a-x-med Posted October 1, 2009 Share Posted October 1, 2009 Is Time Travel Possible? "Not all scientists agree but according to Einstein and quantum theory, time travel could be possible. According to Einstein's special theory of relativity, our lives pass more slowly if we travel close to the speed of light. He has also shown that we live longer if we go and live in an intense gravitational field. Einstein has thus opened up the future and shown that it is possible to slow down time for ourselves, leave the Earth and come back to meet our grandchildren or our great-grandchildren. But he has not shown that it is possible to come back! Physicist Steven Hawking has suggested that it is not possible to go back in time because you could kill your own grandmother before your mother or father were born and so make it impossible for you to be born. But could it still be possible?" I say this - E=mc^2 If the thing is m kg, it needs E=mc^2 energy to get a speed of light. But how? Then it will disappear, Because, if the thing is 100 kg, it needs a material with 100 kg, which changes in energy and moves the thing with the speed of light, If they will together, then the whole mass will 200 kg, and 100 kg of the material will give an energy near light speed, not a light speed, just c/2 we shall get, This energy must be given from abroad, and it is impossible, so i mean, we never can move with speed of light. Link to comment Share on other sites More sharing options...
Moontanman Posted October 1, 2009 Share Posted October 1, 2009 For FTL see this link http://en.wikipedia.org/wiki/Alcubierre_drive Link to comment Share on other sites More sharing options...
swansont Posted October 1, 2009 Share Posted October 1, 2009 If you built a time machine, you could travel back in time, but only to the point where you built the time machine. Right now, at the particular place you are sitting, at the time when you are sitting there, one of two things is true: either there is a closed timelike curve passing through that point in spacetime, or there is not. And that situation will never change — no matter what clever engineers may do in the future, if they create closed timelike curves they cannot pass through events in spacetime through which closed timelike curves did not pass (corollary of Rule 6). Or in plain English: if you build a time machine where there wasn’t one before, it may be possible for future travelers to come back to that time, but nothing can help you go back to times before the machine was built. http://blogs.discovermagazine.com/cosmicvariance/2009/05/14/rules-for-time-travelers/ Link to comment Share on other sites More sharing options...
elas Posted October 1, 2009 Share Posted October 1, 2009 If you built a time machine, you could travel back in time, but only to the point where you built the time machine. Right now, at the particular place you are sitting, at the time when you are sitting there, one of two things is true: either there is a closed timelike curve passing through that point in spacetime, or there is not. And that situation will never change — no matter what clever engineers may do in the future, if they create closed timelike curves they cannot pass through events in spacetime through which closed timelike curves did not pass (corollary of Rule 6). Or in plain English: if you build a time machine where there wasn’t one before, it may be possible for future travelers to come back to that time, but nothing can help you go back to times before the machine was built. http://blogs.discovermagazine.com/cosmicvariance/2009/05/14/rules-for-time-travelers/ You are implying that all previous times still exist, where are they? Link to comment Share on other sites More sharing options...
a-x-med Posted October 1, 2009 Author Share Posted October 1, 2009 http://www.scienceforums.net/forum/showthread.php?t=44478 -1 Link to comment Share on other sites More sharing options...
Horza2002 Posted October 1, 2009 Share Posted October 1, 2009 Time travel is possible and is essential in our everyday life! The GPS network requires such precise calculations of its positions that the time dilation resulting from its speed must be taken into account otherwise the system fails. In addition, slight annomalies in the orbit of Mercury have also been explained by the time dilation effect caused by the Sun's gravtiational field. There are many more cases in which time dilation occurs, so yes it is possible to time travel. At present, physics doesn't think it's possible to travel at the speed of light, only close. Link to comment Share on other sites More sharing options...
a-x-med Posted October 1, 2009 Author Share Posted October 1, 2009 the thread is not about time travel, i have already gave a time travel possible variant, please check it out http://blogs.discovermagazine.com/co...ime-travelers/ In this topic, i am speaking about , if we can move with a speed of light, Link to comment Share on other sites More sharing options...
swansont Posted October 1, 2009 Share Posted October 1, 2009 You are implying that all previous times still exist, where are they? Where is a time? Like, "Where is 2 PM?" That question doesn't make sense. What is implied here is that closed timelike curves can exist, as far as our current understanding of physics goes. Link to comment Share on other sites More sharing options...
iNow Posted October 1, 2009 Share Posted October 1, 2009 At present, physics doesn't think it's possible to travel at the speed of light, only close. Well... Unless you're a massless particle such as a photon. Link to comment Share on other sites More sharing options...
mooeypoo Posted October 1, 2009 Share Posted October 1, 2009 Is Time Travel Possible?"Not all scientists agree but according to Einstein and quantum theory, time travel could be possible. According to Einstein's special theory of relativity, our lives pass more slowly if we travel close to the speed of light. He has also shown that we live longer if we go and live in an intense gravitational field. Einstein has thus opened up the future and shown that it is possible to slow down time for ourselves, leave the Earth and come back to meet our grandchildren or our great-grandchildren. But he has not shown that it is possible to come back! Physicist Steven Hawking has suggested that it is not possible to go back in time because you could kill your own grandmother before your mother or father were born and so make it impossible for you to be born. But could it still be possible?" Can you share the source you're quoting, please? EDIT: It seems you've copied it from here: http://www.firstscience.com/home/articles/big-theories/is-time-travel-possible_1741.html?comment=all Please make sure to supply the citation of a quoted piece of someone else's work. More than it being common courtesy, it's also a good way to avoid plagiarism and is part of the forum rules. Link to comment Share on other sites More sharing options...
J.C.MacSwell Posted October 1, 2009 Share Posted October 1, 2009 If you built a time machine, you could travel back in time, but only to the point where you built the time machine. Right now, at the particular place you are sitting, at the time when you are sitting there, one of two things is true: either there is a closed timelike curve passing through that point in spacetime, or there is not. And that situation will never change — no matter what clever engineers may do in the future, if they create closed timelike curves they cannot pass through events in spacetime through which closed timelike curves did not pass (corollary of Rule 6). Or in plain English: if you build a time machine where there wasn’t one before, it may be possible for future travelers to come back to that time, but nothing can help you go back to times before the machine was built. http://blogs.discovermagazine.com/cosmicvariance/2009/05/14/rules-for-time-travelers/ For the infinith(sp?,never did get that right and never will) time, don't bring that argument up again! Link to comment Share on other sites More sharing options...
bascule Posted October 2, 2009 Share Posted October 2, 2009 Right now, at the particular place you are sitting, at the time when you are sitting there, one of two things is true: either there is a closed timelike curve passing through that point in spacetime, or there is not. And that situation will never change — no matter what clever engineers may do in the future, if they create closed timelike curves they cannot pass through events in spacetime through which closed timelike curves did not pass (corollary of Rule 6). Or in plain English: if you build a time machine where there wasn’t one before, it may be possible for future travelers to come back to that time, but nothing can help you go back to times before the machine was built. Heh, reminds me of Primer. Link to comment Share on other sites More sharing options...
ydoaPs Posted October 2, 2009 Share Posted October 2, 2009 For FTL see this link http://en.wikipedia.org/wiki/Alcubierre_drive Alcubierre drive is inherantly unstable and the inertial bubble would be irradiated. Link to comment Share on other sites More sharing options...
a-x-med Posted October 2, 2009 Author Share Posted October 2, 2009 Can you share the source you're quoting, please? EDIT: It seems you've copied it from here: http://www.firstscience.com/home/articles/big-theories/is-time-travel-possible_1741.html?comment=all Please make sure to supply the citation of a quoted piece of someone else's work. More than it being common courtesy, it's also a good way to avoid plagiarism and is part of the forum rules. yea, i write it in the "..." then write , i say... Link to comment Share on other sites More sharing options...
mooeypoo Posted October 2, 2009 Share Posted October 2, 2009 yea, i write it in the "..." then write , i say... yeah, no, you still need to give the source of your citation. Link to comment Share on other sites More sharing options...
a-x-med Posted October 2, 2009 Author Share Posted October 2, 2009 yeah, no, you still need to give the source of your citation. ok, my, bad ))) Link to comment Share on other sites More sharing options...
elas Posted October 2, 2009 Share Posted October 2, 2009 Where is a time? Like, "Where is 2 PM?" That question doesn't make sense. What is implied here is that closed timelike curves can exist, as far as our current understanding of physics goes. Closed timelike curves are a mathematical prediction, not an understanding. In order to travel back to any historical instant (such as 2pm) either, every particle has to revert to its position at that historical instant or you have to fake it by recreating that position artificially; it does not exist (somewhere) at this instant and therefore cannot be 'traveled' to: it has to be recreated. 'Closed timelike curves' just like 'pointlike particles' are phrases created to explainlike an understanding.Time is a measurement not an entity; it is not a reality that one can travel to. (Just as you cannot go to a 'metre', but you can go to a 'metre of_ _ _ _ ') PS. To get to the 'pointlike' one man's 'implicationlike' is another man's 'speculationlike', it's all a bit 'profressionallike'. Link to comment Share on other sites More sharing options...
swansont Posted October 2, 2009 Share Posted October 2, 2009 Closed timelike curves are a mathematical prediction, not an understanding. In order to travel back to any historical instant (such as 2pm) either, every particle has to revert to its position at that historical instant or you have to fake it by recreating that position artificially; it does not exist (somewhere) at this instant and therefore cannot be 'traveled' to: it has to be recreated. 'Closed timelike curves' just like 'pointlike particles' are phrases created to explainlike an understanding.Time is a measurement not an entity; it is not a reality that one can travel to. (Just as you cannot go to a 'metre', but you can go to a 'metre of_ _ _ _ ') PS. To get to the 'pointlike' one man's 'implicationlike' is another man's 'speculationlike', it's all a bit 'profressionallike'. If this is a continuation of your complaint about mathematical prediction and its role in science, as it appears to be, then take it elsewhere, rather than hijack this thread. That also applies if you wish to discuss the nature of time, rather than the physics of it. Link to comment Share on other sites More sharing options...
elas Posted October 2, 2009 Share Posted October 2, 2009 (edited) If this is a continuation of your complaint about mathematical prediction and its role in science, as it appears to be, then take it elsewhere, rather than hijack this thread. That also applies if you wish to discuss the nature of time, rather than the physics of it. Have looked up CTC and find that what I am trying to say has already been said: http://en.wikipedia.org/wiki/Closed_timelike_curve Existence of closed timelike curves places restrictions on physically allowable states of matter-energy fields in the universe. Propagating a field configuration along the family of closed timelike worldlines must eventually result in the state that is identical to the original one. This has been explored by some scientists as a possible approach towards disproving the existence of CTCs. So my answer to the original question is that universal expansion is time related therefore time travel requires an alteration in the volume occupied by the universe; on the other hand reaching a state identical to the original one is not time travel it is a reconstruction of the present that matches a moment in time that no longer exists. places restrictions on physically allowable states of matter-energy fields in the universe. I wrote "every particle has to revert to its position at that historical instant or you have to fake it by recreating that position artificially"; that is the physics of it. Edited October 2, 2009 by elas Link to comment Share on other sites More sharing options...
Banshii Posted October 2, 2009 Share Posted October 2, 2009 I don't believe time travel is possible as described by most people. This is because I believe time is relative. What may seem like time travel to the observer, may not actually be time travel to the one "experiencing" said time/space deficiencies. Maybe "deficiencies" isn't the right word to use... fluctuations maybe? I have a theory to back this up but I'm short for time at the moment. Link to comment Share on other sites More sharing options...
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