# Questions tagged [time-dilation]

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### Gravitational Time dilation for motion in a gravitational field [duplicate]

An astronaut is travelling towards a black hole in a space ship traveling at 0.8 C. The guy’s position is not fixed relative to the black hole. He is travelling towards it from a distance. How to ...
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### Where does ones relativity begin/end? [duplicate]

If there were a space ship moving close to the speed of light, that was large enough for a smaller ship inside of it to reach close to the speed of light and it opened its hanger doors and the smaller ...
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### Measuring time dilation of SR by a mechanical clock

I think this is a very basic question, but relativity is always not intuitive to me. When we say that time goes slow when moving (viewed by another inertial coordinate system), we just assume that ...
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### Can a system's orientation relative to direction of motion create additional relativistic effects?

Setup Consider an observer, at rest, holding two perfect clocks: The first perfect clock is ordinary--with no additional distinction. The second perfect clock has a special constraint, as it is ...
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### How do I calculate time dilation on GPS satelites due to Earth's mass?

I found this answer which gives as the formula $$T_2 = \frac{T_0}{\sqrt{1-\frac{2GM}{c^2 R}}}$$ that should result in the time $T_2$ passed on a GPS satellite while $T_0$ seconds pass in the center ...
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### What if looked inside a moving spaceship, from Earth?

So we all know about time dilation, and how Alice travelling in a spaceship relative relative to Bob ages more slowly than him. When Alice gets back to Earth, she has biologically aged time $t$, ...
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### Would you reach a singularity before evaporation of the black hole? [duplicate]

When going to a physics camp the other day, we discussed the Schwarzchild-metric for a rotational symmetric non-spinning black hole and its famous time-dilation properties. However, we know that ...
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### When a clock was flown around the world,was time dilation mutual?

Time dilation is always mutual - both clocks are travelling relative to each other and both must observe that the other clock is slower than themselves. Since motion is relative, and it is not ...
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### How can we have different speeds relative to a same point for a same object?

A day last not the same at all altitudes (https://aapt.scitation.org/doi/10.1119/1.5000802), meaning earth has different angular velocities. What is the actual rotation speed of the earth to the ...
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### Yet another question about time dilation

I thought I had understood special relativity, at least the idea of the clocks with light pulses and rods from the book The Meaning of Relativity. But going through the basic illustration of the time ...
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### Does an object falling into a black hole appear to become flat for an outside observer?

In special relativity when an object moves close to the speed of light it will appear redshifted due to time dilation. In addition the object will also appear to be length contracted. But what about ...
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### Shapiro time delay for signal with velocity $v<c$? (updated)

Consider appendix A in this paper. Here a situation is considered where a particle is moving along the red $z$-direction, while experiencing the symmetric gravitational potential of two massive ...
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### Kip Thorne's time traveling wormhole and conservation of energy

Using this article as a basis: https://www.space.com/28000-physicist-kip-thorne-wildest-theories.html So you build a wormhole, put one end in your backyard (for convenience your backyard is on an ...
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### How can I calculate time dilation between our clock, and clock in satellite? [duplicate]

We know satellite is moving , so there should be time dilation due to motion, also we know due to Earth's Gravitational field there should be time dilation, what should I do, just calculate both of ...
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### Wormholes and Time Machines

According this paper: Morris, Michael S. and Thorne, Kip S. and Yurtsever, Ulvi (1988) Wormholes, time machines, and the weak energy condition. Physical Review Letters, 61 (13). pp. 1446-1449. ...
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### Time Dilation Equations and Varying Interpretations

I have been seeing problems involving time dilation but the interpretation used by some people is not always the same. $$\tag{1} \Delta t' = \gamma \Delta t$$ If we think about the twin B going ...
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### A little help on Gravitational time dilation

Could somebody explain Gravitational time dilation in layman's term for me please!? And in the formula of Definition, it mentioned a capital H, but it didn't ...
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### Time dilation for opposite sides of the planet

If time passage depends upon the speed of the movement trough space, does the time pass differently on the opposite sides of the planet since Earth is rotating and orbiting the Sun at the same time ...
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### What's inside a frozen star?

Consider a specific black hole whose whole mass is located at the event horizon. How such a black hole can form is beyond he scope of this question. Perhaps a spherical shell made of the neutron star ...
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### Formulaic representation of time differential

It is a known fact that time passes at a different rate on earth than it does elsewhere in the universe. Where a second on earth passes uniformly, at an altitude of 11000 or also passes uniformly but ...
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### How much energy needed to cross the galaxy in time $t$?

Sorry if this is a dumb question. A friend of mine just asserted that it's possible to get anywhere in the universe in less than 30 seconds of your time due to time dilation. I do imagine that'll ...
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When traveling at the speed of light (v=c), left under the radical you would have 0. This answer would be undefined or infinity if you will (let's go with infinity). The reference time (T0) divided by ...
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### Time dilation moving with the speed of light

I'm having some issues with special relativity. I must misunderstand something but i'm not sure what. I would very much appreciate your help. We can see from time dilation, if you are traveling with ...
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### 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, T, of a clock is a formula that must continue to hold even if time dilates. Let ...
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### How is time affected by the bending of space-time?

By Newton's Laws, we can calculate the effect of gravity, but he didn't give the actual reason for gravity. I searched the internet for it, but all the answers have this "bending of space-time" stuff. ...
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### Explanation of time dilation derivation [duplicate]

One way time dilation is derived is as follows. A light source inside a train sends photons vertically to a mirror on the ceiling of the train. Observer A is inside the train and observer B is outside....
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### Why does time dilation require events to occur at same point in space?

I was reading through "University Physics with Modern Physics ~ Sears and Zemansky" and they mentioned the following paragraph in time dilation : We may generalize this important result. In a ...
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### Derivation of Lorentz Contraction WITHOUT light roundtrip

A typical Lorentz Contraction proof relies on the axiom that "the speed of light is constant" and goes as follows. Given: Frame $F_1$ moves at speed $v$ relative to frame $F_0$. In frame $F_1$ sit 2 ...
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### Mistake in simple calculation in special relativity [closed]

I am just learning a little bit of special relativity on my own and am obviously still quite confused. I would appreciate it if someone could point out the error in the following calculation: Let A ...
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### Would time dilation affect temperature?

This answer on Astronomy.SE got me thinking about temperature, and our definition of it. The answer is to a question about why the temperature of a black hole is so cold when it absorbs so much energy,...
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### Does one age quicker at higher altitudes?

See title: Does one age quicker at higher altitudes? A few years ago I heard that you would age slightly faster (or slower) at higher altitudes. Is this true? What is the theory or evidence for ...
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### Time dilation near a black hole

If an Object exists near a black hole where 1 hour of its time is observed by a distant observer as 10 hours, then is total amount of light emitted by Object (in that one hour) toward the distant ...
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### How does emitting light while moving not break the law of conservation of energy?

Say you have 2 identical LED monochromatic flashlights. The battery lasts exactly 1 hour. We are able to calculate the energy emitted as photons from the LED by Planck's Law: $E = h\nu$. Now if we ...
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### What would I see if I watched alien TV through a telescope?

Let's say I created a telescope so powerful that I could even see and perfectly track a television screen on a planet that orbits a distant star. Also assume that this star is moving at a high ...
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### Time Elapsed for a moving observer to reach a reflected pulse of light

Alice is moving towards a mirror with a velocity of $0.8c$. She sends a pulse of light toward the mirror when she is at a distance $L$ from the mirror and she times how long the pulse of light takes ...
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### What is the difference between relative time dilation and absolute time dilation

I know special relativity says that traveling at high speeds (or really any speed) causes time dilation; and General relativity says that gravity also causes time dilation. I was wondering if relative ...
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### Why does gravity cause time dilation?

I know there have been several posts asking the same or similar questions, but I haven't been able to grasp this from reading any existing questions. My question is: why does gravity cause time ...
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### How does LIGO detect Gravitational Waves if they bend both space and time?

Please note that this is not an inquiry into the mechanisms of technology that LIGO uses to detect gravitational waves. Also, I am not a flat-earther. I was watching physicists vs. flat-earthers ...
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### Special Relativity Muon Decay [duplicate]

When talking about how muons reach earth even though their half-life is very short the explanation of time dilation is given. From earth's frame of reference, the Muon's clock is "slowed down" so is ...
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### Is my understanding of time dilation correct?

Let's say that a spaceship moves with speed $v$ relative to an observer in earth. Let's make the calculations for the reference system of earth, so the observer is stationary and the spaceship is ...
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### Why do GPS satellites care about Earth clock at all? (relativity)

Many online resources make grandiose claims about how GPS would be useless without relativistic corrections. Specifically, they outline that satellite clocks runs slower by 7μs/day due to special ...
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### Time dilation due to gravity [duplicate]

I'm getting conflicting statements when it comes to time dilation due to gravity. Some sites say time slows down near the source of gravity and some say it's faster. Can anyone she'd some light on ...
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### Does a Foucault pendulum move quicker above than below of the apparatus?

Because of gravity on earth, a time period is slower at low altitude than at high altitude. Does a Foucault pendulum move quicker above than below of the apparatus because of gravitational time ...
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### Measuring time in the photoelectric effect

Consider the following hypothetical: An atom is traveling with a velocity of v to the left, directly towards an incoming photon, as crudely depicted below. p----> <----A Question (1): What is ...
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### Gravitational Time Dilation Inside a Massive, Non-Uniform, Non-Rotating Sphere

I know the time dilation (relative to an observer at infinity) outside a non-rotating sphere can be found from the Schwarzschild metric to be $$t_{0}=t_{f}\sqrt{1-\frac{r_{s}}{r}}$$ where $r_{s}$ is ...
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### Special Relativity: Which is the correct time taken for a pion travelling between two detectors?

I'm struggling to ascertain which reference frame (pion or detectors) has the 'longer time taken' in the following example: Consider a pion which is travelling at 0.95c. It passes two detectors 34m ...
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### How can a mechanical clock tick slower due to time dilation?

I was about to watch Interstellar for the third time when I decided to do some research on its phenomena. Time dilation is the one that struck me most. I have read and read about it and understand -- ...
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### How can I play more using relativity? [duplicate]

One day I was playing and I thought if I could play more. So I thought of a scenerio in which I would play for 15 minutes but 5 minutes time would be passed in the whole universe. So anyone except me ...