What is Time travel: Definition and 344 Discussions

Time travel is the concept of movement between certain points in time, analogous to movement between different points in space by an object or a person, typically with the use of a hypothetical device known as a time machine. Time travel is a widely recognized concept in philosophy and fiction, particularly science fiction. The idea of a time machine was popularized by H. G. Wells' 1895 novel The Time Machine.It is uncertain if time travel to the past is physically possible. Forward time travel, outside the usual sense of the perception of time, is an extensively observed phenomenon and well-understood within the framework of special relativity and general relativity. However, making one body advance or delay more than a few milliseconds compared to another body is not feasible with current technology. As for backward time travel, it is possible to find solutions in general relativity that allow for it, such as a rotating black hole. Traveling to an arbitrary point in spacetime has very limited support in theoretical physics, and is usually connected only with quantum mechanics or wormholes.

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  1. vibhuav

    Is Time Travel Comparable to Space Travel in Physics?

    First of all, my background: I am an engineer interested in physics; so I am not very well versed with the nitty-gritty details and the math of physics. These are my thoughts and would like your comments: In some sense, time travel, being able to move back and forward in time is the...
  2. Pattonias

    A topic for amusement Debunking Time Travel

    I don't know if this has been discussed before, but I offer this paradox to debunk time travel. If time travel was possible, given an infinite amount of time from the point of its discovery and perfection; then someone eventually would have traveled back in time and made its existence known...
  3. H

    Is Time Travel Possible or Just Science Fiction?

    Is time travel is possible?
  4. S

    Time travel when velocity> light speed

    Not sure if this will have anything to do with quantum mechanics.. but... Ok so if you're traveling faster than light speed, then what do you see? I'm not talking about the whole doctor who scenario, its like traveling faster than sound, if the jet pilot is traveling faster than the sound it...
  5. S

    Is Time Travel Discussion Allowed in Physics Forums?

    i´m new in this fisics forum but, i would like tomake some questions about time travel...is there any specific place to put that kind of questions?
  6. A

    Light & Time Travel: Can the Light See Us Stopped?

    1.Light is moving so fast that is apparently stopped.But it ain't.Photons of light come and go. Now the question: Is light seeing us stopped?Like we arent moving? Thats a dumb question.Of course the light sees us stopped.If i ride a photon of light from Sun to Earth everything is stopped.8...
  7. T

    Paradox which questions time travel to the future

    You all have heard of the paradox whereas when you travel to the past and kill your grandfather you should not have existed in the presence whatsoever because you have killed your origins. So far so good...but I thought of another case, which I believe is more interesting since so far the...
  8. P

    Exploring the Physics of Time Travel at Light Speed

    Why would time stop if you travel at the speed of light?
  9. L

    The Truth About Time Travel: Separating Fact from Fiction

    So I was watching a video on youtube. http://www.youtube.com/watch?v=QM28eErikAo" It says that the faster you travel through space, the slower you travel through time, and that if you went faster than light, you could go back in time. Is this true? Forget about it being impossible to go...
  10. T

    Exploring Inertial Mass and Time Travel Possibilities

    No pitchforks please (and lay off the caps with the big 'D' on them too) Following staying up until 4am (all good stories start like this), and making small talk with a friend doing a degree in physics, we both decided to harp on about theoretical theories such as string etc, and as hours...
  11. T

    Name for a particular time travel paradox

    I have thought of an interesting property of time travel based on Novikov's self-consistency principle. I'm sure it's not wholly original, but if someone has heard of it before, I'd really like to know the name given to it so I can research it: If you find yourself next to a future version of...
  12. E

    Special Relativity Time Travel to Future - Could You Watch the News on Earth?

    If you are traveling away from Earth on a spaceship near the speed of light, it is well known that the moving clocks on the ship run slower relative to stationary clocks on earth. I was wondering if while on the space ship, you could watch the news on TV and see events progress at a...
  13. T

    Compact Sapcetime and Time Travel

    Someone here once said to me, via post, that "any compact spacetime must have closed timelike curves". Are there any good references out there on why that is / how that is derived? As an after thought... Isn't it true that a particle traveling in one direction in time is equivalent to its...
  14. E

    Time Travel Theory: What Are Your Thoughts?

    What are your thoughts about this?
  15. Mentallic

    Superman and Time Travel: Is It Possible?

    In the movie, when superman flies near light speed, he manages to reverse time? Was the story-line just completely off from a physical perspective or is there some truth to this phenomenon? I understand that time would slow down for superman from a human's perspective. Maybe I just didn't...
  16. T

    Exploring Time, Wormholes and Time Travel with Ian Morison

    I was just watching Ian Morison on Fora.tv about Time, in chapter 14 he talks about wormholes and time travel. You can see the time travel part here: http://fora.tv/2009/03/19/Ian_Morison_Its_About_Time#Journeying_Through_Space_and_Time_in_a_Wormhole Anyhow, in short he mentions opening a...
  17. B

    Can Time Travel Create Paradoxes?

    I was wondering the feasbility of time travel. Has it been proven not possible? Has it been proven theortically possible? I have always been interested in time travel, even if it seems like science fiction, but was wondering from scientist, professors, etc, if it has been an 'unsolved'...
  18. D

    What is the Relationship Between Speed of Light and Time?

    How time Travel work ? ok i know some of the basic about speed of light... You can't get to the speed of light ... You can't reach the speed of light cause According to Einstein's special theory of relativity, and E= MC ^2 objects gain mass as they accelerate to greater and greater speeds. Now...
  19. V

    Wormholes and time travel - Problem

    Under the general relativity principle, If you take a wormhole, put one end into a gravitational well, then take it out, there would be a time difference between the two openings of the wormhole. But, what effect would it have on the wormhole if you keep the middle area of it near a...
  20. J

    Exploring the Possibility of Time Travel Along a Vector Line

    I don't know much about physics, but I was wondering the other day whether what I was thinking was a popular theory. If time is like a one dimensional line and it starts at the orgin and it grows like a vector along the line as time progresses, then wouldn't it only be possible to travel back...
  21. P

    Any arguments for time travel back in time (the past)?

    Theres the Butterfly effect and Grandfather paradox which makes logical time travel into the past difficult. Is there any theory or anything which suggests it may be possible?
  22. T

    Time Travel and Conservation Laws

    I'm doing some research into time travel for a presentation I have to give in a month or so, and I'm currently looking at the compatibility of Time Travel and the Laws of Conservation. Sending an object back in time would increase the mass - and hence the energy - in the Universe at this...
  23. C

    Is Proper Time the Only Measure of Motion in Spacetime?

    If time is a curvature in spacetime as described in relativity, then picture this. If there is a curvature in spacetime time is going in one direction (let's call this curvature 1) but then could time travel not be possible by having a second curvature in curvature 1 but going in the opposite...
  24. P

    The Limitations of Time Travel: Ignoring Spatial Movement

    Okay, I read this on a blog so I'd post it the way it ias with the link: "There is one aspect of time travel that nobody considers, whether in science or science-fiction (at least, i am not aware of it), something that has the potential of rendering time travel, even if it is possible...
  25. Q

    Possibility of Time Travel at Light Speed

    if it is possible to travel faster than the speed of light will we be seeing the future or the past?
  26. A

    Calculating Gravitational Time Dilation in black hole/Future Time Travel

    First of all, (following Einstein's theory of Gravitational Time Dilation (I'll just call it GTD,)) objects (such as us) age slower near strong gravitational fields than in empty space. The higher the local distortion of spacetime due to gravity, the more slowly time passes. So according to GTD...
  27. K

    Having trouble understanding why FTL implies time travel

    I found a decent page explaining this but it's a little deep for my understanding. I think I understand the basics of special relativity where the speed of light remains constant regardless the velocity of 2 observers, the laws of physics do not depend on location or motion, and that length...
  28. Y

    Time Travel in Special Relativity

    Since I only learned special relativity but not yet general relativity, please bear with me that our discussion will be limited to the scope of special relativity, that is, suppose we would not utilize special spacetime topology, such as worm hole and black hole. I ran into some video about...
  29. Math Jeans

    Backwards Time Travel: Breaking the Heisenberg Principle?

    I had a thought that I wanted to run by physicsforums so all of you can tell me that I'm wrong and make me feel better. One of the main issues with the concept of time travel into the past is that we don't know whether is breaks any physical laws in the process. Here is what I believe...
  30. M

    Exploring Time Travel in the Quantum World

    Is time travel possible quantum world?
  31. T

    Is Time Travel Physically Possible? Professional Advice

    Hi, I want to know from proffesionals if time travel is physically possible. Thanks, Tony
  32. S

    Twin Paradox and Time Travel (Special Relativity)

    Homework Statement Identical twins Speedo and Goslo join amigration from the Earth to Planet X. It is 20.0 light years away in a reference frame in which both planets are at rest. The twins, of the same age, depart at the same time on different spacecraft s. Speedo's craft travels steadily at...
  33. 3

    Is Time Travel Possible with a Device That Slows Down Time?

    If we have two balls, a red and blue ball, and the red ball passes the blue ball at 99.9% the speed of light, would "time" for the red ball pass slower than it does for the blue ball? If it does, and if speed is just relative, couldn't we say the blue ball is passing the red ball at 99.9% the...
  34. W

    Is Time Travel Possible? Exploring the Science and Fiction Behind It

    i would just like to know where to get some good info on possble time travel and some people personal views on it. Thanks.
  35. S

    What has the speed of light got to do with time travel?

    Just wondering what the connection is between them, I understand that it relative to what we see but time in general? why not the speed of sound as its only another sense right? Just interested to know why light is so special? thanks guys, :smile: Sorry messed up title should be speed of...
  36. E

    Is Time Travel Possible and Already Happening in Our World?

    Two objects lie motionless in an isolated frame. One object accelerates to a speed v, then then holds that speed for an amount of time t. This causes the accelerated object to travel a time t_s into the still motionless object's future. v=\frac{c\sqrt{t_s^2+2t_st}}{(t_s+t)} If you're...
  37. Whitestar

    Time Travel: No worry about paradoxes

    I'm no theoretical physicist or physicist of any kind, but I have some basic grasp of how the universe works and after thinking long and hard about time travel, I don't think we have to worry about the paradoxes which are inherent to time travel when time traveling into the past. If we are to...
  38. C

    Absolute Zero and time travel?

    I've been told that as a person approaches the speed of light, time relative to others being viewed slows. when you make the speed of light ( if possible, I’m aware of distance change and mass increase and of the immense amount of energy needed to possibly reach this speed to push that mass)...
  39. G

    Exploring Time Travel: Physical vs Mental Effects

    I think I know why we can't time travel backwards. I have been researching like mad at my skool and I think i have the answer. If I'm wrong, PLEASE tell me. This is for a research paper, and I am trying to navigate my way out of the math and stuff: We are in the present, while physical...
  40. D

    Where does time travel fastest? And a moving galaxy/light speed question.

    Hello, I’ve been browsing these forums for a while now; I like physics and I get really interested in all sorts of physics stuff. My main interest is space because I find it really fascinating. I have two questions that I’ve been curious about for a while now; The first question is about...
  41. M

    Exploring the Possibilities of Time Travel

    Hello everyone, I am new to this forum and would greatly appreciate your expertise in answering (or attempting to) a few questions for me. I don't care if you focus on one or all of them, but any answers are appreciated! These are about time travel, with a focus on traveling BACK in time...
  42. M

    Time Travel: Will it ever be possible, how soon, how far, etc.

    Hello everyone, I am new to this forum and would greatly appreciate your expertise in answering (or attempting to) a few questions for me. I don't care if you focus on one or all of them, but any answers are appreciated! These are about time travel, with a focus on traveling BACK in time...
  43. A

    Does moving at high speeds actually slow down time?

    the basic theory is that if you travel fast enough then time will go slower for you then the rest of the universe. doese anybody know if this is true or not?
  44. Q

    Can Future Generations Really Travel Back in Time?

    Note: For copyright reasons, I'm trimming the original post, which appears to be a direct quote from http://news.yahoo.com/s/livescience/20070820/sc_livescience/timetravelmachineoutlined Also, the peer-reviwed article is at...
  45. Ivan Seeking

    Time travel discussion with Ron Mallet tonight

    Dr. Ron Mallett shares his research into time travel. http://www.coasttocoastam.com/ This is highly controverial, and my understanding is that it has been shown that his solutions are not valid. A PF discussion about this: https://www.physicsforums.com/showthread.php?t=147946
  46. D

    Exploring the Possibility of Time Travel

    does anyone thinks time travel is possible?
  47. O

    Cramer's time travel experiment

    There was some publicity recently about John Cramer not being able to get funding for an experiment that he claims could prove "retrocausation" or backward time travel. I'm confused as to what the experiment is supposed to show. Cramer seems to be saying the outcome will depend on whether or not...
  48. M

    Exploring the Twin Paradox: General Relativity & Time Travel

    How many of you over here are familiar with the twin paradox? I am personally quite fascinated with this phenomenon predicted by General Relativity. In a nut shell, since your relative time slows down at speeds close to the speed of light, it implies that if, say, your twin brother were to go...
  49. C

    Time Travel using the gravitational field of a circulating light beam

    I saw this paper on time travel. Does anyone think its plausible?http://www.physics.uconn.edu/~mallett/main/research_activities.htm
  50. vincentm

    Quantum Entanglement and time travel

    I'm not buying this for reasons of paradoxes, but Brian Greene is saying that time travel backwards is possible. Source what do you guys think?
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