From: eric gisse on
Da Do Ron Ron wrote:

> Tom R wrote:
>>It should be clear that using Einstein's synchronization
>>method ... will GUARANTEE that the one-way speed of light
>>will be measured to be c.
>
> How is this guaranteed? (That is, what exactly did Einstein
> do to make it happen?)
>
> ~~RA~~

I'd suggest reading about it.
From: Darwin123 on
On Jan 11, 3:53 pm, "Androcles" <Headmas...(a)Hogwarts.physics_r> wrote:
> "Cwatters" <colin.wattersNOS...(a)TurnersOakNOSPAM.plus.com> wrote in message
>
> news:PeidnakCrdUz6NbWnZ2dnUVZ8oidnZ2d(a)brightview.co.uk...

> Why don't YOU try?
>  http://www.androcles01.pwp.blueyonder.co.uk/lightclock.gif
> Poverty stricken, can't afford a LED and a phototransistor?
> Don't know how to debounce a switch?
> Don't know how to hook up an oscilloscope?
1) Do you know what the triggering dial on the oscilloscope does?
2) Do you pay attention to cable lengths on the trigger?
3) What signal do you trigger off of?
4) Have you tried changing cable lengths?
5) If you don't use a trigger signal, how do you synchronize the
switch with the display?
From: Inertial on

"kenseto" <kenseto(a)erinet.com> wrote in message
news:f84dbe65-a6ab-4a71-bb9c-b7a6d66f1041(a)u41g2000yqe.googlegroups.com...
> On Jan 11, 5:29 pm, Tom Roberts <tjrob...(a)sbcglobal.net> wrote:
>> kenseto wrote:
>> > one-way isotropy is not a direct measure of the value of the
>> > one-way speed of light. Why? You can have 200,000 Km/sec isotropy or
>> > 300,000 Km/sec isotropy.
>>
>> No. It is true that tests for isotropy do not directly measure the value
>> of the
>> speed. But once they demonstrate isotropy then the value of the one-way
>> speed
>> involved can only be equal to the KNOWN value for the round-trip speed of
>> light
>> in vacuum. After all, the round-trip paths used in such measurements
>> consist of
>> two one-way paths in series.
>
> The problem with that approach is that the value for the round-trip
> speed of light is the average of (outbound speed +inbound speed)/2.
> Clearly this does not tell you that the outbound speed is equal to
> inbound speed as required by the one-way isotropy.

If there is one-way isotropy, then the inbound speed must be the same as the
outbound speed which must be the same as the two way speed

[snip]
> The Michelson-Morley experiment was done with short distances and even
> that showed 6 fringe shift. This small fringe shift was attrubuted to
> experimental error. But what if the arms of the MMX is much longer
> will there be larger fringe shift?

That was tried

> The point is, in aether theory, the
> value for the one-way speed of light is distance dependent.

No

> Your
> anisotropy experiments does not address this issue at all.

No .. the measurements of the speed of light address it. One way anisotropy
addresses the the one way speed is the same in all directions.

From: GogoJF on
On Jan 11, 7:59 am, kenseto <kens...(a)erinet.com> wrote:
> Why physicists refuse to measure the one-way speed of light directly?
> The answer:
> The one-way speed of light is physical distance dependent.
> BTW that's why they invented a new definition for a meter length: 1
> meter=1/299,792,458 light second
> Using this definition the one-way speed of light is c by definition.
>
> Ken Seto

Ken: You keep going about your business, demanding why a one-way,
unidirectional measure of light should not be performed. So far, all
that I have heard is that- the isotropy of light automatically implies
a one-way measure of c, the fact that anisotropy does not exist (MM)
means that light is isotropic and that the two-way would average out,
that there is 2x in summation divided by 2, that a one way measure
would lead to errors beyond the usefulness of the experiment, that it
is not meaningful, that it is not possible to perform, and, last, but
not least, that it is not useful.
From: Ace0f_5pades on
On Jan 12, 5:22 am, Sam Wormley <sworml...(a)gmail.com> wrote:
> Physics FAQ: How is the speed of light measured?
>
> http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/measure...
>
> Physics FAQ: What is the experimental basis of Special Relativity?
>    http://math.ucr.edu/home/baez/physics/Relativity/SR/experiments.html
>
> 3.2 One-Way Tests of Light-Speed Isotropy
>
> http://math.ucr.edu/home/baez/physics/Relativity/SR/experiments.html#...
>
> Note that while these experiments clearly use a one-way light path and
> find isotropy, they are inherently unable to rule out a large class of
> theories in which the one-way speed of light is anisotropic. These
> theories share the property that the round-trip speed of light is
> isotropic in any inertial frame, but the one-way speed is isotropic only
> in an æther frame. In all of these theories the effects of slow clock
> transport exactly offset the effects of the anisotropic one-way speed of
> light (in any inertial frame), and all are experimentally
> indistinguishable from SR. All of these theories predict null results
> for these experiments. See Test Theories above, especially Zhang (in
> which these theories are called “Edwards frames”).
>
> Cialdea, Lett. Nuovo Cimento 4 (1972), pg 821.
> Uses two multi-mode lasers mounted on a rotating table to look for
> variations in their interference pattern as the table is rotated. Places
> an upper limit on any one-way anisotropy of 0.9 m/s.
>
> Krisher et al., Phys. Rev. D, 42, No. 2, pg 731–734, (1990).
> Uses two hydrogen masers fixed to the Earth and separated by a 21-km
> fiber-optic link to look for variations in the phase between them. They
> put an upper limit on the one-way linear anisotropy of 100 m/s.
>
> Champeny et al., Phys. Lett. 7 (1963), pg 241.
> Champeney, Isaak and Khan, Proc. Physical Soc. 85, pg 583 (1965).
> Isaak et al., Phys. Bull. 21 (1970), pg 255.
> Uses a rotating Mössbauer absorber and fixed detector to place an upper
> limit on any one-way anisotropy of 3 m/s.
>
> Turner and Hill, Phys. Rev. 134 (1964), B252.
> Uses a rotating source and fixed Mössbauer detector to place an upper
> limit on any one-way anisotropy of 10 m/s.
>
> Gagnon, Torr, Kolen, and Chang, Phys. Rev. A38 no. 4 (1988), pg 1767.
> A guided-wave test of isotropy. Their null result is consistent with SR.
>
> T.W. Cole, “Astronomical Tests for the Presence of an Ether”, Mon. Not.
> R. Astr. Soc. (1976), 175 93P-96P.
> Several VLBI tests sensitive to first-order effects of an æther are
> described. No æther is detected, with a sensitivity of 70 m/s.
>
> Ragulsky, “Determination of light velocity dependence on direction of
> propagation”, Phys. Lett. A, 235 (1997), pg 125.
> A “one-way” test that is bidirectional with the outgoing ray in glass
> and the return ray in air. The interferometer is by design particularly
> robust against mechanical perturbations, and temperature controlled. The
> limit on the anisotropy of c is 0.13 m/s.

Thanks for the links,

Must admit, I would like help relating to
http://relativity.livingreviews.org/Articles/lrr-2005-5/download/lrr-2005-5Color.pdf
I'm only at a basic understanding of 4 vectors transformation able to
(with some difficulty) transform Energy with respect to momentum.

its still early days for me. officially start learning RT soon,

still, can I ask you to take part in the thought experiment
@ http://groups.google.com/group/sci.physics/browse_thread/thread/e01480c15e001830?hl=en#