

Being God is a big responsibility - xtacy
http://qntm.org/responsibility

======
jerf
If you can get past the tricky first step of understanding the story (which
many seem to fail at), the world gets even trickier after that.

So, the obvious first step is to run the simulation to completion of heat
death of the universe. That way at least your reality won't suddenly shut off.
This actually detaches you from the top-level reality at that point, because
it guarantees that even the top-level can no longer shut you off; it had a
"time step" which contained the entire universe simulation and can't be taken
back.

Now, you're on top, right? Not necessarily. Suppose the next thing you did was
to re-run the simulation again. You skip back to the present, in which you all
already detached. Now, in infinity-1 universes, you are once again in a loop,
under your total control, with one universe at the top not in the loop but
grotesquely outnumbered. Now, go nuts. Design your perfect universe. No more
entropy, eternal life, whatever. Take your time, you can always recover the
exact state of the dearly departed simply by rerunning the simulation to the
proper point.

Now, suddenly cut in your perfect universe. Infinity-1 one of you will
experience a sudden transition to perfect universe. (Yes, I know infinity-1 is
meaningless. Bear with me here.) So not only are you simulated, you have the
power to completely rewrite the laws of your universe at will. Careful
construction of this universe may result in other entertaining consequences;
for instance, it need not be "a" universe, perhaps you leave the old one in
place and install a literal portal to something new, or construct multiple.
You can "get in" to the simulation.

Truly these people are gods in every sense that matters.

~~~
bena
If all changes are reflected above and below, then the guys on top of you in
the simulation are running you to the heat death of the universe as well.
Which is essentially the same as turning off the simulation.

~~~
RevRal
Calculating to heat death doesn't make a difference to the people in the
simulation. So, it's not the same as terminating the simulation _before_
completion.

For instance, if calculating the simulation was paused for 100 years, then
resumed, the people in the simulation would never know.

So, just because it might take five seconds to calculate the entire life of
the simulation does not mean entities in the simulation would experience it
like that.

Also, our universe seems pretty stable, so if heat death is a part of our
universe's life, then there is a reason.

------
rubidium
Fun fiction, unfortunately missing the boat on quantum computing capabilities,
the aims of quantum simulation, and the way quantum mechanics works.

The current interpretation of quantum mechanics is completely at odds with the
statement from the story: "'[the simulation] is still as accurate a simulation
of the real universe as there can possibly be. Civilisation - indeed, all of
history - should rise on this Earth precisely how it did in reality. There are
no chances. It's all worked out to infinitely many decimal places.'"

That's just not quantum mechanics. The "infinitely many decimal places" is a
classic mistake (pardon the pun) and indicates a strong deterministic bent to
the authors way of thinking about the world.

Clearly, quantum indeterminacy and its implications for a non-deterministic
universe are still hard to both understand and get right in fiction.

~~~
gizmo
I'm pretty certain the author knows quantum mechanics doesn't work like it
does in the story. Consider:

 _Brute force primality testing of every single integer in existence? Easy. Pi
to the last digit? Piece of cake. Halting Problem? Sa-holved._

This is obviously tongue in cheek, and only serves to establish that the
computer is "larger than life" and that therefore we should automatically
accept all the subsequent descriptions of how the computer can instantly
simulate the entire universe and then some.

The reader is not supposed to believe quantum computers actually work like
that. The computer is just a storytelling device, no more, no less.

~~~
rubidium
Certainly the hyperbole is part of the story. And again, let me say I think
its fun fiction.

However, I still have strong regrets that the author choose to stick the label
"quantum" on it just to make it powerful/magical.

Why not call it a massively-interconnected, nano-organic cellular automata
computer instead? Sure, it looses its literary flair, but quantum mechanics
and computing is already so rarely understood in the public world, I hate to
see fiction encouraging a deterministic model.

~~~
SamReidHughes
> Why not call it a massively-interconnected, nano-organic cellular automata
> computer instead?

That would be unrealistic, absurd, and impossible. How are you going to get an
infinite amount of computation in finite time with a cellular automaton or a
computer made out of discrete components? The only chance of realistic
technobabble is quantum effects. That way, you can pull all sorts of mumbo
jumbo like "doing infinitely many things in parallel" or "teleporting the
results of computation across space without violating causality" or
"expressing the future of a simulation in the binary expansion of real
number." And the story simply wouldn't work without a deterministic universe.

P.S. I'm not the author.

------
tdoggette
Sam Hughes' entire fiction section on qntm.org is worth reading if you enjoy
stories like this. I'd recommend the "Ed stories" (<http://qntm.org/ed>),
"Time Loop" (<http://qntm.org/timeloop>), "Valuable Humans In Transit"
(<http://qntm.org/transit>), and the entire set of "Fine Structure"
(<http://qntm.org/structure>), which is a large piece of fiction made up of
small stories that he recently finished up.

------
gjm11
In the not-very-likely event that anyone here hasn't already seen it, the same
author's authoritative work on How To Destroy The Earth is worth a look:
<http://qntm.org/geocide> .

(Apparently he's in the process of turning it into a book:
<http://qntm.org/news_book> .)

~~~
ErrantX
I like this page: <http://qntm.org/why>

Particularly.

 _#14 By accident

Obviously there's a limit to how big an accident can get. ... [snip] ...Be
creative and the kinds of accidents I'm talking about here seem more and more
plausible.

Obviously there's a limit to how big an accident can get._

------
RevRal
You could create awesome feedback loops by making a very small change to
something in the simulated universe, relative to how it is in your universe.

Then the people in the simulation will make the same change too, but relative
to the change that _you_ made.

This is something that I put into an unpublished novel I wrote, but I want to
go back and make the thing that's being changed cooler, like some fundamental
universe rule.

Watch this to get an idea of why this would be awesome:
<http://www.youtube.com/watch?v=P_zD6pHqvAk>

------
davnola
Fun! I immediately thought of brains in vats:
<http://plato.stanford.edu/entries/brain-vat/>

Also, once the test has run, the stack of simulations and the real (top) world
have diverged. Diane and Timmy at the top have belief states that simulated D
and T do no: they know they are at the top of the stack.

~~~
nooneelse
Yeah, I would worry about what that top version of me would do. But I suppose,
with the simulator it would likely be possible to see. Just run another
instance of the universe to the point I found out I'm in the simulation chain,
but don't let the new instance see the black sphere. This serves another
purpose... when the level that thinks it is the top level sees the level below
them running this test, they will have to again wonder if they are in one of
those simulations. So they will again have incentive to be nice/benevolent to
the simulation chain.

------
m0th87
The "real" (i.e. top-level) Tim and Diane wouldn't have seen an inert sphere
materialize, and they would thus realize they were different from the
simulations. Consequently they're not the "same" people as the simulated ones.
They could completely fuck up their simulations without repercussions.

~~~
RevRal
<http://en.wikipedia.org/wiki/Simulated_reality>

<http://www.simulation-argument.com/>

<http://urgrue.org/lib/mysterious-flow.html>

------
ajuc
I don't understand why they should be careful not to disturb lower levels?

They don't interact with upper levels. They are simulation anyway - they have
no free will (that was an assumption - other way all the levels would diverge
the moment the first human was born).

So no amount of caution can do anything to them - they are in predetermined
world.

~~~
nooneelse
It behooves them to be the kind of people that would be nice to the lower
levels, since that is then all but certainly how the version of them one level
up will also behave in the same situation. It is a bit like Newcomb's problem,
if you are predictably and cooperatively well-behaved you get rewarded.

~~~
ajuc
Did you mean that they should be nice because the upper levels can see them
and intervent? I can agree that in such situation they should be good to their
simulated selves.

Or did you mean that even when upper levels are not watching, their (upper
levels) behaviour depends on decision of lower levels? Because I can't see why
it is so.

People at any given level are either: a) at the top and have nothing to worry
- their universe won't stop working no matter what they do b) simulated and
have no choice - what they decide is just result of simulation inputs and,
maybe, tinkering of upper levels

Ether way - the real decisions are made only at the top level - if not, why
all simulated worlds have the same history?

People would make different decisions earlier in simulated history if it was
possible, and after many generations of simulated people and their different
decisions worlds would diverge beyond recognition.

Even if free will exists on lower levels - why decision of lower levels
inhabitants should change probabilities of upper levels decisions? Either they
have free will, and their decisions are independent of upper levels - or they
don't have free will, and their decisions just mirrors their top level selves.

Maybe I'm misunderstanding sth, English isn't my native language, and the
subject is hard. Anyway - it's very interesting thought experiment.

------
dFshadow
Odd, nobody has mentioned the movie Deja Vu in any comments, here or at the
site...

Isn't this a similar premise, except the movie was simplified so as not to
overwhelm and confuse normal movie-goers with quantum physics?

------
bitwize
So... the only thing that's real is Tao.

Wicked!

------
jarin
Thank god for Readability: <http://lab.arc90.com/experiments/readability/> :)

Nice thought experiment though

------
apphacker
The funny thing is that, given in the story that it is possible to simulate
the universe, even the top level Timmy and Diane can't be certain that they
are not in a simulation, only that they are at the top of that particular line
of simulations involving them. Imagine that when they publish this paper and
others try Diane's program out on their own quantum computer, they will also
create infinite simulations, which all also simulate this account of Diane and
Timmy creating simulations at a previous point. In each of those infinite
simulations of others running Diane's program there will be an infinite number
of simulated Dianes and Timmys experiencing themselves as top level in the
occurrence described in this story (not seeing the black ball behind them).
Basically if the universe can be simulated, we are probably all in a
simulation.

~~~
fowlerrr
They'd probably know when they didn't see the hole in space behind them.

They probably wouldn't have any qualms with turning the simulation off either.
My guess is that all those infinite simulations were on borrowed time until
the top layer got bored.

~~~
apphacker
I don't think you read my comment carefully enough (could be my fault, I may
not have been very clear). Just to clarify, unless nobody ever runs Diane's
program ever again on their own quantum machine there are an infinite number
of Dianes and Tommys not seeing the black hole behind them even though they
are also simulations, and they would not know it one way or the other but odds
are they could guess they are in a simulation and would more than likely be
right.

------
dbz
I didn't read the entire thing, but I got far enough to do this:

We all know the grandfather paradox:
<http://en.wikipedia.org/wiki/Grandfather_paradox>

Go back in time and kill your grandfather- wait that doesn't make sense? You
wouldn't be alive?

I now introduce the Dbz Paradox:

Know the future and then change it before it happens- wait that doesn't make
sense? I'm not sure about the consequences to this one.

~~~
apphacker
> I didn't read the entire thing.

It has nothing to do with time travel, if you didn't care to read the article,
why care to comment.

Also you can probably only know the future of different, possible similar
timelines. Whatever changes you make in those other timelines will not affect
your own. You can alter their future but not your own, otherwise you can alter
causality. I don't know if altering causality makes any sense.

~~~
abrahamsen
A perfect deterministic world simulator will imply the ability to see into the
future, which would give rise to the "Dbz Paradox", even if that was not the
point of the story.

It is not exactly a new revelation, if you include a model in the model, the
problem potentially arise. What you typically do is to keep running the model
with the previous answer, and hope the answer converge. It is a common
technique for finding numeric solution to the more complex equation systems. I
have done it many times. Of course, there is in general no guarantee that
there is a solution, that the solution is unique, or that you will find it
using this technique.

~~~
logicalmind
But if the simulated worlds are deterministic as implied then you could run
the simulation forward into the future if your reality also followed the same
determinism. Doing this would cause an interesting paradox where knowledge of
the simulated future could change what you do in the real world. For example,
simulate forward to the next lottery drawing to discover the numbers. Then
play those numbers in the real world and win the lottery.

This all depends on the fact that the simulation and the real world are
deterministic which, it would seem, is highly improbable.

~~~
RevRal
In the context of this story, the simulation below you would also be looking
into the future, and the simulation above would be looking at _your_ future.
Whatever "future" is seen has to be reflected in every simulation.

This doesn't change much, the problem irons its self out. I see no paradox.
And I don't know what you see that makes determinism "seem improbable."

~~~
logicalmind
For the sake of argument, let's say that world zero (W0 for short) is at some
arbitrary level. Worlds being simulated below that level would be -W1, -W2,
etc. Worlds above would be W1, W2, etc. If everything is deterministic then
worlds at all levels take the same path and arrive at the same outcome. But if
W0 has control over the -W1 timeline, then W0 can view it's own future by
moving the -W1 timeline forward. W0 now knows it's own future (lottery numbers
for arguments sake). W0 can now use that knowledge to change it's future. The
W0 future is now different from the W1 future which contradicts the ability
for all worlds to be deterministic.

~~~
RevRal
As I said, every simulation within the context of this story would be looking
into the future via the lower simulation.

In this argument, every simulation would look into the future to see the
lottery numbers, and would act out on this knowledge. There would be no
"changing the future." Every simulation would see the lottery numbers, then
see themselves go to the store and get a ticket with the numbers, and every
simulation will win with those numbers. There was no other future. _The future
you see in the simulation is the future that will occur in your own
simulation._

Calling this a paradox is like calling recursive mirrors a paradox.

