Question

If we have two reference frames K and K' which are moving relative to one another, special relativity suggests that there would be time dilation. In K, time appears to pass slower in K', whereas in K' time appears to pass slower in K.

The most common proof of this is by using light clocks and demonstrating that from one perspective, light has to travel a greater distance and therefore the clock would go slower. I have two questions that I'd appreciate help with:

Surely time dilation is a consequence of the peculiar way of measuring time with a light clock. If I used a mechanical clock, or an atomic clock where there are no distances involved, wouldn't the time be the same?

I don't understand why we can assume light travels the same in all reference frames. Is there a proof?

Answer 1

Time dilation is a fundamental consequence of special relativity, not specific to light clocks. It occurs because the speed of light is constant in all reference frames and is supported by experimental evidence.

Step-by-step explanation:

Time dilation is the phenomenon of time passing slower for an observer who is moving relative to another observer. It is not specific to light clocks, but rather a fundamental consequence of special relativity.

When two reference frames are moving relative to each other, the time measured in one frame appears dilated or stretched out from the perspective of the other frame.

This is because the speed of light is constant in all reference frames, and the measurement of time is interconnected with the measurement of distance.

Therefore, even if a mechanical or atomic clock is used, time dilation still occurs in the same way.

As for the assumption that light travels the same in all reference frames, it is a fundamental postulate of special relativity known as the constancy of the speed of light.

Numerous experiments and observations have confirmed this postulate. For example, the Michelson-Morley experiment showed that the speed of light is independent of the motion of the observer.