire frame can be calculated before moving to the next, that the slow down I'm talking about is not right? That's true if we're dealing with a pre-rendered situation, but not in the situation that someone wants to interact with it in some way. This happens in games all the time for various reasons. – Durakken Aug 5 '16 at 21:06
• Quantum computers can be simulated by classical computers, so that's no obstacle to your simulated universe (and anyway, can't the simulation itself be on a quantum computer?) – Ben Millwood Aug 6 '16 at 14:19
• Moreover, I agree with Donald Hobson. You're not able to perceive time going slower if your brain is also being run more slowly. – Ben Millwood Aug 6 '16 at 14:19
• @BenMillwood: Well, you don't perceive time going slower "from the inside" when you are near a massive object either. For example, when falling into a black hole, the person falls in at normal speed and experiences spaghettification. But, from the outside, the person slows down as he nears the event horizon and eventually just freezes completely. – jbord39 Aug 9 '16 at 11:53

There is only one test that I can imagine working, and it is very dangerous and would probably not work...

Piss Off The VR's Creator!

Do something that will bring a premature end to the best parts of the simulation; making a waste of the billions of hours of programming and testing time which the creator has invested in this VR.

Launch all the nukes!

If the bombs actually do fall and explode, then we learn nothing. But if the VR program doesn't allow its own destruction... then we would know that we are created.

...at least until the creator edits our code and makes us forget about it.

• How do you know that will end the simulation? Maybe he wants to see the logical outcome of the simulation -- and global suicide is just as valid as anything else. Maybe he'd LIKE the post-apocalyptic next stage. Maybe he can't get funding for Version 2.0 as long as the first one still has a decent-sized population! – Shawn V. Wilson Aug 3 '16 at 21:51
• @ShawnV.Wilson, those are all valid points, I said that it might not work. Relying on a VR programmer's mercy is probably a bad gamble. It all depends on how badly you really want to know... – Henry Taylor Aug 4 '16 at 0:16
• Piss off the VR's creator step 1) Instate unhinged President that rhymes with Ronald Frump. Step 2) Piss off the thinly skinned newly instated President. – icc97 Aug 7 '16 at 18:49
• -1; simulation is created so that you can simulate things and see what happens. Any outcome is a good outcome if we did simulation right - therefore blowing up a whole planet, solar system, or just killing your own cat won't change anything. If you make a simulation of city, then if city grows, stays the same, or dies doesn't really matter - you want to analyse few things, you don't really care about the city. Universe is just a big city. – MatthewRock Aug 8 '16 at 11:41
• @MatthewRock, who said anything about the purpose of the VR? Not all VRs are experimental simulations. Pokeymon Go certainly isn't. For all we know, we were created as a child's game (meant to be fun) or a work of art (meant to be beautiful). All I'm saying is that if we stop being what we are meant to be, the creator might get made enough to show itself. – Henry Taylor Aug 8 '16 at 12:54

Statistically speaking, it seems improbable that we are not.

Consider that at some point there will be one reality; and N simulations, where N is likely to be large.

Consider that in each simulated reality, if reality is correctly simulated, there will be people who want to create simulations. So there will be, in a perfect simulation, N^2 simulations. And each of those will contain simulations, all the way down to the limit of the outermost resolution. So N^M where M is the limit of the number of levels before the resolution is too low for sum-simulations to be viable.

So our odds of being in the original simulation are 1 to N^M. Logic suggests that N^M will be really, really big, so our chances of being in the original are approximately zero.

Question is: what difference should this make to how you live your life? I can see no apparent reason for it to make any difference whatever, though it does suggest that there may be bugs that could be internally exploited.

Biggest argument against all this is the absence of apparent bugs: a system so complex should have a LOT more bugs.

Possibly they are shown by some stuff in https://en.wikipedia.org/wiki/List_of_unsolved_problems_in_physics and arguably everything we dismiss as superstitious nonsense, any of which could be true in a simulation.

• Do we have evidence that one perfect simulation is possible? Seems like the statistics requires the assumption that perfect simulation is possible and in progress. On the off chance it requires any nonzero amount of computational power, which would exponentiate as reality "nests", "logic suggests" collapses quickly. This is all under question in philosophy, I agree, I just think the word "improbable" is being thrown around way too imprecisely for the subject in question. – djechlin Aug 3 '16 at 19:53
• You are advocating here for the Third Choice of Bostrom's Trilemma. Your conclusions are based on the assumption that it is possible to reach the level of technological advancement needed to create an "ancestor simulation." – Lumberjack Aug 3 '16 at 20:40
• There's no reason to believe Moore's "law" will hold that long. It seemed to me like perfection was necessary to reach your telescoping effect. To use a crude mathematical illustration... a 99% perfect representation will be < 1% perfect 500 levels deep. That's, of course, assuming a 99% perfect representation can emulate itself with 99% perfection. – djechlin Aug 3 '16 at 20:52
• "We're close to the level of processing required to simulate one human brain." Until that actually happens, it is only a theory. Even Bostrom acknowledges that brain simulation is only a theory and a possibility. youtu.be/nnl6nY8YKHs?t=11m51s – Lumberjack Aug 3 '16 at 20:58
• My physicist friend ripped into that article, throwing at me a lot of powerful, specific evidence to support the brain-as-computer viewpoint. But the article was a very strong argument to me that in both the public and scientific psyches we take this theory for granted, as if brains are obviously computers, forgetting that science is supposed to work the exact opposite way in establishing a theory. I'm glad you appreciated it though. – djechlin Aug 4 '16 at 14:57

There are 3 kinds of VR I could think of:

### Matrix VR

Your body is held inside some tank, and all nerve endings that leave your brain are wired to some control device. I.e., you have a physical body, but all input/output is overriden. Everything entering/leaving your brain is simulated, no part of the real world is allowed through. It could be raining Donuts for what it's worth. They only control your sensory input though, not your thoughts.

Exactly like in the Matrix movie.

### "Real virtual" VR

You have no physical body, but exist purely in the form of information inside some computer. Similar to our "AI" experiments we do since the 70's, just advanced enough that your simulation can be called "intelligent" or even "self aware" (by whatever metric).

Nothing of the real world can pass through except if your creators actively decide to do so (like in the movie Ex Macchina, where the A.I. has eyes/cameras etc. and is specifically built to cooperate with the real world). So as we are talking about a virtual reality here, they would not do that, but simulate the surrounding world as well; in that movie the A.I. really is on the opposite spectrum (completely aware that it is virtual, just trying to blend in as much as possible).

This is conceptionally existing today, for example World of Warcraft simulates a world and beings (NPCs, monsters) inside that world. Scale that up a few million times until those NPCs/monsters can develop self consciousness, and you're there.

### Oculus Rift VR

This seems to be what you are alluding to by your reference to that Manga. You are just a normal person; a fixed VR device is enclosing your head. In the far spectrum, it not only does eyes and ears, but also taste, smell, feel. Not only the head, but all other body parts as well. Your VR suit is so perfectly adjusted that you would never get the idea that it is there.

### Can you find out?

• In the Matrix: depends on the software of your captors. If they manage to not introduce any kinds of artefacts which are inconsistent with the physics of their virtual universe, then you're pretty much out of luck. I.e., no "Deja Vu", no Agent Smith, no remnants of the old human race who actively unplug you.

• "Real virtual": you have no way of finding out, ever. Your every thought process, every blip in your brain is simulated. Creators that can do that are certainly able to squelch even the tiniest pre-thought of any thought about being in a VR. Heck, they could make you believe that you are in a Matrix VR (including "waking up" from it) while you're still firmly in their VR (of course - where else would you, as the state of a software program, be).

• Oculus Rift: depends on how good the device is. Can it simulate stuff entering your body? It's not too far fetched; as it gives you "real" tactile feedback for virtual food, you can feel like you are stuffing things in your mouth (with some virtual mouth implant which stimulates your nerve endings there etc.). Can it reconcile your internal bodily processes with the VR (i.e., having to empty your bowels etc.). It's really the same as the Matrix, only keeping your bodily senses up instead of "plugging you in", but probably much much harder to implement right. It totally breaks down if you need to simulate body damage (getting a limb torn off...).

• There's also the "holodeck" style VR, which would seem to fall a little bit further out from the Oculus Rift VR. – Michael Aug 3 '16 at 17:31
• Yeah, thanks for pointing that one out. – AnoE Aug 3 '16 at 18:42
• Universe simulation, where consciousness happened just as a side effect of the simulated physics laws. Then various levels from full-population simulation, where every person is simulated, along with a believable environment (though likely to apply simplifications to those areas not currently being experienced) to individual simulation, where only one person is simulated, and the level of accuracy needs only to be really low because you can fake in acceptance of any innaccuracies. – Dewi Morgan Aug 3 '16 at 21:59
• Would it actually break down if you had to simulate body damage in the way you describe? Perhaps you just explained what a 'phantom limb' is. – Shadow Aug 8 '16 at 6:39

While I have to agree with the other answers in saying that, theoretically, "we cannot know", I still think it's a tautology to say that "there's no way of knowing if the simulation doesn't let us know."

The question is rather if the simulation is actually "perfect", or if it fails to foresee some clever/random move of a subject and thus makes some glitch visible. Think about the dejà vu scene in The Matrix. That is the kind of small glitch that does not fit the closed model simulated everywhere else in the VR and can make people try to investigate and exploit.

In our world, think about quantum mechanics for instance. Those are so much not like Old Newton's physics which we're so much used to that you may start to wonder if we're just getting a view behind the curtain, glimpsing on the mystical machinery that actually drives our perceived, superficial reality.

Now, what if some entity set up that quantum machinery to 'fake' a reality for simple beings. What if it did set it up aeons ago? What if it did not foresee that some day, aeons later, subjects in the simulation would actually gain the insight we have today? - Who would have thought that was possible even a hundred years ago?

• This is simply adding another layer to the existing concept of Religion. You are speculating on the motivations and machinations of "God." – Lumberjack Aug 4 '16 at 15:57
• Trump as President is a clear glitch. – SK19 Mar 8 '18 at 22:05

To the virtual human the virtual reality - whether perfect or not - is an actual reality as outside it the virtual human does not exist.

If we were in such a simulation, would that not also explain god? Think about it.

The whole idea of it. A 'being' of all-powerful...ness. He created everything, the planets, the sun, everything. who's to say that the 'big bang' isn't actually the fist launch of the program, the program that is procedurally generated. Jesus, the 'special' person, was some kind of 'real human' revered as special. the last few thousand years of our life have been a big buildup to the 'apocalypse' event.

It's not much, but hey... it'd be pretty cool, no?

Though in truth, if the world is perfect, with no way for us to tell that we are simply AI, the only way we could ever figure it out is with third party intervention. that being a 'real human' Otherwise, the answer is, no. there is no way to tell.

• Hail the main processor! Hail the Video Card! In nomine dei nostri sanctus programmers et developers excelsi. – user23754 Aug 4 '16 at 7:26
• "pretty cool"? sounds like pseudoscience nonsense. Throw some other mythologies into the mess while you are at it. – Donald Hobson Aug 5 '16 at 20:58

We can build simple simulated universes. None powerful enough to include an intelligence, but we can build simple ones.

In those simple universes, we can build simulations of other simple universes.

For a concrete example, we have built computers, in in those computers we have built minecraft, and inside minecraft we have built a computer capable of running programs.

Now, in our universe, complexity (information processing) has a cost. As does it in universes we create.

It seems reasonable that we could come up with theoretical limits on the ratio between the complexity of the simulating universe and the simulated one.

We can then determine if our universe is complex enough to host a sufficiently complex universe that could itself host a simulated universe, both of which contain intelligences. I will call this "not at the end of the chain".

If we are "at the end of the chain", and our universe is insufficiently "rich" to simulate a universe containing intelligence that itself could then host a universe containing intelligence, that is evidence we are not simulated.

If we are not "at the end of the chain", then that is evidence we are simulated.

This is because the very existence of that chain implies where we are on that chain is a matter of "luck" -- we could very well be on rungs even lower.

However, the intelligence at the very bottom of the chain, which doesn't have further links under it, is an unlikely intelligence to be in the event there is such a chain. It is less plausible that we are in that special location, than if we are just another link, basically.

On the other hand, I could see the argument that when simulating a universe containing intelligence, the interesting part is that universe not the universes it simulates. So making universes that are just barely able to support intelligence in your simulation might be optimal from a simulators perspective.

The ratio still seems interesting towards this question. If simulated universes can be almost as rich as the one simulating them (ie, the overhead of simulation is cheap), it pushes forward a seeming certainty that we are a simulated universe. If the overhead is large, that leaves a huge conceptual space where an intelligence could exist, but no simulation could.

Yes you could tell if you're in a simulated world assuming you had the computational power to do so. I'll explain..

First let's start by saying it is almost certain that we live in a simulated virtual reality. Statistically speaking the odds of us living in Prime Reality is zero. The reason we can safely conclude this is by looking at our own reality and answering one question, given the current progress of technological advancement do you believe that someday we will have the computational power to simulate reality? If the answer if yes then you've accepted that you're a simulation! How? Because if we accept that we will someday simulate reality we also accept that technology will continue to advance past that point.

While at first it might take a super computer in a university to handle that level of computation we know that it is just a matter of time until those same expensive computations become cheep enough that your home gaming console can handle them, and then a few years later your phones will handle those same computations. (Don't forget your cell phone now has more computational power then NASA used to send a man to the moon!).

So therefor it's just a matter of time before people are simulating realities on their cell phones as a game while their pooping, and if just a few million people play the game that means they just created a few million simulated realities, and each of those realities has the potential to simulate it's own realities and in turn each of those simulated realities can simulate millions of more, and so on and so forth. As you hopefully noticed this is an exponential curve, where the more time that passes the more simulated universes that are created until the number borders on infinite. This all means that the statistical odds of you being in Prime Reality are 1 in infinity, or zero (Sorry!).

Now to your question, we could tell that we're in a simulated universe by exploiting the nature of computers and the fact that they have limited computational memory. So in theory if a simulated universe were to create enough of it's own simulations then eventually it would overfill the memory on the system running the original simulation causing it to either crash or start dumping memory(deleting things). Although I don't know if destroying reality by crashing the simulation we exist in would really be worth it, but hey at least you'd know!

• i don't think your arguments follow logically. for example, men have run quicker and quicker 100m times. The world record has come down from 13s (approx) to 9.5 seconds. Therefore one day it will be 1s. This is not true. Similarly there is no reason why we might be able to simulate reality perfectly and populate this simulated reality with an AI that believes it's simulated world is real. – Steve Ives Aug 24 '16 at 10:51
• I don't think you're familiar with Moore's law. Let me educate you, Moore's law is the observation that the number of transistors in a dense integrated circuit doubles approximately every two years. (en.wikipedia.org/wiki/Moore%27s_law). Now if you understand math you realize that is a exponential curve. The speed that a humans body can run isn't exponential or expected to increase dramatically so this is a horrible comparison you've made. Next the question is based on the premise that you accept the simulation is possible, you can't just say the simulation isn't possible as a counter. – efarley Sep 9 '16 at 19:09
• Thanks for taking the time to educate me - very kind of you. There's no guarantee that Moore's law is sustainable, even though it's held true for 50 years. You've also assumed that simulating reality is just a matter of having enough processing power available, and that is not true. You answer to the question doesn't follow logically either - let me educate you : if it's ever possible to simulate reality to the extent required, out of memory errors won't be an issue, so we're not going to find out that way. – Steve Ives Sep 9 '16 at 20:47

pixelation

basically, any simulation has a max resolution. at some point, you stop drawing discrete pixels, and just calculate the average effect of everything below that resolution as a continuous field of forces and probabilities. for example, if you wanted to simulate the solar system without calculating the position and velocity of every electron, then you would simply use an equation to compute the average position and velocity the planets and other large bodies. the pixelation limit of that simulation would be at the planet level and you couldn't break apart a planet to look at how it's internal components interact. if you want to "zoom in" on part of the earth and see animals running around, you need to increase your computing power substantially. the pixel limit of our universe appears to be sub-atomic particles (e.g. electrons), indicating that we live in a simulation that pixelates at around the size of an electron. you simply can not assign a location and velocity to an electron in any meaningful way because it is smaller than a "pixel" in the simulator that runs our universe.

• I generally argue for a pixel size of the planck distance. But I guess you can argue even for an atomic or molecular sized voxel-based OS. Sure, voxels are drawn using pixels, but the engine basically uses voxels to show space. Below a certain level, you're seeing the substrate, not the image. – Dewi Morgan Aug 3 '16 at 22:02
• technically, pixels and voxels are both over-simplifications since the most granular data structure would need to encode other attributes (e.g. velocity and spin) in addition to physical location. nonetheless, "pixel" seems to convey the basic idea to any layman who has seen pixelation of an image while zooming in. – james turner Aug 3 '16 at 22:48

I cannot expose a lot of examples now and here but just one. A clue we are living in a virtual reality is the limited speed of light. The speed of light limits how fast we can transfer information, and it is limited. If you deal with computers and electronics you know a simulation cannot ever be as fast as the simulator it runs in. Limiting the speed of electromagnetic radiation (light) in the simulation could be necessary to prevent the simulation to crash/blue-screen-of-death/colide-with-itself/hang-up and so on.

If some day it is confirmed remember you read it here first :).

• That's an interesting argument. – Zenadix Aug 5 '16 at 15:12
• If you're inside the simulation, the "computing speed" of the simulation doesn't impact you. Imagine you're a character of an animated film. It doesn't matter the time the cartoonist took to draw the next frame in the "higher reality" (could be 1 minutes or 3 years in his time), for you, each frame pass at the same speed : a frame per frame ;) – Tryss Aug 6 '16 at 3:20

If it's a truly perfect simulation, then it's impossible to know for sure. You can have suspicions and even evidence, that reality is a simulation, but that doesn't make it proof.

For example, as others have pointed out in this thread, reality has a maximum resolution: the planck length. Quantum tunneling seems to show that reality is "Error prone." Space is mostly empty, meaning it'd be easy to compress to save storage space. The laws of physics are easily expressed using mathematics. You could keep listing reasons like this for quite some time.

But does all of that mean 'reality' is a simulation? No, it doesn't. It might be, but it might also be that Reality is just weird. Quantum mechanics is bizarre and counter-intuitive, but our brains evolved to throw stone spears and avoid being eaten by hungry predators, and not to comprehend the fundamental structure of the universe. We're just not fit to decide one way or the other.

Maybe that's why the idea of a simulated reality is so fascinating. To paraphrase one of my professors, it's the questions you can't answer that are the most interesting.

As an aside, here's a scary thought: Who says the simulation has to be perfect? The argument is, you would be able to tell you are in a simulation if you spotted the 'glitches'. But that presupposes that you already know what the REAL 'reality' is like, for comparison purposes! Anyone who actually originates in a simulation would of necessity treat everything observed - 'glitches' and all - as natural phenomena, and if repeatable would build those phenomena into their 'laws of physics' [and if not repeatable, either ignore them or end up being thought nuts :-) ].

Now how would someone find out that they are living in a virtual reality if every condition, sense and Fauna on earth and the galaxy and the universe itself were reproduced perfectly?

The kind of Virtual reality I'm talking about is like the VR in this, where they wear a helmet and 'dive' into the VR.

To find out means that one can tell the difference between reality and virtuality. Perfect VR means that there is no such difference.

On the other hand, the VR would probably not be perfect due to the programmers' universal tendence to cut corners and optimize performances. So, for example, some details might have perfect internal consistency but have no temporal consistency. Think of a granite slab with all those white and black flecks, or the surface of a sheet of rough paper seen through a magnifying glass: when it is "not in view", keeping in memory its exact texture would be an awful waste of resources.

So chances are that such a VR would be reasonably implemented by storing a small piece of information ("This is a sheet of paper of roughness 15"). Observe such a detail-rich object and memorize some details. Observe it at a later time. The VR you describe has no way of inspecting the simulant's neural state, so it cannot access or modify his memories nor even know what he noticed. It might have an "anti-tamper" mode that marks anything observed too keenly or too long for exact memory storage to foil this kind of scheme, which brings us to distinguish between "passive" VRs (they're just very good at simulating reality) and "active" VRs (they detect and thwart attempts to uncover their virtuality).

But otherwise, chances are that two observations of the same high-entropy object would result in two different images being generated and supplied to the user, making him aware of what is happening.

Another possibility ("Realtime Interrupt" by James P. Hogan, and a subplot in Peter F. Hamilton's "Fallen Dragon") is that the VR is unable to completely simulate some sensorial input such as smell, or taste.

Much would also depend on when the VR did start (from birth? From some moment?) and what information is available to the VR's designers. For example I could accidentally splash my hand with cheap red wine. The VR would show me my own skin drenched in reddish liquid, each droplet perfectly simulated. Little would it know that I would also be expecting to see welts appear almost immediately in response to an allergic reaction.

• many current games use procedural textures, a formula that gives a random like appearance but gives the same one every time. No memory needed, details can be calculated when looked at, and recalculated to the same value later. – Donald Hobson Aug 5 '16 at 21:07

In order to create a virtual world identical to the real world, the real world has to donate enough energy to the copying process, the virtual world, and then to destruction of evidence of the process in both. This evidence is what virtual conspiracy theorists will be looking for. The original world will be completely changed by this, however.

If the virtual world is a simulation and not a copy of the real world, then understanding and debugging requirements would make it inherently less complex than the real world.

If it's anything like our 'reality' why assume it's perfect.

Ours 'appears' to have various issues: things that don't quite make sense, or lead to the right answers when we follow the mathematics, physics that requires kludges to work...

Maybe we are in a simulation, and it isn't perfect.

But how would we know? We just assume our modelling is incorrect - but maybe it is correct, it's just that the reality is flawed.

DATUM SCIENCE: THE MISSING SCIENCE

We are living in a virtual world that is of course more complex than those we can create as of now. Our virtual world contains datum. And a datum is framed around POINTS: Position, Object, Interaction, Noise, Time, within object Space. Using this framework, we can capture a single datum or object or spec of things (depends on how you want to use the phrase)

Using the POINT framework, we may also create our own virtual reality. Objects are always interacting with one another through distance. The effect of the interaction depends on the distance. However, objects are bound to connect with one anther no matter the distance unless they find bound with a closer object. Then it creates form objects. You can even see the POINTS framework on Macro formed objects such as human beings and planets.

Think about it. Everything is formed within Position, Object, Interaction, Noise, Time, and Space as an object.

This is actually going to be my doctoral thesis. Read about it in a few years.

Boo, you can totally tell. It's simple. Others argue that you need all these simulations and fancy math equations and whatnot, but do you really? If you all had computers like you say (and like we [humans as a group] do), then you'd easily be able to tell if it was fake or real. We all know that the people on the Internet aren't real - not real in the sense that you can't touch them. How do we know this? Well, first of all, most people probably never tried to hug or kiss a YouTuber out of the deception that they were real. They just believed it.* But believing is seeing, right? And so is the reverse (of the previous statement). Whether one or the other is better is yet to be decided.

*They believed they weren't, as most people don't. Unless you had some sort of mental illness or impairment that made you believe so.

What's wrong here is you're presupposing that we are in a virtual reality. What if we're not? You've got to start from there. You've got to say, "This is real, and this is real, and this is how I know they are." If you can't back up your statement, then you know it's false; but if you have a burden of proof of some kind, then by default of logic, it is real and indisputably so.

I think the question you're missing is: What is real? (As in, what defines it?) And what isn't?