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Something wrong with the description of time dilation?


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I thought about it, and those experiments with time dilation use clocks, but clocks aren't measuring time, they are just counting the number of times a quartz crystal vibrates or the number of times a gear turns of gears that turn. So, wouldn't a dent in the fabric of space make it tick slower since it would be a higher force of gravity being put in the gears which means that the same amount of energy won't make something travel the same amount of distance in time?

 

So, how does time itself actually effect a quartz crystal vibrating? Shouldn't the effect of a dent in the fabric of space just be that because there's a high force of gravity, that it's harder for the quartz crystals to move? And then when objects move faster, don't faster moving objects just distort they distort the fabric of space more (having a higher gravitational pull)?

I mean, a photon doesn't have mass, so I don't think it distorts the fabric of space the same way, which is why different energy photons will still travel at C, since if photons did have mass, a different amount of kinetic energy to move the mass would make them travel at different speeds.

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I thought about it, and those experiments with time dilation use clocks, but clocks aren't measuring time, they are just counting the number of times a quartz crystal vibrates or the number of times a gear turns of gears that turn. So, wouldn't a dent in the fabric of space make it tick slower since it would be a higher force of gravity being put in the gears which means that the same amount of energy won't make something travel the same amount of distance in time?

If it were some force of gravity between objects, then different clocks would be effected different ways.

On top of that, when the clock is in free fall there won't be a force between different components (other than tidal forces).

 

 

So, how does time itself actually effect a quartz crystal vibrating? Shouldn't the effect of a dent in the fabric of space just be that because there's a high force of gravity, that it's harder for the quartz crystals to move? And then when objects move faster, don't faster moving objects just distort they distort the fabric of space more (having a higher gravitational pull)?

I don't quite follow. If you're saying that a moving object would produce a gravitational force in its own frame, then this would imply a preferred reference frame and provide an easy way to disprove all of relativity.

As to the gravitational field around an object that is moving in a frame, you would probably have to ask someone more knowledgable to me.

It will change the field, but I'm not exactly sure how.

I mean, a photon doesn't have mass, so I don't think it distorts the fabric of space the same way, which is why different energy photons will still travel at C, since if photons did have mass, a different amount of kinetic energy to move the mass would make them travel at different speeds.

Photons do carry energy-momentum. If you were to somehow keep 10^17 joules of photons which were all travelling in different directions together in a tight ball, it would have a similar gravitational effect to around about a kilogram of matter (at least until they spread out a few nanoseconds later).

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In addition to what Schrödinger's hat said, gravitational time dilation does not vary with the force. It varies with the gravitational potential. So a change in force cannot explain it. Further, relativity has kinematic time dilation, which appears with no gravity at all.

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I thought about it, and those experiments with time dilation use clocks, but clocks aren't measuring time, they are just counting the number of times a quartz crystal vibrates or the number of times a gear turns of gears that turn.
Good stuff.

 

So, wouldn't a dent in the fabric of space make it tick slower...
No. The typical picture you see of a "dent" shows space-time, not space. Apply your clock thinking above to a parallel-mirror light clock. When it ticks slower it isn't because there's "a dent in space", but because space is different there.

 

since it would be a higher force of gravity being put in the gears which means that the same amount of energy won't make something travel the same amount of distance in time?
No. Like Swanson said, it's gravitational potential that relates to time dilation. The force of gravity at some location depends upon the local slope of gravitational potential at that location.

 

So, how does time itself actually effect a quartz crystal vibrating? Shouldn't the effect of a dent in the fabric of space just be that because there's a high force of gravity, that it's harder for the quartz crystals to move? And then when objects move faster, don't faster moving objects just distort they distort the fabric of space more (having a higher gravitational pull)?
Time doesn't affect a quartz crystal vibrating. A concentration of energy does. It "conditions the surrounding space". It alters it, and motion through it. Clocks clock up that motion, and when they go slower, we call it time dilation.

 

I mean, a photon doesn't have mass, so I don't think it distorts the fabric of space the same way, which is why different energy photons will still travel at C, since if photons did have mass, a different amount of kinetic energy to move the mass would make them travel at different speeds.
Photons don't have mass, but it isn't mass per se that causes gravity, it's energy. If you trap a photon in a mirror-box you increase the mass of that system, and the result is more gravity, but the photon causes gravity whether it's in the box or not. Note however that you can't practically measure it - after all, a huge concentration of energy like a star causes only a slight effect. Different-energy photons travel at the same speed because that's the way space is. Think of photons as waves or pulses, not billiard-ball particles.
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In addition to what Schrödinger's hat said, gravitational time dilation does not vary with the force. It varies with the gravitational potential. So a change in force cannot explain it. Further, relativity has kinematic time dilation, which appears with no gravity at all.

 

Doesn't an increase in kinetic energy increase an object's relative mass, and more mass distorts the fabric of space more? I think energy distorts the fabric of space better than matter, which is why scientists were planning on trying to accelerate mass particles to the speed of light using the gravitational fields generated by high power photon lasers rather than just giving particles kinetic energy which obviously wouldn't work.

 

Also swan, just move this thread then, don't make a big deal out of it, just move it.

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Doesn't an increase in kinetic energy increase an object's relative mass, and more mass distorts the fabric of space more? I think energy distorts the fabric of space better than matter, which is why scientists were planning on trying to accelerate mass particles to the speed of light using the gravitational fields generated by high power photon lasers rather than just giving particles kinetic energy which obviously wouldn't work.

 

No. Gravitational time dilation is due to the potential present from an external object. It doesn't depend on the mass (relativistic or otherwise) of the object itself.

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No. Gravitational time dilation is due to the potential present from an external object. It doesn't depend on the mass (relativistic or otherwise) of the object itself.

 

Potential present is not a term I'm familiar with, nor is the internet apparently. So if a clock accelerates to near to speed of light, so what if it accelerates to near the speed of light? Why would how much kinetic energy it has effect how it perceives time or how other objects perceive its time if its not distorting the fabric of space in a way that's proportional to it's kinetic energy? Unless time universality flows at a specific speed and the only thing that changes is how we perceive that flow?

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Potential present is not a term I'm familiar with, nor is the Internet apparently. So if a clock accelerates to near to speed of light, so what if it accelerates to near the speed of light? Why would how much kinetic energy it has effect how it perceives time or how other objects perceive its time if its not distorting the fabric of space in a way that's proportional to it's kinetic energy? Unless time universality flows at a specific speed and the only thing that changes is how we perceive that flow?

Swansont is referring to the gravitational potential present at the location of the clock.

 

Since you seem to doubt that time really does slow down due to the velocity that two different clocks may have relative to each other, or due to the position of one clock relative to the other in a gravitational field (that is, each is subject to a different gravitational potential), you may find this helpful:

 

Special relativity predicts that the frequency of the atomic clocks moving at GPS orbital speeds will tick more slowly than stationary ground clocks by a factor of d070db637ad0ed1a55595f799ace0447.png

 

, or result in a delay of about 7 μs/day, where the orbital velocity is v = 4 km/s, and c = the speed of light. The time dilation effect has been measured and verified using the GPS.

 

The effect of gravitational frequency shift on the GPS due to general relativity is that a clock closer to a massive object will be slower than a clock farther away. Applied to the GPS, the receivers are much closer to Earth than the satellites, causing the GPS clocks to be faster by a factor of 5×10^(-10), or about 45.9 μs/day. This gravitational frequency shift is noticeable.

(ref. http://en.wikipedia....eral_relativity )

 

The complete Wikipedia article cited goes into more detail about how these effects are calculated and what steps are taken to compensate for them so that the clocks on GPS satellites stay "in sync" with the clocks in the receivers on the ground. These effects are real. If we didn't compensate for the combined effects of special relativity (time dilation due to relative motion) and general relativity (time dilation due to greater gravitational field strength) our Garmins and Tom-Toms would be useless - they would accumulate errors in the range of ten kilometers per day. How we "perceive" the flow of time has nothing to do with the proper operation of these devices.

 

Chris

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Swansont is referring to the gravitational potential present at the location of the clock.

 

Since you seem to doubt that time really does slow down due to the velocity that two different clocks may have relative to each other, or due to the position of one clock relative to the other in a gravitational field (that is, each is subject to a different gravitational potential), you may find this helpful:

 

 

(ref. http://en.wikipedia....eral_relativity )

 

The complete Wikipedia article cited goes into more detail about how these effects are calculated and what steps are taken to compensate for them so that the clocks on GPS satellites stay "in sync" with the clocks in the receivers on the ground. These effects are real. If we didn't compensate for the combined effects of special relativity (time dilation due to relative motion) and general relativity (time dilation due to greater gravitational field strength) our Garmins and Tom-Toms would be useless - they would accumulate errors in the range of ten kilometers per day. How we "perceive" the flow of time has nothing to do with the proper operation of these devices.

 

Chris

 

Wait, I was already agreeing with that. All that demonstrates is that the dent in the fabric of space also effects time since things operate slower in a higher gravitational field. But what about time slowing objects moving? How does having more kinetic energy make an object approaching light speed distort the fabric of space more as to cause it's time to slow even if there's no other objects around it for 4000000000000000 light years?

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Wait, I was already agreeing with that. All that demonstrates is that the dent in the fabric of space also effects time since things operate slower in a higher gravitational field.

Be careful here. A difference in potential does not require a difference in local gravity. As an extreme example, you can imagine a uniform gravitational field (one that does not change strength with altitude). Two objects placed at two different heights in this field will be at different potentials, and two clocks place at different heights in this field will run at different speeds even though they feel exactly the same gravitational force.

 

But what about time slowing objects moving? How does having more kinetic energy make an object approaching light speed distort the fabric of space more as to cause it's time to slow even if there's no other objects around it for 4000000000000000 light years?

 

 

It doesn't. Dilation from motion is just due to the fact that clocks in inertial frames with relative motion measure time and space differently from each other.

Edited by Janus
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Be careful here. A difference in potential does not require a difference in local gravity. As an extreme example, you can imagine a uniform gravitational field (one that does not change strength with altitude). Two objects placed at two different heights in this field will be at different potentials, and two clocks place at different heights in this field will run at different speeds even though they feel exactly the same gravitational force.

 

It doesn't. Dilation from motion is just due to the fact that clocks in inertial frames with relative motion measure time and space differently from each other.

 

But why does a clock having more kinetic energy effect how someone else sees how many times a quartz crystal inside it vibrates?

 

Ok, a digital clock doesn't use gears, it uses minerals and electrical signals, so when you move a digital clock near the speed of light, your seeing how many times the quartz crystal vibrates or how many times an electrical current causes an impulse. So how does moving effect that? I can see with gravity that it slows the passage of time at a higher gravitational potential, but I don't see why I wouldn't accurately count how many times a clock is vibrating its quartz crystal unless the measurement of time in that instance isn't due to time it all, its just due to mechanical forces effecting the motion of the electrical currents and minerals inside the clocks.

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But why does a clock having more kinetic energy effect how someone else sees how many times a quartz crystal inside it vibrates?

 

Ok, a digital clock doesn't use gears, it uses minerals and electrical signals, so when you move a digital clock near the speed of light, your seeing how many times the quartz crystal vibrates or how many times an electrical current causes an impulse. So how does moving effect that? I can see with gravity that it slows the passage of time at a higher gravitational potential, but I don't see why I wouldn't accurately count how many times a clock is vibrating its quartz crystal unless the measurement of time in that instance isn't due to time it all, its just due to mechanical forces effecting the motion of the electrical currents and minerals inside the clocks.

 

It's the motion. That is has more energy is incidental, and the amount of the dilation doesn't depend on the energy, i.e. two clocks with the same KE will, in general, not experience the same time dilation (it will only happen in the specific case of having equal mass). The effect on time is a direct consequence of the speed of light being constant in all inertial reference frames. Time is slowed. It's not a mechanical effect — the clock doesn't "know" that it's moving, and as you point out, it happens independently of the construction of the clock.

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But why does a clock having more kinetic energy effect how someone else sees how many times a quartz crystal inside it vibrates?

 

Ok, a digital clock doesn't use gears, it uses minerals and electrical signals, so when you move a digital clock near the speed of light, your seeing how many times the quartz crystal vibrates or how many times an electrical current causes an impulse. So how does moving effect that? I can see with gravity that it slows the passage of time at a higher gravitational potential, but I don't see why I wouldn't accurately count how many times a clock is vibrating its quartz crystal unless the measurement of time in that instance isn't due to time it all, its just due to mechanical forces effecting the motion of the electrical currents and minerals inside the clocks.

 

It has to do with the very "nature" of time itself.

 

Here's an analogy:

 

You have two men standing on a featureless plane. They start walking in slightly different directions at the same rate. After having walked a certain distance they check up on each others progress. Man 1 looks around to find that Man 2 is behind him and to his left. Man 2 looks around to find that Man 1 is behind him and to his right. Each man judges forward progress as progress in the direction that he, himself is walking. By this judgement,each man considers the other man as having made less forward progress than himself and while walking is make progress more slowly than he is.

 

Since they are on a featureless plane, there is no method of determining which is correct in any absolute manner and each man's definition of forward progress is as good as the others.

 

Now replace forward progress with time passage and walking in different directions with having relative velocities with respect to each other, and you have an idea of how time dilation works.

 

Nothing physically interacts with a clock to slow it down (just like nothing interacts with either of the men to slow his pace), but because of the nature of space-time, each clock measures its own time passage as being faster than time passage for a clock moving relative to it.

 

Then why is it the if we send a clock away at high speed and then return it, it comes back showing less time? If both clock see each other as running slow, how can one end up with less time at the end?

 

To answer that, consider whats happens if one of the men in our example turns so that his new path takes him back to intersect the other man's path. Keeping in mind, that he judges forward progress as being in the direction he is facing at the time, what happens to the other man's "forward progress" when the man turns toward him? (If an object is behind you and to your right, what happens if you turn to your right?)

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It has to do with the very "nature" of time itself.

 

Here's an analogy:

 

You have two men standing on a featureless plane. They start walking in slightly different directions at the same rate. After having walked a certain distance they check up on each others progress. Man 1 looks around to find that Man 2 is behind him and to his left. Man 2 looks around to find that Man 1 is behind him and to his right. Each man judges forward progress as progress in the direction that he, himself is walking. By this judgement,each man considers the other man as having made less forward progress than himself and while walking is make progress more slowly than he is.

 

Since they are on a featureless plane, there is no method of determining which is correct in any absolute manner and each man's definition of forward progress is as good as the others.

 

Now replace forward progress with time passage and walking in different directions with having relative velocities with respect to each other, and you have an idea of how time dilation works.

 

Nothing physically interacts with a clock to slow it down (just like nothing interacts with either of the men to slow his pace), but because of the nature of space-time, each clock measures its own time passage as being faster than time passage for a clock moving relative to it.

 

Then why is it the if we send a clock away at high speed and then return it, it comes back showing less time? If both clock see each other as running slow, how can one end up with less time at the end?

 

To answer that, consider whats happens if one of the men in our example turns so that his new path takes him back to intersect the other man's path. Keeping in mind, that he judges forward progress as being in the direction he is facing at the time, what happens to the other man's "forward progress" when the man turns toward him? (If an object is behind you and to your right, what happens if you turn to your right?)

 

But if it was purely based on motion and not something mechanical, wouldn't the clock return to normal once it landed back on Earth? I mean your not moving anymore, so the clock should return to the same rate, but for some reason it doesn't. Plus when people fly a clock in a jet, then that's further away from the Earth which means less gravity.

Also, wait, making it go "faster"? I thought the closer you approached the speed of light, the slower the rate of your time flowed to other people. I'm asking why THAT happens, because if you fly a clock in a jet it will be faster since there's less gravity distortion due to it's height off the ground.

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But if it was purely based on motion and not something mechanical, wouldn't the clock return to normal once it landed back on Earth? I mean your not moving anymore, so the clock should return to the same rate, but for some reason it doesn't.

 

What happens for Man 2 once he intersects Man 1's path and then turns again to walk in the same direction as Man 1? He will find himself making progress at the same rate as Man 1, but walking behind him. With clocks, the clock upon landing on Earth runs at the same rate as the Earth clock but will still finds itself running behind the Earth clock.

 

Also, wait, making it go "faster"? I thought the closer you approached the speed of light, the slower the rate of your time flowed to other people.

 

If you are moving with respect to someone else (or they are moving with respect to you, there is no difference) you both will determine that the other person's clock is running slower than your own. It isn't until one of you undergoes an acceleration that matches their speed to the other that you will end up with a situation where both of you will agree that his clock has accumulated less time.

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...I thought the closer you approached the speed of light, the slower the rate of your time flowed to other people. I'm asking why THAT happens..

It's called Special Relativity. The Wikipedia "Introduction to special relativity" article is a good place to start if you're asking why clocks in relative motion to each other slow down (relative to each other). It has many links that can provide you with more in-depth information. It can be found here:

 

 

http://en.wikipedia....cial_relativity

 

Chris

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But if it was purely based on motion and not something mechanical, wouldn't the clock return to normal once it landed back on Earth? I mean your not moving anymore, so the clock should return to the same rate, but for some reason it doesn't. Plus when people fly a clock in a jet, then that's further away from the Earth which means less gravity.

Also, wait, making it go "faster"? I thought the closer you approached the speed of light, the slower the rate of your time flowed to other people. I'm asking why THAT happens, because if you fly a clock in a jet it will be faster since there's less gravity distortion due to it's height off the ground.

 

It does return to the same rate (i.e. frequency) once you are back in the same frame of reference. The accumulated time difference (phase) is there, but that difference will remain constant.

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It does return to the same rate (i.e. frequency) once you are back in the same frame of reference. The accumulated time difference (phase) is there, but that difference will remain constant.

 

So your saying a clock goes higher off the ground, there's less gravity pulling on it due to less distortion, so the quartz crystals vibrating the clock can vibrate at a faster rate with the same amount of energy, but then when they return, since its the same gravity, they start vibrating at the same rate with the same amount of energy put into vibrating as before?

 

Also, what about that traveling towards the speed of light thing? For some reason if you traveled near the speed of light (at least in conventional ways), then for some reason time would pass slower for you than for other people.

Edited by questionposter
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So your saying a clock goes higher off the ground, there's less gravity pulling on it due to less distortion, so the quartz crystals vibrating the clock can vibrate at a faster rate with the same amount of energy, but then when they return, since its the same gravity, they start vibrating at the same rate with the same amount of energy put into vibrating as before?

 

It depends on what you mean by "less gravity" Dilation occurs because the gravitational potential is smaller, not because the value of g has changed.

 

Also, what about that traveling towards the speed of light thing? For some reason if you traveled near the speed of light (at least in conventional ways), then for some reason time would pass slower for you than for other people.

 

It's a direct consequence of the speed of light being constant in all inertial frames. The only way that can happen is for space and time to "mix" and that means time slows for moving objects.

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So your saying a clock goes higher off the ground, there's less gravity pulling on it due to less distortion, so the quartz crystals vibrating the clock can vibrate at a faster rate with the same amount of energy, but then when they return, since its the same gravity, they start vibrating at the same rate with the same amount of energy put into vibrating as before?

 

No. The gravity the object feels has nothing to do with time dilation. While a clock sitting on the surface of the Moon feels less gravity than one on the surface of the Earth, and runs faster than one on the Earth, a clock sitting on the surface of Uranus would also feel less gravity than one sitting on the surface of the Earth, yet a clock on the surface of Uranus would run slower than one on the Earth.

 

Time dilation isn't about something physically altering how the clock operates, it has to do with the very nature of "Time".

 

Also, what about that traveling towards the speed of light thing? For some reason if you traveled near the speed of light (at least in conventional ways), then for some reason time would pass slower for you than for other people.

 

No, what happens is that if you accelerate up to the near the speed of light (relative to your starting point) and then return to your starting point, you will find that your clock has accumulated less total time then one that stayed at your starting point. Why this happened would be a matter of dispute between you and someone who stayed behind. They would say that time ran slow for you while you were going away and coming back. You on the other hand would say that time ran slow for them while you were going away and coming back, but their time "jumped forward" during the turn around period when you went from going away to coming back, and that this jump forward resulted in your clock reading less time than theirs when you meet up again.

 

Again, it has nothing to do with anything physically acting on the operation of your or his clock, but with the way we compare "time" between different reference frames.

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Again, it has nothing to do with anything physically acting on the operation of your or his clock, but with the way we compare "time" between different reference frames.

 

But it's not just a frame of reference, physical things happen. If I traveled at 99.9999999% the speed of light, a piece of metal left out in the rain would rust if I traveled one second of what I count. That's not a frame of reference, that's the passage of time changing somehow so that physical aging doesn't physically effect me the same as the environment around me. But despite swan's comment about the speed of light looking constant somehow, I'm not seeing why time proportionally slows to movement. So what if space and time are mixed in an aether-like fabric? Again, I ask what moving has to do with that.

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But it's not just a frame of reference, physical things happen. If I traveled at 99.9999999% the speed of light, a piece of metal left out in the rain would rust if I traveled one second of what I count. That's not a frame of reference, that's the passage of time changing somehow so that physical aging doesn't physically effect me the same as the environment around me. But despite swan's comment about the speed of light looking constant somehow, I'm not seeing why time proportionally slows to movement. So what if space and time are mixed in an aether-like fabric? Again, I ask what moving has to do with that.

Moving has to do with Special Relativity, which Wikipedia has a very good introductory article about here: http://en.wikipedia....cial_relativity

 

If your looking for examples of how the strange consequences of Special Relativity have been tested, Wikipedia has that covered in another article here:

 

http://en.wikipedia....cial_relativity

 

Chris

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