Re: Question about light clock and derivation of time dilation

In article <42ced2ee$0$18642$14726298@xxxxxxxxxxxxxxx>, sue jahn says...

>> >> That's not correct. The angle of reflection is equal to
>> >> the angle of incidence. If a light beam hits a mirror
>> >> at an angle of 80 degrees, then it will bounce off at
>> >> 80 degrees.
>> >
>> >So how many times do you have to add 180 to 90 to
>> >get to a number that is not divisable by 90?
>>
>> What are you talking about?
><<if light hits a mirror at 90 degrees,
>it will bounce off at 90 degrees. >>
>Your words
>
>Sue...

Yes. In the frame in which the mirrors are at rest, the
light hits at an angle of 90 degrees. In the frame in
which the mirrors are moving at speed v, the light
hits the mirrors at an angle theta given by

cos(theta) = v/c

Angles are not invariant, either in Galilean relativity
or special relativity.

You seem to be having trouble with aspects of the light
clock thought experiment that have *nothing* to do with
relativity. Everything I've said about the light clock
would be true in Galilean relativity, as well. I think
you need to work the problem out in Galilean relativity
(or any theory that you think you understand) first.

--
Daryl McCullough
Ithaca, NY

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