Re: Clock synch

jt64@xxxxxxxx wrote:
Tom Roberts skrev:
In SR, measured with coordinate clocks, the one-way speed of light is
also isotropically c in every inertial frame.

I am not sure though that isotripical measured speed of light c in
every inertial frame is compatible with isotropical "symmetric
roundtrips" within SR

How could is possibly not be? If the one-way speed is isotropic in a given inertial frame, then so must the round-trip speed be isotropic; this applies to all inertial frames.


since LC can shorten/elongate distance in one
direction of path between A and B depending on who measure.

I have no idea what you mean by LC.

In relativity you must be more specific about what you mean by "distance", in particular: in what frame is it measured?


But maybe
it all is a null game where the time dilation actually cancel out the
shortening/elongating.

There is no "time dilation", in the sense of a clock physically ticking slower, or in the sense of "time moving slower". There is no "shortening/elongating", in the sense of a given object physically getting shorter or longer.

The effects called "time dilation" and "length contraction" in SR are not physical effects, and are due to different measurement procedures used by differently moving observers. They are purely geometrical projections of an invariant interval onto a coordinate axis, just as you are familiar with in Euclidean geometry.

If you hold a meterstick parallel to the X axis, it will
subtend 1 meter on the X axis. Hold it at 45 degrees and
it will subtend 0.707 meters on the X axis -- that is "X
contraction" in precisely the same sense that there is
"time dilation" and "length contraction" in SR. But this
example happens in the XY plane, and those other effect
happen in the XT plane. An inclined line in the XT plane
is relative motion, not relative orientation.


Tom Roberts
.

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