Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Time dilation

  1. Apr 27, 2013 #1
    what is the exact mechanism by which time dilates for a fast moving object.
    Can the time dilation be explained by any other theory other than relativity.
     
  2. jcsd
  3. Apr 27, 2013 #2

    tiny-tim

    User Avatar
    Science Advisor
    Homework Helper

    welcome to pf!

    hi lakshminarayan! welcome to pf! :smile:
    there is no mechanism for time dilation

    there's only the geometry, of space-time
    Nope! :smile:
     
  4. Apr 27, 2013 #3

    phinds

    User Avatar
    Gold Member
    2016 Award

    It is an observational effect, not a local one. The moving object does not experience time dilation. Right now, as you are reading this, you are MASSIVELY time dilated from the frame of reference of a particle in the LHC because relative to it, you are traveling at very close to the speed of light.. Do you feel any different?
     
  5. Apr 27, 2013 #4
    How can there be geometry to space time, if space time is infinite?
     
  6. Apr 27, 2013 #5

    Nugatory

    User Avatar

    Staff: Mentor

    Geometry is about the distances and directions between points. Whether the points are in an infinite space or not doesn't matter.
     
  7. Apr 27, 2013 #6
    But time dilation is a real phenomenon which has been tested. I might not experience time dilation, but I know time dilates for the moving object if I test it. How can it be relative when I know the result way before the relation is established between me and the moving object.
     
  8. Apr 27, 2013 #7

    HallsofIvy

    User Avatar
    Staff Emeritus
    Science Advisor

    You can't possibly know what time dilation is if you do not know how fast the object is moving relative to you.
     
  9. Apr 27, 2013 #8

    phinds

    User Avatar
    Gold Member
    2016 Award

    You misunderstand completely. Reread post #3
     
  10. Apr 27, 2013 #9

    Nugatory

    User Avatar

    Staff: Mentor

    If some observer is moving relative to you, will be able to calculate that observer's clock dilation - his clock will run slow relative to your clock.

    However, we could equally well say that the other observer is at rest and that you are moving relative to him - and then we will calculate that your clock is running slow relative to his clock.

    Both calculations are equally correct. This is a real phenomenon that has been observed and tested. (And before you ask which clock is "really" the slow one, google for "relativity of simultaneity").

    However, you'll notice that in both cases we are calculating the time dilation between a clock that is at rest relative to an observer and a clock that is moving relative to that observer. The entire calculation of time dilation depends on relative motion.
     
  11. Apr 27, 2013 #10

    ghwellsjr

    User Avatar
    Science Advisor
    Gold Member

    The best way I know to understand Time Dilation is to look at the geometry of the spacetime diagrams for a couple of Inertial Reference Frames (IRFs) depicting the same situation and using the Lorentz Transformation process to get from one IRF to the other. The situation we will consider is a clock that is stationary in the first IRF. The spacetime diagram is simply a plot of the position (or distance from the spatial origin) of the clock along the horizontal axis versus time along the vertical axis. Here is the first diagram:

    attachment.php?attachmentid=55498&stc=1&d=1360334514.png

    Pretty boring, isn't it? It shows that as time progresses from 0 seconds to 10 seconds, the clock stays at the spatial origin with the coordinate at 0. I also show each second of time as a blue dot.

    Now we use the Lorentz Transformation to see how an IRF moving to the left at 60% of the speed of light would depict this same situation:

    attachment.php?attachmentid=55499&stc=1&d=1360334514.png

    In this IRF, the clock is moving to the right at 0.6c. You can see that because at the Coordinate Time of 10 seconds, the blue line is at the Coordinate Distance of 6 light-seconds. You can also see that what took 10 seconds in the first IRF takes 12.5 seconds in this IRF.

    Things take longer when they are moving in an IRF. And this is the simplest explanation of Time Dilation that I know of based on Special Relativity. Does it seem simple to you? If not, please let me know where you need some more explanation.
     
  12. Apr 28, 2013 #11

    russ_watters

    User Avatar

    Staff: Mentor

    "relative" does not mean unknown or unpredictable.
     
  13. Apr 29, 2013 #12
    Time dilation can be explained outside of the framework of relativity. There is even a mechanical explanation. If you assume that all matter is made of some form of electro-magnetic fields which can only propagate at c than you see that any circular process would come to a standstill if the corresponding system moves with c. Better said its clocks freeze.

    ob_cat
     
  14. Apr 29, 2013 #13

    Mentz114

    User Avatar
    Gold Member

    Matter is not 'made of some form of electro-magnetic fields', so that balloon won't fly.
     
  15. Apr 29, 2013 #14
    Impulse is force by time. It's normal, if you give impulse to a particle also you give it time. Moreover, when a particle receives impulse, mass and time are increased in the same proportion.
     
  16. Apr 29, 2013 #15
    No, but if it is possible to improve the understanding of relativity and what it describes.
     
  17. Apr 29, 2013 #16
    There are theories which explain matter this way. And that was the questions right? Those who have brains to think for them self can look into them and take their conclusions. I know of course that the standard model doesn't explain the structure of matter that way. In fact it doesn't explain it at all. So any theory which does should be welcomed to enriched our understanding of our particles structure. That doesn't mean that they are complete or without contradictions. But they exist and that is a truthful answer to the posters question, right?

    vb_cat
     
    Last edited: Apr 29, 2013
  18. Apr 29, 2013 #17

    Mentz114

    User Avatar
    Gold Member

    Where ? Can you give a reference ?
     
  19. Apr 29, 2013 #18
    interesting.
     
  20. Apr 29, 2013 #19
    This is one of them, not very complete but interesting nevertheless. That said one has to look for themself there are a lot of weird theories out there some have a few good ideas. These are not my theories I only point out that there are theories which of course do not fit well into the standard model.
    <<link deleted>> - the only one I can remember the link you need to google for more.

    lc_cat
     
    Last edited by a moderator: Apr 29, 2013
  21. Apr 29, 2013 #20

    phinds

    User Avatar
    Gold Member
    2016 Award

    La-la-land blogs do not count as valid references on this forum.
     
    Last edited by a moderator: Apr 29, 2013
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Time dilation
  1. Time dilation argument (Replies: 31)

Loading...