Re: E = 3/4 mc? or E = mc?? The forgotten Hassenohrl 1905 work.

On Sun, 8 Dec 2024 8:19:33 +0000, Paul B. Andersen wrote:

Den 07.12.2024 22:19, skrev Paul B. Andersen:

Den 06.12.2024 21:00, skrev J. J. Lodder:

Paul B. Andersen <relativity@paulba.no> wrote:
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According to:
https://www.bipm.org/utils/common/pdf/si-brochure/SI-Brochure-9.pdf
(2019)
The SI definitions are:
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The relevant defining constants:
  Δν_Cs = 9192631770 Hz  (hyperfine transition frequency of Cs133)
  c = 299 792 458 m/s (speed of light in vacuum)
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The relevant base units:
Second:
  1 s = 9192631770/Δν_Cs  1 Hz = Δν_Cs/9192631770
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Metre:
  1 metre = (c/299792458)s = (9192631770/299792458)⋅(c/Δν_Cs)
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The home page of BIMP:
https://www.bipm.org/en/measurement-units
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Give the exact same definitions, so I assume
that the definitions above are valid now.
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https://www.bipm.org/utils/common/pdf/si-brochure/SI-Brochure-9.pdf

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If the speed of light is measured _with the meter and second
defined above_ it is obviously possible to get a result slightly
different from the defined speed of light.
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So I was not "completely, absolutely, and totally wrong".

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You were, and it would seem that you still are.
You cannot measure the speed of light because it has a defined value.
If you would think that what you are doing is a speed of light
measurement you don't understand what you are doing.

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Yes, I was indeed "absolutely, and totally wrong",
but not completely wrong.

I disagree that you were wrong at all.
1) The expression "c" has multiple meanings. On the one hand, it is,
   according to a widely accepted geometric model of spacetime, a
   constant that expresses the relationship between units of space and
   units of time. This "c" is given a defined value of 299792458 m/s,
   and because it has that value by definition, it cannot be measured.
2) Another meaning of "c" is the speed of photons in vacuum. Photons
   are, to the best of our knowledge, massless, and according to the
   above geometric model of spacetime, all unimpeded massless
   particles travel at the speed "c" given in definition (1).
Does the above-mentioned geometric model of spacetime, this "theory",
correspond to reality? All tests of predictions made by that model
(in the absence of gravity) have thus far validated its predictions.
But although well-validated, this theory (SR) is not proven and can
never be. Other theories of physics exist that are far beyond my
competency to discuss, which would predict different results of
physical measurements.
So it is legitimate to ask questions like, "Is the speed of light
in vacuum completely independent of wavelength"? since alternative
theories of physics envision scenarios where the SR prediction breaks
down.