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Who here believes the universe is a computer simulation?

40 points by dsowers ↗ HN
Just out of curiosity, I wanted to see how many people here think the simulation theory of the universe is quite probable. If you're not familiar with it, here is a good synopsis: http://www.simulation-argument.com/simulation.html

57 comments

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mcherm
I believe that it is a moot question.

Let me explain what I mean. Some people say that Ben Franklin messed up when he named positive and negative charge -- that the charge which is on the electron should have been called "+" instead of "-". Imagine legions of physicists arguing back and forth over this issue, some vigorously defending "=" and others advocating for "-". It would all be wasted breath: they are just NAMES, and it doesn't MATTER which name you use. What matters is building a transistor, which depends on understanding that it's electrons that carry the charge, not on what the charge is called.

Similarly, any time that two MATHEMATICALLY equivalent theories both explain the facts, I personally don't care which one is true... I don't want to spend time debating it, and honestly I don't believe that one is more "true" than the other. Is classical mechanics driven by Newton's laws or by the Lagrangian "action is zero"? Both! Either one implies the other.

And this is how I view the question of whether the universe is a simulation. Finding out the laws of our universe seems interesting. Finding out whether those laws are implemented by a universe or a computer simulation of a universe... there is no meaningful difference so I don't care.

Suncho
Who here believes that computer simulations are universes?
lotharbot
One definition of "universe" is everything that exists. Another definition says a "universe" is everything that exists and is connected (so there can be several universes that don't interact with each other.)

If I create a fantasy world in my head, the people and places exist in my head; if I create a fantasy world in my computer, the people and places exist on my computer. Thus, at least in some sense, they exist. In a way, everything within the simulation makes up a universe; in another way, it's more like a sub-universe that has internal interactions as well as external interactions with the simulation hardware. From the perspective of a simulated character who doesn't know about the computer or my brain, they live in their own universe.

(P.S. are you the Suncho from the Descent world? If so, it's good to see you again.)

Suncho
Yes. One definition of "everything that exists" is "everything that exists and is connected." We can think of the universe as a directed graph and "everything that exists" as nodes that are reachable from where we're standing. From within a sub-universe, "everything that exists" is a subset of "everything that exists" for someone standing in a containing universe.

(P.S. Yes. Hi Lothar. Small world.)

diminish
I want to believe in universe is a computer simulation, because that way all because less serious. What disturbs me is that, in history, people usually tried to explain the existence by using the most sophisticated machinery available. and today it is a computer.....are we making a mistake?
Suncho
If your goal is to understand the universe around you, wanting to believe something can be a mistake. Similarly, trying to explain the cause of existence can also be a mistake. Use the simplest explanation that fits your observations. I find it helpful to start from solipsism and build from there.
alperakgun
so, the universe is a room.
Malic
Is that a Sapphire and Steel reference?
alperakgun
was not, but I now learned about Sapphire and Steel, thanks to your comment.
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MarkPNeyer
if we are in a simulation, we could possibly hack our way out of it.

i've thought for a while now that the "speed of light" limit is a result of a distributed consesnus algorithm taking a bit of time to convergd.

also, quantum mechanical noiss is leakage current flipping bits in memory.

tiptap
"On two occasions I have been asked, 'Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?' I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question."
Juha
"if we are in a simulation, we could possibly hack our way out of it."

Interesting, software engineers know there are no programs without bugs. Some weirdest things in physics like quantum entanglement may just be bugs in the simulation :)

trentlott
They act more like quick fixes used to get it running on schedule
bpowah
It is a moot question. A simulation is just a name of a thing that is a part of the universe. The current definition covers simple things like thoughts or sentences and some simulations (ex: the Bay Model) are not really distinguishable from the real world. The term simulation may be used to help us think differently about hard-to-get information or help conceptualize some impedance to information but the definition of the term would have to be generalized greatly to apply. In other words, any "discovered" universe-as-simulation (or more more to the point the discovery of the simulation's "operator") would look very unlike any conventional definition of the term "simulation" and would probably just look like "more universe".
dsowers
I don't think it's a moot question, in the sense that forcing yourself to think about some of these intangible things is a good exercise in philosophical thought. But I see your point. Probably not wise to spend too much time on a question like this.
rsanchez1
You should care. Whichever one provides deeper insight leading to greater understanding should take precedence.

The fundamental difference between knowing that electrons do the moving and knowing whether the universe is a simulation or a universe is that there haven't been testable predictions (yet) using the simulation hypothesis. That is why it is a moot question (so far).

RodgerTheGreat
This seems to fail Occam's Razor. The argument boils down to "Our observations are consistent with what we'd see if we were in a simulation, so we're probably in a simulation" modulo some specious asymptotic extrapolation. There's nothing impossible about the idea that we're living in a computer simulation, but unless the idea is falsifiable it does not constitute a rational, scientific theory.
mrj
Occam's Razor is just a guide... The simplest case is not always the explanation.
rm445
Perhaps it is falsifiable. Perhaps there is some object with a fractal property that would be enormously expensive to compute, but that nature can determine without computation. Perhaps such an object could be produced, and it could be shown that its property would be of such near-infinite complexity to rule out us running in a simulation.

Or perhaps I've just spouted some technobabble. The point is that we are at such an early stage of thinking about such things that they may yet be put on a scientific footing. And if we do find answers to age-old philosophical conundra (the universe-simulation one not being much different to older questions about what we can determine about reality) then any answers that come will come from science, not philosophy.

dexen
> and it could be shown that its property would be of such near-infinite complexity to rule out us running in a simulation.

I believe a fractal is not a viable experiment.

You hinge the experiment on assumption any simulation would be bound by memory size or time taken to compute. Practical constraints aside (matter and space is quantized at very small scale, so the depth of computation is finite), I don't believe we can just assume such limitations.

I believe memory shouldn't be a problem for a fractal, because properties of the fragment you are trying to observe can be computed directly from equations describing the fractal, never mind the scale.

As for time taken to compute, it is not observable. We don't know of any reliable timing source outside of the hypervisor[1] to compare time taken for computation to; the supposed VM is free to take as long as it needs to to advance to compute state, before advancing one http://en.wikipedia.org/wiki/Planck_time

* * *

It could be argued the http://en.wikipedia.org/wiki/N-body_problem of all the celestial bodies already puts our supposed VM to a good test ;-)

---

[1] if we knew one, it would make the experiment moot, as we would have a direct proof we're inside of a simulation ;-)

daniel-cussen
Anybody else who's played Minecraft :)

I've toyed with the idea, with the notion that the laws of physics are written such that it's easier and cheaper to simulate the universe.

But then one would have to ask, If the universe is a simulation, what is the seed number?

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Aqueous
We'll never know. If the universe is a simulation then it's similar to a virtual machine running on top of a hypervisor. The virtual machine doesn't know that it's not a real machine unless its hypervisor tells it so. From inside the virtual machine, there is no meaningful distinction to be made between being a real machine and being a virtual one.
linker3000
You've obviously never had to plug a non-mainstream USB device into a virtual machine and get USB passthru to work properly!

If we could find a cosmic equivalent to plug into the universe we might just be able to determine whether we're in a real or virtual one after all.

dexen
We could know. If we ever broke out, that'd be a definitive proof that there is a layer above our reality.

To continue your VM and hypervisor analogy, there is a class of hacks in which virtualized software breaks out of the VM and is able to observe and/or mannipulate host. For example, http://www.theregister.co.uk/2008/02/25/vmware_critical_vuln...

[edit]

Moreover, even without breaking out, it is -- in some cases, at least -- possible to detect presence of hypervisor by carefully timing computations. Albeit those methods seem to depend on access to a timing source that is reliable (i.e., outside of hypervisor's control). For example, http://www.cs.cmu.edu/~jfrankli/book_chapters/virtual_machin...

Aqueous
Haha - but I doubt that our post-human overlords have enabled the cosmic equivalent of 'Shared Folders' in our simulation. In any case this is an example of the host giving its VM enough information to determine that it is, in fact, a virtual machine.
unconed
The hypervisor analogy is silly IMO, because it assumes 'hardware assisted virtualization', i.e. that the simulated matter/instructions are implemented simply by using real matter/instructions in their normal way, but in a controlled environment.

For the general case of virtualization, breaking out of the simulation would be as impossible for us as it would be for a video game character.

xkcdfanboy
If the computer running the simulation is on a network, and robots/spaceships etc exist, we could break out onto other devices and recreate ourselves as programmed robots.
DizzyDoo
It's an interesting question, are we in a Matrix, or computer simulation, or the slightly older theory from 1641 where Rene Descartes imagined an omnipotent demon lying to him. Maybe I'm simplifying the question, but I reckon it boils down to how do we know what we know? Am I sat in front of a computer screen now, or do I just believe I am?

I'm not really a philosopher, at all, but the Oxford Companion to Philosophy says:

"Do you know that you are looking at a... book right now rather than, say, having your brain intricately stimulated by a mad scientist? The sceptic carefully describes this alternative so that no experiment can refute it. The conclusion that you really are looking at a book, however, explains the aggregate of your experiences better than the mad scientist hypothesis or any other competing views."

which I think makes sense to me. I've met one or two people who say they believe that they live in a Matrix/Alien computer simulation, but observing, they live as if they don't.

Aqueous
Kant had an interesting reply to Descartes.

He said that the "world of objects in themselves" - i.e. numinal reality, or a reality independent of our perception - must exist in order for us to have experience at all. The reason? We know that there is a reality because something must persist between each one of our "computations" - our perceptions - in order for us to be able to order our perceptions in time.

We just don't know anything about that reality besides that it exists.

To sum up: We do live in reality at some level. How many layers we are removed from the bottom-most substrate,how many simulations-within-simulations we are in, is something we might not ever know. Kant actually said we can't ever know.

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melling
Yeah, sometimes I think we're just some kid's high school experiment. God only knows. :-)

I really wouldn't put too much time into this. Votes don't matter. Even if we all agreed, it wouldn't matter.

I'd put more time into things that do matter.

c16
If so, let's hope no one hits ctrl + c.
Aqueous
Who cares? If someone hits control-C then our process is killed immediately and we were none the wiser that we ever existed. Of course, if our process has shut down hooks it would give us time to think about what's happening, which might suck.

I would rather someone 'kill -9'ed us instead of using Control-C.

Apocryphon
Like if we were turned into a zombie process?
tiptap
Why don't you want to copy and paste the universe?
Estragon
This is like asking whether god exists. Until there is some evidence one way or the other, it is pointless to consider the question seriously. Though it's worth noting that the total ignorance implied by the lack of evidence about the purpose of the universe implies that any specific speculation on the question is almost certainly incorrect.

Fun to think about, though. Have you read Greg Egan's Permutation City or Diaspora?

http://gregegan.customer.netspace.net.au/PERMUTATION/Permuta...

http://gregegan.customer.netspace.net.au/DIASPORA/DIASPORA.h...

dsowers
I haven't. They look interesting. I'll check them out.
lionhearted
It's a pretty compelling thought experiment... the largest implication would be that there potentially would be some sort of "afterlife"-esque thing possible if we are in a simulation. Either being simulated more often, or possibly "promoted" to a layer above where we're currently at.

If it was true, and you wanted to exist some more, then it might be thinking about what would be make you in-demand in the higher level up. Perhaps some generalized broadbased creative knowledge combined, combined with an interesting well-thought perspective, and good communication skills?

planetguy
It seems rather ontologically extravagant. I think they're vastly underestimating the amount of computing power it would take to seamlessly simulate a universe.

Still, there's one way to test the simulation hypothesis: build our own planet-sized universe-simulating computer and see if our own universe has a segfault.

jamespitts
A computer simulation of what? A universe?

How about this: the universe is an artificial life machine aimed at generating some interesting diversity. The intention is that the slime on planets begin performing galactic-scale engineering. Yes, we're a brilliant ant farm in God's den.

joejohnson
A while ago, this article was on HN: http://www.theatlantic.com/technology/archive/12/03/were-und...

The article is based on an interview with Nick Bostrom, a philosophy professor at Oxford. His thoughts on the computer simulation scenario are very interesting. I've reproduced them below, but I recommend reading the whole interview; it's very fascinating. From the interview:

"Can you explain the simulation argument, and how it presents a very particular existential risk?

Bostrom: The simulation argument addresses whether we are in fact living in a simulation as opposed to some basement level physical reality. It tries to show that at least one of three propositions is true, but it doesn't tell us which one. Those three are:

1) Almost all civilizations like ours go extinct before reaching technological maturity.

2) Almost all technologically mature civilizations lose interest in creating ancestor simulations: computer simulations detailed enough that the simulated minds within them would be conscious.

3) We're almost certainly living in a computer simulation.

The full argument requires sophisticated probabilistic reasoning, but the basic argument is fairly easy to grasp without resorting to mathematics. Suppose that the first proposition is false, which would mean that some significant portion of civilizations at our stage eventually reach technological maturity. Suppose that the second proposition is also false, which would mean that some significant fraction of those (technologically mature) civilizations retain an interest in using some non-negligible fraction of their resources for the purpose of creating these ancestor simulations. You can then show that it would be possible for a technologically mature civilization to create astronomical numbers of these simulations. So if this significant fraction of civilizations made it through to this stage where they decided to use their capabilities to create these ancestor simulations, then there would be many more simulations created than there are original histories, meaning that almost all observers with our types of experiences would be living in simulations. Going back to the observation selection effect, if almost all kinds of observers with our kinds of experiences are living in simulations, then we should think that we are living in a simulation, that we are one of the typical observers, rather than one of the rare, exceptional basic level reality observers.

The connection to existential risk is twofold. First, the first of those three possibilities, that almost all civilizations like ours go extinct before reaching technological maturity obviously bears directly on how much existential risk we face. If proposition 1 is true then the obvious implication is that we will succumb to an existential catastrophe before reaching technological maturity. The other relationship with existential risk has to do with proposition 3: if we are living in a computer simulation then there are certain exotic ways in which we might experience an existential catastrophe which we wouldn't fear if we are living in basement level physical reality. The simulation could be shut off, for instance. Or there might be other kinds of interventions in our simulated reality."

dsowers
Thanks for the clear breakdown.
rsanchez1
What do we have to fear if it is shut off? No one will know inside. It may be shut off and resumed many times, but the state is saved. Either way, we won't perceive it.
Ty2Runr
I dont't think so, but my avatar does.
noodly
Not me. It boils down to the meaning of universe - if you define it as everything, nothing outside it exists, as there's no outside, in particular there can't be any machine, that simulates the universe, otherwise we wouldn't call it universe. If you define universe as computable subset of everything we have access to, it might be possible to simulate that universe, using computing machine if this machine had access to enough resources outside that universe to hold its state.
Nuss
This universe is a simple computer program. Starting from the building blocks of life. Hydrogen has one proton and one electron, Helium 2, Lithium 3 and so on.. Adding one proton changes the whole element. Mixing these makes the whole universe. What we see as solid is 99% empty space. What we think we see is 1% of the visual spectrum. Soooo i wouldnt even bother thinking. We dont even exist.:)
maverickscholar
BELIEVES??? What is this? A religion?

You can suspect. (That's honest.) Then, not being intellectually lazy like "believers," you have to apply the scientific method to test your suspicions. (Note: Using philosophy and semantics is no proof at all. It's physics or nothing. You could start with the double slit photons experiment.)

toemetoch
I'd say it's not a simulation but a crappy, cheap emulation. Lack of FTL, 'nuf said.
max2grand
I'm still leaning towards you all just being a figment of my imagination. I'm not crazy, but being the only being in the universe it's understandable that I would have imaginary friends.
hoylemd
I believe it. I think that the fact that we can conceive of the concept strongly implies that it's possible, and therefore there's a pretty high probability that that's what our universe is.