
Are We Living in a Computer Simulation? - uptown
http://www.scientificamerican.com/article/are-we-living-in-a-computer-simulation/
======
danbruc
I am definitely in the this idea is nuts camp. It's the equivalent of a couple
of cell in Conway's game of life trying to figure out what computer
architecture the program is running on, who build the computer and what our
universe looks like. Arguments like simulating ancestors and whatnot
implicitly assume that the computer owners are in some sense similar to us
which seems totally unjustified, we have certainly simulate way more things
that are different from us than similar to us. What justification do we have
that concepts like space and time and simulating something and ancestors even
make sense in the outer universe?

Or mathematics. Mathematics is of course good at describing our universe, we
created it for that. Well, that is probably a bit too simplistic but anyway.
And what would you expect the outer universe to be like? A structureless
random mess without rules that could be described by mathematics? How would
you make a simulation in such an environment? If you have some time to kill or
want to write a science fiction novel, go ahead, think about it, but there are
certainly more relevant problems to our existence than pondering whether we
are one or a billion levels deep in a stack of simulations.

~~~
TheOtherHobbes
All of which is true. But I think there's a more subtle problem: if you could
simulate evolving creatures in a universe, how could you tell if they were
truly sentient?

Being sentient as an experience is completely different to appearing to show
sentient behaviour. You can make a model of sentience that's as complicated as
you can invent, and you'll still have no idea whether or not a modelled
sentience is having a sentient experience of the universe around it, or
whether it's faking its responses mechanically.

The corollary is that having a model isn't enough to simulate a universe, You
also need some way of knowing when sentience has been achieved.

Nothing in our current technology is anywhere close to even beginning to
understand how to do that.

~~~
visarga
> if you could simulate evolving creatures in a universe, how could you tell
> if they were truly sentient?

I think that AlphaGo is sentient in the domain of Go play. In other words, AG
was conscious in that space of table positions and game strategies. A number
of Go experts were so impressed that they said they could hardly tell which is
the human and which is the computer. They gained so much respect for it that
they awarded it the highest dan rating. I'd award it a Turing Test pass, at
least on Go play.

To answer your question, I'd take the same approach as Turing: if it behaves
like a human or better, then it is conscious in that particular domain. The
difference from common machine learning applications was reinforcement
learning - the fact that it was embedded in an external world, interacted with
it and the opposing player and learned from experience - it behaves
essentially like us, in a loop of perception-decision-action. And we are like
it, if you look down the stack, we too are just a pattern of chemical
reactions and electric currents that have no innate subjective feeling to
them. There is no "unobtainium" or "magic fairy consciousness dust" in our
brains either, and we shouldn't try to essentialize consciousness, it is not a
pure essence like space and energy, it's an emergent quality.

~~~
smaddox
Great post. I just wanted to add that space and energy could very much be
emergent phenomenon, as well. Take for example Wolfram's conjecture that the
universe might be modeled as a causal network [1], in which our 4D spacetime
emerges from the connections between nodes, and energy/particles emerge from
the complicated dances of knots in the network. It might sound pretty far
fetched, but it seems to me at least as reasonable as the universe being
modeled by a small set of equations.

[1] [http://blog.stephenwolfram.com/2015/12/what-is-spacetime-
rea...](http://blog.stephenwolfram.com/2015/12/what-is-spacetime-really/)

------
nickcano
I love contemplating this idea, but really hate when people write about it.
They always talk about "The Matrix" or being "Video Game Characters", which
really muddies the water. Of course a lot of people will reject the idea when
presented like this. The Matrix, for one, is real humans in a real universe
being plugged into the simulation of the real universe, which seems absurd.
The idea of being inside a video game detracts from people's inherent feeling
of free will and self awareness, because it seems to imply they are either a
pre-programmed NPC or a character being controlled by some consciousness
outside of the simulation. I feel like this flawed first impression makes them
less likely to entertain the idea.

At least the way I think about it, these analogies are neither accurate to the
theory nor necessary to explain it to the layman. Let's look at it
academically. If our technology had the capacity to completely simulate any
sort of universe, you can bet a least one research team would do just that.
Well, if you, like me and many others, think of the intelligent mind simply as
a very powerful and self-aware computer capable of learning and abstract
thought, and if the so-called universe simulated by researchers has a model of
matter capable of creating the logical gates needed to replicate such a
computer, and the simulated universe contains natural processes by which these
logical gates might evolve, then you must agree that it is possible
intelligent life may emerge in such a simulated universe -- no matter how
different, similar, big, or small it is in comparison to our own. Then,
following the same reasoning, you must also agree that there is the slightest
possibility that the nested universe may produce one or multiple collections
of intelligence capable of the same thing.

In this thought experiment, the simulation isn't imprisonment, doesn't violate
a sense of self-awareness or free will, and doesn't even rule out the concept
of a god or ultimate creator. It simply abstracts the container in which our
universe lives from something mysterious to something relatively relatable to
our current technology.

Another interesting thought is if we ever become capable of simulating such a
universe, it seems much more likely than not we're also a simulation, since
there's a possibility for each simulation to produce it's own simulation or
collection of simulations.

~~~
breuleux
> Another interesting thought is if we ever become capable of simulating such
> a universe, it seems much more likely than not we're also a simulation,
> since there's a possibility for each simulation to produce it's own
> simulation or collection of simulations.

There's a lot of "ifs", though, for the argument to work:

The simulations must support a higher density of life than the universe does.
If you need a planet the size of Jupiter and a hundred years to simulate one
second of life on Earth, then each nested layer of simulation is going to make
the number of simulated humans _smaller_. It seems highly dubious to me that
simulations could be dense enough: if you can build a simulator capable of
evolving a million life forms, couldn't you slash all the overhead of
environmental simulation and use these same resources to build _ten_ million
life forms that interface with the real world directly (imagine nano-life, if
that helps)?

There must be sound economic reasons to build these simulations. Otherwise,
too few of them will exist, and they will not be run for long enough. I can
think of a few reasons, like research or entertainment, but I do not think
they would suffice. Specialized, focused simulations are useful. Simulating
whole universes is overkill. It's a waste of resources.

~~~
simdude
There is no reason to assume that the same physical rules and limitations of
our own universe apply to the universe that is simulating us. Our universe
could be a drastic simplification of the "real" one, indeed this
simplification is the kind of potential evidence the article mentions us
looking for.

I remember reading once that the limitation on speed of light could be a
performance optimisation. Isolating each "light cone" of local spacetime
allows the simulation to be distributed and run on separate compute clusters,
because it limits things to local interactions rather than universal ones.

Things in superpositions only becoming "set" after observation... that is just
lazy evaluation. It's fun to think about.

~~~
nickcano
>I remember reading once that the limitation on speed of light could be a
performance optimisation.

>Things in superpositions only becoming "set" after observation... that is
just lazy evaluation.

I've always thought about it this way also, I'd love to get a source on where
you read it so I can see a different take than my own.

Some other things to consider:

1\. Planck length is the most granular unit or pixel the computer can measure.

2\. The time it takes to move one Planck length at the speed of light is the
time of one iteration of the simulation's "main loop".

3\. The reason time dilates as you approach the speed of light is because the
faster a particle moves, the more the main loop must access that particle, and
the more the particle's state may be in a "being processed" lock where it
can't be mutated by anything else.

Just some thing I've always thought about when trying to see if I could use
code patterns and processes to quantify the behavior of the universe. Of
course, I wouldn't say I believe these things as fact or anything, just
awesome to think about.

~~~
breuleux
> The reason time dilates as you approach the speed of light is because the
> faster a particle moves, the more the main loop must access that particle,
> and the more the particle's state may be in a "being processed" lock where
> it can't be mutated by anything else.

There's a simpler reason, I think. Any mechanism or "clock" must have moving
parts of sorts (atoms, exchange particles like photons, etc.) which means that
when functioning or "ticking", some parts move faster than some other parts.
But if the mechanism is moving at the maximum speed, it can only be the case
that some parts move at c, and others move slower, but these slower parts can
never catch up, so the clock disintegrates. It can only remain whole if all
parts move at maximum speed, which means it is static: it is frozen in time.

I imagine that given a speed distribution for all components of the mechanism,
there would be a smooth time dilation effect as the speed of the whole
mechanism increases. I'd have to calculate. In any case, I think time dilation
is basically _necessary_ in a system with a maximum speed. I'd expect to see
something similar in cellular automata, regarding complex objects that can
move at various speeds.

------
esmi
Doesn't look like they added anything to the debate to me. But given that it
has been going on 2500+ years I suppose that is not surprising. :)

[https://en.wikipedia.org/wiki/Allegory_of_the_Cave](https://en.wikipedia.org/wiki/Allegory_of_the_Cave)

See also,
[https://en.wikipedia.org/wiki/Brain_in_a_vat](https://en.wikipedia.org/wiki/Brain_in_a_vat)

~~~
maxander
There's certainly been something changed, if not added- the idea is slowly
getting more pessimistic. Plato thought we could get out of the "cave" simply
through sustained rational thought. Brains-in-vats thinkers at least said we
were still true beings in the "real" world, even if deluded ones. But
simulationists think we're _entirely_ beings of the "lower realm."

------
allisthemoist
> “You’re not going to get proof that we’re not in a simulation, because any
> evidence that we get could be simulated,” Chalmers said.

This is where the argument starts to sound like creationist claims that god
put the bones of dinosaurs on Earth just to test our faith.

~~~
valine
As someone with a conservative upbringing, I can't say I've heard that
argument. In my experience the most common explanation is that the dinosaurs
died in Noah's flood along with the rest of the animals. The dinosaurs that
survived on the ark were unable to adapt to the new environment and went
extinct shortly after. While I don't doubt the "God put dinosaur bones here to
test our faith" argument has been used by Christians, I can't imagine it's
very prevalent.

~~~
brianbarker
I heard it as a mormon growing up.

~~~
grahamburger
I don't think I ever heard this growing up as a Mormon, at least not as
something considered as a serious belief. My Aunt quipped once how silly it
was that my Granpda (also a Mormon) believed that 'the Jews planted dinosaur
bones to discredit Christianity' \- he's dead now and I don't know if he
actually believed that, but it's possible that he did.

My experience growing up as a Mormon is that questions of how exactly God
created the world are mostly left up to science. I haven't seen any hints of
evolutionary science being considered 'taboo' with any seriousness in quite a
long time.

------
bcherny
It would have been interesting to hear Wolfram's take on the debate. The
debate revolved around "why would future intelligent beings want to simulate
lesser intelligent beings from the past?". But the broader picture is that
given enough time, "intelligence", which really means "computation", is an
emergent phenomena of the universe at large. Given enough time, the universe
will simulate itself.

We perform computations in the same sense that complex weather patterns do -
there's nothing intrinsically special about our ability to compute. So it's
naive to think that we're the ones being simulated - the _universe_ may be
simulated, and we are but one emergent property of that universe.

~~~
breuleux
A universe can't really "simulate itself". There is inherent overhead to
simulation, so a _perfect_ simulation of a physical system would have to be
larger and slower than the system it's simulating.

Any simulation worth running would be an approximation of the real thing, with
many corners cut. Because of butterfly effects, any approximative simulation
will diverge from the original, and the more corners you cut, the faster that
will happen (so ancestor simulations would require near perfect accuracy, so
they would probably be prohibitively expensive).

If we are a simulation, our parent universe would be several orders of
magnitude more complex than this one. It's not clear to me why such a
simulation would be made (what purpose it would serve to the parent universe).

~~~
robotresearcher
That's not necessarily true in discrete systems. For example we can cache
results of common interactions for reuse. See HashLife and relatives, for
example: a vastly more efficient way to compute game of Life without
considering one cell at a time, but giving identical results.

~~~
breuleux
I'm aware, but I think the efficiency of these methods is rather
circumstantial: they work well because of the way our computers are organized.
What you are comparing are two simulation methods, with are _both_ very far
removed from what they simulate.

Instead, imagine implementing HashLife _inside_ a Game of Life universe. It is
possible, because the system is Turing complete, but the overhead would be
horrific: probably thousands of cells for each cell you try to simulate. You
would have to duplicate the cache all over the place to minimize roundtrip
costs, each cell would be a whole machinery to allow signals to be routed
there, plus logic to handle synchronization issues between each "unit", and so
on.

It's a very neat idea that works very well with our computer systems, but if
you were to implement it using the resources of the simulated system, it would
be a catastrophe. And similarly, I don't think you could build a physical
"cache" that can simulate physical interactions faster than they happen,
except in a few contrived cases.

------
maxander
> “What happens,” Tyson said, “if there’s a bug that crashes the entire
> program?”

What if there's a bug in the simulation, and the whole computer goes up in
flames- but then the experimenter restores from a backup, fixes the bug, and
re-runs the simulation with the same random seed. Things proceed again exactly
as before, and pass the bug-triggering point without incident. Do we notice
anything happened?

~~~
vaibhavkul
Who (and where) is this experimenter? What if he (and his world) is also
simulated?

What _is_ real?

~~~
User2048
>Who is this experimenter?

The Creator.

>Where is this experimenter?

Right here. Right now. Everywhere. All time. No time. Outside this Universe.
Inside this Universe. We are inside of him. The universe is just a small part
of him. He has no definable form. This Universe, and all these things that
exist in the present moment, are part of his form. All things that have
existed, and all things that will exist, that's just a small part of his form.
Even things that don't exist are another small part of his form. Time is a
restriction that he puts on this universe. Time is just another part of him, a
part of him where he chose to limit and restrict himself to the rules of time
that he himself made up. He has no restrictions, no limits.

>What if he (and his world) is also simulated?

He is already everything and nothing. Nothingness is already part of him.
There's no world where he lives in, because that already is a part him. There
is nothing beyond him. Because that nothingness beyond him, is also part of
him. The things that exist are part of him. The things that don't exist are
also part of him. He encomapss everything and nothing, all of infintity and
all of the void, all of extistance and all of non-existance. All time and all
space. No time and no space. All those things are just parts of him. He is sum
the whole of all those finite, infinite, time, timeless, outside, inside,
everywhere, nowhere. He is not limited in anyway. He is unlimited every
everyway.

He is the most foundemental of all. Everything existed because he pretend that
it does. Earth exist because he pretended that billions of years ago, star
dust gather to form a planet called Earth. Earth goes around the sun because
he pretend that Earth follows a rule he made up called Gravity.

When an object push another object, he:

1\. Pretend that there are two objects there. 2\. Pretend that one object is
pushing on another object. 3\. Pretend that the other object have moved
according to a made up rule that he made up: Newtown Force. 4\. Pretend that
there's a scintist and pretend that the scientist "did" see and measured those
object moved.

Most of all, he:

5\. Pretend that there's a guy here typing this out. 6\. Pretend that this guy
typing this out have conscious and free will. In other word, I am just
something he made up and pretend to exist. My free will is just him pretending
I have free will. I am only typing this because he is pretending that I am. It
is him who actually have free will. Free will and conciousness are
fundenmental.

It's just like when you're a little kid, and you have a toy soldier, and you
pretend that he's a Knight. You pretend that he as a sword and a shield. You
pretend that there's a dragon and you pretend that the dragon is attacking a
pretend village. Then you pretend that he fight and slayed the dragon with his
pretend sword. And the pretend village made him into a pretend king.

Everything is just him pretending. Nothing really exist. He just acts like it
exist. And everything have to act like everything exist. Just like the toy
solder have to act like a dragon exist, because you act pretend that the
dragon exist.

------
solidangle
Wouldn't it be amazing if some poor grad student in the future had to explain
to his supervisor that his simulation of the past failed because the people in
the simulation figured out that they were being simulated? That would cause so
many moral issues: do you kill your experiment, or do you let it run until big
freeze?

------
Phemist
I thought SMBC had a fun comic in response

[http://www.smbc-comics.com/index.php?id=3931](http://www.smbc-
comics.com/index.php?id=3931)

~~~
wlesieutre
I was anticipating this one: [http://www.smbc-
comics.com/?id=2535](http://www.smbc-comics.com/?id=2535)

------
evo_9
Whenever I see an article that has much lower upvotes than comments I wonder
why HN doesn't just automatically upvote an article when someone makes an
initial comment (if they haven't already upvoted the article).

If you are interested enough to post a comment then you probably should upvote
the article, even if you don't agree with it. Why? Because it's likely
generating a good and interesting discussion. This article is a great example
of this phenomenon.

------
Animats
Unlikely. The universe has too much gratuitous detail at the subatomic level.
Nothing below the electron level is really necessary. At the macro scale, the
universe is way too big and mostly empty. If this is a simulation, it's
inefficient by tens of orders of magnitude.

If the simulation oversimplifies on the boring parts, we probably would have
picked up on that by now. Although it does make you think about the Copenhagen
Interpretation.

~~~
jfoutz
This is one of my favorite joke theories about relativity. More mass increases
the complexity of the simulation, slowing down time.

~~~
Retric
One of my favorites is the speed of light is simply how fast information can
be passed around processers in a distributed universe simulation.

------
wanda
The premise is absurd if considered superficially and irrelevant if discussed
in detail.

The further you pursue such possibilities, the less significant they become,
because you reach the boundaries of human epistemology.

The difference between simulated and "real" reality is beyond the scope of the
senses and deduction. We would have to be outside the world to know the truth,
and this is of course impossible.

~~~
aws_ls
"epistemology" \-- every time I see this word (normally in @nntaleb's tweets)
I look up google for meaning of this word, get a sense, and then soon forget
:-)

------
d33
> “What happens,” Tyson said, “if there’s a bug that crashes the entire
> program?”

Why do we assume that it's written in C, as opposed to - say - Erlang? ;)

~~~
paulpauper
better than java , otherwise it would be realllly slow. C and Assembly is at
least fast

~~~
d33
I'd prefer slow to "in the best case, everything blows up at once - in the
worst, there's a memory error that if exploited, turns your world into a
dystopia".

~~~
dave2000
“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.”

\- Douglas Adams

------
exratione
The simulation hypothesis is, sadly, perhaps the only self-consistent solution
to the Fermi Paradox, one that doesn't require very unlikely propositions.

[https://www.exratione.com/2015/05/the-cosmological-
noocene/](https://www.exratione.com/2015/05/the-cosmological-noocene/)

All of the other suggestions require all intelligent life without any
exceptions in our past light cone to behave in a consistent way, i.e. fail to
build obvious megastructures, fail to come calling, etc, so as to leave
everything with the appearance of being natural. The Fermi Paradox is more the
Wilderness Paradox in nature. Given that a tiny faction within any
sufficiently advanced civilization could on their own generate self-replicated
probes that converts the observable universe to computronium, and that some
portion of humanity will do that if not stopped, and that we appear in no way
to have exceptional origins or be in an unusual region, that really suggests
there is something fundamental that we don't yet understand.

~~~
Eliezer
Why simulate a very atypical world if the vast majority of intelligent-life
developing worlds are much younger than ours?

------
ciokan
For me it is clear that we will be doing our own simulations in the future. In
short here's how I see our path in relationship with technology and it's rapid
advancement:

human > transhuman > energy (in the grid): immortality at this stage > long
period of answers about our universe, research and exploration > boredom >
nostalgia > depression > take part in simulations where you dive in but to
fully enjoy the "animalic" experience you have to forget who you were and
start fresh. There are some experiences that only in relationship with death
(and knowing that your existence is short) produce really positive effects.
This story can get long and is filled with "ifs" but I don't dismiss the
idea...at all.

------
JohnLeTigre
There is no such thing as a perfect computer that runs eternally or that can
simulate something with an infinite degree of precision.

If we lived in a computer simulation, we would have noticed unusual meta-
physical glitches as discrepancies within the 'order of things'.

For example, if the simulator used floating points, we would actually notice
that numbers end up loosing precision after a certain amount of decimal
points. We would probably have tons of theories about that and wonder why the
metaphysical rules that are involved in counting suddenly change at specific
precisions. etc.

no glitches = no simulation

There are many more problems with this premise but to me, these types of
questions are a waste of intellectual energy so I'll leave it at that I guess,
have fun.

~~~
djsumdog
But the simulation doesn't have to be perfect. It doesn't have to be complete.
Maybe only you and your friends are actually being simulated, and everything
else is just a partial stub. Maybe only the relevant parts are rendered.

I actually read Nick Bostrum's original paper and it's a pretty interesting
read. Basically it looks at the long tail end of things. When you predict
things waaay into the future, you tend to gain accuracy for macro predictions.

For example: our sun will most likely run out of energy and die out one day.
The plate border in East Africa will most likely break apart at some point
causing that continent to split.

The big one: humanity will one day go extinct. ... or...we'll expand to Mars
and other parts of the solar system and thrive for millions of years. There
are other options of course (we get blown back to the stone age, some humans
survive and technology has to restart from a few thousand years
ago...repeatedly...until we either leave this planet or go extinct).

If our machine understanding continues to grow, we should be able to
eventually make machines that can simulate parts of the world we're in. So
either we've already done that (some other we), and we (you and I we) are the
products of their simulation ... or we'll go extinct one day.

...or simulating this world, perfectly or imperfectly, isn't possibly at all.
... and we'll go extinct one day.

~~~
aws_ls
>Maybe only you and your friends are actually being simulated

Why waste so much resources, when it can be just _You_ being simulated?

------
orionblastar
You have to wonder about this. If it is a computer simulation then there is a
God that is running the universe in a computer. Evolution is based on object
oriented programming where one object inherits the class of the last object
but modified in some way. Did God run Bingbang.exe or some other program to
create the universe simulation. Then things all fell into place and sped up
for God until life developed on one planet.

If it is a computer simulation it has more storage than any computer he have
now because of all the galaxies of stars and their own solar systems to keep
track of. Does life exist on some other planet? We don't know until we get
better telescope technology to get a better look at planets.

I do think we live in a computer simulation because there are so many things
in the universe that can kill us, yet we survive to an old age for most of us.
That means there is some unknown force that prevents most of us from dying.
Everything in the universe can be simulated using Math for the laws of physics
and other sciences. Very much like a computer uses math for video game
simulations.

It could be that we exist in this universe and our real bodies are in a
different universe Matrix style and when we die we wake up in the other
universe, and this universe is like training for the other universe that we
can't see because all around us is this simulated universe.

------
SeanDav
There is a rather interesting science fiction movie, called "The Thirteenth
Floor", that explores this concept, in fact if I remember correctly it talks
about nested simulated worlds.

This makes perfect sense to me, if the theory that we are living in a
simulated universe is correct, the exact same logic would apply to the beings
that are running the programs to simulate us and so on, ad infinitum.

~~~
jgroszko
There were a couple different movies that explored this theme around the time
The Matrix came out. eXistenZ is another one that I enjoyed a lot, where video
games become completely immersive, but there's still a few tropes like vapid
NPCs and generic place names that kind of give it away.

~~~
anexprogrammer
There was a late night TV show. 80s Twilight Zone or something of similar
vintage.

Height of the Cold War, on the brink of Nuclear War which after a series of
cock-ups arrives and MAD results. Camera pulls back to reveal "Game Over",
then further to show two alien teens at an arcade machine. A short exchange
and another coin in the slot to start at pre-life. Show ends.

Was refreshingly well done.

------
rl3
If we are simulated, it'd be interesting to know how optimized the simulation
is.

Maybe the simulation is reminiscent of _The Matrix_ in that reality is
essentially an elegant artificial abstraction that acts as glue tying together
the perceptions of each simulation participant.

Perhaps a proper, low-level simulation isn't computationally prohibitive, but
simulating the rest of our universe is. In that case, the cosmos itself may be
an illusion despite an otherwise interference-free simulation.

Or, perhaps the entire cosmos is simulated just as we are—including the
hundreds of billions of galaxies present in the observable universe. This
would heavily imply that computational resources are not finite.

I'd argue that regardless of whether we're in a simulation or not, the sheer
vastness of the observable universe heavily suggests that space may in fact be
infinite—which by extension creates the potential for simulations to exist at
grand—or even infinite—scales.

------
calvins
If we were in a simulation and the simulation would fail to realize its
purpose if a sufficiently large number of beings in the simulation became
aware of the simulation and changed their behavior, how smart would it be to
try to get more and more people interested in the issue and look for "smoking
gun" evidence? ;=-)

~~~
lifeisstillgood
That's the basic religion of Iain M Banks later culture novels.

~~~
gratalis
iirc, 'Surface Detail' explored this in depth from one society's use of a
'virtual hell' afterlife to instill behavioral control in 'the real'. My
favorite Culture character's view on the subject was expressed in 'Matter',
the previous novel in the series, by ex SC agent Xide Hyrlis. In Hyrlis's
view, the characters were experiencing the base level of reality based on an a
moral argument because "... only reality produced ultimately by matter in the
raw can be so unthinkingly cruel." and that to be otherwise "... god or
programmer, the charge would be the same - that of near infinite sadistic
cruelty."

------
vinceguidry
Our entire universe can be represented as a collection of bits of information.
The real question is whether that information can be compressed or not. If it
can be, that means you could store our universe digitally, if it can't, that
means it has to exist in analog. If you can store it digitally, then it almost
certainly is somewhere.

I remember reading about how NES and other cartridge game systems are harder
to emulate than disc-based systems like the PSX. The reason is that cartridges
are more than just flat data storage, they have chips and other electronics on
them that screw with the emulation.

I'm inclined to believe (and I believe it's actually been proven) that quantum
information is incompressible, that would make any algorithm that would
simulate it to have the same time and space requirements as the physical
system.

------
planck01
I suspect that the proof against would be along the lines of:

'The theoretical minimum computer for simulating any 1 particle at realtime is
at least X particles big. If it would be 1 particle it would not be a
simulation. If it would take less it would not be able to capture all possible
states. Eventually, every realistic simulation of a universe will either be
orders of magnitude less complex than reality or will be orders of magnitude
slower than realtime. In both cases realistic simulations of ones universe own
past will never be possible and hardly worthwhile and thus we probably don't
live in one.'

This also says that computing power cannot grow indefinetely.

~~~
outworlder
This argument breaks down if we consider that we don't know anything about the
"host" universe.

It is as if Minecraft beings reasoned that it would be impossible to simulate
them, as the redstone circuits required would be much larger than the
observable universe. Which is fine, except we have nanoscale transistors.

~~~
planck01
Minecraft is many orders of magnitude less complex than our universe. We could
be in a simulation, but then the parent universe would be orders of magnitude
more complex and we would not be a significant simulation of a civilization's
past as the original argument goes.

Of course we might be entertainment, but to explain this universe you would
then have to explain the way more complex universe in which we run. We cannot
proof this is not so, but now it seems pretty similar to the god hypothesis.

------
droffel
For those of you who haven't read this short story (universe simulation is the
theme), I highly recommend it:

[https://qntm.org/responsibility](https://qntm.org/responsibility)

------
zardo
If I play out a few steps of Conway's game of life by hand on a go board, is
that little universe any more real for my moving the stones around?

I think the only thing running the simulation does is let me, an outside
observer, see it. If sentiant gliders show up at some time step, they are
there thinking their pre-determined thoughts whether I get to that point or
not. They exist in the rules and initial conditions, not in the stones and
grid lines.

So if we could be living in a simulation, I don't see the need for a computer,
the program is all you need.

------
mjhm2539
Hilary Putnam says that we aren't.

Basically, if we really were brains in vats, then "we are brains in vats"
couldn't ever be true, because the referents of our discourse wouldn't have
any causal connection to real brains and real vats, and so it wouldn't even be
possible, if one were a brain in a vat, to think the thought or propound the
proposition "I am a brain in a vat", and so, it's necessarily false that we
are brains in vats.

ieas.unideb.hu/admin/file_2908.pdf

~~~
pdabbadabba
This is a fascinating argument, but not because it tells us much about whether
we are brains in vats. Instead, it tells us something deep and interesting
about linguistic meaning, and the mysterious relationship between statements
and propositions.

Putnam is not actually saying that we aren't brains in vats. Rather, he is
saying that we cannot form accurate and meaningful statements to that effect
if we are.

The argument, as I understand it, turns on a statement's ability to refer.
Putnam's point, as you nicely summarized it, is that in order to accurately
describe the world (I make a point here of not talking about whether the
statement is true) a statement has to be causally related to the things it
describes in the right way. This seems plausible.

But this is different (on must theories) from saying that the abstract
proposition that might be represented by such a statement cannot be true. It
could be! The puzzle is just whether you could form a linguistic statement to
properly express that proposition due to the reference problems Putnam points
out.

Putnam's own example demonstrates the point. A bunch of ants cannot draw an
image that represents Winston Churchill in the grass, because they cannot know
what Winston Churchill is or (probably) what he looks like. Any similarity
between an ant-made image, and a real image of Winston Churchill has to be
merely coincidental. Ants cannot close the causal link that we normally
require in order to say that an image "represents" something. But this doesn't
mean that there is no such thing as an image of Winston Churchill. Or that an
ant-made imagine cannot resemble Winston Churchill. It just means that ants
can't form a _representation_ of him!

Likewise, our putative inability to form an accurate statement to the effect
that we are brains in a vat does not mean that we aren't brains in a vat. An
omniscient being (perhaps the one who put us in the vats!) might, for example,
read our silly HN posts about brains in vats and say, "gee, its incredible
that this series of symbols actually matches the symbols that you would use to
form a true statement statement about the world, if only the speaker were in
the necessary causal relation to my vats in order to truly say such a thing."
Likewise, we say about the ants "gee, its amazing that they managed to make an
imagine resembling Winston Churchill even though they don't know what he looks
like and therefore can't truly be said to have 'represented' him."

(There is a parallel line of argument that you might run about our ability to
_know_ something, since knowledge, it is often said, has to be related to the
external world in a certain way in order to be more than a mere belief.)

In any case, classic Putnam.

~~~
civilian
From the first episode of The Magicians, two students reason about being a
brain in a vat:

Quentin: "Am I hallucinating?"

Elliot: "If you were, would asking me help?"

So, I either I don't understand Putnam's argument or it's plainly wrong.

I recognize that when we say "We are brains in the vat" it seems, at the
surface, self-referentially false. Because if we are brains in a vat, we
wouldn't have the experience of being brains in a vat--- we'd have the
experience of walking around and being people. But I can make a statement
like: "Despite my experiences, I think that I am a sentient being that is
contained inside a vat."

His argument that the word "vat" refers to different things in "vat-English"
and normal English doesn't matter. The concept held behind vat & brain are
fundamental enough that they would be self-generating among a community of
sentient beings. If we say: "I am a sentient meatcomputer inside a vase filled
with liquid food" we may be saying something different, but we are still
expressing the core idea.

Even though the simulated world might be vastly different than the host world,
language allows abstractions such that we can make the statement.

Putnam goes on to entertain the idea of a twin earth where beeches and elmes
are switched, or a world where water has a different chemical forumula than
H2O. That is a better starting point, but it doesn't help. I can simply
generalize my statement: "I am a sentient being experiencing a hallucination,
and the brain which executes my thoughts are self-contained in an environment
I cannot perceive, but which nurtures my brain while networking stimulus with
it."

I'd like to add a thought experiment to this. Imagine you have two vastly
different communities with vastly different chemistry, and possibly operating
with more than 3space and 1time dimensions. What would happen if, by the act
of an Angel, both communities were given the rules for chess?

The names of the pieces don't especially matter--- if one community never had
a bishop, we can simply pick a different word. Or call it piece #4.

With enough games played and thought put into it, the communities would
discover tactics. They would compare and contrast the Queen's Pawn vs King's
pawn. They would figure out 3-move checkmate. They would understand why en
passant was a good rule to be added. And despite have different words and
names for all of these concepts, these concepts still refer to the _same
things_. Even if one world played chess with stone pieces, and the other world
used leashed rabbits with hats.

A great example of this is when I went to China and play Go (or Weiqi, as they
call it). I spoke 10 words of mandarin, and they spoke zero english. I was
able to play a couple of games without having any shared language about the
game. In the second game, an older chinese guy would sometimes yell at me and
move the stone I had just played--- essentially saying: "no, that's not the
best move, HERE it is." I didn't always understand why it was the best move,
but often it was plainly clear that I was incorrectly read the truth of the
board.

So. The act of thought supersedes what we immediately refer to in language, by
it's ability to abstract. boom!

~~~
ElComradio
In your thought experiment, you are presupposing many common factors; we can
understand this better perhaps because you are positing "3+ dimensions" so we
can think "the dimensions we see plus a couple more" which makes it seem like
the other community is a superset of ours.

Likewise, in your former, generalized statement, it works if you continue to
think of "our universe". The entire notion of anything remotely resembling a
brain, or anything like what we understand to be cause and effect (like,
nurturing something to keep it functional, or even the very concept of
"functional"...) existing in the host environment (whatever that means! :) )
makes the abstract statement devoid of meaning.

------
tzakrajs
Are we living in a computer simulation that is running atop another computer
simulation and so on in regress ad infinitum? Does asking questions like this
even mean anything? Maybe.

------
talles
> “I was driven to error-correcting codes—they’re what make browsers work. So
> why were they in the equations I was studying about quarks and electrons and
> supersymmetry? This brought me to the stark realization that I could no
> longer say people like Max are crazy.”

Is he loosely associating mathematical constants with arbitrary error codes
that we made up in computing?

~~~
CocaKoala
He is not. An error code is a way to refer to an error. Error-correcting code
is something else entirely; it is a way to encode information in which small
errors in the transmission of the information can be detected and possibly
corrected.

For a simple example: I want to send you 5 bits of data, and you receive
01101. You assume (but cannot prove) that you got the right data; maybe a bit
was flipped somewhere and I actually sent you 11101!

So you and I agree that we'll include a parity bit in our messages. If I'm
sending you an odd number of 1-bits, the parity bit will be 1. If I'm sending
you an even number of 1-bits, the parity bit will be 0.

So now, I send you five bits of data, plus one parity bit. You get the message
011011. You see that you have fives bits, 01101, and a 1 for the parity bit,
which means that you should be expecting an odd number of 1-bits. That is what
you have, so you can assume that as long as no more than 1 bit can be flipped
in transit, you have the data with no malformations.

This concept can be extended to detect more errors (what if two bits get
flipped) and to detect where the errors take place, which helps to correct
them. That's why it's called error-correcting code.

~~~
talles
And what this has to do with "quarks and electrons and supersymmetry"?

~~~
CocaKoala
Hell if I know, man. If I did, I'd have included it in my explanation! But
there was a pretty fundamental misunderstanding of what was being said, and I
felt like it was worth explaining what I knew so that at the very least,
incredulity was being expressed for the correct reason.

------
visarga
If we are, then it means computer simulations aren't infused only with
computing power, but also consciousness, as we are self evident proof of. It's
a simulation with consciousness, a completely different thing than what we
usually simulate (weather, proteins, old software on emulation)

~~~
onion2k
We might be a bug.

------
duncan_bayne
Meta: as per usual, I'm finding the HN discussion far more stimulating than
the original article.

------
snowwrestler
I'm not a physics genius. But to me it seems like the enthusiasm for this
theory is based on some very old cultural assumptions about man vs. nature.

For example:

> “If I were a character in a computer game, I would also discover eventually
> that the rules seemed completely rigid and mathematical,” said Max Tegmark,
> a cosmologist at the Massachusetts Institute of Technology (MIT). “That just
> reflects the computer code in which it was written.”

Computers are not exempt from nature, of course. The reason a computer works
is because the physical laws of our universe can be described mathematically.
If quantum theory didn't work mathematically, then neither would a computer.

So Tegmark is probably assigning the correlation the wrong way. A computer can
only exist in a universe with mathematical physical laws; therefore the
detection of mathematical laws doesn't tell us whether we're in a computer
ourselves.

Likewise:

> Furthermore, ideas from information theory keep showing up in physics. “In
> my research I found this very strange thing,” said James Gates, a
> theoretical physicist at the University of Maryland. “I was driven to error-
> correcting codes—they’re what make browsers work. So why were they in the
> equations I was studying about quarks and electrons and supersymmetry?

Information is also not exempt from nature; it is a physical thing that is
subject to the same laws of the universe as anything else. And what we call
information theory arose from our study of real physical systems, like
telegraphs and telephones.

Now, maybe information theory will turn out to be a better mathematical
framework for describing the laws of the universe. But that does not mean that
it is any more likely that we're living in a simulation. One mathematical
framework is not more "natural" than another. And there are plenty of examples
of where a math framework developed in one context became useful in another.

We use computers, and I think we still see ourselves as somehow distinct from
the rest of nature. This lends itself to a somewhat supernatural way of
thinking, like "I use a computer to manage information, so therefore if
everything is information, then there must be a super-me running a super-
computer."

But taking scientific theory at face value, a computer running SimCity is just
as natural as a cat, or a palm tree swaying in the breeze. If our theory says
that everything is information, then so are we, and so are our computers--so
there is no need for anything else to explain that.

------
dcip6s
If we are, let's hope they don't accidentally reboot the computer.

------
paulpauper
Aghhh not this again. This is pseudoscience/creationism marketed to
scientists. It's impossible to flasify this, since any evidence for or against
simulation can be a part of the simulation.

~~~
ksenzee
> This is pseudoscience/creationism marketed to scientists.

It's not science at all, pseudo- or otherwise. It's philosophy. And I see no
link to creationism. If we're in a simulation, it's not turtles all the way
down. Somebody's running the simulation. The same ontological questions we
grapple with now simply apply to that person instead of to us.

~~~
JoeAltmaier
Heh - no reason for that to be true. The folks running the simulation could be
very unlike us - maybe N-dimensional beings, or they exist across multiple
universes, or heck maybe in a 2-dimension world. I can simulate more
dimensions on my computer than I exist in! Why couldn't they?

Anyway their ontological questions might not be anything like ours. Perhaps
they ARE god, and don't need to wonder about that.

~~~
vinceguidry
> Perhaps they ARE god, and don't need to wonder about that.

If they were, how would they know?

~~~
JoeAltmaier
Can God make a rock so big, that even God can't move it?

------
tomc1985
Surely the energy demands for such a simulation would be... astronomical.

~~~
jsnider3
If that wasn't a pun, it was an accurate point.

~~~
tomc1985
Both? :)

------
sjg007
I thought the answer would be no because there are computable and non-
computable functions. If we are in a simulation then we should not be able to
reason about them.

Also then p!=np.

------
bingobob
[http://www.imdb.com/title/tt0139809/](http://www.imdb.com/title/tt0139809/)

------
AnimalMuppet
Are we living in a computer simulation? No.

Can I prove that? No. Is it false even though I can't prove it? Yes.

Not everything that cannot be disproven should be taken seriously.

------
jjman
One way to prove this, is for us to create a simulated world smart enough that
can discover itself and make its own simulated versions.

------
bcheung
Rene Descartes proposed this question in his "Meditations" essay (the one
where we get "cogito ergo sum" from).

~~~
lbolla
Actually, "cogito ergo sum" comes from "Discourse on the Method".

------
talles
Is that Scientific American bringing up some sort of science/philosophy on a
"creator" (a.k.a. God)?

------
reddog
I love it. Tyson just said that there is a 50% chance that the intelligent
design people are right.

------
FloNeu
hmm... hail you mighty big creators of the simulation I live in - please
provide me with some cheat codes so i can get some more money, women and toys
- also to unleash the wrath of gozilla on a random city of sim earth :D Sounds
like a fine religion to me :)

------
Yaa101
If we do, then it's a very advanced one.

But does it really matter? does REAL free will really exist?

------
tempodox
Seriously? I can't believe the SciAm actually published this article.

------
jqm
No but we are living in a mental simulation.

------
ksikka
Relevant Movie: The Thirteenth Floor.

------
pteredactyl
Is there life after death?

------
justinlardinois
So is there some super-universe version of HN where people are arguing about
implementation details of our simulated reality?

~~~
aws_ls
Yes. And they are all discussing beneath a 'Show HN' link with 500+ points. I
am wondering if that show HN simulation demo is in JavaScript as well?
Hopefully in WebAssembly by now (or by then, based on perspective)

------
seivan
Once I start seeing Hungry for Apple ads then I'll know for sure.

~~~
goda90
My man!

~~~
doubov
Slow dowwwwwnnnn!

~~~
theseatoms
You don't knooowwwwww me!

