IMO, regardless of entanglement, we can only ever look back, but never go there. As long as we are of a physical nature, then, if time can be reversed only at FTL, it would physically impossible to go back.
Moreover, by reversing time we would be reversing universal entropy and that would involve speeding up everything to travel FTL, which of course would be impossible. Thus if an individual were able to travel FTL, he himself would reverse his entropy and if arriving at a point where he would not yet be born, he would if fact no longer exist and his image in the present would fade into a ghostlike condition, or as mentioned before into “vagueness”.
When we think about traveling back in time, the time traveler’s experience of time is just the same a normal. So he gets into his time machine with his watch on at 5pm. Lets say the journey takes 10 minutes. So at journeys end his watch says 5.10pm.
He get’s out of the time machine and his watch continues to tick forwards as normal and he has aged by 10 minutes as normal.
Stephen
Stephen, Thanks for that link.. I recall seeing that episode, and in fact, based my proposed thought experiment on it (see minutes 22-26). I simply exchanged their use of an alien with communication space probes that could communicate instantaneously with earth. I didn’t watch the full episode again, but if I recall correctly they did not propose that there are any credible theories for travelling to the past other than through a worm hole. I may not recall correctly, but I think they also considered the paradox issues of changing the past and brought up hypotheses about the possible existence of infinite parallel universes as a way to address that.
Tim, a little trick for quoting individual paragraphs. Select Fast or Post Reply button. Then copy and paste the passage you wish to quote. Then insert [ quote ] (no spaces) before the passage and place [ / quote ] (no spaces) after the passage. This will place the quoted passage in the shaded area. You can then edit in the author’s name or hightlight parts of the quote.
Tim, a little trick for quoting individual paragraphs. Select Fast or Post Reply button. Then copy and paste the passage you wish to quote. Then insert [ quote ] (no spaces) before the passage and place [ / quote ] (no spaces) after the passage. This will place the quoted passage in the shaded area. You can then edit in the author’s name or hightlight parts of the quote.
Stephen, Thanks for that link.. I recall seeing that episode, and in fact, based my proposed thought experiment on it (see minutes 22-26). I simply exchanged their use of an alien with communication space probes that could communicate instantaneously with earth. I didn’t watch the full episode again, but if I recall correctly they did not propose that there are any credible theories for travelling to the past other than through a worm hole. I may not recall correctly, but I think they also considered the paradox issues of changing the past and brought up hypotheses about the possible existence of infinite parallel universes as a way to address that.
I don’t think it matters much whether we could realistically achieve time travel. I think it just helps to think about it when thinking about time and what it is to persist through time.
I think it’s particularly interesting that problems about changing the past come up. Why do they? Are these scientists thinking in terms of the block universe of their theories? If so of course we wouldn’t and couldn’t change the past, we’d just be spread out through the block occupying spacetime that is so extremely curved that it meets at an earlier time.
Actually, there are some who are now working on developimg quantam communication devices where communication may be possible that is either either instantaneous or so much FTL, that it is essentially instantaneous.
No. Information, energy or matter cannot travel faster than light. In all the applications of quantum entanglement (cryptography, teleportation), there is always a second channel which is not based on entanglement in itself.
TimB - 28 December 2011 01:35 PM
Given that time moves from the past to the present to the future, I am quite at peace with the thought that my conscious abilities arose from matter and evolution and that my conscious abilities have some causal effect, in a teeny tiny way, on life, the universe and everything. But, again, what I am trying to get my head around is what IF, time, past, present, and future (as some theories suggest) is all happening now. What happens to our notion of causality, in that case? Perhaps nothing. I am just proposing the question.
Speaking in such ways is completely confusing: time does not move, movement is in time. One can speak of a direction of time, as a direction does not necessarily means movement (e.g. an arrow, or a static force). ‘Now’ is also a concept in which time is hidden. So with some mathematical tricks, one can formulate natural laws in such a way that in the calculations there is no difference between time and space dimensions. But when wants to translate the results of these calculations to observations, one must translate them back to our normal time. And in this time causes never precede its effects. So this is a constraint we cannot forget when we do our calculations. One can compare this with other simple constraints: e.g. that when A is one meter to the left of B, and C one meter to the right of B, then A is left of C. It is certainly possible to design a geometry in which this is not the case, but that is just not the situation we find in a laboratory. So my conclusion: no change in our conception of causality.
TimB - 28 December 2011 01:35 PM
TimB: I also take for granted that I am conscious. (If not, the joke’s on both of us.)
GdB: ...time does not move, movement is in time. One can speak of a direction of time, as a direction does not necessarily means movement (e.g. an arrow, or a static force). ‘Now’ is also a concept in which time is hidden…
Is it not perplexing to you that our movement in the past, now, and in the future could potentially be observed to be happening simultaneously? (By asking that, I am not disagreeing with the pragmatism of your full response.)
GdB: No. Information, energy or matter cannot travel faster than light. In all the applications of quantum entanglement (cryptography, teleportation), there is always a second channel which is not based on entanglement in itself.
I think the jury is still out on that. My simple thought (which of course may be completely off base) is this: Even though the 2 observers cannot control the outcome of an entangled quantum event (they can only observe it), the act of observing a series of event/s (whatever the outcome) or not observing an outcome in a timed sequence, could provide for communication much like a crude kind of morse code. If so, this would probably not be of any practical applications over relatively short distances (like from here to the other side of the Earth), but over cosmic distances it might.
GdB: No. Information, energy or matter cannot travel faster than light. In all the applications of quantum entanglement (cryptography, teleportation), there is always a second channel which is not based on entanglement in itself.
I think the jury is still out on that. My simple thought (which of course may be completely off base) is this: Even though the 2 observers cannot control the outcome of an entangled quantum event (they can only observe it), the act of observing a series of event/s (whatever the outcome) or not observing an outcome in a timed sequence, could provide for communication much like a crude kind of morse code. If so, this would probably not be of any practical applications over relatively short distances (like from here to the other side of the Earth), but over cosmic distances it might.
GdB, Upon further review… It appears to me that your assertion above is correct. I looked and couldn’t find any evidence of most recent thinking on quantum entanglement as other than a dead end in regards to FTL communication. I continue to hope that someone will achieve it. (Perhaps the recent possible evidence of FTL neutrinos… Or I saw that a fellow named John Cramer was looking into something called retrocausality, but I couldn’t find anything about what he is doing currently.) I still think communication with the future could be possible if there was FTL communication, though I doubt that if it does happen that it will be in my lifetime. It might be that even if it were possible, that there would be no payoff for doing so.
GdB: ...time does not move, movement is in time. One can speak of a direction of time, as a direction does not necessarily means movement (e.g. an arrow, or a static force). ‘Now’ is also a concept in which time is hidden…
Is it not perplexing to you that our movement in the past, now, and in the future could potentially be observed to be happening simultaneously? (By asking that, I am not disagreeing with the pragmatism of your full response.)
No, not really. The perplexing is short before: that the time dimension can be treated as a space dimension in relativity, and then all the effects that follow from it, like time dilatation with high velocities and under gravitation.
TimB - 29 December 2011 11:23 PM
GdB, Upon further review… It appears to me that your assertion above is correct. I looked and couldn’t find any evidence of most recent thinking on quantum entanglement as other than a dead end in regards to FTL communication.
Several theories allow faster than light processes, but they all fail at last at the principle of causality.
For Write4U: as a Dutchman, you could read Marten Toonders ‘Heer Bommel en de minionen’. It is about time travel. If you’ve read it, we can discuss it…
As a child I read most of the books but I must admit I have forgotten most of the stories. My favorite comic series was Kapitein Rob. It influenced me to see the world as merchant marine and later my love for sailing.
Thanks GdB, I’ll certainly check it out, but I am no longer fluent in dutch, so I am not sure that I can comment on the subtleties. I’ll let you know.
