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.

View More On Wikipedia.org
Recent contents Top users
  1. P

    Time dilation formula explanation?

    Can anyone explain how the time dilation formula works? T=t/(√(1-v^2)/c^2))... ... What does the 1 stand for? Why include it? Can you write down the process of the formula?... How does ((C*t)^2))/c^2-v^2 lead to the time dilation formula? Please explain the process.
  2. H

    Mathematical name of time dilation curve

    In mathematics, what is the name (type) for a curve given by velocity and time dilation? Specifically, I want to find a name for the curve y=1/(1-x^2)^{1/2} This curve is derived from the equation of a unit circle (x-a)^2+(y-b)^2=r^2 where y=(1-x^2)^{1/2}
  3. I

    Muon Time Dilation: Exploring Earth's Perspective and Resolving the Muon Paradox

    when muons are created in the atmosphere and fall to Earth the Earth clock runs faster. Thus, the "slower" muon clock allows more of them to reach the Earth's surface. But from the muons' perspective, the Earth is moving towards the muon. Shouldn't the muon's clock run "faster" and there should...
  4. Art_Vandelay

    Time Dilation with Two Spacecraft

    I want to write a science-fiction story concerning the rapid increase in technology affecting the speed at which spacecraft travel and passengers age (relative to each other). Theoretically, would it be possible that a son leaves a certain time (a number of years) before his father to...
  5. O

    On the question of experimental evdidence for 'real' SR time dilation?

    Do experiments like 1971's Hafele & Keating show that SR relativistic effects of time dilation are not mere products of measuring symmetry? Does such an experiment show that for the jets it is their clock that has kinematic time dilation in relation to the other clock that 'remains'...
  6. Greg Bernhardt

    Time Dilation Definition: What is Time Dilation?

    Definition/Summary Time dilation is the factor by which an inertial observer measures another observer's clock as going slow. Time dilation is composed of two factors: 1) a relative factor of \sqrt{1\ -\ v^2/c^2} for Lorentz time dilation, which depends only on the velocity of the clock...
  7. C

    Atomic Vibrations & Time Dilation: The Reality Behind Our Perception

    We measure time based off of atomic vibrations, so time dilation from gravity and velocity are nothing more than pressure applied to the atoms, slowing their vibrations. This isn't an accurate measure of what we consider time, but more of a measure of the reaction of atomic vibrations under...
  8. O

    Is Time Dilation Relative in Special Relativity Experiments?

    If velocity is relative and if we cannot say which is moving away from what *objectivley, how do we say that time dilation is relative as well if we can tell who experienced the time dilation, as special relativity shows - and other experiments (muon concentrations etc). For example the jets...
  9. F

    Time dilation measurement and events

    Hello Forum, An event is a point in spacetime with spatial coordinates and a time coordinate: (x,y,z,t). An event does not have a duration since it only lasts for an instant t. We can talk about time duration to mean the temporal separation between two different events, correct? In the...
  10. Tranceform

    Does Time Dilation Affect Observations in Baseball?

    Homework Statement A baseball player at home plate hits a pop fly straight up (the beginning event) that is caught by the catcher at home plate (the ending event). Which one or more of the following obeservers record(s) the proper time interval between the two events? (a) A spectator sitting...
  11. S

    Gravitational Time Dilation and Age of Astronaut

    Hello Everyone, I am new to this forum. I understood from sources that space-time is like a fabric. The massive bodies bend the space around it, hence the gravity. If time is 4rth dimension, so, the space is bent in time due to mass. that pretty much explains stopping of time in black holes as...
  12. W

    Time dilation and curved space

    I am trying to get an understanding of general relativity one tidbit at a time. I have a vague concept of why curved spacetime causes the effect we call gravity. However, there's an aspect of it (ok, there' are quite many aspects of it, but I'm concentrating on this one right now) that I can't...
  13. R

    Muons: Why time dilation takes precedence?

    I was browsing through old threads and a user named universal_101 kept asking about why we can use muons as a direct measurement of time dilation but only an indirect measurement of length contraction. It was pointed out that the two go together and cannot be separated, but it got me thinking...
  14. J

    Time Dilation of Charged Particle "p

    Picture: - - - ---------------------------------- p -> ---------------------------------- + + + Positively charged particle "p" is initially moving to the right between two capacitor plates. Is the...
  15. Rookie

    Time Dilation, Spaceship Problem

    Homework Statement A spaceship has traveled for 14 years at an average speed of 90% of the speed of light. Its round trip from Earth has taken 14 years according to clocks on the ship. (a) How long has the journey taken according to Earth clocks? Homework Equations t = t’ / (1-v2/c2)-1/2The...
  16. A

    Special relativity time dilation question

    Out of interest I'm studying a book "A first course in general relativity" which is a great book in my opinion because it explains the subject very well. I'm a beginner though and I have a hard time understanding one particular thing mentioned quite early in the book. I'm attaching a scan of a...
  17. J

    Kinematic time dilation in black holes

    Black hole A moves at slow velocity, and there's an Einstein light clock hovering near the event horizon. Black hole B moves at high velocity, and there's an Einstein light clock hovering near the event horizon. The black holes are identical. And the light clocks are at the same...
  18. T

    Does Time Dilation Really Happen?

    I will just describe a common thought experiment to do with special relativity and a question I have about it. Note this question only applies to the realms of SPECIAL relativity. Imagine a scenario in which there are 2 spaceships A and B. Each spaceship has its own clock. Spaceship B moves...
  19. J

    How Does Gravitational Time Dilation Affect Human Physiology and GPS Technology?

    Hi people, please could someone enlighten me on gravitational time dilation. I have read online that some places, such as neutrons stars, warp time so much that time can pass 100 times slower than it does on Earth. I was just thinking about a human heart beating. If a healthy heart rate on Earth...
  20. A

    Distance dilation and length contraction

    I am trying to get another insight in what I think is currently for me a contradiction. I have searched the forums, and the web but come to the following assertion: The coordinate distance is the computation of the proper distance times the gamma-factor, while the "coordinate" length is a...
  21. J

    Length contraction/time dilation mutually exclusive?

    Hello Physics Forums! I'll try to cut right to the chase. I'm studying both length contraction and time dilation in my physics class and it seems these two occurrences are mutually exclusive. That is, in any given situation, only time will be dilated or length will be contracted. This doesn't...
  22. A

    Are length contraction and time dilation conventions?

    Since many authors call simultaneity between events a convention, and that under the specific set of rules we may choose a convention or a coordinate system relative to an IRF (or non-inertial) to describe space time, I wonder what's the relation between this and the effects of length...
  23. R

    Resolving the Twin Paradox: Clock Readings on Space Ships in Relative Motion

    This has bothered me for a long time. I understand that time varies with velocity relative to the observer. But what about this case -- Suppose we have 3 space ships: A, B, and C. They are spaced widely apart with B in the middle and A and C at opposite sides to B. A and C are moving towards...
  24. G

    Did I experience time dilation or something?

    So, I am learning about atomic clocks. I went to this website: http://tycho.usno.navy.mil/simpletime.html And I started watching the atomic clock on that website tick away. It was ok and cool. At the moment, the website is frozen with "Loading..." for each time zone. When I started...
  25. D

    Near black hole event horizon time dilation?

    Lets say we have a couple objects, one very close to a black hole, one a little farther out and then one a good distance away. Would the one very close to the black hole see the other ones time moving much quicker than their own time? How about just as they are going to hit the event horizon...
  26. NATURE.M

    Need Clarification for time dilation effects

    So basically, my physics class has begun focusing on SR. And i just wanted to clarify something. I have been referencing: http://physics.mq.edu.au/~jcresser/Phys378/LectureNotes/SpecialRelativityNotes.pdf On page 23, it states "A clock will be observed to run at its fastest when it is...
  27. A

    Time dilation, length contraction and relative simultaneity on Earth

    The three main effects of SR occur in inertial frames and change the description of space-time relative to a particular observer. My question here is how do these effects occur on Earth, since we know that motion on Earth is non-inertial. I know that we travel at small speeds and that we can't...
  28. T

    Time dilation, is this correct?

    I just watched a video that kind of warped my understanding of time dilation. It said that not only would time appear slow from the point of view of someone standing still looking into something going near the speed of light but if you were going near the speed of light things that are...
  29. A

    Rotating object time dilation

    As I've red, different points on the rotating disk, or rotating object have different velocities and so they should time dilate differently. Points on equator are for instance quicker than those in Scandinavia. When we take an inertial frame that has zero velocity with respect to the Earth as a...
  30. rjbeery

    I GR as a Graded Time Dilation Field in Euclidean Space?

    The title says it all, really. Are we able to describe GR in terms of a Graded Time Dilation Field in Euclidean space? From http://cpl.iphy.ac.cn/EN/Y2008/V25/I5/1571 we can see that light curvature can be analogously described via a material with a graded index refraction, so my question is...
  31. W

    Derivation of formula for time dilation

    I know how to derive the lorentz time dilation equation. I am wondering how to derive the equation for gravitational time dilation: T=To(1/(sqrt(1-(2GM)/(Rc2)))
  32. O

    Find total E of muon using time dilation

    Homework Statement An Ω- particle has rest energy 1672 MeV and mean lifetime 8.2*1011 s. It is created and decays in a particle track detector and leaves a track 24 mm long. What is the total energy of the  particle? Homework Equations E=\frac{mc^2}{\sqrt{1-(\frac{v}{c})^2}}...
  33. S

    Confusion about time dilation and length contraction

    Hi all, I tried searching for this but failed to find an answer to my question. I am having an issue with properly interpreting the equations for time dilation and length contraction. Let's assume that I am standing still and a train is passing by next to me (moving with uniform velocity). Let...
  34. Buckethead

    Is acceleration the same as gravitational time dilation?

    It seems that time dilation does not occur due to acceleration alone. It surprised me to learn this due to the equivalence principle as I was under the impression that one could not experimentally know the difference between being accelerated in space and being at rest in a gravitational field...
  35. C

    Time Dilation: An Overview of an Experiment

    Hello, It is my understanding that in the case of two observers (A and B) passing each other at high speeds that due to time dilation observer A would be moving in slow motion with respect to observer B, whereas observer B would be moving in slow motion relative to observer A (i.e. each...
  36. G

    Uncovering the Mystery of Time Dilation in Mechanical Watches

    I am currently taking an undergraduate modern physics course that offers a brief overview of relativity. Let us consider a scenario where we have one clock on Earth in a rest frame, and one clock traveling in space at a constant speed v. we have some sort of mechanism for viewing the traveling...
  37. R

    Trying to understand time dilation better

    I'm only an amateur enthusiast when it comes to physics and have no background in science at all. It's just something I enjoy thinking about. One thing I am really finding difficult to get my head around is how time dilation works. So I've put a thought experiment below and would appreciate it...
  38. R

    Time Dilation Observed in Relative Frames: A Simple Question

    There are only two frame moving relative with each other at certain velocity. One frame see the other going right and the other to the left. Isn't it contradict that each see the other time running slow and both are correct? And this isn't the case , where one twin leave Earth and each see...
  39. S

    Time dilation on fast massive objects

    The popular thought experiment states, that if of two identical twins one is left on Earth an the other is embarked on a spaceship and sent into open space at near-c velocity, time for the traveling one will pass slower than for the one left on earth, due to the speed. On the other hand, time...
  40. M

    How Does Time Dilation Affect Pion Decay in Particle Physics?

    The proper mean lifetime of ##\pi## mesons(pion) is ##2.6x10^{-8}s##. Suppose a beam of such particles has a speed of .9c. a) What would their mean life be as measured in the lab? b) How far would they travel(on average)before they decay? c)What would your answer be to part (b) if you...
  41. M

    Time Dilation and Length Contraction

    I had a quick question about Time Dilation and Length Contraction. Are the two just different ways of measuring/describing the same effect? Or rather they both follow as a consequence from one another? i.e. I can find how much a length is contracted by finding the dilated time interval and...
  42. V

    Is there a known parametrization for time dilation in the FLRW metric?

    Hi, could anyone help me out? The FLRW metric in spherical coordinates is: \;\; ds2 = dt2 - a(t)2(dr2 + r2dΩ2) \;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\; (1) I am considering a similar metric of the format: \;\; ds2 = \frac{1}{a(t')^{2}}dt'2 - a(t')2(dr2 + r2dΩ2)...
  43. C

    Time Dilation: Current vs Massless Universe

    Disclaimer: I have no formal education in physics. I watched a TedTalk http://www.tedxamsterdam.com/video-wubbo-ockels-on-time-and-gravity/ and it got me thinking. Dangerous, I know. As I understand both velocity and gravity have an effect on our perception of time. How much does our...
  44. G

    Kinematics of Relativity: Deriving Dilation Time

    I'm about to ask derivation of dilation time in terms of Special Relativity. I saw explanations in Introduction to Classical Mechanics by David Morin that dilation time is formed by assumption that light speed is absolute refers to all inertial reference. He derived it by comparing 2...
  45. GeorgeDishman

    Gravitational time dilation for a spherical body of finite radius

    I am considering the gravitational time dilation at the centre of a spherical, non-rotating body (such as the Earth). The usual formula for gravitational time dilation is √(1-r_s/r) where r_s is the Schwarzschild Radius and r is the radius of the clock compared to one at infinity, however, this...
  46. H

    Understanding the Twin Paradox in Time Dilation

    Hello! I am currently learning the theory of relativity, but have a hard time understanding the time dilation concept. In my example down here, the subscript “A” will be used to denote “in the frame of reference of observer A”; the subscript “B” will be used to denote “in the frame of...
  47. S

    Time dilation to go a specific distance

    Traveling on a spaceship to Alpha Centauri A, 4.37 light years away, at a velocity of 0.92 c, if you just calculate the time by dividing the distance by the velocity: t = \frac{d}{v} = 1.496 x 10^8 sec = 4.74 years Is this the time from the Earth reference frame? Then the time on the spaceship...
  48. N

    Time Dilation Effects of Hypothetical Zero Gravity Pocket

    If you could create a small space on Earth in which a person could fit that was totally unaffected by gravity, or that was sheltered from the gravitational affects of external sources of gravity, what sort of affect on time dilation would be observed? Both for the person in the pocket, and for...
  49. S

    Time dilation and uniform circular motion

    Hi, I've taken a course in SR and studied GR on my own, but I do not know how to solve problems of this type. This is just purely for fun, not homework related at all. A particle of mass m is moving on a circle of radius R at constant linear velocity v = .8c. If the particle makes N...
  50. B

    What is the use of time dilation.

    I mean the application,such as because of the time dilation, humans can observe some particles which don't have long lifetime,and know it
Back
Top