# Questions tagged [time-dilation]

This tag is for questions regarding the 'time dilation' which is the lengthening of the time interval between two events for an observer in an inertial frame that is moving with respect to the rest frame of the events (in which the events occur at the same location).

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### Does Mass Actually Displace Space-Time, or does Mass only Distort it?

1. Question Given the plethora of space-time illustrations, there is a sense that space-time is actually being displaced by mass, (planets). But on its face, this doesn't really make sense because ...
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### Could Space-Time Displace or Distort Itself? [closed]

1. Question Could space-time distort and displace space-time? If space-time can interact with surrounding space-time, then which ...
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### is $LT$ a Lorentz invariant?

We know the relations of time dilation and length contraction $$L=\frac{L_0}\gamma\\ T=\gamma T_0$$ If we multiply them together, we get $$LT=L_0T_0.$$ This holds for all $L$ and $T.$ So, is $LT=L'T'$ ...
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1 vote
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### Can black holes fully merge, according to a distant observer? [duplicate]

According to a distant observer, an object falling into a black hole doesn't disappear behind the even horizon but rather red-shift due to time dilation. Does the same apply to merging black holes? ...
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### Time dilation in Einstein's train example (lightning strike)

In Einstein's famous thought example involving a fast-moving train (say with a velocity of $c/2$), we assume that lightning strikes occur simultaneously at the front and rear end of the train as ...
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### Do satellites in orbit create Relativity paradoxes? [closed]

Can someone point out the flaw in this very realistic scenario below? I will start by stating established first principles of the applicable orbital and relativistic conditions. Then I will describe ...
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### How to properly combine kinetic and gravitational time dilation effect?

I developed a time dilation calculator that includes both kinetic (Lorentz Factor) and gravitational (Schwarzschild Metric Formula) factors to assess the time difference between Earth and satellites. ...
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### Do you always experience the gravitational influence of other mass as you see them in your frame?

You see a galaxy far away. That galaxy is attracting you with a certain amount of gravity. I'm wondering if the gravity influence of the galaxy on you, as measured by you, always ends up being what ...
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### Tug of war between observers in frames with different rate of time

You have a very dense hollow sphere of matter. Observer A is inside the sphere inside a rocket. Observer B is in an identical rocket outside the sphere where the ring's gravity is negligible. They are ...
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### Physical meaning of $vx/c^2$ in Lorentz transformation

In Lorentz transformation, this is the formula of time dilation $$t' = \gamma \left( t - \frac{vx}{c^2} \right)$$ It can be derivated from the formula of length contraction and be proved ...
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### John, in his spaceship traveling at relativistic speed, is crossing the Milky Way in 500 years. How many supernovae explosions would he experience?

John, in his spaceship traveling at a stable relativistic speed, is crossing the Milky Way in 500 years of his own time. How many supernovae explosions would he experience? From my reference frame on ...
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### How can I find the distance between planet and black hole?

With the movie Interstellar how I can find time dilation of the Miller's planet? Do I need find the distance between the planet and the black hole? Then I can find the time dilation? If not, please ...
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### Topological illustration of spacetime dilation: which function should I use for isometric lines spacing?

Scientific popularization, when it comes to illustrating spacetime dilation around massive objects, often relies on the description of a two-dimensional square-grid, which can be regarded as a cross-...
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### When it comes to getting closer to the Schwarzschild radius, how is discrete a limit?

From Keeton (2014) in Principles of Astrophysics: Using Gravity and Stellar Physics to Explore the Cosmos, Gravitational time dilation near a large, slowly rotating, nearly spherical body, such as the ...
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### Does time always dilate? [closed]

Consider a frame $O$ and a moving with speed $v$ relative to frame $O'$. By $(x,t)$ we denote the spacetime coordinates of a point. For two events $A, B$ happening in $O$, consider the following ...
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### Time function as a function of energy (from velocity and gravity)?

Is there any formula, preferably in terms of energy, for the time dilation an object experiences taking both relativistic velocity and mass into account? I see both formulas frequently, but haven't ...
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### If velocity is relative, why does time dilate for some observers and not others? [duplicate]

I'm trying to get my head around relativity and time dilation. What I can't figure out is how time can dilate for fast-moving observers if all velocity is relative. Here's a scenario: Alice and Bob ...
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### Failures on deriving the Lorentz factor: using light clocks to calculate the dilation on space and time

I wanted to check my understanding of special relativity and set up one experiment that could lead to deriving the Lorentz factor. Usually, the deriviation for the Lorentz factor is explained using a ...
1 vote
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### Calculating time dilation from a solution to the Dirac equation

Suppose I have a Muon in a potential well. Its wavefunction is a solution of the Dirac equation, a relativistic version of the Schrodinger equation for spin 1/2 particles. Because the particle is &...
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1 vote
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### How would a spacecraft travelling near light speed say 0.9c compensate for time dilation in radio communication from spacecraft to earth?

For a spacecraft travelling at 0.9 c for 5 seconds, only 5 seconds would have passed for an observer on Aircraft, while 26.31 second would pass for a stationary observer watching from Earth. In a ...
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### Gravitational time dilation correct assumption?

I have seen time Gravitational time dilation experiments measured using atomic clocks on airplanes, such as the Hafele–Keating experiment. The clocks aboard the airplanes were slightly faster than ...
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