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5
votes
4answers
79 views

Can a ultracentrifuge be used to test general relativity?

With today's ultracentrifuge technology, they can spin so fast that the sample can be subjected to accelerations of up to 2 millions Gs. That is equivalent to two solar masses. Has someone tried to ...
-1
votes
0answers
25 views

In Time Travel, can there be multiple of you? [on hold]

Perhaps a silly question, but one that I did not feel confident on an answer of 'yes'. When you travel back in time, say 1yr or 1ns, are there now duplicates of you in that time?
1
vote
2answers
60 views

Length of Day and year on massive Earth

Say, a planet has the same orbital periods as Earth (365 days in a year, 24 hours in a day, etc. with respect to Earth-bound clocks), but the planet has double the mass. So, time must pass more slowly ...
4
votes
1answer
205 views

Movie Interstellar - Question about Escape Velocity

The movie Interstellar shows people on a water planet where time is dilated so much that 1 hour is equal to 7 years back on Earth. Even though they lift off from Earth using a Saturn-V two stage ...
1
vote
2answers
71 views

How is strong time dilation consistent with weak tidal forces?

Nolan's latest film, Interstellar, takes pains to explain to lay audience members that the passage of time slows in the presence of strong gravitational fields (as per Einstein's theory of General ...
1
vote
2answers
48 views

Time Dilation Experiment [duplicate]

I am currently thinking of doing an experiment for science fair involving time dilation which will use the equations for both time dilation based off of speed and for gravitational dilation to ...
0
votes
1answer
63 views

Applying Lorentz Transformations and Time Dilation

My question is based on a popular question, usually posed in introductory courses on the special theory of relativity. Two rockets are on a collision course. Rocket 1 is traveling at the speed ...
0
votes
0answers
37 views

Just as time changes in a gravitational field, does energy? [closed]

I've been doing some recreational physics and wanted to see if I could come up with a formula for energy/time equivalence. I decided to start with the formula for gravitational time dilation. $$ ...
2
votes
2answers
865 views

How long is a second in zero gravity?

General relatively predicts that gravity creates time dilation and a relatively slower passage of time for the observer experiencing larger acceleration. For an observer experiencing zero ...
2
votes
1answer
44 views

Does space-time cause time dilation at relativistic speeds?

I'm trying to understand the concept of the space-time continuum and it's effect on time dilation but am having difficulty with parts of it. To me there seems to be two separate components to time ...
2
votes
4answers
137 views

If Julian Barbour is Correct, is the Speed of Light Special?

According to this article in Discover Magazine, Albert Einstein's Theory of Relativity is wrong, because it didn't fully live up to the ideas of Einstein's idol, Ernst Mach. Mach proposed a truly ...
1
vote
2answers
79 views

Does space between objects contract?

I had a question, let us assume a coordinate system where there is 2 objects moving at relativistic speeds (at same velocity) for the observer therefore the observer will observe the length ...
2
votes
3answers
127 views

Can length contraction really be derived from time dilation? Does speed equal speed?

I am referring to Wikipedia: "Length contraction can also be derived from time dilation." with the following proof which seems to be the result of a circular reasoning. The proof uses only one and ...
7
votes
1answer
309 views

What is the maximum time dilation factor when orbiting a rotating black hole?

Suppose one spaceship is stably orbiting a rotating black hole and another is far away from the black hole. What is the maximum time dilation factor between the two ships? Can it be made arbitrarily ...
0
votes
0answers
47 views

Is it OK to see time dilation and (relativistic) mass increase as phenomena that avoid $c$ being reached? And how about length contraction?

I think I have been exposed since years ago to this line of reasoning: if $ v\to c $, then $ \Delta t \to \infty $. As $\displaystyle v=\frac{\Delta s}{\Delta t} $, it's like a natural reaction to ...
0
votes
2answers
44 views

Time dilation in outer space vs in a gravitational field? [duplicate]

I have been wondering how could aging process differ for a person moving close to velocity of light or for a person close to a very strong gravitational field compared to a person who is in a slow ...
2
votes
0answers
58 views

Falling into the black hole: a picture from the infinite distance [duplicate]

This question was bugging me for many years. Here it was argued that it would take an infinite time for somebody (suppose, an astronaut) to fall into the black hole, given that it is not his time, but ...
0
votes
0answers
31 views

Transverse doppler effect in light

In most books to explain transverse Doppler effect the following example is given: Consider a source that emits flashes at frequency f 0 (in its own frame), while moving across your field of vision ...
1
vote
2answers
498 views

Gravitational time dilation caused by a galaxy, and by

In a word, if you are sitting on the Earth, if I'm not mistaken you are experiencing Time Dilation compared to being in deep solar system space. Due to the mass of the Earth. However. We're all ...
2
votes
3answers
117 views

Problem with understanding time dilation (moving clocks can run faster?)

I ran into a serious problem with the Lorentz transformation and time dilation. In the standard configuration you have one observer S and another one S' with their x-axis aligned. I assume S to be at ...
3
votes
2answers
113 views

Does this proof for time dilation ignore length contraction?

A simple proof for time dilation can be found here http://en.wikipedia.org/wiki/Time_dilation#Simple_inference_of_time_dilation_due_to_relative_velocity What I am confused about is that when the ...
0
votes
0answers
32 views

Relativistic Doppler Effect and the Sagnac effect

What I think I know about the Sagnac effect can be found here. It occurs to me that the equations for calculating the time do not take the Doppler effect into account. I'm familiar with the very ...
-2
votes
1answer
98 views

Why is it legitimate to only observe motion, but call it time, such that concepts like “the relativity of simultaneity” are seen as possibly genuine? [duplicate]

My question is asking for evaluation of a new concept or paradigm within the framework of the current mainstream physics understanding of Relativity. Specifically, that concept or paradigm being that, ...
0
votes
3answers
50 views

why does a change in velocity cause length contraction, mass gain and the slow down of time? [duplicate]

How did the universe 'know' to do that? Or is there an intuitive explanation for it?
0
votes
2answers
39 views

Time Dilation, Multiple Earth's?

I was reading about time dilation and suddenly a question raised in my mind. (This might be a misconception but please do correct me if I am wrong) I read that if we travel near to the speed of ...
1
vote
4answers
58 views

Time dilation if earth was stationary

Being on earth, we are constantly flying through space at incredible speeds. We revolve around a sun in a system that revolves around the center of the galaxy that is hurling itself through space. ...
0
votes
0answers
33 views

How can the clock c1 be synchronized with the clock c2?

A clock c1 is situated at a distance $L$ from an observer carrying a clock c1. How can the clock c1 be synchronized with the clock c2?
-1
votes
1answer
62 views

How fast must Nadia travel so that she is the same biological age as her twin upon returning to Earth? [closed]

Two twins, Nadia and Aidan, decide to have an adventure when they turn 21. Aidan chooses to travel to a distant star 10 light years away at a speed of 0.8c. Nadia decides to travel to a closer ...
0
votes
2answers
86 views

Time dilation confusion

I'm just starting to learn about special relativity, and I'm a little bit confused about something. Take the example of an observer in $S$ on the ground observing a train move at constant velocity $v$ ...
0
votes
1answer
148 views

Time Dilation Problem [closed]

I'm having some trouble using the time dilation formula. Say an astronaut leaves Earth for 10 years, at 0.85c. How much time has passed according to an observer on Earth? I tried using the ...
1
vote
2answers
43 views

Special Relativity Question: Doppler shift

Imagine an observer watching a moving rocket carrying on it both, a light source and a clock. If on the rocket the clock is synchronized with the frequency of the light being emitted then will not a ...
0
votes
1answer
53 views

Can someone explain effects of time dilation on expansion of universe [duplicate]

I'm not a physics guy, but this is something I have always wondered about. If a clock flown by an object of high mass runs slower, what is the effect of this in regards to the density of the universe. ...
1
vote
2answers
55 views

De facto superluminal travel?

It seems that the limitation to subluminal travel can be practically circumvented (so to speak...not breaking any physical laws here) if we consider the viewpoint of the traveler, not some outside ...
3
votes
0answers
67 views

How can one explain gravitational time dilation in non-rotating bodies? [closed]

A clock on the surface of the Earth (assuming it does not rotate) will accumulate around 0.0219 seconds less than a distant observer over a period of one year (assuming the observer is using ...
0
votes
2answers
98 views

Confusion about proper time

A spacecraft flies away from earth with a speed of 4.8 million meter per second relative to the earth, and then returns at the same speed. The spacecraft carries a clock that has been synchronised ...
2
votes
1answer
203 views

A clock in freefall

Time dilation calculated using Schwarzschild metric for a non rotating spherical body is: $$t_0=t_f\sqrt{1-\frac{2GM}{rc^2}}$$ For such a non rotating spherical body, what would the time dilation of ...
2
votes
1answer
46 views

The Great Atomic Clock of Kansas

It is said that astronauts on the ISS experience time slightly slower than the rest of us. (I believe that the lesser gravitational field would increase their rate of time, so that affect must be ...
1
vote
2answers
98 views

Do the effects of special relativity occur instantaneously?

Imagine a second earth one lightyear away from our earth. Now imagine a bunch of scientists with a plane and some atomic clocks who are living on this second earth and who perform the Hafele-Keating ...
0
votes
1answer
37 views

Special Relativity - Reconciling 3 different frames

A Space Station S has two ships parked at it: P - PuttPutt and Q - Quick. S, P and Q synchronize their clocks. At noon P and Q take off in the same direction. P quickly accelerates to $c/4$ and Q ...
2
votes
3answers
67 views

In terms of physics, does the phrase “time slows down” mean the same thing as “things happen more slowly?”

The common definition of "time" is a type of measurement, like size. But the sentence "size gets bigger" doesn't make any sense. Is "time slows down" an odd phrasing of "events occur more slowly" or ...
1
vote
0answers
34 views

Special relativity allows arbitrarily low travel times between two locations [duplicate]

I wish I had a good way of illustrating this, but anyway, doesn't the following travel strategy allow you to get anywhere in arbitrarily little time? You're at rest at the origin of space-time, and ...
0
votes
1answer
100 views

Does physics recognize the particle of light separately from the wave of light? [closed]

To frame this question, we need to assume that time freezes when traveling at the speed of light. This is theoretically congruent with Einstein's theory of relativity and the theory of time dilation, ...
34
votes
4answers
5k views

Does time move slower at the equator?

While answering the question GPS Satellite - Special Relativity it occurred to me that time would run more slowly at the equator than at the North Pole, because the surface of the Earth is moving at ...
2
votes
3answers
650 views

Would a craft travelling increasingly close to the speed of light appear to be decelerating?

I've been pondering the implications of time dilation. Is it right to assume that if a craft was travelling at a speed very close to the speed of light (>= 0.9999c for example), that to an external ...
3
votes
4answers
225 views

Traveling between two planets at rest to one another [duplicate]

If I travel at relativistic speed from planet A to planet B which are at rest relative to one another, I will be younger than people on A or B when I arrive. However how does this mesh with the fact ...
0
votes
2answers
64 views

Moving towards a clock at .866C [duplicate]

If you set up a clock that sends out a light pulse every second, and move towards it at a speed of .866c, will the clock appear to run faster?
0
votes
4answers
78 views

How can time dilation be symmetrical? [duplicate]

I recently posted a version of the twin paradox with a twist but here I'd like to propose a new thought experiment all together. Take two clocks, A & B, and place A 1 AU away from B. Once the ...
0
votes
0answers
154 views

Twin Paradox Without Acceleration

So I've been doing a lot of reading about the twin paradox and have encountered several different explanations that strive to resolve it. First off let me start by saying general relativity is not an ...
2
votes
1answer
48 views

what if the time is zero in one reference frame

Consider measuring the length of an object in another frame of reference. Of course this should happen at the same instance in the frame of reference the measurement takes place in. but using Lorentz ...
4
votes
4answers
704 views

Time dilation derivation of special relativity

In almost all of the derivations using the postulates of special relativity (SR), we use experiments involving light signals. For example, we make a clock using a light signal or measure lengths using ...