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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Time dilatation of a free falling observer [duplicate]

I have two questions about time dilation near a black hole. (I question) The relation $d\tau^2 = (1-\frac{r_s}{r}) dt^2$ between the proper time $d\tau$ of an observer near a B.H. and the time dt ...
Daniele Antonucci's user avatar
-1 votes
1 answer
37 views

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 &...
Kevin Kostlan's user avatar
1 vote
1 answer
86 views

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 ...
adarshsrivastva's user avatar
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1 answer
42 views

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 ...
hammond's user avatar
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1 answer
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Time observed in a clock when you start moving relative to it

There's an example given by Brian Green, https://www.youtube.com/watch?v=XFV2feKDK9E&t=17675s To be precise the example start at 04:56:00. In brief it is as follows: There are two persons Gracie ...
Ankur's user avatar
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1 vote
2 answers
125 views

Does infinite time dilation increase a photons energy to collapse to a black hole, and does it do the same for matter?

As I understand the mass of an object doesn't increase in a gravitational field according to general relativity. It just follows a geodesic, its worldline. Now imagine a small marble falling straight ...
Apsteronaldo's user avatar
-2 votes
0 answers
47 views

Symmetrical Time Dilation [duplicate]

I have lately been researching time dilation and relativity, and thought about this phenomenon: Take two people, Observer A, and Observer B, who are both carrying clocks. Observer A travels through ...
user392759's user avatar
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Symmetrical Time Dilation [duplicate]

I have lately been researching time dilation and relativity, and thought about this phenomenon: Take two people, Observer A, and Observer B, who are both carrying clocks. Observer A travels through ...
user392759's user avatar
-6 votes
0 answers
54 views

If time dilation is infinite at an event horizon, how can black holes expand or move in space? [duplicate]

General relativity seemingly both predicts and precludes the existence of black holes as we understand them. It's general consensus that time dilation at an event horizon is infinite relative to any ...
Max Karson's user avatar
3 votes
4 answers
784 views

Gravitational Time Dilation and the Apparent Speed of Light

It has been proven that time far away from Earth is faster than time on the surface of Earth, due to gravitational time dilation. (GPS satellites take gravitational time dilation to account.) Would ...
Michael Ejercito's user avatar
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Are quantum tunneling slow down by time dilation affected? [duplicate]

If i setup to clock to work at the same rate at stationary. The first clock operated on quantum tunneling. Setup electron to tunneling and repel another electron. Which acts as sensor. The second ...
Siwagorn Kidkarn's user avatar
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I have a theory on how maybe we can get out of the black hole. At least seems like it [duplicate]

So what I was thinking was that imagining you fell into a black hole and made past the event horizon and falling towards the center of the black hole. Now what I am assuming is that when you are ...
Hryday Saini's user avatar
-1 votes
4 answers
97 views

Does the speed of light determine how slow time can move?

Since moving faster makes time move slower. Does that mean that there is an absolute minimum rate at which time passes? If so. Is there also a maximum?
NewToPi's user avatar
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1 answer
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Observed time period in distant clock when moving towards it

Imagine, 2 persons ('A' & 'B') are 6 light years apart in space, stationary to each other and with no gravitation acting on anybody. Suppose 'B' starts his clock which also shows years, months and ...
Ankur's user avatar
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1 answer
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Effect of gravitational time dilation on a classic weighted pendulum clock versus a hybrid pendulum clock with a battery

A classical pendulum clock is powered by gravitational potential energy by weights. While a hybrid pendulum clock is somehow propelled by electric current. Both have the same pendulum swing as the ...
Apsteronaldo's user avatar
2 votes
4 answers
107 views

A thought experiment regarding special relativity [duplicate]

I am currently delving into the intricacies of Einstein's theory of relativity and striving to grasp its fundamental essence and implications. Your assistance would be greatly appreciated. Here's my ...
Kyriakos's user avatar
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2 answers
49 views

Observing an event horizon while approaching one

A thought crossed my mind that I realized was hard to conceptualize so I decided to simplify the question by putting it in terms of event horizons. If I am an observer approaching black hole "A&...
Diniden's user avatar
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2 answers
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Gravitational effects on a celestial body and the difference between a pendulum and a regular clock

Imagine a planet with the same properties as Earth, this time moving in an elliptical orbit around a heavy star of a large number of solar masses. Also imagine that the surface of this planet is as ...
Apsteronaldo's user avatar
0 votes
4 answers
136 views

How to apply the time dilation formula?

I am learning special relativity and still not sure how to correctly apply the time dilation formula. Take for instance the following example: A spaceship leaves earth and travels to Alpha Centauri 4....
MaoMe's user avatar
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0 answers
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Derive this gravitational time-dilation formula

How is the following gravitational time dilation formula from this Wikipedia article derived? $$T_d(h) = \exp\left[\frac{1}{c^2}\int_0^h g(h') dh'\right]$$ where $T_d(h)$ is the ''total'' time ...
Hans's user avatar
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1 vote
1 answer
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How does the mirror clock work in an accelerating spacecraft?

I recall Feynman explaining time dilation in a moving spacecraft using a clock which counts reflecting light. As I understand it, to a stationary observer the path the light takes is longer than it is ...
releseabe's user avatar
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-3 votes
1 answer
105 views

Why do we say kinetic time dilation requires velocity, not just speed?

Every formula and every discussion about kinetic time dilation uses Velocity (or we could say relative velocity). But velocity is a vector with both direction and magnitude. But it seems to me that ...
foolishmuse's user avatar
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4 votes
2 answers
278 views

Photoelectric effect under the influence of gravitational time dilation

If the energy of a photon increases under the influence of time dilation in a gravitational field, does this have an effect on the photoelectric effect? Does this mean that the photoelectric effect in ...
Apsteronaldo's user avatar
4 votes
5 answers
636 views

What can we accept in thought experiments in relativity?

Although title is more broad, and you are welcome to give examples, I will ask about why we accept certain things as acceptable in Einstein's thought experiments using a specific experiment: Consider ...
Mahammad Yusifov's user avatar
1 vote
0 answers
86 views

How does a curvature in time equate to Newtonian gravity? [duplicate]

I often read that a curvature in time (the rate at which clocks tick) near a massive object, is considered to be the source of Newtonian gravity. This got me wondering, does General Relativity use the ...
4D Menu Systems's user avatar
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1 answer
67 views

Doubt about the derivation for the formula of time dilation

If I imagine a photon being released from the plate below as soon as the plates start moving, shouldn't the photon hit the opposite plate a bit behind the point where it would have hit if the plates ...
Jojo cat's user avatar
0 votes
2 answers
211 views

What is missing in this gravitational time dilation derivation?

I am confused about one derivation of the gravitational time dilation. Consider a one dimensional time-independent gravitational field. Two clocks are at rest with respect to the gravitational field ...
Hans's user avatar
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0 votes
1 answer
96 views

Are astronauts really younger than the rest of us after their trips to space? [closed]

I have seen this commented in a million places on social media (see here as well as places like HowStuffWorks, Business Insider, and even Scott Kelly makes the claim in the Guardian. Their reasoning ...
Curious Layman's user avatar
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1 answer
65 views

Is the invariance of the 4-dim scalar product the fundamental law behind time dilatation and length contraction?

The Lorentz Group is defined as the group of all transformations that leaves the 4-dim. scalar product invariant. An implication of this definition is that the absolute value of the first matrix ...
Xhorxho's user avatar
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1 answer
147 views

How would time dilation near a rotating black hole differ to a non-rotating black hole?

Suppose that we have a non-rotating black hole with mass $M$. We know that the time dilation $\Delta t'$ at a distance $r$ to the center of the black hole is given by $\Delta t' = \Delta t \sqrt{1 - \...
Kenneth Kho's user avatar
1 vote
4 answers
147 views

Is constant acceleration the same relative to other objects at all velocities?

If you are accelerating at a constant rate of 10 $m/s^2$, will you see things around you move at 10 $m/s$ faster every second, even when approaching the speed of light? a) If not: How do you calculate ...
Zach's user avatar
  • 21
4 votes
4 answers
951 views

How does gravitational time dilation apply to observers in free-fall?

My question is whether an observer in free-fall about a massive object experiences the gravitational time dilation associated with that object. Apparently the answer is "yes it does". What I ...
john's user avatar
  • 87
-1 votes
1 answer
80 views

Relativity Time Dilation with a twist- Apparent Paradox [duplicate]

Imagine identical triplets on Earth: Ana, Barb, and Evelyn. Ana launches in a spaceship traveling .85c. She knows time on Earth is elapsing 1.9 times faster. A few months later, Barb launches in a ...
BobA's user avatar
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0 votes
0 answers
37 views

Is there a formula for gravitational time dilation at the cosmological scale?

There is a standard formula for gravitational time dilation used in eg the operation of the global positioning system. It is based on the integration of g(h) where g is a function relating ...
John Hobson's user avatar
2 votes
3 answers
880 views

What is the time dilation due to acceleration?

what is the formula to calculate time dilation due to acceleration. I have tried to search in google to find out the answer but I couldn't find any equation to calculate the time dilation due to ...
Arjun Raj's user avatar
0 votes
1 answer
67 views

Relativity of Simultaneity- Train Experiment with 2 Countries signing Contract

I am having a hard time understanding the implications of one of the popular variations of the thought experiments associated with Relativity of simultaneity. The example goes as follows. 2 countries ...
Tartaglia's user avatar
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-1 votes
2 answers
58 views

Time Dilation According to Stationary Object [duplicate]

Hello I am learning time dilation and I'm getting confused with some concepts: Consider the given scenario, in the frame of reference of the Earth an event takes 2 seconds to occur. In the frame of ...
import_hill's user avatar
1 vote
1 answer
164 views

Time dilation for different observer in black hole metric

If I have a 2d Schwarzschild metric $$ dS^2 = -(1-\frac{r_s}{r})dt^2 + \frac{dr^2}{1-\frac{r_s}{r}} $$ I want to find the relation between the time of an asymptotic observer $t$ and the proper time of ...
Physics Koan's user avatar
1 vote
0 answers
79 views

Photon speed for an observer at the photon sphere [closed]

I am asked to compute the orbital period of a photon, in the Scwarzschild spacetime, at the photon sphere for an observer at the same radius, $r^\star=3M$. I have computed the result, $\Delta T=6\pi M$...
Alexandre Zagara's user avatar
-3 votes
3 answers
175 views

How can a bullet at 99.9% speed of light hit a moving target? [closed]

Assume a bullet travels 99.9% the speed of light fired at a slow moving target. If an ant was strapped to that bullet, allowing enough distance, from the ants point of view time is moving much slower ...
Dan 's user avatar
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0 votes
6 answers
158 views

If time runs slow for moving train, how can it cover same distance in less time than someone on the ground unless the track decreases in its view?

According to special relativity, Δt=γ*Δt' ... (1) Where, Δt is the time the train takes to completely pass by me according to my watch, Δt' is the time I should see has passed for someone on the train....
AYM Shahriar Rahman's user avatar
1 vote
0 answers
62 views

How to read time-dilated clocks? [duplicate]

I just don't get how if two people are moving relative to each other, either clock as seen from the other's perspective is slower. Consider this: A and B are stationary relative to each other and ...
John Smith's user avatar
1 vote
3 answers
150 views

Deriving time dilation from line element

I am having trouble deriving the time dilation. I am using $(-, +, +, +)$ sign convention. For Minkowski metric, the line element is equal to: $$ds^2 = -c^2dt^2 + dx^2 + dy^2 + dz^2$$ For a motionless ...
Yachim's user avatar
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1 vote
1 answer
95 views

The apparent dilatation of time in General Relativity

Maybe this a dumb question, but, is the gravitational dilatation of time caused because a particle travelling through a geodesic in a curved space-time must cover a larger distance than the one ...
Álvaro Rodrigo's user avatar
1 vote
3 answers
191 views

Equivalence Principle in Newtonian Physics vs GR: A Thought Experiment

I have a question regarding the equivalence principle as it applies in Newtonian Physics and General Relativity. Consider a thought experiment involving a free-falling elevator. Inside the elevator, ...
Kenneth A's user avatar
-2 votes
2 answers
96 views

Seperation Between a Rocket and an Emitted Photon

I am studying for an exam on Special Relativity, and I made a toy problem to practice, but I ended up confusing myself. I know something is wrong with my intuition, but can someone please point where ...
RudyJD's user avatar
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0 votes
1 answer
69 views

Is it more accurate to say space in a weaker gravitational field is contracted, or that time is faster?

Little thought experiment. An observer places a mirror and a clock 1 lightyear away from a black hole. He then goes in the black hole's gravitational field at a point where he sees the clock tick at 2 ...
Zach's user avatar
  • 21
0 votes
3 answers
164 views

Understanding time dilation in layman's terms

I would love to have a better understanding of Einstein's theory of relativity and how time dilation in particular works with a simple example. Let's say I have twins. One takes a trip to a far away ...
Marc's user avatar
  • 1
-1 votes
2 answers
76 views

What's the resolution of gravitational time dilation?

Time dilation near a gravitating mass depends on the distance to that mass. So I assume that time at 1 meter from a very massive object goes slightly slower than at 1.01 meters, and also slower than ...
Jaime Caffarel's user avatar
5 votes
3 answers
2k views

Lorentz Transformation or Time Dilation? [closed]

Say there is a spaceship really far away from Earth moving at 80% the speed of light (away from Earth-edited), at some point a radio signal is sent by observers on Earth. I need to be able to ...
Klegzart's user avatar

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