Re: Why SR? (was: Source Independency of Light Speed Without an Aether???????)

"Bruce Richmond" <bsr3997@xxxxxxxxxxx> wrote in message news:9d2fd128-0fe3-43db-8f8e-634275ca04f9@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On Jul 1, 11:49 pm, "Whoever" <no...@xxxxxxxxxxx> wrote:
"Bruce Richmond" <bsr3...@xxxxxxxxxxx> wrote in message

news:3b21d130-b93e-4e7e-8486-9fe5c6ae61bd@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

> If the coordinate system is constructed using light
> signals that by definition travel at isotropic c then there is no way
> you can measure the speed of light to be anything but c. Call it
> circular if you like but it is true. And that is a property of the
> coordinate system. You could have made it differently if you wanted
> to.

You could .. but there is not really anything else that makes sense.

Well you could defer to the sync of another frame.

And what does that mean? One still needs to know what sync means for a given frame in order to sync clocks with some other frame

Does the space
station have its own time or do they use a particular time zone on
earth?

You're bypassing the question .. one still then has to ask how does one synchronise with a clock on earth. What does it mean for the clock on the space station and that on earth to be in sync? (not that they could anyway, as they tick at different rates, so they would immediately go out of sync)

That would make more sense than adjusting their clock each
time they pass into another time zone, or worse yet continuously
adjusting to match the solar time of the point they are passing over.

Still doesn't answer the question of what is a sensible alternative of clock sync to that proposed by Einstein

Some people wave arms about absolute time and absolute sync .. yet they
can't define what that means, or how to achieve it (ie how to set up two
clocks in absolute sync), or how to measure it (ie how to check if two
clocks are in sync or not). Other than naive concepts like looking at the
clocks from a midpoint and seeing them show the same time (and we all know
what that assumes) :):)

I don't think anyone here was trying to invoke an absolute time.

They have been .. not by you though

I
was just pointing out that in SR the speed of light being isotropic c
is not an assumption, it is a property arrived at by how the
coordinate system is constructed.

Yeup .. but there is not really any sensible alternative.

If it was an assumption it could be
proven wrong. As it is, if the speed of light is measured to be
anything other than c an error was made because it has to be c.

It has to be isotropic from the postulate that the speed of light is c.

The clock sync then comes from that postulate .. as any other sync would not be showing the correct speed for light (ie it would be an error).

If it was possible to show that light speed is isotropic (perhaps comparing wavelength and frequency of light going in opposite directions?) without using remote clocks, then that would 'prove' the clock sync as 'correct' ??


.

Relevant Pages
Quantcast