Re: Photon, Momentum, Mass

On May 10, 2:11 pm, Bilge <dubi...@xxxxxxxxxxxxxxx> wrote:
On 2007-05-09, Jeckyl <n...@xxxxxxxxxxx> wrote:

<snip>

Do you agree with Jeckyl's post that the "geometry" of the universe
has no effect in the FOR of the source, but only affects things in
other FORs?

That is not what he said and attempting to straighten out your
misunderstanding is not worth the effort, since you have never
once made the slightest effort to understand anything which
might jeopardize your 15th century grasp of physical phenomena.

What I said was that from the FoR of the source, the light is emitted at,
and measured at, c .. it never goes faster or slower than c as far as the
source is concerned, so there needs to be no explanation of what makes it
NOT travel at c from the FoR the source, because it always DOES travel at c
from the FoR of the source.

The above may have what Jeckyl was trying to say, but what he said
was:

"The geometry affects how someone else (another FoR) measure the
light ..
that measurement is independant of the source speed."

<snip>

What there DOES need to be is a 'geometry' that explains how the different
FoR all measure the same speed for light.

Your last sentence is not quite accurate. In order to measure distances,
you need to define a metric. For a physically sensible result, you can
choose two groups of transformations that preserve the metric: the
galilean group and the poincare group. In both cases, there exists a
``lightlike'' vector which is invariant under the respective group
of transformations and which has a velocity `c' which is frame independent.
In the galilean case, that velocity is \infty.

Once you choose a group of transformations either c is finite or c is
infinite. The reason that vern thinks there must be some ``cause''
for `c' to be constant and finite is that he assumes a geometry where
`c' is constant and infinite so that he has to find some way to fix
his erroneous assumption, which otherwise makes incorrect predictions.

The identification of `c' with the speed of light is an historical
artifact due to the desire of einstein to explain maxwell's equations
as his motivation for developing special relativity. The identification
is only correct if maxwell's equations are correct (which implies
the photon is massless). This has been explained to vern (and to many
other kooks) before in an attempt to get them to separate geometry from
the theory of electromagnetism. The choice of geometry only contrains
the possibility for the theories which are self-consistent with the
geometry and I can easily write down a relativistic theory of E&M in
which the speed of light is not `c' and which contains a massive photon.

So it appears that the use of the word "geometry" is purely
mathmatical as opposed to representing a physical model. The term
"metric" is just a mathematical concept for describing distance.

Tom stated that classical theories assumed Euclidean space. What I'm
struggling to understand is how time works in Euclidean space. I've
always assumed that time is just an abstract concept and cannot affect
a physical model in any way. Newton's concept of time is that it is
invarient. It seems that any other mathematical model changes the
nature of time, which is inherently undefendable.

Vern

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