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

On Jul 2, 3:02 am, "Whoever" <no...@xxxxxxxxxxx> wrote:
"Bruce Richmond" <bsr3...@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@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

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

It means just what it says. If you are on the train you could adjust
the tick rate of your watch so that it stays in agreement with the
clocks on the embankment. It would make sense if the purpose of your
trip was to report on activities observed along the embankment. But
it would leave you with a coordinate system in which light did not
travel at isotropic c.

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)

Most clocks have an adjustment for their tick rate. I think my train
example answered your question.

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

On the space station receive timing signals from the ground to varify
that you have the tick rate of you clock set right. For any
experiment using multiple clocks on the station use slow transport.

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

By "anybody" I meant John and myself. I know there are cranks around
here.

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.

Depends on your purpose. When you travel into a different time zone
you adjust your watch to agree with those around you. There is a
definite line at which the change is supposed to be made. You may
have only traveled ten miles, but if you crossed that line you better
adjust your watch or you are the odd one.

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).

I'm pretty sure that's what I was saying. I only added that because
it comes from the postulate it will agree with the postulate. It is
obvious but some people don't see it.

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' ??

I thought in science you could prove something correct, you could only
show what was not correct. The fact that I can do experiments that
are in agreement with LET does not prove LET correct and SR wrong ;)

.

Relevant Pages

  • Re: Why SR? (was: Source Independency of Light Speed Without an Aether???????)
    ... clocks on the embankment. ... I'm not talking tick rate, but sync. ... can one show isotropy without measuring the speed directly. ...
    (sci.physics.relativity)
  • Re: Einsteins Train Gedanken Re-visited
    ... the one moving with the earth would stay 'still' ... see we need to make it explicit) what do you claim about the clocks ... appropriate speed would keep it in sync. ... frame would then be inertial. ...
    (sci.physics.relativity)
  • Re: Einsteins Train Gedanken Re-visited
    ... >>> Earth itself is accelerating as it travels in its orbit about the ... >> see we need to make it explicit) what do you claim about the clocks as ... appropriate speed would keep it in sync. ... galaxy etc. its pretty much impossible to get a perfectly inertial frame .. ...
    (sci.physics.relativity)
  • Re: Einsteins Train Gedanken Re-visited
    ... the one moving with the earth would stay 'still' ... I thought the whole purpose of this exercise was to get clocks in sync ... frame would then be inertial. ...
    (sci.physics.relativity)
  • Re: Daylight Savings 2007 - Problems
    ... Set sync for every 5min ... Our clocks are showing anything within a range of 3 hours. ... between the client and server" all over the place. ... At work I have a utility that syncs with atomic clocks via internet, ...
    (microsoft.public.windowsxp.general)