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From: David on 7 Dec 2007 12:37
I've been trying to find experimental verification that c is constant
by looking for experiments where wavelength and frequency are measured
independently of each other and results from moving sources are
compared to the results from stationary sources - like the wavelength
of light with frequency f (as measured in a rest frame) from a moving
star compared to the wavelength of light with the same frequency f
created by a source in the rest frame. But I wasn't able to find any
experiment where wavelength and frequency are measured independently
to confirm that their product is a constant.
Is there a published result of this type of experiment available?
Thanks,
David Seppala
From: Androcles on 7 Dec 2007 12:51

"David" <dseppala(a)austin.rr.com> wrote in message
news:8t0jl3l4bgberie9neifj33k9hg61fhql3(a)4ax.com...
: I've been trying to find experimental verification that c is constant
: by looking for experiments where wavelength and frequency are measured
: independently of each other and results from moving sources are
: compared to the results from stationary sources - like the wavelength
: of light with frequency f (as measured in a rest frame) from a moving
: star compared to the wavelength of light with the same frequency f
: created by a source in the rest frame. But I wasn't able to find any
: experiment where wavelength and frequency are measured independently
: to confirm that their product is a constant.
: Is there a published result of this type of experiment available?
: Thanks,
: David Seppala

Sagnac.
http://www.androcles01.pwp.blueyonder.co.uk/Sagnac/Sagnac.htm






From: dlzc on 7 Dec 2007 12:56
Dear David:

On Dec 7, 10:37 am, David <dsepp...(a)austin.rr.com> wrote:
> I've been trying to find experimental verification that
> c is constant by looking for experiments where
> wavelength and frequency are measured independently of
each other and results from moving sources are
> compared to the results from stationary sources -

http://adsabs.harvard.edu/abs/1975NTvA....5...17K
... the title will give you search terms.

Photoelectric (or bolometer) gives you energy (related to frequency),
and diffraction gives you wavelength.

David A. Smith
From: Eric Gisse on 7 Dec 2007 17:55
On Dec 7, 8:37 am, David <dsepp...(a)austin.rr.com> wrote:
> I've been trying to find experimental verification that c is constant
> by looking for experiments where wavelength and frequency are measured
> independently of each other and results from moving sources are
> compared to the results from stationary sources - like the wavelength
> of light with frequency f (as measured in a rest frame) from a moving
> star compared to the wavelength of light with the same frequency f
> created by a source in the rest frame. But I wasn't able to find any
> experiment where wavelength and frequency are measured independently
> to confirm that their product is a constant.
> Is there a published result of this type of experiment available?
> Thanks,
> David Seppala

Explain what you have tried in your research thus far, and we'll see.
One would think someone who has had people explain SR to him for years
would have picked up enough of the terminology to do some basic
research himself...
From: Tom Roberts on 29 Dec 2007 22:52
David wrote:
> I've been trying to find experimental verification that c is constant
> by looking for experiments where wavelength and frequency are measured
> independently of each other and results from moving sources are
> compared to the results from stationary sources - like the wavelength
> of light with frequency f (as measured in a rest frame) from a moving
> star compared to the wavelength of light with the same frequency f
> created by a source in the rest frame. But I wasn't able to find any
> experiment where wavelength and frequency are measured independently
> to confirm that their product is a constant.

Consider the operation of a standard lab He-Ne laser. The 3S->2P
transition of neon is Doppler broadened to about 1.5 GHz [#]. The
wavelength is 632.8 nm, and for mirrors 30 cm apart there are about 1
million wavelengths between the mirrors, with spacing between
longitudinal modes of 400-500 MHz. So typically 3 or 4 longitudinal
modes of the mirrors overlap the Doppler-broadened linewith of the
lasing transition in Ne.

[#] I don't have a reference for the intrinsic linewidth
of this transition, but the observed 1.5 GHz Doppler-
broadened width is consistent with the thermal computation
given in _Fundamentals_of_Light_Sources_and_Lasers_, by
Mark Csele. So the intrinsic width is considerably smaller
than the Doppler broadening, and that is all that matters here.

The frequency and wavelength separations of the different longitudinal
modes are fully consistent with the speed of light being constant. This
implies that for moving Ne atoms, the product of frequency times
wavelength for the lasing transition does indeed equal c. This is
optical spectroscopy, and these values are known quite accurately.

This example also refutes Henri Wilson's "BaTh", which claims that the
wavelength of light emitted from a source is the same in all inertial
frames -- for the Doppler-broadened lasing transition to excite multiple
longitudinal modes in the mirrors its wavelength MUST vary with speed.

Note that without the Doppler broadening of the lasing transition, He-Ne
lasers would be vastly more difficult to set up and get working.


Tom Roberts
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