What is Time dialation: Definition and 70 Discussions

In physics and relativity, time dilation is the difference in the elapsed time as measured by two clocks. It is either due to a relative velocity between them (special relativistic "kinetic" time dilation) or to a difference in gravitational potential between their locations (general relativistic gravitational time dilation). When unspecified, "time dilation" usually refers to the effect due to velocity.
After compensating for varying signal delays due to the changing distance between an observer and a moving clock (i.e. Doppler effect), the observer will measure the moving clock as ticking slower than a clock that is at rest in the observer's own reference frame. In addition, a clock that is close to a massive body (and which therefore is at lower gravitational potential) will record less elapsed time than a clock situated further from the said massive body (and which is at a higher gravitational potential).
These predictions of the theory of relativity have been repeatedly confirmed by experiment, and they are of practical concern, for instance in the operation of satellite navigation systems such as GPS and Galileo. Time dilation has also been the subject of science fiction works.

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  1. P

    How can time dialation cause gravity?

    Hi, I believe the general notion is that gravity is an effect caused by the warping of spacetime. I've read that clocks are running faster in Satellites by about 50 micro seconds per day (or 2 micro seconds per hour) compared with on the Earth's surface. As one moves from the Satellite...
  2. F

    Relating gravity to time through black holes and Gravitational time dialation?

    Right, it's been a long time since I've done anything physics related, and I've never been an expert to begin with, just a level standard, but was having a bit of a chat with a friend earlier and wanted to see if what we were saying makes any sense atall? We were having a bit of an...
  3. 0

    Time Dilation: How Much Fuel for 99.999999% of Speed of Light?

    If you where going to use a ship to go 99.999999% of the speed of light, for one hour of non dilated time, how much fuel would you carry? enough to keep your ship going for the amount of dilated time or non dilated time. (sorry for the badly worded question.)
  4. F

    Confusion between simultanety and time dialation

    Let events 1 and 2 occur at and in frame S. In frame S' they occur at https://www.physicsforums.com/latex_images/18/1880804-3.png https://www.physicsforums.com/latex_images/18/1880804-3.png [PLAIN]https://www.physicsforums.com/latex_images/18/1880804-4.png...
  5. rcgldr

    GR - time dialation at center of a planet

    The gravitational force is zero at the center of a planet, but the GPE is at a peak minimum (most negative). What happens to the time dilation factor inside the surface of a planet of uniform density versus at the surface of that planet.?
  6. P

    Moving clocks and time dialation question

    i'm revising for an exam and have this question posed (this isn't homework) what is the maximal velocity for a clock being transported from london to new york if the time difference to a stationary clock should be less than 10^-8 seconds. i'm not allowed to use calculators. i've tried...
  7. Gib Z

    Will clocks in space show the same time after slowing down?

    Imagine someone is traveling in space, very fast past me in a spaceship. We both observe each others clock's running slower than our own, and by the same rate as well, as our relative velocities to each other are equal. So say that spaceship slowed down to zero, and then the clocks were...
  8. P

    Who Ages Faster in Relativistic Travel?

    i have read about the experiment of people ageing slower when moving at velocity and don't quite understand. here's my experiment: two people, person A and B, start off in the same referance frame (both are, say 20yrs old). person A flies off in one direction and person B in another. they...
  9. P

    Understanding the Lorentz Time Contraction Equation

    Can someone give me a simple derivation of the ux/c^2 in the numerator of the Lorentz time contraction equation? u = relative velocity Why isn't the equation just (t-x/c)/gamma because of the time delay in light going from x to O. I am guessing because the source is moving away from O...
  10. 4

    How much does Earth's time dilation decrease with distance from the surface?

    Exactly how much does Earth's time dilation decrease with distance from the surface? I know that it's way to small to ever notice and probably even mesure with today's instruments, but I'm trying to calculate how many billionths or trillionths [or less] of a second a clock might run faster if...
  11. N

    Actual and observed time dialation

    I'm going to state that two inertial bodies that close distance on each other will (becouse of loss of simultaneity)observe time dilation. Also i will state that when one body accelerates it will actually time dilate from its frame of origin. So with this stated, if a rocket traveling under...
  12. R

    Can Time Dilation Be Used to Identify a Moving Frame of Reference?

    see the attchments Referring to fig 1 We have a clock that is used to set the time on a second clock. At point A is a laser. At B there is a photon detector. The laser at A fires a photon, shown as the red broken line. The photon makes its way from point A to point B. At A there is also...
  13. R

    Exploring Time Dilation: The Effects of Velocity on Time

    time dilation is a function of only velocity ie if you are traveling @ C in any direction time stops yes? Time dilation is not dependent on any other parameter other than velocity?
  14. E

    Solve Time Dilation: Get 24hr Solution in 105hrs

    [SOLVED] Time Dialation Help Homework Statement A bomb is placed on a space probe just before it's launched. The timer is set to trigger the bomb after exactly 24hrs. The probe travels away from Earth on a straight line at v=.9c. How long after launch will the observers on the Earth see the...
  15. J

    A question about time dialation

    I understand that clocks move slower as they approach c. I also understand that clocks move slower on more massive bodies. My question is are these two phenomena consistant and cumulative? For example. We have two masses of significantly differeing masses and both have clocks on...
  16. D

    Time dialation at Earth's center

    I understand that a clock on the surface of the Earth is observed to run more slowly than a clock in orbit or a clock "at infinity". What about a clock situated at the center of the earth. Would it be slowed because of the concentration of mass? Or would it run normal speed because there is no...
  17. D

    Does Earth's Rotation Affect Time Dilation Between Day and Night?

    hello everyone, to start off, I'm in no way a physics expert but I think I understand time dialation. for all of this, use the sun as a reference frame. I was reading a thread on here and I thought of something. I'm pretty proud of myself for thinking of this but I would like someone with more...
  18. A

    Understanding Time Dilation: How Fast Do You Have to Go?

    Hi I was wondering about how fast do you have to go before time dilation comes into effect P.S. I'am no Qauntum physics professor so I don't know a lot about relativity
  19. C

    Is time dialation really *time* dialation?

    I was reading some interesting articles at wikipedia on black holes and time dialation: http://en.wikipedia.org/wiki/Black_hole http://en.wikipedia.org/wiki/Time_dilation I remember this subject interested me greatly when I was in high school physics. I'm pretty rusty now, so bear with...
  20. M

    Time Dilation Formula: Calculating Rel Speed Diff b/w Objects

    could someone tell me the formula to figure out how much relative time speed difference there is between two or more objects of unequal mass?
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