# 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. ### I Can someone falsify this analogy contradicting time dilation?

A spaceship travels at the speed of light from the sun to the earth and back, infinite acceleration and deceleration. Sunlight takes about 8 minutes to reach earth. On the trip to earth, the sun seems to be frozen. On the trip back, sun activity appears to resume and is seen at 2x speed. The...
2. ### I From our reference frame, how would a black hole ever form?

Looking at Kruskal diagrams, it seems to me we should not be able to see evidence of black holes. Assuming our frame is a hyperbola of roughly constant ##r## in such a diagram, as the black hole's constituent mass comes together time slows (from our POV) to the extent that it never crosses the...
3. ### I Light Clock Relativity: Why Divide T_moving/T_stationary?

In special relativity I can get ## \gamma ## , ## \frac {T_B}{T_A}=\gamma ## Why do I not go ##{T_B} - {T_A} = \gamma## ? ##T_B = \frac {2H} {c^2 - v^2}## . ## T_B ## is the moving light clock. ## T_A = \frac {2H} {c^2} ## . ##T_A ## is the stationary light clockI assume LaTeX doesn't work...
4. ### I Time Dilation Paradoxes Near C: Exploring the Twin Paradox of Special Relativity

I'm struggling to wrap my head around the twin paradox in special relativity especially when dealing with multiple vectors. In my thought experiment say I have a set of twins. Both set out in opposite directions and intend to sling shot around two different black holes(luckily equidistant from...
5. ### I Time & Gravity in Rotating Faster Than Light?

If a person was rotating on a verticle axis from head to toe like the Earth or quasar. If nothing can go faster than light, from the person's perspective looking at the stars traveling across the night sky, if you increase the rotation of the earth, stars further than a certain critical distance...
6. ### I Can Black Holes Transport Mass Back in Time?

According to Einstien's theory of evolution, the closer to the speed of light that an object travels, the slower it appears to move to an outside observer. (see https://www.thenakedscientists.com/forum/index.php?topic=40951.0) To take this to the next step once an object crosses the event...
7. ### I Time Dilation: Does Gravitational Field Strength Matter?

Hi I have 2 questions. There are 2 planets and one clock on each of them. One of them has a bigger gravitational field strength. And two clock have same distance from the core. 1-) Does time dilation occur between two? Which clock ticks slower? 2-) If time dilation occurs, which formula...
8. ### I SR Time Dilation in Rigid Structure Clocks

Special relativity says that all clocks will show same time dilation, irrespective of clock mechanism. But Time period of a clock is a formula that must continue to hold even if time dilates. Let us look at a tuning fork clock. Here time period depends on the dimensions of the vibrating...
9. ### I Interstellar Travel Without Propulsion or Time Dilation

I hope this is the right forum for this question. Imagine alien tech allows them to travel 1 million light years to Earth instantaneously. No thrust, vector, propulsion was involved. They didn't have to approach the speed of light, with its attendant increase in mass. Having arrived at earth, in...
10. ### Simple Special Relativity Problem of Length Contraction

Hello, I'm self-studying Ta-Pei Cheng's Relativity, Gravitation and Cosmology. Problem 2.8 is the following: Two spaceships traveling in opposite directions pass one another at a relative speed of ##1.25 \times 10^8## m/s. The clock on one spaceship records a time duration of ##9.1 \times...
11. ### Special Relativity: Traveling to Regulus

Homework Statement A visit to Regulus is on my bucket list. However, it is 77 light years away. Assuming I will live only another 40 years, can I make it to Regulus? How fast would I have to travel (at constant speed) to get there in 40 years? Homework Equations t1 = t0...
12. ### B Relativity’s Effect on Consciousness

So there will be a few hypothetical in the original story here, but in the end ill wrap it up with what I believe are facts. My question, how does Einstien’s theory of relativity interact with consciousness? Let’s say I have a twin, he becomes a farmer and I become an astronaut. I go to space...
13. ### I Time Dilation: One Year in Jupiter = How Many Years on Earth?

If we assume I live in Jupiter and there is one year passed in my clock how many years passes in the earth? And how can I use that Equation in the attached?
14. ### B Why is interstellar travel so hopelessly difficult?

So, I have been thinking about TRAPPIST-1 and how far away that system is from us. It is 40ly away from Earth, according to our frame of reference. This is often put in a way that makes one think that even at speeds close to that of light, it will take almost 40 years to get there. The muons in...
15. ### Special Relativity -- two ships moving in one dimension

Homework Statement You approach an enemy ship at a speed of 0.5c measured by you, and the ship fires a missile toward your ship at a speed of 0.7c relative to the enemy ship. What speed of the missile do you measure, and how much time do you have measured by you and the enemy ship before the...
16. ### A Time dilation for the clock in the orbit

Suppose that we want to compute the total time dilation for a clock located in an orbiting satellite relative to the clock in our cell phone on the ground. Consider two different approaches below. 1. Use special relativity and compute time contraction due to velocity. Use approximation of...
17. ### B Solving Weird Time Dilation Question w/ Spaceships

I put the prefix as intermediate because I wasn't really sure how complicated of a question this is, I am currently a junior in high school... So basically if you were to have two spaceships with people the exact same age in them traveling at 99% the speed of light and they were traveling...
18. ### B How Does Time Dilation Influence Perceived Velocity?

Hello I have a question about how time effects velocity:So we have a car on Earth traveling 200m with 5 seconds we get that car moves 40m/s and 40x3600=144000 and 144000:1000=144km/h so car on Earth travels 144km/h now let's consider a that there is observer on spacecraft traveling 0.5c...
19. ### I Calculating Radius and Mass of Disc for Velocity 0.75C

Imagine a disc witch has a radius of R=1000m and a mass M=1000kg, this disc sits on an cube that is considered static it has no velocity in any direction whatsoever. There is a light clock with the length L=17.45240644m (approximately the same as the arc length for 1 degree on the disc θ=1)...
20. ### Does the bullet reach its target?

Homework Statement As outlaws escape in their getaway car, which goes 3/4c, the police officer fires a bullet from a pursuit car, which only goes 1/2c. The muzzle velocity of the bullet (relative to the gun) is 1/3c. Does the bullet reach its target according to Galileo? According to Einstein...
21. ### Relativity - Length Contraction Problem

Homework Statement You are watching a race between two space ships who pass you moving at different constant speeds. In your reference frame, both ships are the same length while moving. It takes the first ship 26.8 minutes to get to the finish line a distance 14 light-minutes away. It takes...
22. ### Can someone falling into a black hole see the entire future of the universe?

Hi. Alright, so I'm not extremely informed with matters regarding special relatively so I have some basic questions that I'd like to ask you guys. My first question is that for an individual approaching near light speeds, would slowly moving objects appear to be moving much faster? The person...
23. ### Time Dilation & Effects of Gravity: Exploring the Possibilities

[don't know whether i is the correct thread prefix, will change if requested/possible] Now I will start off by saying I'm only an interested lay person, and haven't studied this but was thinking about time dilation and it's correlative effects with gravity. Higher gravity, time slows down...
24. ### B Travel at 3,000,001 m/s: Time Travel Explained

would that person go into the future?why? also if i travel 1,000,000 m/s on Earth and my friend travels 20m/s per second on Earth would we experience 2 different time frame? so basically the second question is if someone travels a different speed than me on Earth whether the difference of speed...
25. ### Time Dilation Confusion: Need Help Understanding

Hello. I need some help understanding time dilation. So the idea is that moving clocks tick slowly. Say there was an observer A who, by his frame of reference, is stationary, and he sees an object B moving past it at high velocity. From what I understand, to A it would appear as if B's clocks...
26. ### What causes magnetic repulsion and attraction?

is magnetic repulsion and attraction is due to the bending of curvature of spacetime?
27. ### Time Dilation Effects of Warp Travel | 65 Characters

I was looking at Time Dialation a bit today and some of the experiments with it. Considering time goes approximately 1/3 as fast as normal, under 100% the speed of light, what would happen if you went past the speed of light with a craft capable of warping. Would it have no effect due to the...
28. ### Calculating moving speaker through two detectors

Homework Statement A speaker emitting sound at a frequency of 20 Hz is moving in the +x direction between two detectors. The speaker is moving at a speed of 30 m/s and the detectors are wired so that they flash red (λ = 700 nm) when the pressure is a maximum and green (λ = 700 nm) when the...
29. ### Calculating Rocket Velocity to Sun

Homework Statement An astronaut went to sun from Earth by a rocket. According to the clock in the rocket, the traveling time was 5 minute. What was the velocity of the rocket? ( Earth is 8 light minute away from sun) Homework Equations t = \frac {t_0}{\sqrt {1 - \frac{v^2}{c^2}}}The Attempt at...
30. ### 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...
31. ### Special Relativity Time Dilation Santa question

I am doing a presentation and want to make sure I'm not misunderstanding something very fundamental. My argument goes like this: t0 = ϒt Santa is moving very fast and from his point of view he is in proper time. This means that if it takes him t0 seconds to deliver a present, the amount of...
32. ### Time Dilation in General Relativity: Twins Paradox Explained

I have always been confused about time dilation in General Relativity. In the twins paradox, it is the traveling twin that ages slower. However, could you not just as easily say that it is the non-traveling twin that is moving away from the other? So why is it the traveling twin and not...
33. ### Time dialation effect on observed speed of light

Assume observer is located on the surface of the Earth with a small amount of time dilation due to gravity. There are two beams of light moving approximately parallel to the surface of the Earth at some moment in time and the reflection of the beam off some objects back to the observer is being...
34. ### Time Dilation on Spinning Atoms?

would time dilation occur if for example, i was making a hydrogen atom spin with the center of spin the atom? would time dilation occur? because it didn't really traveled distance... or, if so spin a muon, would it decay faster if i was to spin it in an incredible amount of speed? but then if...
35. ### Gravity offsetting Velocity's Time Dialation? Trouble Understanding

Hi All, I am new to these forums. I've been studying relativity in my down time at work and I am having a bit of trouble understanding why gravity doesn't offset velocity in the popular "aging/time travel" theory/scenario. I’ll explain: What I think I understand: The speed of light is...
36. ### Two Events in Special Relativity with on Time Dialation

Homework Statement A Nova is a sudden, brief brightening of a star. Suppose Earth astronomers see two novas occur simultaneously, one in the constellation Orion and the other in the constellation Lyra. Both nova are the same distance from Earth, 2.5 E 3 c.y (lightyear) and are in exactly...
37. ### Time dialation in different parts of a fast moving rocket

I have no idea if I am picturing this whole scenario wrong, so please hear me out and try to point me in the right direction. Anyways, say we have a fast moving rocket with a person in it. Lightning strikes a side of it. So the light traveling from the bolt to the person/observer is traveling...
38. ### Does time dialation cause mass reduction in GR?

I love Physics! I've been thinking about if... you were in a room with a window, bouncing a ball... and you were looking at another building where you could see a room with a person bouncing a ball, but ... their time was moving at half speed (Caused by gravitational time dilation only ( not...
39. ### Time Dialation and Biological systems

Can anyone prove that Time Dialation affects biological systems?
40. ### Light speed; time dialation theory and its age

Hi All.. I have a basic doubt in time dilation theory. As per time dilation theory, when an object moves with the velocity of light, then relatively its time becomes zero. In that case, light is traveling at 'velocity of light'. So for light, there is no age? Or I misconcepted time dilation...
41. ### Hypothetical question about time dialation

A spaceship has managed to accelerate to 86.6% of lightspeed. Focusing on special relativity would fuel consumption remain the same, better, or worse as opposed to traveling at non-relativistic velocities, what about breathable air? I understand that the rate of fuel consumption would...
42. ### Confusion with time dialation.

Reading Brian Cox and Jeff Forshaw's book "Why does E=MC2". They mention that satellites speed up with time, but, then reading Wiki it says the crew of the ISS experience the slowing of time. Which one is correct? I'm slightly confused. Both experience a weaker gravitational pull and high...
43. ### Time dialation when viewing across the universe

Hi. Just watched a Nova special with Brian Greene, "The Fabric of the Universe/The Illusion of time", describing significant time dilation when two frames are moving towards or away from each other at low velocities, when the two frames are separated by great distance. This left me with a...
44. ### Is the Distance Traveled by Light Affected by Time Dilation?

When you derive the time dilation equation, and you see the light move straight down in one frame and in the other frame you see it move on a diagonal because the object is moving. My question is in the moving frame when you use the horizontal distance to derive the distance that the...
45. ### Can time dialation really just be the slowdown of physical processes?

In special relativity physicists talk about time dilation, saying that as an object moves faster relative to another that its "clock" moves slower and therefore time slows down. Could it be fair to say that time doesn't actually slow down, but all matter and energy reactions slow down and...
46. ### Specific relativity Length Contraction and Time dialation question

Special relativity Length Contraction and Time dilation question Homework Statement Planet X is 18 Light Years from earth, A spaceship moving towards the Earth at a speed of 0.82C (Measured from Planet X) fires a series of 1.2 cm long and 2.1 gram mass (as measured by the pilot) projectiles...
47. ### Gravity time dialation and acceleration?

Good evening. After reading about the recently created record-breaking precision quantum clocks i got thinking about how gravity affect time. Suppose we have two clocks that are precise enough to register the gravity-induced difference of time rates at distances of a few meters up/down...
48. ### Will two clocks be synchronized after a period of time dialation?

As 2 time pieces are moving relative to each other in a non accelerated reference frame, they will both see the other as slow. As time goes on, the amount of observed error in the other clock will continue to grow greater and greater. Let's say that after a while both clocks are 10 hours ahead...
49. ### Schwarzschild Radius, Constantcy of Light speed, and Time Dialation

First off, I'd like to point out that I am by no means an expert in this area, and I am only doing some casual research as a personal interest topic, and have some further unanswered questions that I'm unable to find reasonable answers for. These questions are all inter-related, so I'll post...
50. ### Time Dilation: 1.25yr Trip at 2.40x10^8m/s

An astronaut is traveling at a constant speed of 2.40x10^8 m/s relative to Earth through space. according to timing devices aboard the space vehicle the trip took 1.25 years. how long did the trip last if measured relative to earth HELP PLEASE!