"PD" wrote in
oups.com:

On Feb 17, 5:12 pm, HW@....(Henri Wilson) wrote:
On 17 Feb 2007 08:54:45 -0800, "PD" wrote:

...
Tell me what is wrong with my derivation...

Nothing is wrong with your derivation. Your conclusion that it
implies circularity is what's wrong.

.....

I showed how to derive the formula with trivial mathematical
circularity. Does that make me as great as Einstein ...or greater...?


Well, Henri, as I explained to you in great detail, there is nothing
circular about it. You started with the presumption that c is
constant, independent of the reference frame, and used that derive the
correct rule for the addition of velocities. That is precisely the
right way to do it. Circularity would entail concluding what you
started with, and that is not what you're doing. If you will read my
response quoted above once more, you will perhaps understand that a
little better.

Henri, another way of saying it is this:
If one is speaking of how SR says things 'should be', then one must (at
least for the sake of the discussion in progress) accept the postulates of
SR and the derived conclusions.

If one is doing so, then the BaTh statement c'=c+v would be expressed (in
SR) as c' = composition(c,v) and the results will always be c.

Nothing terribly unexpected about this. But it does invalidate attempts to
say that SR requires photons leaving a moving source to know the velocity
of the target so that they arrive there at c.

The other important point PD made might be reworded as "if we were to
compute the 'relative velocity' using any other rule than the composition
rule, the results would not agree with expermental data".

For example, two particles approach each other at v1 and v2,
if v_effective=v1+v2 were correct, rather than
v_effective=composition(v1,v2)
then dozens of years of expermental data from particle accelerators around
the world would have given much different results from those that have been
seen.

The composition formula gives the correct results for all experiments
anyone has been able to run(as far as I know).

While this does NOT prove SR is correct, it clearly proves that we can NOT
use v_effective = v1+v2 under any circumstances where either v1 or v2 are a
significant fraction of c and get the correct (as verified by experiment)
predictions.



--
bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

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