Time Travel/Chaos Question

[Hulavuta]

I have a question that relates to Time travel, and chaos. Let's say you're watching someone roll a die, and it lands on a 6. Now you go back in time a few seconds and the person rolls the die again. Does it have the chance to land on a different number, or is it going to hit a six again? Are the variables going to be able to produce a different outcome, or are the variables going to repeat themselves and provide the same outcome? In other words, is the die going to have a second chance, or is its fate determined?

Keep in mind that you have no effect on the outcome, you're simply watching someone else do it. And the type of time travel does not involve any alternate dimensions, (it's simply a short rewind) so please give me a straight answer.

[MCP]

No one knows. Any sort of answer is hypothetical.

Your axiom:
1. No effect on the outcome by traveling backwards in time.
Cannot prove or disprove this.

My 'guess' is on a short enough time scale, one could work it all out such that they could travel a few minutes back in time and not effect the die roll, although it may effect something else. It may not be so easily detectable by current sensors, but there is likely change somewhere.

Many time travel science fiction stories deal with going back in time to "correct" something only to have it horribly, and ironically, backfire against the specified plan. Some even go so far as to say the events they watched previously had already taken into account the fact that they were going to have traveled back in time, and thus didn't change at all.

It's all just guesses right now.

I always look at the universe as relatively infinitely complex state machine that is best observed, at least by today's standards, via probability. So traveling back in time by an individual may or may not have already been taken into account by the current events.

Robots and analysis of bugs use probabilistic state machines to interact with their world. That's about as state of the art as it gets today, probably.

[bigkahuna]

In other words, is the die going to have a second chance, or is its fate determined?

Fate determined. In MP, $random variables are always the same even if you save load to prevent out of synch. Since Real Life is multiplayer, all dice rolls are in synch

No seriously, I believe that it would have the exact same outcome. I don't have some brilliant scientific formula to back me up, but just common sense.

[Pentarctagon]

it would probably depend on if the act of traveling back in time was able to affect any of the environmental factors that determined the die roll in the first place.

[bigkahuna]

it would probably depend on if the act of traveling back in time was able to affect any of the environmental factors that determined the die roll in the first place.

Well of course, but I believe he asked for a straight answer (a.k.a. barring the time travel quandaries).

[PeterPorty]

Just "going back" wouldn't change a thing, since the dice's outcome isn't really random, and depends in the way it is thrown and the way it "bounces", taking into account the surface it hits, the strength of the roll, the position of the hand, ETC. Therefore, unless you move the person's hand, or at least do ANYTHING while you're back in time, the outcome will be the same. This is merely because nothing is random, but not because of "fate", since if you actually did something, it could change.

[ancestral]

AFAIK, you cannot go back in time… only forward.

gg

[johndh]

Just "going back" wouldn't change a thing, since the dice's outcome isn't really random, and depends in the way it is thrown and the way it "bounces", taking into account the surface it hits, the strength of the roll, the position of the hand, ETC. Therefore, unless you move the person's hand, or at least do ANYTHING while you're back in time, the outcome will be the same. This is merely because nothing is random, but not because of "fate", since if you actually did something, it could change.

This. No such thing as random, only the appearance thereof. Something looks random if we don't understand the factors that make it happen the way it does, but that all falls away as soon as we understand the mechanisms.

[Reepurr]

A person rolls a dice. It comes up as "6".
You go back in time.
The person rolls the dice again, in the exact same way. And because of that, it comes up as "6".

Unless you interfere, logically the person will always do the same thing, in the exact same way, and so our dice will always be "6". Unless you interfere, anyway.

[Drakefriend]

Just "going back" wouldn't change a thing, since the dice's outcome isn't really random, and depends in the way it is thrown and the way it "bounces", taking into account the surface it hits, the strength of the roll, the position of the hand, ETC. Therefore, unless you move the person's hand, or at least do ANYTHING while you're back in time, the outcome will be the same. This is merely because nothing is random, but not because of "fate", since if you actually did something, it could change.

This. No such thing as random, only the appearance thereof. Something looks random if we don't understand the factors that make it happen the way it does, but that all falls away as soon as we understand the mechanisms.

Actually, we know there is real randomness. No one can say what anything will do on quantum level but the statistical probabilities, and chaotic systems can make massive changes when the starting situation is changed by infinitisimals.
And therefore. we have cannot say more about the effect of the dice roll then we could say "before" the roll that happened before the time travel, as something might haave changed, which that could also include the time travel itself.
Not regarding the, er, little problems with time travelling to the past (both physical and logical).
I'm sorry.Im' so sorry.

[Velensk]

There is a quote from Alpha Centauri that I rather appreciate: "Einstein would turn in his grave. Not only does God play dice but the dice are loaded."

My answer to the actual question, as far as our physicists are able to determine the universe does to some extend or another operate on what appears to be a random number generator on the quantom level. They are not sure exactly how this works. If it works like the RNGs we use for computers (which I find rather unlikely) then yes going back in time would reset the cornel for the RNG to exactly what it was before. However as we don't know how it works and speculation about traveling time is always pure speculation so far I would say the safest answer is, we don't know and it dosn't matter.

[Alarantalara]

Quantum mechanics suggests the answer could be yes, if the object were small enough.
http://en.wikipedia.org/wiki/Double-sli ... experiment
At the size of a die though, all the randomness averages out and you would still see a 6.

[johndh]

Actually, we know there is real randomness. No one can say what anything will do on quantum level but the statistical probabilities, and chaotic systems can make massive changes when the starting situation is changed by infinitisimals.

I'm not a quantum physicist (thankfully), but I would dispute that. In our early history, we may have thought lots of things were random because we couldn't predict them, and then as we learned more about how the world works, the gap in our understanding shrank, so our beliefs about what is random also shrank. See the Wikipedia article on God of the Gaps and mentally replace all instances of "God" or "god" with "randomness" and you'll see where I'm going with this. I predict that, with an infinite understanding of science, it would be understood that there is no such thing as randomness. Things at the macroscopic level move in predictable ways, while things at the subatomic level move at (thus far) unpredictable ways, so some people think that they must operate according to different rules. This is akin to early philosophers who believed that the planets and stars operated according to different rules than objects on Earth, simply because their explanations of motion didn't work for both. However, when Newton came along, it became clear that all these objects indeed act according to the same rules. It is my belief that, if the scientific community believes different rules apply in different situations, it's only because their laws and theories are flawed and they have yet to figure out a way to consistently explain the different phenomena. In other words, the "randomness" at the subatomic level must be, if anything, akin to a pseudo-random number generator, which only appears random because the mechanisms are obscure to the observer.

[Velensk]

I'm not inclined to be sure that either true randomness cannot exist or that the laws of physics are the same everywhere.

I don't see who scientists can prove or disprove either.

Does it matter right now?

[Sgt. Groovy]

Keep in mind that you have no effect on the outcome, you're simply watching someone else do it.

According to Heisenberg, you can not observe a system without influencing it.

My guess is that when a second version of the observer (the first one is still there, observing the first round) pops out of nowhere, it is enough to startle the dice thrower and influence the outcome.

There's a time travel paradox here, though, in that the both versions of the observers are observing the same die cast, at the same time, so they must see the same outcome.