21 ms·

Time Travel (2006)

119 points by panic 8y ago

bananatron 8y ago
> There might already be fundamental difficulties with that, coming from quantum gravity, but let's ignore that for now. Let's.
charliebrownau 8y ago
Considering most people that support the Global Socialist Left refuse to admit that gender is based on biology and science and DNA What hope is their to work out * Faster the Light Travel * Anti Gravity * Solar Shielding * Time Travel
guide42 8y ago
> This question has a very long history of being studied by physicists on weekends. How much of science is done on weekends? I feel that investigations without capital investment is done in a hobby-type schedule. Probably these discovers (if any) might don't change our reality immediately, but are not worth the investment?
z3t4 8y ago
If we solve Cryosleep we don't need to go faster then light, just aim carefully and hope that the computers have not died by radiation when it's time to wake you up in a million or so years. As time seem to appear infinite. But what if when we wake up, all the mass in the universe (except our space-craft) have been sucked into another dimension, will time still exist !?
- saagarjha 8y ago
  Except that this means that you are disconnecting yourselves from anyone who is not in cryosleep, as they would have all died. Incidentally, this problem exists even when moving at close-to-light speeds as well :(
  - jacobush 8y ago
    Or almost as if you move away from friends and family. The human condition.
    - TeMPOraL 8y ago
      If you move away, you usually can come back. Now it's two months out and it's two months back, when you're pushing the speed of light Twenty years on your homeworld's track, pushing the speed of light And your friends are gone and your lovers too And there's damn-all left that you can do And you try to lie, but you know it's true, pushing the speed of light Pushing the speed of light https://www.youtube.com/watch?v=ud6LiVJkwyA https://www.youtube.com/watch?v=ud6LiVJkwyA
      - jacobush 8y ago
        That text sent shivers down my spine. As for our mundane world: You usually can come back, but shit often gets in the way. I guess I'm getting kinda old-ish.
      - izzydata 8y ago
        This reminds me of the final battle in the anime Gunbuster where they are trying to save the human race while traveling at light speed. They know if they engage the alien race they will never be able to see their friends or family again. I think they ended up returning 12000 years later to find the entire planet waiting for them with a light display across the Earth that says "Welcome Home".
      - konart 8y ago
        Thank you for sharing this
    - TremendousJudge 8y ago
      Not that long ago, people would migrate to another continent and literally never hear again about the people they left behind. I have a great grandfather that did that. It's really not that different from migrating to another star in that sense.
- coldtea 8y ago
  >As time seem to appear infinite Well, isn't the universe scheduled to "die off" due to low entropy in 10^100 years or so?
  - jessriedel 8y ago
    Yes exactly. It sounds like a long time unless you're waiting around for your classical computer to brute-force solve a problem for which quantum computers have an exponential advantage.
fouc 8y ago
> if closed timelike curves existed, then quantum computers would be no more powerful than classical ones. If we find quantum computers are no more powerful than classical ones, well then perhaps CTCs exist. -- Although what if quantum computing is actually a result of CTC under the space time fabric? (Probably a nonsensical proposition eh?)
- jessriedel 8y ago
  It's generally considered inelegant but not nonsensical. There exist hidden-variable theories that reproduce all the normal predictions of quantum mechanics (including quantum computations), but they require non-local interactions. I think a restricted set of CTCs could mediate those interactions.
- deleted 8y ago
  [deleted]
madmaniak 8y ago
Time doesn't exist therefore you can't travel in it.
- vermilingua 8y ago
  [citation needed]
  - hellofunk 8y ago
    I agree that a citation is useful, but I know that I've seen articles about how the variable for time cancels itself out in many important physics derivations, suggesting that time is at least not an important factor in the reality of the universe, and thus possibly does not exist.
    - sidusknight 8y ago
      You could say the exact same thing for eg. mass.
  - madmaniak 8y ago
    Citation would be needed for a time proof. I don't know about such.
  - madmaniak 8y ago
    Also it's really weird to ask for citation for a simple implication. Science is based on proofs, not on quotations.
  - deleted 8y ago
    [deleted]
  - mindcrime 8y ago
    >> Time doesn't exist therefore you can't travel in it > [citation needed] What do we want? Citations! When do we want them? It doesn't matter!
  - GoblinSlayer 8y ago
sys_64738 8y ago
I would equate time travel to being a memory and thought process. We're able to regenerate the images of events in our minds vividly when we think about past events which make us happy (e.g. child birth) or things that make us sad (e.g. manager screaming at us due to another bug crashing our software). This is time travel to the past by my definition. For time travel to the future, I think it's about predicting future events of a few seconds before they happen, based on past knowledge we've gained or learned. An example of this for me is seeing a situation where somebody is about to crash their vehicle, as the driver doesn't see another vehicle then it happens. I recall a recent fender bender like so in Manhattan during January. I knew it was about to happen given there wasn't the space then crash. So those are my definitions of time travel.
- toper-centage 8y ago
  Have you watched Stein's Gate? If we could send a little bit of data to the past maybe we could fit our memories.
philliphaydon 8y ago
I love movies and TV shows about time travel. But I just don't think it's possible at all. If you could travel back in time, that would mean that future and the past must co-exist with the present. If the pasts exists for us, the future exists, which means events have already happened, which means if time travel was to be invented then it would have already happened and someone would have traveled back to the past. But if traveling back to the past, and changing something, then any changes to the past would alter the future, but changing the past could prevent time travel being invented which would mean the person never traveled back to change the past to alter the future to begin with... Unless changing the past splits time into 2 with both outcomes. If the purpose of traveling back in time is to fix a problem that occurs in the future, but the act of changing the past splits time, then the time you knew would not be altered, only the alternative timeline you created. But if the past and future already exist, and time travel is possible, then all possible futures have ready happened and all possible pasts have already happened which would mean you have infinite timelines of every possible outcome of time itself. Because any change to the past in a given timeline only splits time to another outcome for the timeline, we would never know if our future changed or not making the entire event pointless. I only believe it's possible to travel to the future, but not 'skip' in the same way back to the future does. Only freeze ourself and awake in the future which is kind of just pausing and letting time pass by. ^ my opinion.
- TremendousJudge 8y ago
  >I only believe it's possible to travel to the future Don't want to sound pedantic, but we do this all the time. Also, time travel to the future (in a "when you come back 80 years have passed" sense) is something that happens at relativistic speeds; this is fact as far as physics is concerned.
- alexanderdmitri 8y ago
  First thing that occurs to me as a work around for this paradox is to think of traveling into the past as recreating a certain state as opposed to actually "reversing" the clock so to speak. Like pulling a commit hash from a while a back and then forking the repo. Maybe we're just not on a fork yet?
foobaw 8y ago
https://en.wikipedia.org/wiki/Timeline_of_the_far_future https://en.wikipedia.org/wiki/Timeline_of_the_far_future Maybe someone from the future could update this for us.

Time Travel (2006)

119 points by panic 8y ago

> There might already be fundamental difficulties with that, coming from quantum gravity, but let's ignore that for now. Let's.

charliebrownau 8y ago

Considering most people that support the Global Socialist Left refuse to admit that gender is based on biology and science and DNA What hope is their to work out * Faster the Light Travel * Anti Gravity * Solar Shielding * Time Travel

guide42 8y ago

> This question has a very long history of being studied by physicists on weekends. How much of science is done on weekends? I feel that investigations without capital investment is done in a hobby-type schedule. Probably these discovers (if any) might don't change our reality immediately, but are not worth the investment?

z3t4 8y ago

If we solve Cryosleep we don't need to go faster then light, just aim carefully and hope that the computers have not died by radiation when it's time to wake you up in a million or so years. As time seem to appear infinite. But what if when we wake up, all the mass in the universe (except our space-craft) have been sucked into another dimension, will time still exist !?

saagarjha 8y ago
Except that this means that you are disconnecting yourselves from anyone who is not in cryosleep, as they would have all died. Incidentally, this problem exists even when moving at close-to-light speeds as well :(
- jacobush 8y ago
  Or almost as if you move away from friends and family. The human condition.
  - TeMPOraL 8y ago
    If you move away, you usually can come back. Now it's two months out and it's two months back, when you're pushing the speed of light Twenty years on your homeworld's track, pushing the speed of light And your friends are gone and your lovers too And there's damn-all left that you can do And you try to lie, but you know it's true, pushing the speed of light Pushing the speed of light https://www.youtube.com/watch?v=ud6LiVJkwyA https://www.youtube.com/watch?v=ud6LiVJkwyA
    - jacobush 8y ago
      That text sent shivers down my spine. As for our mundane world: You usually can come back, but shit often gets in the way. I guess I'm getting kinda old-ish.
    - izzydata 8y ago
      This reminds me of the final battle in the anime Gunbuster where they are trying to save the human race while traveling at light speed. They know if they engage the alien race they will never be able to see their friends or family again. I think they ended up returning 12000 years later to find the entire planet waiting for them with a light display across the Earth that says "Welcome Home".
    - konart 8y ago
      Thank you for sharing this
  - TremendousJudge 8y ago
    Not that long ago, people would migrate to another continent and literally never hear again about the people they left behind. I have a great grandfather that did that. It's really not that different from migrating to another star in that sense.
coldtea 8y ago
>As time seem to appear infinite Well, isn't the universe scheduled to "die off" due to low entropy in 10^100 years or so?
- jessriedel 8y ago
  Yes exactly. It sounds like a long time unless you're waiting around for your classical computer to brute-force solve a problem for which quantum computers have an exponential advantage.

fouc 8y ago

> if closed timelike curves existed, then quantum computers would be no more powerful than classical ones. If we find quantum computers are no more powerful than classical ones, well then perhaps CTCs exist. -- Although what if quantum computing is actually a result of CTC under the space time fabric? (Probably a nonsensical proposition eh?)

jessriedel 8y ago
It's generally considered inelegant but not nonsensical. There exist hidden-variable theories that reproduce all the normal predictions of quantum mechanics (including quantum computations), but they require non-local interactions. I think a restricted set of CTCs could mediate those interactions.
deleted 8y ago
[deleted]

madmaniak 8y ago

Time doesn't exist therefore you can't travel in it.

vermilingua 8y ago
[citation needed]
- hellofunk 8y ago
  I agree that a citation is useful, but I know that I've seen articles about how the variable for time cancels itself out in many important physics derivations, suggesting that time is at least not an important factor in the reality of the universe, and thus possibly does not exist.
  - sidusknight 8y ago
    You could say the exact same thing for eg. mass.
- madmaniak 8y ago
  Citation would be needed for a time proof. I don't know about such.
- madmaniak 8y ago
  Also it's really weird to ask for citation for a simple implication. Science is based on proofs, not on quotations.
- deleted 8y ago
  [deleted]
- mindcrime 8y ago
  >> Time doesn't exist therefore you can't travel in it > [citation needed] What do we want? Citations! When do we want them? It doesn't matter!
- GoblinSlayer 8y ago

sys_64738 8y ago

I would equate time travel to being a memory and thought process. We're able to regenerate the images of events in our minds vividly when we think about past events which make us happy (e.g. child birth) or things that make us sad (e.g. manager screaming at us due to another bug crashing our software). This is time travel to the past by my definition. For time travel to the future, I think it's about predicting future events of a few seconds before they happen, based on past knowledge we've gained or learned. An example of this for me is seeing a situation where somebody is about to crash their vehicle, as the driver doesn't see another vehicle then it happens. I recall a recent fender bender like so in Manhattan during January. I knew it was about to happen given there wasn't the space then crash. So those are my definitions of time travel.

toper-centage 8y ago
Have you watched Stein's Gate? If we could send a little bit of data to the past maybe we could fit our memories.

philliphaydon 8y ago

I love movies and TV shows about time travel. But I just don't think it's possible at all. If you could travel back in time, that would mean that future and the past must co-exist with the present. If the pasts exists for us, the future exists, which means events have already happened, which means if time travel was to be invented then it would have already happened and someone would have traveled back to the past. But if traveling back to the past, and changing something, then any changes to the past would alter the future, but changing the past could prevent time travel being invented which would mean the person never traveled back to change the past to alter the future to begin with... Unless changing the past splits time into 2 with both outcomes. If the purpose of traveling back in time is to fix a problem that occurs in the future, but the act of changing the past splits time, then the time you knew would not be altered, only the alternative timeline you created. But if the past and future already exist, and time travel is possible, then all possible futures have ready happened and all possible pasts have already happened which would mean you have infinite timelines of every possible outcome of time itself. Because any change to the past in a given timeline only splits time to another outcome for the timeline, we would never know if our future changed or not making the entire event pointless. I only believe it's possible to travel to the future, but not 'skip' in the same way back to the future does. Only freeze ourself and awake in the future which is kind of just pausing and letting time pass by. ^ my opinion.

TremendousJudge 8y ago
>I only believe it's possible to travel to the future Don't want to sound pedantic, but we do this all the time. Also, time travel to the future (in a "when you come back 80 years have passed" sense) is something that happens at relativistic speeds; this is fact as far as physics is concerned.
alexanderdmitri 8y ago
First thing that occurs to me as a work around for this paradox is to think of traveling into the past as recreating a certain state as opposed to actually "reversing" the clock so to speak. Like pulling a commit hash from a while a back and then forking the repo. Maybe we're just not on a fork yet?

foobaw 8y ago

https://en.wikipedia.org/wiki/Timeline_of_the_far_future https://en.wikipedia.org/wiki/Timeline_of_the_far_future Maybe someone from the future could update this for us.