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Kinematic time dilation or else named constant velocity time dilation is an apparent time dilation effect but with real consequences on how we measure time and our everyday life like the GPS satellites which loose in average 7μs in time each day compared to clocks on the surface of the Earth due this Special Relativity (SR) kinematic effect. At the same time they gain time about 45μs due the gravitational time dilation effect GPS and Relativity

These two opposite effects must be accounted for 45-7= +38μs per day, a total amount of time dilation the clocks on the satellites are going relative ahead in time (faster) compared to the clocks on the Earth surface and compensation must be applied so all clocks are in synchronization.

We know from experiments for certain, that acceleration affects matter slowing down at the molecular scale vibrations and therefore has a physical effect on matter and also on tick rates of clock time measuring devices from the mechanical, electronic to atomic clocks. Therefore gravitational time dilation has an actual physical effect on matter.

This above, includes also biological clocks and the aging process of living organisms. A man on Jupiter would age slower than a man on Earth, assuming he/she is immune to the hostile environment of Jupiter :)

I am curious about if this is also the case for the SR constant velocity time dilation phenomenon and it actually affects matter independent of frame of reference? Since the velocity is constant in this case I expect no any forces to be present on the moving matter.

Therefore the tick rate of the clock must not be affected by the constant velocity and the measured time must flow at a constant pace. Which means the kinematic SR time dilation effect is not a matter phenomenon effect but an apparent time measurement information sharing effect of relative moving clocks due the finite speed of light and their different positions in space. The time measured on the clocks is not shifted only the information of the measured time shared between the two observers is shifted in time.

Are there any experiments that can show that SR time dilation has an actual effect on matter?

A quite simple experiment would be according to the above information to compensate a GPS satellite for a year only for the gravitational time dilation (i.e. clock on satellite runs +45μs faster per day) and do NOT compensate for the whole year for the kinematic SR time dilation effect (i.e. clock on satellite appears to run -7μs slower per day). According to the above information at the end of the year the clock on the orbiting GPS satellite would lack in time about 365x(-7μs)= -2.55 ms. Bring the satellite down to Earth from orbit to stationary position and read out its clock time.

If the clock on the stationary satellite would then found to be lacking around -2.55 ms within the error bars of this experiment then this would conclusively prove that SR constant velocity time dilation has an actual physical effect on matter and is not just an apparent relativity effect!

silverrahul
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Markoul11
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  • The classic example of time dilation producing a measurable effect is muons passing through Earth's atmosphere. Which I think shows pretty clearly that time dilation has "an actual physical effect". – M. Enns Apr 21 '21 at 19:54
  • Yes I agree and I know about muons experiment. But as you also pointed out, that the measurement is affected. This however does not mean that the actual pacing of time is varied within the frame of reference. – Markoul11 Apr 21 '21 at 20:02
  • "But as you also pointed out, that the measurement is affected." @M.Enns said that there is a measurable effect, not affect. Also, when you say "This however does not mean that the actual pacing of time is varied within the frame of reference." What do you actually mean? You seem to be using jargon that is not standard. – Daddy Kropotkin Apr 21 '21 at 21:36
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    There are lots of problematic statements in this question. Kinematic time dilation and "gravitational" time dilation are not separate phenomena. – ProfRob Apr 21 '21 at 22:10
  • " that the measurement is affected. This however does not mean that the actual pacing of time is varied within the frame of reference " The measurement is affected BECAUSE the actual pacing of time is varied in that frame of reference . It is like measuring your weight on the moon, and saying that the measurement is affected by gravity, not the actual weight. Measurement of weights on moon is affected BECAUSE the weight of the object is affected – silverrahul Apr 22 '21 at 06:05
  • quote: " Measurement of weights on moon is affected BECAUSE the weight of the object is affected" But how can this be at constant velocity? – Markoul11 Apr 22 '21 at 06:11
  • You mean the example of the moon ? I was must making an analogy. My point is that when you have a device for measuring something, and the device is showing that the "something" is changing, then the conclusion should be that the "something" is changing. Not that your device is changing . Unless you have a good explanation for how your device is changing – silverrahul Apr 22 '21 at 06:17
  • A relativistic effect does not mean necessarily that it applies also within a single frame of reference thus making it also absolute for a single reference. My argument is that gravitational time dilation is both a relativistic and absolute effect whereas SR kinematic constant velocity time dilation is a pure only relativistic effect. It is not that the matter of the two objects is time dilated but rather the information traveling from one observer to the other that is time dilated. – Markoul11 Apr 22 '21 at 12:33

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We know from experiments for certain, that acceleration affects matter slowing down at the molecular scale vibrations and therefore has a physical effect on matter and also on tick rates of clock time measuring devices from the mechanical, electronic to atomic clocks. Therefore gravitational time dilation has an actual physical effect on matter.

We do not say that the slowing down of molecular vibrations etc. is an actual physical effect on matter. Rather, it is an effect on the flow of time. BUT, If this is how you define "physical effect on matter", then SR time dilation effect does the same thing as well. It also affects matter slowing down at the molecular vibrations scale and also affects the tick rates of clocks and all time measuring devices, from the mechanical , electronic, to atomic clocks. So, SR time dilation also has an actual effect

" Are there any experiments that can show that SR time dilation has an actual effect on matter? "

Like i said earlier, neither SR or GR time dilation has an actual effect on matter, but rather they have an effect on the rate of flow of time in a certain frame. Of course, under GR, the motion of matter is affected by the spacetime curvature but that is a different issue. If you are asking whether there have been any experiments done to show SR time dilation, there have been multiple experiments done to confirm the SR time dilation effect. https://math.ucr.edu/home/baez/physics/Relativity/SR/experiments.html#Tests_of_time_dilation

" A quite simple experiment would be according to the above information to compensate a GPS satellite for a year only for the gravitational time dilation (i.e. clock on satellite runs +45μs faster per day) and do NOT compensate for the whole year for the kinematic SR time dilation effect (i.e. clock on satellite appears to run -7μs slower per day). According to the above information at the end of the year the clock on the orbiting GPS satellite would lack in time about 365x(-7μs)= -2.55 ms. Bring the satellite down to Earth from orbit to stationary position and read out its clock time.

If the clock on the stationary satellite would then found to be lacking around -2.55 ms within the error bars of this experiment then this would conclusively prove that SR constant velocity time dilation has an actual physical effect on matter and is not just an apparent relativity effect!"

This could be done, but it is definitey not a SIMPLE experiment. You would have to mess with the GPS satellites, thus rendering all GPS systems worldwide inoperable for a year, just to provide experimental verification for something that has already been verified by many experiments.

silverrahul
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  • Thank you for the explanations provided. One last thing, I still don't get it how constant velocity can cause forces on the moving object and has an effect on the object's matter (i.e. time dilation) within the same frame of the object? Since there is no acceleration there are also no forces exerted on the object. Wouldn't that then also imply that constant velocity time dilation is not only a Relativity phenomenon but also absolute within the object's frame of reference? – Markoul11 Apr 22 '21 at 12:20
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    @Markoul11 Constant velocity does not cause forces on the moving object. It is only our measurements of time and length that change – silverrahul Apr 22 '21 at 13:19