Could knowing the state of the universe at time T allow to predict the state T+1?
Quantum physics today tells us that we may not predict outcomes with certainty. We perceive events as random.
So is this old philosophical fantasy of an all knowing computer possible? Meaning that all particules at a time T would have a determined state.
If it is, and assuming that there is going to be some randomization to go from T to T+1, how precise of an estimation could we get of the future?
- can a weather forecast for the next day be 100% reliable?
- can we answer questions like "if hitler had died as a kid" with 100% reliability?
- how much further could we predict from T, with good accuracy, knowing that there is randomness?
This post was sourced from https://worldbuilding.stackexchange.com/q/3148. It is licensed under CC BY-SA 3.0.
1 answer
Yes and No
Quantum mechanics is full of probability. You simply can't get around it. You can never know for sure if a particle at time $t$ in the future will be at point $A$ or point $B$. Quantum mechanics forbids it. Sure, the odds could be essentially 100-to-1 against that it will be at point $B$, but there's still a chance that it could be there. So there will always be randomization.
However, there's a scale where this doesn't matter a lot, and that's on the macroscopic scale. Yes, there's a chance that a baseball hurtling towards you will move an inch to the left for a split second, but that would require every single particle in the ball to move one inch to the left. Once you combine all those wavefunctions, you find that that is really improbable.
So if you want to make a large scale simulation, you can sort of ignore that. That's one reason we didn't really think about probability being extremely important in physics until we could work with tiny particles, because the effects didn't show up on a macroscopic scale. So while you can't predict the minute details of each particle's motion, you can model the ball fairly well.
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