What is Time dilation: Definition and 999 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. M

    Relativity question involving time dilation

    Homework Statement A muon has a lifetime of 2.20 x 106 s when at rest, after which time it decays into other particles. A) Ignore any effects of relativity discussed in this section. If the muon was moving at 0.99 c, how far would it travel before decaying into other particles, according to...
  2. C

    Black Hole Time Dilation And Observation Of Accretion

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  3. SpiderET

    Some easier equotation for gravitational time dilation?

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  4. P

    Symmetrical time dilation implies relativity of simultaneity

    This is something I've been meaning to write for a while, I finally got the time to do it, though the topic isn't currently "hot". I'm sure it will pop up again, though. Imagine we have two observers, moving at a constant velocity relative to each other far away from any objects that might...
  5. E

    Distance from Black Hole to experience Time Dilation

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  6. thrush

    Time Dilation: SR Basics & Confusion

    Hi everybody, I'm learning Special Relativity, and probably ok with four vectors, the metric equation, the Lorentz Transform, and the Doppler shift, etc., but enough about me. I'm still a little confused about time dilation. In several hypothetical examples of SR that I have seen, two...
  7. L

    Time Dilation: Does Total Speed Matter?

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  8. Grimble

    Time dilation: speed relative to what?

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  9. E

    Time Dilation & Visual Observation of Black Holes

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  10. Michaelcomputer

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  11. DDov

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  12. D

    How does GPS correct for time dilation?

    Hi all,as I understand it, GPS satellites are offset prior to launch in order to correct for the time dilation that they experience in orbit. I am very confused about how this works in practice. I think the velocity of a GPS satellite wrt a position on Earth would depend on the position on Earth...
  13. julianwitkowski

    Time Dilation Effects on Observer Perception

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  14. 1977ub

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  15. S

    Time dilation in the field interpretation of GR

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  16. Rene Manzano

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  17. R

    Special Relativity WS#2 -- Earth-Pluto SuperShuttle line time dilation

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  18. S

    Do gravitational time dilation effects cancel out or add up?

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  19. THE HARLEQUIN

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  20. THE HARLEQUIN

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  21. I

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  22. L

    Would the Big Rip make time stop?

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  23. C

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  24. B

    Time Dilation Effects on a Probe

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  25. D

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  26. A

    Get confused about time dilation

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  27. E

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  29. Serious Max

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  30. dragoneyes001

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  31. abrogard

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  32. Einstein Devotee

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  33. W

    Exploring Gravitational Time Dilation & Event Horizons

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  34. N

    Time Dilation and Relative Time

    I was reading in Clifford M.Will's book "Was Einstein right? Putting General Relativity to the Test" that there was an experiment done where in October 1971 an experiment was done with radioactive clocks, and plane trips taken going with the spin of the earth, and against it. He reports: "The...
  35. L

    Why does time appear to slow down on a moving spaceship?

    Please forgive my ignorance in STO, but I don't understand something about the following thought experiment. Spaceship flies from Earth with large speed. We observe the clock inside the spaceship from Earth with strong telescope. We see the clock showing 12:00. When we see on the clock 12:05 (in...
  36. Palpatine

    Help Applying SR to Calculate Time Dilation

    I made this pic to illustrate my problem. A spaceship (labeled B) departs from a space station (labeled A) at 80% the speed of light (0.8c). A applies the time dilation principle and calculates that B's clocks are running slower than his. Some time later a smaller craft (labeled C) detaches...
  37. M

    Time Difference between two inertial frames of reference

    Homework Statement Let S and S' be two inertial frames of reference where S' is moving at a velocity of 0.6c relative to S. When x = x' = 0, t = t' = 0, where t and t' are time of the clocks on S and S' respectively and x and x' are the x-coordinates of the S and S' frames respectively. An...
  38. C

    Lorentz Transformation - Clock

    Homework Statement Use the Lorentz Transformation equations to derive the formula relating the time period of a moving clock to that of a stationary clock Homework Equations X'=y(X-vt) Y'=Y Z'=Z t'=y(t-vx/c^2) The Attempt at a Solution t'=1/sqrt(1-(v/c)^2) . (t-vx/c^2)
  39. H

    Time Dilation at Near Light Speed: Answers to a Thought Exercise

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  40. CaraKboom

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    I've been trying to get my head around time dilation in order to understand the relationship between space and time. I do not have a maths brain, I tend to understand things better as narrative concepts. I've read a lot of introductory material, but I'm having trouble making the link between...
  41. A

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  42. S

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    On a science test that I took the other day, one of the questions inspired me to ask a question of my own. The original question was a multiple choice question that went something like this: if someone shoots a gun horizontally and simultaneously drops another bullet, which one would hit the...
  43. Ganesh Ujwal

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    Why isn't length contraction permanent even though time dilation is? It's my understanding that when something is going near the speed of light in reference to an observer, time dilation occurs and time goes slower for that fast-moving object. However, when that object goes back to "rest", it...
  44. M

    Special Relativity and time dilation

    Homework Statement Two spaceships are traveling with a relative velocity of 1.2x10^8 m/s, both carrying clocks. According to the captain of each ship, the other captains clock ticks more slowly than his own. By what factor do the clocks disagree? Homework Equations 1/(1-(v^2/c^2))^1/2The...
  45. D

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    Let's say the gravity around a planet of mass M is accurately modeled by the Schwarzschild metric. Then an observer (A) at infinity sees a stationary clock (B) at distance R from the center of the planet being gravitationally time dilated by the factor ##\sqrt{1-\frac{2GM}{Rc^2}}##, i.e. if B...
  46. M

    Geometry of Time Dilation

    I was recently exploring time dilation from Gravity and from velocity and I came up with an interesting derivation that I have not seen before. I was wondering if there is a paper published showing these relationships like this before and where I could find it? First you start with the...
  47. ubergewehr273

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  48. L

    Can time dilation cause confusion in the twin paradox?

    Hi, In the often cited example of a person in a rocket traveling past Earth at high speed - I think I understand that both the person on Earth and on the rocket could view the other as being the party that's actually moving. And so if they could view the other party, they would both see the...
  49. H

    Time dilation - effect on clock or 'time' itself?

    I understand that this topic have been discussed many times, but I just haven't found the answer, at least one I could understand. I'm not a physicist, just curious. I've been reading all around the internet about time dilation and SR. I understand that time dilation is real, at least when it...
  50. O

    Gravitational Time Dilation: Observing Planet Life

    Hello , my question is : If we could observe a planet life so far away from the Earth with so much gravity that it makes time pass more slowly on that planet , what would we see? Like what can we say about motions of lifeforms living on that planet? Would they be moving in slow-motion in the...
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