What is Dilation: Definition and 1000 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. W

    Space ships turning+time dilation

    I am planning a hard-ish science fiction novel and I was wondering about space ships turning when going at extremely high speeds (in my case .33c). My question is can ships going this speed turn without sending the crew through the windshield so to speak? If its a stupid question let me know...
  2. N

    Time dilation and lorentz transformation

    i have a quick question, that is according to the lorentz transformation, the moving frame will have the longer time than the frame in the rest. so is that means if I'm on a moving car for my whole life, my time will greater than those who are in the rest relative to the earth?
  3. S

    Time Dilation: Triplet Paradox makes no sense

    Triplets, three boys. Assume all this happens on the same day and at the same time. Boy A: leaves Earth in vessel going .9c in zig-zag directions for thirty days. Returns to earth. Boy B: leaves Earth in vessel going .9c but goes in straight line (15 days), turns around and returns to Earth...
  4. B

    Gravitational time dilation from the metric

    How does one go about finding what the gravitational time dilation is from the metric? Is it simply t'/t_0=1/\sqrt{g_{tt}}? It seems that could be true for static metrics, but perhaps not more dynamic ones like the Kerr metric. My confusion on this arises on how to treat the time cross terms...
  5. X

    Gravitational time dilation in the center of a mass

    Hi, I understand that according to general relativity the time dilation experienced due to gravity gets more significant the more you go down in a gravitational well, so the maximum should be at the center of the mass. But I can't really rhyme that idea with the idea that the time dilation has...
  6. E

    Do GPS Clocks Really Run Slower Than Earth Clocks Due to Time Dilation?

    I had such success with all your answers to my last SRT question here I’ll try another. The LT seems very symmetric. To the observers in each frame, the other’s clocks appear slower, etc. Is that true for out GPS satellites? If we ignore the GRT effect of speeding up their clocks, I think it is...
  7. V

    Time dilation and length contraction

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  8. A

    Gravitational Time Dilation and Twin Paradox ?'s

    Disclaimer: I am relatively illiterate on the subject so please try to keep explanations generally understandable. Aerospace undergrad programs get zero exposure to relativity I suppose. [Gravitational Time Dilation] First I want to know if I am correct in saying that the gravitational...
  9. P

    Does the Starting Point Influence Time Dilation Observations?

    There is a spaceship moving close to c on a journey to a planet. The observer on the planet, sees through his telescope, that the clocks on the ship appear to be running slower than on the planet. The observer on the ship, sees the clocks on the planet appear to be running faster than on the...
  10. R

    Time Dilation in Spinning Cylinder Room: Can We Break the Speed of Light?

    In the spinning cylinder room example mentioned in relativity, where the nearest distance between 2 point is actually curved line.. and light take a straight pass right, which is farer than the curved line due to time dilation in the middle of the room due to a smaller acceleration than side of...
  11. C

    Can someone confirm that this is how time dilation works?

    I'm not sure if the way I understand it is correct or if it is slightly inaccurate, so I will just write it as I understand it and hope you can all my point out my errors. As I understand it, there are 4 dimensions. 3 of space and 1 of time (first question. Is time actually considered an extra...
  12. B

    Basic Special Relativity (Time Dilation)

    Homework Statement The Concorde traveled 8000km between two places with an average speed of 375 m/s. What is the time difference between two atomic clocks, one on the train and one at rest with respect to the train? Homework Equations T=AT' where A is the Lorentz gamma factor The...
  13. I

    Time Dilation: Can You Chase Something Too Fast?

    Forgive me if this has already been asked as I'm trying to understand this, but I can't seem to find the right info.. Basically, what I want to know is if it is possible to chase something so fast that you won't catch it due to time dilation. If an object is traveling at a low sublight speed...
  14. W

    Relativity problem solving help time dilation

    Relativity problem solving help! time dilation http://courses.physics.illinois.edu/phys225/sp2013/homework/225-hwk01.pdf Please click on the top link ^ to see the questions. I have already solved them and turned it in, however i would like to see how others would approach the questions and...
  15. L

    Time Dilation- Atomic clocks

    Homework Statement Two atomic clocks are synchronized. One is placed on a satellite which orbits around the Earth at high speeds for a whole year. The other is placed in a lab and remains at rest with respect to the earth. You may assume both clocks can measure time accurately to many...
  16. B

    Gravitational Dilation of Time

    Im having trouble understanding the gravitational dilation of time concept. I know its states that time go slower on higher gravitational potentials and i know it has to do with light loosing energy (decrease in frequency) as stated in Stephen Hawking's Book "A brief History of Time". How does...
  17. A

    Time Dilation vs Differential Aging

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  18. A

    Calculating Time Dilation of a Rocket.

    Homework Statement The problem was asking to find the time dilation of a rocket traveling upwards at 100,000 m/s with the reference point being Earth for a duration of a day. Homework Equations 1/√(1-(β^2)) Δt = γΔt' The Attempt at a Solution I've calculating gamma to be...
  19. Y

    Gravitational time dilation and special relativity time dilation

    Looking at the two equations for time dilation they seem very similar $$t_{surface} = t_{space} \sqrt{1-\frac{2GM}{rc^2}}$$ $$t_{moving} = t_{observer}\sqrt{1-\frac{v^2}{c^2}}$$ I was hoping someone could explain more how they are connected? I'd like to think that a fast moving object...
  20. A

    Why is Time DILATION Called Time DILATION?

    I would like to know why it is called time DILATION and not time CONTRACTION?
  21. T

    Exploring Time Dilation: From Twin Paradox to Maximum Speed of Future Spaceships

    Has any experiments been done equal to this scenerio where the twin leaving Earth and seeing Earth time dilated.. but when the twin reverses and returns to earth, the Earth speeds up or go in fast motion? If time dilation is slowing down.. what is the term for time speeding up? Also what...
  22. Buckethead

    Hafele and Keating time dilation question

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  23. A

    Physical explanation of velocity time dilation

    In SR, pure relative velocity between two observers causes a time dilation between them. It seems that if the two observers were at rest w.r.t. each other at some point in time, then the one who accelerates to achieve the relative velocity is the one who gets time dilation (i.e. comparatively...
  24. A

    Time Dilation & Length Contraction, Further Thoughts

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  25. T

    Time dilation in relativity of simultaneity related to twin paradox

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  26. coktail

    Time Dilation: Object slowing down vs Subject speeding up

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  27. P

    Relativity - Time Dilation - Solving for t

    Homework Statement A spaceship approaches Earth with a speed of 0.6c. A passenger in the spaceship measures his heartbeat as 60 beats per minute. What is his heartbeat rate according to an observer who is rest relative to Earth? 1. 48 beats per minute 2. 56 beats per minute 3. 65 beats per...
  28. M

    Exploring Time Dilation in Space Travel

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  29. S

    Q: "Time Dilation: Faster = Longer Wait?

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  30. C

    Basic Relativity Question (Time Dilation)

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  31. F

    Time dilation effects of relative velocity vs gravitational force?

    I've been wondering.. If a person (A) is, say, on top of Mt. Everest, he would be moving faster than a guy (B) at the foot of the mountain since A is further from the center of the earth, but he would also be experiencing a weaker gravitational force than B. So, for which of the invidividuals...
  32. D

    If light appears frozen due to time dilation, how do its fields fluctuate?

    I guess I have no problem with time dilation for stuff moving at less than c, but the step from less than to to c, is confusing me.
  33. S

    How fast must a spaceship travel to reach Alpha Centauri in 10 years?

    The distance to Alpha Centauri is 4,3 light years. How fast would a spaceship have to travel to get there in 10 years, according to the crew? The answer *should* be 0,395c. So far I've gotten all sorts of answers but not much close, so I seem to be approaching the problem the wrong way.
  34. Mordred

    Time Dilation vs Percieved age of Universe

    I've pondered a hypothetical problem Take as time perspective "A" as being relative time dilation of Earth Time dilation "B" being half of "A" slower due to relativistic effects. assuming both "A" and "B" were both formed at the same time say 5 billion years ago. If you were to...
  35. G

    Time Dilation: Travel from Solar System to Proxima Centauri

    If someone was to travel from the solar system to Proximi Centauri, I believe that from their point of view time would pass normally and regardless of how fast they were travelling, the speed of light would still be c. As I understand it, as the person traveling approaches c relative to Earth...
  36. 7

    Time dilation and Minkowski diagram

    After i figured out how to show length contraction in this topic. I tried to use a similar way to show time dilation in Minkowski diagram. Time dilation means that time interval between two events is the shortest in the frame in which those two events happen in same place. We call this frame its...
  37. A

    Is asymmetric time dilation in twin paradox possible in SR?

    I am trying to understand if SR can explain a real, measurable velocity time dilation as seen in experiments/observations like GPS satellite or Bailey et. al. Let us say we have twins sitting in their identical, individual spaceships in space, close to each other, and far away from any large...
  38. A

    GR time dilation from SR by EP

    As I understand it from what I have read the gravitational time dilation concept was arrived at through the equivalence principle. That the differential dilation at different locations in an accelerating system were derived from SR and included in GR by EP. But I have never encountered the...
  39. N

    Calculating Time Dilation at Half the Speed of Light

    Homework Statement At what speed relative to a laboratory does a clock tick at half the rate of an identical clock at rest in the laboratory. Give your answer as a fraction of c (speed of light) Homework Equations Δt=Δt'/√1-^2 The Attempt at a Solution My professor assigned this...
  40. M

    Does time dilation only affect matter that has mass?

    Does time dilation only affect matter that has mass? For example, A spaceship is 1 light year away from Earth at rest. It sent out a radio wave to Earth then travels at 99.99% of the speed of light. On Earth, from our perspective, we will receive that radio wave 1 year later but the spaceship...
  41. O

    Modern Physics Qs - Time Dilation & Relativity

    Q1. Time Dilation Question Homework Statement Three identical triplets leave Earth when they reach the age of 21, in the year 2121. Each triplet goes on a spaceship journey that takes T years, as measured by a clock in each spaceship. During the journey they travel at a constant speed v, as...
  42. S

    Questions relating to time dilation

    1. Is there anyway we can measure time without depending on or using light? If we can, what are they and do special relativistic effects still take place in "close to c" relative velocity situations by using this method of time keeping? 2. My second question relates to relative movement. Time...
  43. R

    Time Dilation and it's formula

    Hi, so I think I have a problem with how I am thinking about time dilation anyway here it is so if two events occur at the same position say light beam going up then back down and this occurs in frame S', this would be the proper time right? the interval between the two events. Now the...
  44. R

    Spacetime diagrams: ct axis and time contraction and length dilation

    Hi, this isn't really a homework problem... but I'm just wondering I see the time axis as c*t, now people say that its to scale the time axis so that the world line of light is 45 degrees. But if you were to multiply time by the speed of light, wouldn't you just get the units metres or...
  45. R

    What happen time dilation is videotaped?

    I am sure this question is a lot more elementary than a lot of other posts on here - I am definitely a layman rather than a specialist, so I hope this isn't a problem. My hypothetical question is this: Person A is standing directly on earth, looking at his watch (so moving at the same speed...
  46. M

    Misunderstanding something: circular time dilation loop

    Hi.. Speedo, flying in space, is at large speed compared to c relative to his brother on earth. Therefore, after a long time meeting at rest relative to each other, Speedo aged less than did his brother from his brother perspective. But from Speedo's point of view, his brother was also moving...
  47. A

    Time Dilation Comparison: Mass vs Speed

    Firstly does a typical massed object surely prone to both kind of time dilations in its lifetime?? Consider 2 cases.. Firstly a person on a heavily massed planet where his time dilation is due to mass of that planet and in other case same person moving at c/2 away from any significant massed...
  48. C

    Time Dilation and physical processes

    If you travel at a sufficiently fast speed, then according to relativity, you will age at a slower rate compared to your slower moving contemporaries. This implies that biological functions (say, of a person) and mechanical functions (say, of a machine) are literally functioning at a slower...
  49. B

    Which Train Explodes First in the Time Dilation Paradox?

    Hi, I am new to this forum, and I wish I get some help here. I really can't find any solution to this paradox; I am going to deny all the special theory of relativity because of this. The paradox is very simple, here it is: Consider two persons sitting on two adjacent trains at rest...
  50. T

    Time Dilation: Explaining Why Velocity of Light is Perpendicular

    Hello When we try to find a formula for time dilation, we think of a situation where the velocity of the other frame is perpendicular to the velocity of the light (http://en.wikipedia.org/wiki/Time_dilation) Why is this? I know if we try any other direction there is length contraction...
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