Would absolute prediction work?

[Shinova]

Let's imagine that near the beginning of the universe some god-like being or race built a computer with practically infinite computing power that takes into account every single variable in the universe, all the atoms, particles, and whatever, and ran the model as a simulation.

Do you think that this model would turn out to be exactly the same as how the universe has played out so far?

[DPDarkPrimus]

No, because there would be a different variable in the universe; namely, the computer with practically infinite computer power.

PARADOX.

[Shinova]

No, because there would be a different variable in the universe; namely, the computer with practically infinite computer power.

PARADOX.

Okay then, this computer exists outside the universe.

[OmegaGuy]

I think the uncertainty principle would make that impossible.

I'm no expert though.

[Teleros]

Yeah, uncertainty would certainly mess things up in the long run - although the Arisians have a pretty good stab at it in the Lensman series.

[DogsOfWar]

Given the uncertainty principle, the computer could only come up with all possible outcomes to the universe and their probabilities.

[Rye]

Let's imagine that near the beginning of the universe some god-like being or race built a computer with practically infinite computing power that takes into account every single variable in the universe, all the atoms, particles, and whatever, and ran the model as a simulation.

Do you think that this model would turn out to be exactly the same as how the universe has played out so far?

Assuming such a computer existed, how could it not?

[HRogge]

It would only work if nobody knows or future would be already deterministic.
Otherwise the "perfect prediction" would change the result...

[Eris]

I'd like to point out to all the people invoking the shade of Heisenberg that they've got it completely backwards. In the very short run the computer could not predict the outcome of certain events. And by short run I mean on the scale of a few quantum events, since if you go long enough quantum mechanics turn into a set of probabilities that always come out completely predictable. (Actually, that's true even on the scale of a few quantum events, but it takes a bunch of them for it to even itself out as it were.)

Really, if they weren't, what's the point of calling it science to begin with? We have stunningly accurate predictions in QM, in fact. That's what's so interesting about it. It just happens that those predictions incorporate probabilities. In the long run, we make ideal predictions, and furthermore, all this doesn't matter after you scale up to the point where collapse starts kicking in.

[Ariphaos]

Essentially, it becomes a mirror Universe in and of itself.

[Darth Smiley]

I'd take that another step further - it IS a universe in and of itself. The inhabitants of which would speculate endlessly about whether they were 'real', then just shrug and say it doesn't matter, because it can't be proved one way or the other.

Hey, wait a minute...

In serious sense, it would HAVE to be another universe. Think about it. How, exactly, is it going to store ALL THE INFORMATION IN THE UNIVERSE in less space/mass than the actual universe. In that case, what's the point?

[Winston Blake]

No, mainly because of the aforementioned probabilistic nature of reality (as far as we know). However, even if you had a completely deterministic universe, then no matter how large 'practically infinite' is, there are limits to how accurately you can make predictions.

I recall that weather forecasting will never be accurate beyond a week or so because there's an actual asymptote - the idea with chaos theory is that the harder you try, the harder it gets to make accurate predictions. Even incredibly small rounding errors (like the effect of a single person exhaling) can profoundly affect the resulting weather.

So even with determinism, you would need to perfectly know the initial conditions i.e. all characteristics of the universe at a certain time, to infinite precision. Of course, that's impossible.

[Fingolfin_Noldor]

Issac Asimov's Foundation universe was based on the idea that it was possible to come up with a set of predictions on how groups of people predict. Seemly because groups of people tend to behave more predictably.

[Eris]

So even with determinism, you would need to perfectly know the initial conditions i.e. all characteristics of the universe at a certain time, to infinite precision. Of course, that's impossible.

In practice, this is true, but the computer itself is handwavium, so this gives me an idea.

Assume the universe is governed by a variant of Bohm's theorem, or some hidden variable theory that's Lorenz invariant, compatible with relativity and so on, and further is governed by no other principles, natural or supernatural. Now assume this infinitely powerful computer simply had within it the information that cataloged all the physical variables in the universe at a given time, and further had all the equations necessary to fully describe all physical processes that could occur. Given arbitrary time, such a computer in such a situation could model the universe and predict any event occurring an arbitrary amount of time after the initial time.