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Muhammad Zubair
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Is time dilation an actual phenomenon or it is just an apparent change relative to some other frame of reference? If it is so then why the age of a person slows down and elongates actually?
Muhammad Zubair said:Is time dilation an actual phenomenon or it is just an apparent change relative to some other frame of reference?
Muhammad Zubair said:If it is so then why the age of a person slows down and elongates actually?
I agree w/ Ben that you have to be careful using such terms because they SEEM to have precise definitions in English, but do not in physics, due to some subtleties that you are not yet aware of.Muhammad Zubair said:Is time dilation an actual phenomenon or it is just an apparent change relative to some other frame of reference? If it is so then why the age of a person slows down and elongates actually?
The first direct measurement of time dilation was done as described here: https://en.wikipedia.org/wiki/Ives–Stilwell_experimentMuhammad Zubair said:Is time dilation an actual phenomenon or it is just an apparent change relative to some other frame of reference? If it is so then why the age of a person slows down and elongates actually?
harrylin said:The first direct measurement of time dilation was done as described here: https://en.wikipedia.org/wiki/Ives–Stilwell_experiment
As you may get from the description, it is an actual phenomenon that has been measured. Classical physics postulates no time dilation and it leads to a different prediction of what will be observed.
Everything is a matter of interpretation. "Transverse Doppler" was the first positive test of time dilation (I wrote "direct" but I meant it in the sense of "positive", different from MMX), Also IMHO the test with cosmic ray muons was more direct and therefore more impressive.bcrowell said:Ives-Stilwell experiments are some of the most high-precision tests of SR, but they are not direct tests of time dilation. I think it's a bit of a stretch even to say that they are indirect tests of time dilation. What you observe is the forward and backward longitudinal Doppler-shift factors. The discrepancy between these numbers and the values predicted by some nonrelativistic expression can be interpreted as a time-dilation effect, but that's very indirect, and it depends on what nonrelativistic expression you think is appropriate.
If you want a more direct test from the same era as the original Ives-Stilwell, a better example would be cosmic ray muons, Rossi and Hall, 1941.
harrylin said:Everything is a matter of interpretation. "Transverse Doppler" was the first positive test of time dilation (I wrote "direct" but I meant it in the sense of "positive", different from MMX), Also IMHO the test with cosmic ray muons was more direct and therefore more impressive.
Oops sorry that's very right - my memory failed me although in fact I knew it!bcrowell said:The first tests of the transverse Doppler effect were not until the 1960s: H. J. Hay et al, Phys. Rev. Lett. 4, 165 (1960); W. Kündig, Phys. Rev. 129, 2371 (1963).
Ah yes, evidently my memory was "polluted" by such comments! Thanks for making me understand how this happened.You will find people referring to Ives-Stilwell experiments as tests of the transverse Doppler effect, but that's misleading. In Ives-Stilwell experiments the Doppler shifts being measured are longitudinal. When they say that these experiments test the transverse Doppler effect, what they mean is that if you factor the effect somehow into a nonrelativistic factor and a relativistic factor, the relativistic factor can be interpreted as a time dilation factor. Since the transverse Doppler effect is purely a time-dilation effect, people will sometimes refer to this as a test of the transverse Doppler effect.
Time dilation in relativity theory is the phenomenon where time appears to pass at different rates for observers in different frames of reference. This is due to the concept of space-time, where time is relative and can be affected by factors such as gravity and velocity.
Time dilation occurs due to the principle of relativity, which states that the laws of physics are the same for all observers in uniform motion. This means that as an object moves faster, time appears to pass slower for that object compared to a stationary observer.
The equation for time dilation is t' = t / √(1 - v²/c²), where t' is the observed time, t is the proper time (time measured by a stationary observer), v is the relative velocity, and c is the speed of light. This equation is known as the Lorentz factor.
Time dilation has a significant impact on space travel, especially when traveling at high speeds. As an object approaches the speed of light, time appears to pass slower for that object, meaning that astronauts on a space mission would age slower compared to people on Earth. This effect is known as the twin paradox.
Yes, time dilation can be observed in everyday life, although the effects are extremely small and can only be measured with highly precise instruments. For example, the clocks on GPS satellites have to be adjusted to account for the time dilation caused by their high orbital speeds relative to the Earth's surface.