Re: A little challenge for relativists.


vern@xxxxxxxxxxxx wrote:
> shevek wrote:
> > John Kennaugh wrote:
>
> [...]
> > [..]
> >
> > I agree - replace the word 'ether' with 'electromagnetic field' and
> > you'll get a lot more agreement as well without really changing the
> > content.
>
> With an ether model, there is a distinct mechanism to explain why the
> speed of light is independent of the source; that's the way fluids
> work. Substituting the word "electromagnetic field" for the word
> "ether" takes away the physical model which explains source
> independence.

Not really. A field can be a physical model as well. The word comes
from fluid mechanics - a velocity field in a fluid is a physical model
for example. By saying "field" you are only considering a certain
moment of a distribution function.

> Aren't you really just saying that an electromagetic
> field is responsible for light speed's source independence, but I don't
> know why or how?
>

Maybe.. Why and how are just not specific enough questions. We know
how to apply Maxwell's equations that describe certain states of the
electromagnetic fluid / ether field.. but as to the actual constituents
of this fluid and what properties they could have seems to be in
question.

>
> This thread has been interesting. Bilge asserts that the speed of
> light is independent of the source as a function of geometry.
> Space-time just works that way; there's no more reason to question it
> than you would question why a^2+b^2=c^2 in Euclidean space.

I'm with Bilge there, it's an issue of geometry definition - of
agreeing on what we mean by a meter or a second.

> Tom
> Roberts and Harry indicate that it's experimental evidence that is the
> justification for not questioning why or finding a mechanism that
> explains light speed's source independence.

I sort of agree, except it's not really experimental evidence of the
geometry convention, it's experimental use of the convention without
generation of inconsistencies. The protocol is well tested.

> Others, including you,
> seem to lean towards it not being a question that needs to be answered
> to validate SR; it is more of a problem for QM and GR. But I find John
> Kennaugh's reasoning sound. SR should not be accepted regardless of
> the experimental evidence if no mechanism can be posited for why SR
> postulates that the speed of light is independent of the source. A
> light-wave-carrying medium is the only mechanism or model that anyone
> has offered.

Agreed. Thanks for the recap Vern - shevek

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