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

Time relative to speed?

  1. Jun 10, 2010 #1
    ok, im looking for some help, really confused. im also kind of talking out load a bit, but typing.

    Speed = distance / time
    i dont know how i thought of it, or if it is correct, (probably horrifically wrong), but, if time is relative to speed, if no distance is traveled, will time continue normally, as it is relative to speed.

    i mean no distance, as in none, which will require movement, as the planet is rotating, the galaxy moving through space, gravity is still in effect, etc. no distance will be covered, so speed will speed = time. now im very confused.

    can anybody make sence of my blithering an help explain anything about changing the rate of time. actually, thinking about it, this wouldnt work at all. now im off the scale of confusion.

  2. jcsd
  3. Jun 11, 2010 #2
    If s=d/t, and d=0, then s=0, but t could be anything.





    And so on.
  4. Jun 11, 2010 #3


    User Avatar

    Staff: Mentor

    That equation isn't about the passage of time itself, it is only about the time it takes for certain events to occur.
  5. Jun 11, 2010 #4
    oo ar! how did i not see that.
  6. Jun 11, 2010 #5
    As far as I know, time is one of the 4 Dimensions that never stops, whereas one may sit at a specific point in 3D space in some reference frame. Every point in space has a world line so there is always that "motion."

    The standard velocity = distance/time formula refers to the proper distance between two points (which is the same in all frames of reference divided by the time it takes to get there.

    I suppose it is possible to conceptually think of traveling at lightlike speed so the elapsed time from A to B would be zero but by the relativistic momentum equations, it is impossible to get to the speed of light and one would wlays remain in the timelike area of the time-distance graph.
  7. Jun 11, 2010 #6
    May i know what the other 3 dimensions are?
  8. Jun 11, 2010 #7
    i think its like a box, 1 dimension would be a point, two a line, & 3 are depth, hight & width.
    unless there different for complicated physics....
    the 4th is time, and i think einstein said theres 10 (or is it 11?) dimensions. gravity is thought to penatrate all of them, therefore it is so weak in comparison. (lol penatrates all of them). gravity is so weak in comparison, for example, the whole weight of the earth pulling down on a little fridge magnet, yet its being held up by magnetic force.

    i watch too much tv.
    feel free to correct me :D
  9. Jun 12, 2010 #8
    I was thinking of the ordinary cartesian x, y, z dimenesions (no matter what "angle" the frame of reference is in space. I know there is no absolute x, y, or z.

    As far as ten dimensions, that is way out of my pay grade.
  10. Jul 13, 2010 #9
    Time is distance as much as time is not distance. If there was no such thing as distance there would be no such thing as time as you would travel everywhere instantly. Hence time is always greater than distance.

    If time was less than distance time would start going backwards as you would complete your journey before you started it. The reason you can slow down time however in comparison to someone else is as follows.

    Driver a and b start a 100 km journey all variables remaining constant except speed. Driver a travels at 100 km/h and driver b travels at 50 km/h. For the time that driver a is travelling time slows down for him/her in comparison to driver b otherwise he would not be able to complete his/her journey in half the time.

    The first argument is driver a was travelling faster. Problem with that argument is that speed is simply time taken to travel a distance. Hence speed is not separate from time and distance because speed is time and distance. They are both the same.

    Second argument will again be driver a was travelling faster. Replace travelling faster with slowing down time and you have what speed really is. Slowing down time.

    A better example of slowing down time is the lesson I got in high school teaching that if I accelerated away from the earth in a radius at a constant rate for 200 years, upon arriving back the earth would have aged by 40,000 years. The reason is very simple. Because I was travelling distance in far less time than everyone else on the face of the planet time slowed down for me in comparison to everyone else on the face of the earth.
    Last edited: Jul 13, 2010
  11. Jul 13, 2010 #10
    In that equation time is inversely related to speed

    No, no ... time will continue normally anyway. Actually, time dilates with increasing speed relative to an inertial frame of reference using the moving object as the center of a second or moving FOR. There is no absolute inertial frame of reference. The original statement is true as depicted here [speed = distance/time] with reference to a frame of reference which is inertial. Any FOR can be chosen as inertial but once chosen, it must be "stuck with." Time continues in that FOR on and on, as well as any other FOR whether an object "stands still" in relation to that FOR or not.

    Speed does not equate to time as you stated. If no motion in that FOR, time still proceeds in that FOR even though the object in question may be "standing still" in that FOR.

    All the above relates to FORs that are NOT accelerating or decelerating. But, that's another story.

    I hope this answers your specific question.

    Last edited: Jul 13, 2010
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook