Perhaps this belongs in the Philosophy forum.

Imagine having a universe which is an exact duplicate of our universe some time in the past. I do not think it matters if we think of the copy duplicating our universe of 100, 1000, or ten billion years ago.

Would that universe have the exact same history as our universe?

Prior to Quantum Theory, most physicists and perhaps many philosophers would claim that our universe (as well as its copy) is governed by deterministic laws and both universes would have the same history.

Since Quantum Theory is based on probabilistic laws, it would seem to me that the two universes would evolve differently.

The mathematics of probability is based on assumptions of uncaused phenomena, and leads to descriptions of various probability distributions. When originally developed, it was assumed to be a method of dealing with processes for which the pertinent laws were unknown or for which it was impractical to collect the necessary data and do the computations using known laws.

Processes analogous to throwing dice or flipping coins where thought to be deterministic (Id est: Predictable). It was assumed that if you could make precise measurements of all pertinent data and do the necessary computations, then you could predict the results of an

Modern science is now aware of processes much simpler than dice throwing which produce data matching the probability distributions resulting from the assumptions of uncaused phenomena. For example: Radioactive decay matches a Poisson distribution (I think this is the one). Radioactive decay is a very simple process compared to dice throws. If decay data matches a probability distribution, it is strong evidence that it is a random process lacking a causal mechanism.

Consideration of Quantum Theory makes be believe that the above two exact duplicate universes would seem to be the same for a while: Perhaps for only seconds; Perhaps for minute or hours; Surely not for a long period of time like 100 or 1000 years.

I have to say this, if our universe were rewound and left without the possibility of time travel, it would inevitably repeat itself, now, if the universe (note the difference between our and the) repeated itself, there are an infinite number of outcomes and the likelihood that ours repeated is a minute, though not infinite possibility. And in response to another part of your question, in the event that humans were renewed in this idea, then it is actually highly unlikely that the same history would unfold, the rewinding could lead to a possible "residual effect" leading people to have intuitions for or against certain outcomes, for instance, there could be a man at an art institute in Italy who decides out of this prerecognition to allow hitler into the art institute to prevent what happened when he didnt get in. this post is clearly philosophy, but very interesting.

Yes, in my deterministic opinion it would.

I could back it up but i choose not to.

I agree with dinosaur. The thing would be different, how much different would depend on the outcomes of a gazillion processes. It would have to be different to some extent. The thing that comes to mind is that doodad in the last star trek movie with Picard's clone that didn't look quite like him. My understanding is that clones aren't identical to their originals because of the whole stochastic element of cell division, gene copies, etc.

I have a concern though, to say that a random process doesn't have a cause seems wrong to me. It's just that the cause is probabilistic. If certain conditions exist, then a range of things can happen. Those conditions are the cause. The particular of the outcome was based on the cause of the conditions that lead to it. To me, that signifies boundaries. Cause and effect are still there, but more like analog than discrete. Basically a function illuminates the possible outcomes of the cause, rather than the certain outcome. The outcome is certain to be within some boundaries.

, the rewinding could lead to a possible "residual effect" leading people to have intuitions for or against certain outcomes, .
What reason would you have for postulating such a 'residual effect', other than it is a nice idea?

wes,

it is rather simple. The current state of the universe is the effect of its own past and the cause of its own future. You cannot both state that cause and effect are still there and claim that Star Trek: Nemesis got it right. The clone of capt Picard did not end up like himself, Why? Well, it was simply because he did not live the same life as Picard.
If he would have been cloned the next day then he might have missed some things and ended up different, but it is simply not possible, it is deterministic, he HAD to end up there exactly at that time. He HAD to fight in those wars.

It is not simple to illustrate ones point while discussing Star Trek but hopefully you will see my perspetive.

wes,

it is rather simple. The current state of the universe is the effect of its own past and the cause of its own future. You cannot both state that cause and effect are still there and claim that Star Trek: Nemesis got it right. The clone of capt Picard did not end up like himself, Why? Well, it was simply because he did not live the same life as Picard.

You missed the point. If a cause has an effect with a range of values, then cause and effect are still present yet things can turn out differently, dependent on the outcome of the causes in question.

If he would have been cloned the next day then he might have missed some things and ended up different, but it is simply not possible, it is deterministic, he HAD to end up there exactly at that time.

Yes in the same instance of the universe, you're correct. If you rewound it however, you'd create a new instance.

He HAD to fight in those wars.

Only in the particular instance of the causes and particular effects for a particular instance of the universe.

It is not simple to illustrate ones point while discussing Star Trek but hopefully you will see my perspetive.

I see what you mean, but I don't think you caught what I was getting at. Probably a lack of clear writing on my part.

You missed the point. If a cause has an effect with a range of values, then cause and effect are still present yet things can turn out differently, dependent on the outcome of the causes in question.

I see your point but,
If i throw a tennisball towards you, you see it. You anticipate it to land somewhere and you reach towards that place with your hand and you catch it.

You must agree that it sounds utterly insane that the same tennisball would suddently change its path and travel towards outerspace instead of landing in your palm in another identical universe.
There are reasons for this however, the wind could for instance make it change its path, but the wind can also be mapped, it is deterministic. But of course it is humanly impossible to predict such an force but that is not what we are dicussing here.

The state of the universe cannot be changed because it is simply and echo of its past, and as the echo reaches us we will be bound to interact in a certain way and send out an echo for future generations.

I think quantum mechanics tells us something about limitations on available information though. In order to really predict the path of the ball, you'd need more information than you could acquire. You'd need to know all the information regarding every interacting atom involved in applying forces to the ball. Since Heisenburg has informed us that we cannot have all that information, we know our attempts to exactly determine the ball's path is necessarily an approximation.

im sorry but in my oppinion Heisenberg was a fool.
I however think that Laplace's Demon illustrates it rather nicely.

But of course i cannot dispute that it is humanly impossible to obtain enough information to predict an event with 100% accuracy. But to "re-trace" (can one say postdict :)) the stepts of the universe should be feasible, but just as with predicting it would require tremendous computing power and is therefore humanly impossible at this moment.

im sorry but in my oppinion Heisenberg was a fool.
I however think that Laplace's Demon illustrates it rather nicely.

But of course i cannot dispute that it is humanly impossible to obtain enough information to predict an event with 100% accuracy. But to "re-trace" (can one say postdict :)) the stepts of the universe should be feasible, but just as with predicting it would require tremendous computing power and is therefore humanly impossible at this moment.

However, we can't say that if you actually rewound it, things would go exactly the same way. So here.. I'll agree with you that if it was still this instance of the universe rewound, it would have to be the same. However, if you took a copy of it at time x in the past, it seems impossible to me that the stuff would go exactly the same way.

I understand your point and i cannot really say that it is incorrect because it is impossible to tell if you are correct or if i am correct. I however can say that my thought is more depressing than yours because yours at least includes free will :)

Dilbert, I was going to produce a series of counter arguments, involving Chaos Theory, Probability, Synchronicity and Quantun Mechanics, to refute your contentions. However, I suspect these arguments might be wasted on someone who thinks "Heisenberg was a fool". Oh, that I could be so foolish.

Rewind the universe and all would be the same. We live in a deterministic universe. This does not mean we can predict the outcome of events. No mater how much computing power you have the will always have some uncertainty. To know what a single practical will do you would have to know the state of the entire universe, which is impossible.

involving Chaos Theory, Probability, Synchronicity and Quantun Mechanics
To late you mentioned them..
Chaos Theory does not deny a deterministic universe, it is simple an elaborate expression of error.
Probability. Knowing that we cant know everything, probability is the statistical methods we use to make sense of our universe.
Quantum Mechanics is, once again, a statistical method for evaluating the deterministic universe.
Synchronicity has nothing to do with the deterministic universe, it is just a description of like events.

Of course we can never know if the universe is deterministic. To know this you would somehow have to be outside our universe.

predicting it would require tremendous computing power and is therefore humanly impossible at this moment.

Predicting it would require you to know the exact parameters that every smallest piece of matter and energy and point of space had at the exact time of the big bang.
And from there on you would have to do calculations that take into consideration all that information you had, and pass on the variables to the next calculations. Assuming that there is no finite size time unit(time can be split up endlessly), then you would have to do an infinite number of calculations for every finite amount of time.
Now you have two problems: first you need to know all the information there was at the big bang, and secondly, you need infinite calculating power. Ofcourse one could always argue anything, when the word infinity is used, but I would be rather sure that even if the universe would be deterministic, it would not be predictable. Not only humanly and not only at this moment, but never.

In order to predict something, even something trivial one would actually need to know Everything. Not possible, but why would one need to predict it with 100% accuracy, why not settle for 80% ?

The universe is "wound"?. Then rewound would be analogous to wrapping a universal top with a piece of string (use string theory here!) until the universe was "wound". Then throw the univesel top while holding the end using a quick snapping motion of you hand, wrist and arm.therby generating an unwound spinning universe.

Now if the universe were in this condition before being "wound", then yes unwinding the universe would bring it back to the same condition that preceded the universe being wound in the first pace.
Geistkiesel

In order to predict something, even something trivial one would actually need to know Everything. Not possible, but why would one need to predict it with 100% accuracy, why not settle for 80% ?

Because over time, the 80% accuracy will decrease to a infinitely small accuracy, because even the smallest inaccuracy will build up into total inaccuracy.

If you know the exact position and direction of all but one particles in a closed system, then if there is any movement in the system then eventually you will not know the position and direction of no particles.
The only unknown particle will collide with an other particle. Even if you knew everything about the other one, you will know nothing about it after the collision. Now you have two unknown particles. Then four. Then sixteen. etc etc. Until you know nothing about any particles in the system.
In fact you have no way to tell how accurately you know anything in any moment of time t>0.
If you don't know absolutely everything in the beginning of the universe, then after any time, no matter how small, you can't theoretically predict nothing.

Dilbert, I was going to produce a series of counter arguments, involving Chaos Theory, Probability, Synchronicity and Quantun Mechanics, to refute your contentions. However, I suspect these arguments might be wasted on someone who thinks "Heisenberg was a fool". Oh, that I could be so foolish.
Don't let the reference to chaos theory stop your march. Fractal math has some interesting things to say about chaos and randomness. There are some conditions where generating the graphical representaions of a mathamatical loop "do until" will generate points within limits forever. The nth point can not be predicted, and is only found by generating the output with the loop. The point are not analyzable. The function never degenerates to zero or nor exceeds an upper limit.

geistkiesel

Dilbert, I was going to produce a series of counter arguments, involving Chaos Theory, Probability, Synchronicity and Quantun Mechanics, to refute your contentions. However, I suspect these arguments might be wasted on someone who thinks "Heisenberg was a fool". Oh, that I could be so foolish.

All is so confusing with all the uncertainty, but not to fret, we'll let Werner tell us what to do. Werner, Oh Werner . . . where are you? [There, there my dear, here set yourself down. Here . . .my hanky . . . here lI'll wipe the perspiration from your fevered troubled brow.]

Werner Heisbenerg was also a fucking Nazi. Oh that you could be so foolish.
G