
Do we live in a computer simulation? UW researchers say idea can be tested - ph0rque
http://www.washington.edu/news/2012/12/10/do-we-live-in-a-computer-simulation-uw-researchers-say-idea-can-be-tested/
======
electrograv
The scientific paper deals with "the hypothesis that the observed universe is
a numerical simulation performed on a cubic space-time lattice or grid".

Just because the universe may operate with computer-like regularity and grid-
like data structures does not mean "the universe is a computer simulation." At
best it means the fundamental laws of physics are "computer-like".

Whether "resembles a computer simulation" equals "is a computer simulation" is
a metaphysical/philosophical question.

Finding uncanny resemblance between our own reasoning concepts and the
universe is not new - and this uncanny mirroring between abstract mathematical
concepts and the laws of physics has been known for quite some time. It's a
mystery, not an answer. See: "The Unreasonable Effectiveness of Mathematics in
the Natural Sciences" by Eugene Wigner:

<http://www.dartmouth.edu/~matc/MathDrama/reading/Wigner.html>

~~~
caseysoftware
Also.. if we _are_ a simulation, wouldn't those running the simulation see
what we're doing and supply us with the correct results that we would expect?

They could just hardcode it..

~~~
spindritf
Maybe they're not so bright or careful? Or maybe it's all happening too fast
for them?

<http://lesswrong.com/lw/qk/that_alien_message/>

~~~
neumann_alfred
That was the most fascinating thing I barely understood a word of that I read
in a long time. Thanks!

------
ISL
ArXiv paper: <http://arxiv.org/abs/1210.1847>

This work attempts to draw out the presence of a simulation by looking for
tiny violations of known/expected symmetries, which is always worth doing. We
should note, however, that an excellent simulation could exactly cover its
tracks, lest the underlying architecture cause unintended artifacts.

From a CS perspective, the simulation's developer might create unit tests that
guarantee the preservation of symmetries.

A theorist who develops an experimental test that could prove we do _not_ live
in a simulation should be lauded. There are experimentalists (like me) just
waiting for such guidance. John Bell's theorem [1] was/is a shining guidestar
for physics.

[1] <http://en.wikipedia.org/wiki/Bells_theorem>

~~~
seanica
> A theorist who develops an experimental test that could prove we do not live
> in a simulation should be lauded.

That sounds like they would be proving a negative, which is impossible to do.

~~~
alanctgardner2
That's a pretty silly statement. Surely you can prove that 1+1!=3, which is
the negative of 1+1=3. You can also prove that pi is not a rational number,
1/2 is not an integer, etc. There's a post on the front page about attempting
to prove P!=NP.

~~~
evincarofautumn
The typical formulations of all of those proofs are by contradiction,
though—so it may be worth distinguishing “prove” from “demonstrate by proof”.

~~~
alanctgardner2
Is there a distinction between proving and demonstrating by proof? I did a
quick search (I'm hardly a mathematician), to quote Wikipedia:

> a proof must demonstrate that a statement is always true

It would seem that, if you can demonstrate a statement is true for a given
logic, that is proof. Contradiction and exhaustion (which is a bit more
controversial, I think), while less tidy than one might expect, are valid
techniques for showing that a statement is always true, and therefore are
valid ways to construct a proof.

Note: I encourage any and all maths professors to come and tell me off if I'm
way off base.

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freshhawk
This strikes me as equivalent to researchers hundreds of years ago saying
"well if our universe is a clockwork simulation then we should be able to
detect the gears turning by this method".

Certainly interesting ... I'm not sure that we could currently understand a
single principle of a system capable of simulating our universe.

~~~
azakai
Well yes, it is equivalent. And they looked more and more carefully, and never
found tiny clockwork gears, so that was not supported by the evidence.

What they did find were abstract, mechanical laws of physics.

~~~
freshhawk
A more apt analogy would have been testing for a specific number of gears with
a specific number of teeth in a specific configuration. Choosing very specific
hypotheses purely based on your ability to falsify it and no other supporting
theory or evidence seems like a low reward strategy.

I'm certainly not trying to argue against pure research in any way.

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andrewflnr
No it can't. The simulation hypothesis will never be testable. All our
assumptions about the hypothetical computers our universe runs on are based on
things as they are in this universe. We have _no basis at all_ for applying
these assumptions to the host universe. We don't know if the simulation runs
on a discrete computer, a finite computer, or whether it resembles a Turing
machine in any way. We don't know what kind of physical limits there are on
computation, or to what extent those are even recognizable concepts, and
that's just a few highlights. We have _no idea_ what it might be like up
there, or what can be done.

And don't tell me about "likely", you have no data worth mentioning, in
particular about "likely" physics or "likely" motivations of simulators.

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shmerl
This idea is way older. Various mystics already envisioned the metaphysical
structure of the world in such way (i.e. creation of reality through symbolic
transformation - computational idea similar to Markov's algorithms).

See for example Taam Eytzo by R. Pinchas Eliyahu Horowitz of Vilna (18th
century philosopher and mystic): <http://www.hebrewbooks.org/21931>

There are a few papers published on this subject:

[http://www.tandfonline.com/doi/abs/10.1080/01445340.2010.506...](http://www.tandfonline.com/doi/abs/10.1080/01445340.2010.506106)

[http://aleph.nli.org.il/F?func=find-b&request=000509568&...](http://aleph.nli.org.il/F?func=find-b&request=000509568&find_code=SYS&local_base=RMB01)

------
benjohnson
If the universe is a simulation, what's to stop the simulation from
recognizing that it's being tested and dedicating more resources to making the
test result indicate that there is no simulation going on.

~~~
dhughes
Isaac Asimov's 'The Last Question' answers that.

~~~
ComputerGuru
The Last Question is one of my most favorite short stories, and unless I'm
completely missing something, has nothing to do with simulation.

~~~
shmerl
Stanislaw Lem actually has a story precisely on this subject.

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codex
The assumptions in this paper are quite weak. It's like testing whether or not
your code is running in a virtual machine. It can be done, but only if the
virtual machine authors have made some glaring mistake.

Yes, computation is finite, but that doesn't mean that the authors of the
simulation can't use more resources than usual simulating your test of the
simulation. Not all parts of the simulation need to run at the same level of
detail.

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GotAnyMegadeth
Imagine, in the far future, you were able to to create a simulation that was
so advanced that it could accurately recreate everything that has happened in
the universe so far, so that it was an exact replica of history. Also, that
there is a way which you can determine whether you are in a simulation or not.
Assuming you are in the real universe, if you make this measurement, it will
show false, however when your simulation reaches that point in history, the
result would show up true, and reality and simulation would diverge. The only
way to stop this would be to make a more advanced simulation that could not be
detected with any method, or to have some part of your simulation check for
when this test is made, and spoof the result...

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ars
This assumes that reality is simulated using a grid, and particles are either
in that cube or that one.

But that's not the only way to run a simulation - you can make the fundamental
particles the building pieces and simulate them - they can move anywhere they
want, in any direction, they don't live in a grid.

The only thing that matters is their relationship to the particles near them.

Which follows very nicely from relativity which shows that there is no
absolute coordinate system, or absolute energy, only relative distances and
relative energy differences.

i.e. like the difference between polar coordinates and rectilinear ones.

~~~
TeMPOraL
Also the simulation doesn't really even have to involve particles. Stephen
Wolfram did some interesting writing on concept of our reality / laws of
physics emerging from simple computational systems like cellular automaton
[0]. Also Eliezer had some interesting points about how a continous
interpretation of causal networks gives rise to some concepts we recognize
from physics, like space, time and the speed of light binding them together
[1].

[0] - <http://www.wolframscience.com/nksonline/toc.html>

[1] - <http://lesswrong.com/lw/fok/causal_universes/>

------
nnq
food for though (mostly offtopic): what if most simulations are actually
_nurseries_ , run by our descendants as an alternative to mostly random
procreation?

...I imagine that in a very distant and complex hypothetical future, the only
way that super-intelligent beings could reproduce in a way that the offspring
would truly be similar enough to their parents, so that they could feel
empathy one towards another would be either by: (1) clone and mutate an
existing individual (think mind-cloning, like software copying) and mutate,
and (2) _create "children from scratch" and raise them, for at least a few
"eons" in successive simulations of their parents or ancestors pasts_ (any
other alternative, I'd imagine, in a post-singularity world evolving
incredibly fast, would result in offspring so different from their parents
that it would make empathy and the existence of a shared culture with shared
artistic and aesthetic values impossible...)

...maybe we're just "babies" in the first level of a simulated nursery,
waiting to complete the stages to "adulthood" in world of unbound, "software
like", intelligent beings :)

EDIT+: ...just realized that this could be made up into pseudo-scientific
pseudo-theory of reincarnation (which I don't believe in, but I find it
interesting) ...if any buddhist or hinduist mystic reads this and takes my
idea and does something intersting with it, please give me credit as original
author :)

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ComputerGuru
Does it matter? Think about a simulation in a game on your PC. Nothing in that
game actually exists outside the simulation. i.e. as far as anyone/anything in
the simulation is concerned, the simulation is real. You cannot leave the
simulation. You cannot end the simulation. There's nothing _unreal_ about the
simulation for anyone in it.

~~~
TeMPOraL
It does. If the simulation is buggy, we could hack it and "get out of the box"
:). See also: <http://lesswrong.com/lw/qk/that_alien_message/>

~~~
majmun
this happens when you die, universe segfaults, or it continues running in
hell, limbus or heaven. depends on where it lands. hell has 9 rings. goal is
to end up in ring 0 . heaven

------
mynameishere
Has any smart 13-year-old not come up with the notion that the world might be
a computer simulation?

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gojomo
Me layman's hunch is that we would only be able to test this if either (a) the
simulation is flawed, or (b) the simulation designer chooses to give us hints
(perhaps more subtle than 'miracles' or revelatory visions).

------
oes0
The mystery between DMT and brain chemistry is also a valid area to understand
such an idea. DMT is a naturally occurring substance that's in the human body,
animals and various plants. The mystery is that it is almost identical to
serotonin and tryptophan.

But it is not like any other drug. It's almost unfair to call it a drug. Under
its effects, reality looks radically different. You can see the math and
inherent aspects within physical reality. With your eyes closed, the
experience is even more profound.

Of course, it's likely just an artificial experience, a chemical delusion. But
it an amazingly mystical experience, that can be duplicated over and over.
It's unlike any other psychedelic and is the only scientific way I'm aware of
that induces a "real" mystical/spiritual experience.

~~~
freshhawk
You listen to too much Joe Rogan.

------
ck2
I thought the more plausible theory is we are a projection of another
dimension.

But pain and suffering seems far too real and horrible for any of this to be
fake.

~~~
alexmat
How is "fake" pain different from real pain? From my understanding, our neural
correlate of consciousness is in fact a transparent self model simulation our
brain is running, so in that sense all conscious pain experience is "fake". Or
do you mean something else?

------
firlefans
Why do smart people love to debate the most implausible nonsense? Time travel
through singularities anyone?

~~~
the_cat_kittles
While I don't know if it's actually deserving of the title "implausible
nonsense", I think its important to remember that stupid is as stupid does,
and same goes for smart. Someone isn't smart because they have the trappings
of intelligence, its because they did something smart.

~~~
firlefans
"its because they did something smart" So intelligence == 'achievement'? That
makes no sense.

As for nonsense, ok I'll retract that, it is an interesting but highly
implausible topic that gets a large amount of discussion relative to it's
likelihood. It's actually just another way of phrasing "Does God exist?" If
there was a computer (God) simulating this universe and controlling it, then
it'd require a host universe for itself to exist, and it's complexity has to
be greater than what it is simulating. Therefore it is less likely, and not by
an insignificant amount.

~~~
the_cat_kittles
I guess its true that you can't just equate intelligence with achievement. In
my own life, I think I've increasingly used achievement where I used to use
intelligence to gauge how 'smart' someone is. That comment was also trying to
get at the annoyingly pervasive belief people seem to have that you must be
smart because you are a mathematician, say. As an example, novices might think
someone is good at basketball based on how they look on the court- but you
wouldn't say someone is good unless they actually had a big positive effect on
how often their team won. In general, I guess when I say smart, I mean "good"
in some abstract sense.

------
Bogosaurus
Quantum Bogosort

<http://en.wikipedia.org/wiki/Bogosort>

------
rymith
What would be the purpose of a simulation with so much pain and suffering.
Where children get raped, flayed, abused, etc... And don't give me any of that
matrix crap, that was only to make a flawed concept make just enough sense
that you didn't fully think it through until the next bullet time scene. I'm
certainly not on the outside paying for this. I have a degenerative bone
disease that's caused me to have 6 major surgeries in 6 years. If this is a
simulation, when I get out, I'm going to kill the son of a bitch that put me
in here.

~~~
nsxwolf
Very interesting that you can replace 'simulation' with 'God' and your
statements are a perfect recitation of 'The Problem of Evil'.

<http://en.wikipedia.org/wiki/Problem_of_evil>

~~~
jlgreco
The problem with applying that (very reasonable, in my opinion) argument to
this discussion is that it invokes assumptions of benevolence, or even
planning and/or intent.

Those things are largely irrelevant to the question of simulation. There
should be no implicit assumption that a simulation must have any sort of
"deity" behind it. Nothing with intent, purpose, planning, ethics, etc. It
seems much more reasonable to me that such a simulation, if it is in fact the
case, 1) arose "naturally", whatever that may mean, and 2) does not care about
us. This universe, simulated or otherwise, does not care about humans. Why
should we assume the proposed simulation does?

~~~
gliese1337
Well, the idea that the simulators care is the basis for the standard argument
that we're probably in a simulation. After all, it's supposed to be posthumans
running simulations of their evolutionary ancestors. I don't know why they
would do that, but given that premise, why run simulations of your ancestors
if you don't care about your ancestors?

Of course, that provides another answer to the problem of pain- that this is
how it was the first time 'round, and they want the simulation to be
_accurate_.

~~~
jlgreco
Is the simulation just of us though? Or is the simulation of a much larger
portion of the observable universe? We naturally want to be important, but I
don't see any particularly compelling reason to think that we are. I don't see
any reason at all to assume that if we are in a simulation, it is being run by
anything remotely resembling us (or used to resemble us), or indeed by
anything at all.

Is that such a strange concept? The prevailing school of thought, if the
universe is not a simulation, is that there is no mastermind behind it. Seems
natural to me that we would assume the same about any universe simulator.

~~~
gliese1337
It seems to me that's kind of the defining feature of a simulation. If there's
no one behind it, if it just _exists_ entirely on its own, then it is the
natural universe, not a simulation. Even if it looks computationally-based,
that's just The Unreasonable Effectiveness of Mathematics at work.

A simulation _means_ "someone made it". They may not be masterminding details
of our lives, or our civilization, or even our solar system if they only
happen to care about something completely different from that and
incomprehensible to us, but nevertheless calling it a simulation implies that
a creator at least exists.

~~~
jlgreco
You are just pulling that concept from the traditional definition of
"simulation", but there is no particular justification for doing so.

If we detect evidence of what the author of the paper is calling a
"simulation" (that is, our universe is being simulated in a 'meta-universe'),
then we know only one thing about the meta-universe: It can simulate ours. We
don't know that it supports some sort of "life" of it's own, contains anything
with "intent", or contains anything like that at all. We do not know that
there are meta-men in the meta-universe.

Perhaps there better terminology for such implications than saying a 'meta
universe is _simulating_ our universe', but the fact that we are using that
terminology in the meantime does not mean it is reasonable to make the
assumptions about it that you are making. Just because we call our universe a
"simulation" does not mean that there must therefore be meta-men.

(Also I do not understand the point you are trying to make about it being the
"natural universe". If some sort of meta-man made a simulation that we live
in, instead of the simulation arising through non-deliberate means in the
meta-universe, is his meta-universe any less "natural"? Either way the meta-
universe is "natural"; whether meta-men exist or not)

In a nutshell what I am saying is that we should not assume intent unless
there is _evidence for intent_. Evidence for 'simulation' itself should not be
misconstrued as evidence for intent; it would be evidence for nothing but
'simulation' itself.

------
frozenport
arxiv is not a peer reviewed journal

