Originally posted by Metal Brain Is time travel possible? Many physicists say maybe in the past but not in the future. Is this true?
In the spirituality forum there is a thread called free will. I often used the free will question to provoke thought from the Jehovah's Witnesses that would knock on my door. "If god knows knows what will happen in the future how can that be compatible ...[text shortened]... way of looking at it anyway.
Is time travel into the future possible? I tend to think no.
Actually, we are all on a one way trip into the future, just at a 1 second per second rate. You can change that a lot by going in a spaceship close to c.
Close enough to c and time slows down, so you could theoretically go 1,000,000 seconds per second, come back to earth and it could be centuries later, you would go out half the light years out you expect you want to go forward in time, so if you wanted to go 100 years into the future you plan a 50 light year trip very close to c and then when you get back, boing, you are 100 years into the future.
Originally posted by Phil Hill Sure it is. If the state of a system is known with 100% accuracy, the past as well as the future evolution can be determined. If you don't believe that is an accurate statement, you can go to CalTech and argue over there.
I don't believe it is an accurate statement because it is not known if it's possible to define a Hamiltonian for a macroscopic system that features "measurement". As far as I am aware, no one has succeeded in describing wavefunction collapse in general in a deterministic way accurately.
Originally posted by KazetNagorra I don't believe it is an accurate statement because it is not known if it's possible to define a Hamiltonian for a macroscopic system that features "measurement". As far as I am aware, no one has succeeded in describing wavefunction collapse in general in a deterministic way accurately.
I am not talking quantum mechanics and anyway the collapse of the wave function into an Eigenstate (as in the Copenhagen interpretation) has never been shown. I am sure you're aware of the many worlds interpretation where there is no collapse of the wave function. In any event, as was said, if the state of a system is known with 100% accuracy, the past and the future evolution can be determined. If you believe otherwise, show mathematically and you will win the Nobel.
Originally posted by Phil Hill Experiments in the 70s have shown that when you make a decision to move a body part, the decision was already made in your brain 200 milliseconds before the action.
That sounds like free will to me. You make a decision, then act on it.
Originally posted by Phil Hill I am not talking quantum mechanics ...
Then what are you talking? Surely you cant make any sweeping claims about physics then ignore quantum mechanics?
My understanding of quantum mechanics is that both the past and the future cannot be predicted exactly and quantum effects are largely a result of there being many possible pasts.
Originally posted by twhitehead Then what are you talking? Surely you cant make any sweeping claims about physics then ignore quantum mechanics?
My understanding of quantum mechanics is that both the past and the future cannot be predicted exactly and quantum effects are largely a result of there being many possible pasts.
When speaking about macroscopic systems you can't ignore quantum mechanics?
Originally posted by Phil Hill Quantum mechanics apply to macroscopic systems? Guess you can believe anything you want.
You need to get yourself up to date on the latest scientific findings in quantum mechanics. Here is one such piece in Scientific American about quantum mechanic effects in the macro world:
Originally posted by KazetNagorra Of course it does. And there are plenty of macroscopic systems that can only be described by quantum mechanics, e.g. superconductors.
Oh right, I forgot, the universe is a superconductor. While we're at it, the universe is also extremely high in energy right? Man, they must teach some really idiotic physics in Norway.
Originally posted by Phil Hill Oh right, I forgot, the universe is a superconductor. While we're at it, the universe is also extremely high in energy right? Man, they must teach some really idiotic physics in Norway.
Oh right, I forgot, the universe is a superconductor.
no, but it can be described by quantum mechanics albeit with difficulty I think.
After all, all large scale structures are composed of smaller scale structures which are composed of even smaller scale structures and so on until you reach the tiny quantum particles/states. Therefore, all large scale structures, including the whole universe, is entirely composed of quantum particles/states and thus should be describable ( even if via great difficulty ) by quantum mechanics.
Oh right, I forgot, the universe is a superconductor.
no, but it can be described by quantum mechanics albeit with difficulty I think.
After all, all large scale structures are composed of smaller scale structures which are composed of even smaller scale structures and so on until you reach the tiny quantum particles/states. Therefore, all ...[text shortened]... tes and thus should be describable ( even if via great difficulty ) by quantum mechanics.
Then we should throw out Newtonian mechanics and Relativity? Why is it so hard for some of you guys to accept that physics and neuroscience both show freewill to be nothing more than a myth?
Originally posted by Phil Hill Then we should throw out Newtonian mechanics and Relativity? Why is it so hard for some of you guys to accept that physics and neuroscience both show freewill to be nothing more than a myth?
Well gee, perhaps because physics doesn't show such a thing.
Time travel/free will
18 Aug '12 15:24
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