Re: c = constant is still under discussion in this group

Rudolf Drabek wrote:
This matter is not solved in this group.

Sure. So what? The matter is solved to the current accuracy of experiments, and that is what _physicists_ care about. This group does not reflect the consensus of the scientific community; not even close.


It may be that it is solved, but I don't know the source.

The question of whether or not c is constant has been "solved" for many decades. But to find the source you must search the _primary_physics_literature_ and not this newsgroup or the web -- both contain too much wrong information (and even deliberate disinformation) to be of much value.

The FAQ contains a rather large list of references to that literature.
http://math.ucr.edu/home/baez/physics/Relativity/SR/experiments.html


> [...]

You seem hung up on the distinction between OWLS (one way light speed) and TWLS (two way light speed, also known as a round trip measurement). There is no doubt whatsoever that TWLS = c for all measurements made on earth, and for astronomical measurements in which gravitation can be ignored. OWLS, on the other hand, is merely a convention -- to measure it inherently requires two clocks (or equivalent), and you are free to synchronize them in any manner you choose; because the answer depends on the synchronization method _you_ happen to choose, it cannot be of any physical significance.

Note that for situations in which gravitation cannot be ignored, a measurement of TWLS can obtain a result other than c. See, for instance, the Shapiro time delay (which is a direct proof of this for paths earth->mars->earth that pass the sun).


Why do we still have a discussion about this topic in this group in yr
view?

Because there are so many people around here who either do not understand very basic aspects of physics and logic, or are too self-centered and lazy to actually _STUDY_ the topic.


we hopefully can agree
about c +- v or c.

It is not for "us to agree or disagree", it is for _experiments_to_measure_. And they have: If the speed of light from a source moving with velocity v is (c + k v) for some constant k, then experiments and observations put an upper bound on k of around 10^-9.


Tom Roberts
.

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