4 ms·

So the question is, when you broke a vase can you glue it back to the previous state - and the answer is yes. The more exact state you'd like to achieve the mor

So the question is, when you broke a vase can you glue it back to the previous state - and the answer is yes. The more exact state you'd like to achieve the more effort it will require. But having the same state again doesn't mean you've travelled in time, but only that somehow the same state occur one more time (or better to say once again ;) ).

kelnos 8y ago
I think what the parent is getting at is that the progression of states is time. If you think of time as just the entire universe morphing through a progression of different quantum states, and then find a way to modify the quantum state of the entire universe so that it is equivalent to a previous quantum state, then "traveling through time" would easily be a colloquial way of saying what you've done. Though I suppose you didn't really travel; you reset everything -- including yourself -- to a previous state/time. If you could isolate yourself, and then return the rest of the universe to some previous state (while finding a coherent place for your personal newer state in the old rest-of-universe state, possibly editing out the parts of the universe's state that contain the old you), then "traveling" would make more sense. > but only that somehow the same state occur one more time Assuming that state transitions are deterministic (apart from your meddling that allowed you to return to a prior state, that is), then this is equivalent to rolling back time, so the distinction doesn't really matter. If you pick a quantum state that occurred 10 years ago (by your subjective perception of time), then everyone will be 10 years younger, people who were born in the last 10 years will no longer exist, and people who died in the last 10 years will be alive again. Also remember that everyone has their own reference frame when determining time. There's no such thing as "absolute time", or even the absolute passage of time. But that's ok; we don't need that to be the case for this to work out.
coldtea 8y ago
That's for a vase. Why would it have to be the same for time? This presupposes that time is unidirectional -- which it was supposed to prove.

kelnos 8y ago

I think what the parent is getting at is that the progression of states is time. If you think of time as just the entire universe morphing through a progression of different quantum states, and then find a way to modify the quantum state of the entire universe so that it is equivalent to a previous quantum state, then "traveling through time" would easily be a colloquial way of saying what you've done. Though I suppose you didn't really travel; you reset everything -- including yourself -- to a previous state/time. If you could isolate yourself, and then return the rest of the universe to some previous state (while finding a coherent place for your personal newer state in the old rest-of-universe state, possibly editing out the parts of the universe's state that contain the old you), then "traveling" would make more sense. > but only that somehow the same state occur one more time Assuming that state transitions are deterministic (apart from your meddling that allowed you to return to a prior state, that is), then this is equivalent to rolling back time, so the distinction doesn't really matter. If you pick a quantum state that occurred 10 years ago (by your subjective perception of time), then everyone will be 10 years younger, people who were born in the last 10 years will no longer exist, and people who died in the last 10 years will be alive again. Also remember that everyone has their own reference frame when determining time. There's no such thing as "absolute time", or even the absolute passage of time. But that's ok; we don't need that to be the case for this to work out.

coldtea 8y ago

That's for a vase. Why would it have to be the same for time? This presupposes that time is unidirectional -- which it was supposed to prove.