Darwin123 wrote:
[about Hafele and Keating's experiment]
There is a less extreme position that the 1971 HK experiment
was a test of general relativity. It was a test of GR only so far as
SR is part of GR.

This is not "less extreme", this is mainstream -- the H&K experiment can
only be interpreted as a test of GR, because SR is inadequate to analyze it.


The experimental conditions were set up so the
difference in gravitational potential was entirely negligible.

This is not true at all. For the eastbound trip the predicted
gravitational effect was 80% of the kinematic effect, and for westbound
it was 180% -- not "negligible" at all!


This
was an SR experiment. It verified SR and nothing else.

No. But it did confirm GR.


Tom Roberts

Pmb wrote:
"Pentcho Valev" wrote in message
...
On Apr 1, 12:52 am, Tom Roberts wrote in
sci.physics:
Anon wrote:
Because as you get closer to a massive body light is slowed down, this
bends
the rays of light towards the massive object. The same is true of other
massive objects. That is what Einstein said.
As I said before, Einstein said that in 1911, early on the
then-unfinished journey to General Relativity. GR itself does not really
have this property.

Note: Einstein's first work on general relativity (e.g. the equivalence
principle, gravitational time dilation. deflection of light, etc.) was in a
paper published in 1907 called "On the Relativity Principle and the
Conclusions Drawn from it," A. Einstein, Jahrbuch der Radioaktivitat und
Elektronik 4 (1907): 411-462. And contrary to Roberts claim, GR *does( have
this property.

Had you read my full statement, you would know that I said GR has this
property IN THE APPROPRIATE APPROXIMATION, SPEAKING LOOSELY: i.e. for a
suitable meaning of "speed" -- not a LOCAL speed but a NON-LOCAL speed
or a COORDINATE speed. And as I said, 'without approximation, or to
speak more accurately, one must discuss geodesic deviation, not "light
slowed down".'

The primary fault is Valev's, as he is the one who omitted my
explanatory text. But my original post is in this thread.


It is a very simple thing to derive. E.g.
http://www.geocities.com/physics_wor..._in_gfield.htm

That link says explicitly that the computation is the COORDINATE speed
of light. That is, the computed value is a ratio of coordinate
intervals, NOT what one would measure over a local distance using
standard clocks and rulers (one always measures c when one does that).

As I keep saying, and you both (Valev and PMB) keep ignoring: ONE MUST
BE CAREFUL TO AVOID PUNS. There are multiple meanings of the word
"speed" here and you are both oblivious to that fact. Doing physics
requires precision in thought and word, and such unacknowledged puns
destroy the discussion or argument.

The normal meaning of "speed" is what one measures in the obvious way
using standard clocks and rulers; with gravitation this must be over a
local path (short enough so variations in gravitational potential can be
ignored), so the two clocks can be synchronized. The coordinate speed of
light can be essentially anything, and the speed of light measured over
a non-local path can differ from c (e.g. Shapiro time delay). But if you
call those simply "speed" you are sure to confuse your reader (and most
likely yourself) -- that has CLEARLY happened in this thread.


Tom Roberts

On Apr 2, 9:53*pm, Tom Roberts wrote:
Pmb wrote:
"Pentcho Valev" wrote in message
...
On Apr 1, 12:52 am, Tom Roberts wrote in
sci.physics:
Anon wrote:
Because as you get closer to a massive body light is slowed down, this
bends
the rays of light towards the massive object. The same is true of other
massive objects. That is what Einstein said.
As I said before, Einstein said that in 1911, early on the
then-unfinished journey to General Relativity. GR itself does not really
have this property.

Note: Einstein's first work on general relativity (e.g. the equivalence
principle, gravitational time dilation. deflection of light, etc.) was in a
paper published in 1907 called "On the Relativity Principle and the
Conclusions Drawn from it," A. Einstein, Jahrbuch der Radioaktivitat und
Elektronik 4 (1907): 411-462. And contrary to Roberts claim, GR *does( have
this property.

Had you read my full statement, you would know that I said GR has this
property IN THE APPROPRIATE APPROXIMATION, SPEAKING LOOSELY: i.e. for a
suitable meaning of "speed" -- not a LOCAL speed but a NON-LOCAL speed
or a COORDINATE speed. And as I said, 'without approximation, or to
speak more accurately, one must discuss geodesic deviation, not "light
slowed down".'

The primary fault is Valev's, as he is the one who omitted my
explanatory text. But my original post is in this thread.

It is a very simple thing to derive. E.g.
http://www.geocities.com/physics_wor..._in_gfield.htm

That link says explicitly that the computation is the COORDINATE speed
of light. That is, the computed value is a ratio of coordinate
intervals, NOT what one would measure over a local distance using
standard clocks and rulers (one always measures c when one does that).

As I keep saying, and you both (Valev and PMB) keep ignoring: ONE MUST
BE CAREFUL TO AVOID PUNS. There are multiple meanings of the word
"speed" here and you are both oblivious to that fact. Doing physics
requires precision in thought and word, and such unacknowledged puns
destroy the discussion or argument.

The normal meaning of "speed" is what one measures in the obvious way
using standard clocks and rulers; with gravitation this must be over a
local path (short enough so variations in gravitational potential can be
ignored), so the two clocks can be synchronized. The coordinate speed of
light can be essentially anything, and the speed of light measured over
a non-local path can differ from c (e.g. Shapiro time delay). But if you
call those simply "speed" you are sure to confuse your reader (and most
likely yourself) -- that has CLEARLY happened in this thread.

Tom Roberts- Hide quoted text -

- Show quoted text -

Such brilliance.
I hope Tom Roberts can write a book like as "An Idiot's Guide to
General
Relativity". It would help millions immensely. But Roberts seems to
enjoy
taking poke shots at crackpots. Note crackpots are born not to learn
but to repeat the same mistakes. So as Roberts hair gets whiter as
each
year and decade passes by going into his old age, he would meet the
same
people and same argument again and again. I hope he can spend his
talent writing that book.

Or if Roberts is not a born writer. Can anyone of you write "An
Idiot's Guide
to General Relativity?"

cu

On Apr 2, 4:07*pm, Cutix wrote:
On Apr 2, 9:53*pm, Tom Roberts wrote:

Pmb wrote:
"Pentcho Valev" wrote in message
....
On Apr 1, 12:52 am, Tom Roberts wrote in
sci.physics:
Anon wrote:
Because as you get closer to a massive body light is slowed down, this
bends
the rays of light towards the massive object. The same is true of other
massive objects. That is what Einstein said.
As I said before, Einstein said that in 1911, early on the
then-unfinished journey to General Relativity. GR itself does not really
have this property.

Note: Einstein's first work on general relativity (e.g. the equivalence
principle, gravitational time dilation. deflection of light, etc.) was in a
paper published in 1907 called "On the Relativity Principle and the
Conclusions Drawn from it," A. Einstein, Jahrbuch der Radioaktivitat und
Elektronik 4 (1907): 411-462. And contrary to Roberts claim, GR *does( have
this property.

Had you read my full statement, you would know that I said GR has this
property IN THE APPROPRIATE APPROXIMATION, SPEAKING LOOSELY: i.e. for a
suitable meaning of "speed" -- not a LOCAL speed but a NON-LOCAL speed
or a COORDINATE speed. And as I said, 'without approximation, or to
speak more accurately, one must discuss geodesic deviation, not "light
slowed down".'

The primary fault is Valev's, as he is the one who omitted my
explanatory text. But my original post is in this thread.

It is a very simple thing to derive. E.g.
http://www.geocities.com/physics_wor..._in_gfield.htm

That link says explicitly that the computation is the COORDINATE speed
of light. That is, the computed value is a ratio of coordinate
intervals, NOT what one would measure over a local distance using
standard clocks and rulers (one always measures c when one does that).

As I keep saying, and you both (Valev and PMB) keep ignoring: ONE MUST
BE CAREFUL TO AVOID PUNS. There are multiple meanings of the word
"speed" here and you are both oblivious to that fact. Doing physics
requires precision in thought and word, and such unacknowledged puns
destroy the discussion or argument.

The normal meaning of "speed" is what one measures in the obvious way
using standard clocks and rulers; with gravitation this must be over a
local path (short enough so variations in gravitational potential can be
ignored), so the two clocks can be synchronized. The coordinate speed of
light can be essentially anything, and the speed of light measured over
a non-local path can differ from c (e.g. Shapiro time delay). But if you
call those simply "speed" you are sure to confuse your reader (and most
likely yourself) -- that has CLEARLY happened in this thread.

Tom Roberts

Such brilliance.
I hope Tom Roberts can write a book like as "An Idiot's Guide to
General
Relativity". It would help millions immensely. But Roberts seems to
enjoy
taking poke shots at crackpots. Note crackpots are born not to learn
but to repeat the same mistakes. So as Roberts hair gets whiter as
each
year and decade passes by going into his old age, he would meet the
same
people and same argument again and again. I hope he can spend his
talent writing that book.

Or if Roberts is not a born writer. Can anyone of you write "An
Idiot's Guide
to General Relativity?"

Roberts, together with Jean-Marc Levy-Leblond, should first write a
guide to special relativity:

http://groups.google.ca/group/sci.ph...34dc146100e32c
Tom Roberts, Feb 1 2006: "If it is ultimately discovered that the
photon has a nonzero mass (i.e. light in vacuum does not travel at the
invariant speed of the Lorentz transform), SR would be unaffected but
both Maxwell's equations and QED would be refuted (or rather, their
domains of applicability would be reduced)."

http://o.castera.free.fr/pdf/chronogeometrie.pdf
Jean-Marc Levy-Leblond: "D'autre part, nous savons aujourd'hui que
l'invariance de la vitesse de la lumiere est une consequence de la
nullite de la masse du photon. Mais, empiriquement, cette masse, aussi
faible soit son actuelle borne superieure experimentale, ne peut et ne
pourra jamais etre consideree avec certitude comme rigoureusement
nulle. Il se pourrait meme que de futures mesures mettent en evidence
une masse infime, mais non-nulle, du photon ; la lumiere alors n'irait
plus a la "vitesse de la lumiere", ou, plus precisement, la vitesse de
la lumiere, desormais variable, ne s'identifierait plus a la vitesse
limite invariante. Les procedures operationnelles mises en jeu par le
"second postulat" deviendraient caduques ipso facto. La theorie elle-
meme en serait-elle invalidee ? Heureusement, il n'en est rien ; mais,
pour s'en assurer, il convient de la refonder sur des bases plus
solides, et d'ailleurs plus economiques. En verite, le "premier
postulat" suffit, a la condition de l'exploiter a fond."

http://o.castera.free.fr/pdf/onemorederivation.pdf
Jean-Marc Levy-Leblond: "This is the point of view from wich I intend
to criticize the overemphasized role of the speed of light in the
foundations of the special relativity, and to propose an approach to
these foundations that dispenses with the hypothesis of the invariance
of c....We believe that special relativity at the present time stands
as a universal theory discribing the structure of a common space-time
arena in which all fundamental processes take place....The evidence of
the nonzero mass of the photon would not, as such, shake in any way
the validity of the special relativity. It would, however, nullify all
its derivations which are based on the invariance of the photon
velocity."

Pentcho Valev

On Apr 2, 12:12 am, Tom Roberts wrote:
Darwin123 wrote:
[about Hafele and Keating's experiment]
There is a less extreme position that the 1971 HK experiment
was a test of general relativity. It was a test of GR only so far as
SR is part of GR.

This is not "less extreme", this is mainstream -- the H&K experiment can
only be interpreted as a test of GR, because SR is inadequate to analyze it.

The experimental conditions were set up so the
difference in gravitational potential was entirely negligible.

This is not true at all. For the eastbound trip the predicted
gravitational effect was 80% of the kinematic effect, and for westbound
it was 180% -- not "negligible" at all!

I am not sure where you got your numbers. Unfortunately, I read
the articles a long time ago so I can't give my references either.
However, Hafele had an calculation article where he broke up his
calculated results into separate components. One article describes the
experiment and compares it to calculation, one article decomposes the
calculation in SR and GR components. There was no doubt that the GR
component was within experimental uncertainty. The difference between
SR calculations and experiment results was within experimental
uncertainty. The HK experiment (east-west) was a confirmation of SR.
I read accompanying articles by Hafele. He gave estimates of the
"special relativity" part of the correction, and the "general
relativity" part of the correction. The general relativity part was
the theoretical correction subtracted from the correction that could
be performed using special relativity alone. The contribution of this
part was almost exactly the same for the clock going east, the clock
going west, and the NBS clock.
For the first experiment, where the airplanes were going either
eatward or westward, the "general relativity" part of the correction
was small. The GR component was nonzero but experimentally negligible.
The experimental results did not depend on the equivalence principle.
It was simple Lorentz time dilation.
A later experiment by someone else did a similar experiment where
the traveling clocks circled the earth in the North and South
directions. In THAT experiment, the SR component was experimentally
negligible while the GR component matched the experimental results
within the uncertainty. You see that in THAT experiment, the radial
acceleration of all three clocks was the same. The only difference
between clocks was the gravitational potential, because the earth is
elongated at the equator. Again, the article broke the results into an
SR and a GR component. Therefore, the experimental results directly
validated the equivalence principle. Lorentz time dilation was not
directly involved.

On Mar 29, 3:26*pm, Darwin123 wrote:
* * Photons have zero REST MASS, not zero total mass. Since photons
can never be found at rest, each photon has a nonzero total mass.

wrong and assbackwards--read my post

* * If you don't believe A. Einstein, read H. A. Lorentz.
Electromagnetic waves have a nonzero inertial mass. Particles have
mass associated with motion which can be explained by the force fields
the particles drag along. The idea of light being bent is merely an
application of the Law of Equivalence (Einstein's) to the concept of

Elèctric fields ride on gravital fields; elèctric waves ride on the
same. The waves don't holdan mass by definiion; they /do/ mass. If
liht had mass--which it can't any more than $1 hav mass--then beams
and likenesses of everything would ooze toward their attractors.
Fotòns would continually split and breed at lower energies until
everything met infrared death.

electromagnetic mass (Lorentz). It sounds like you are knocking
Lorentz's idea, not Einstein's. Light is not massless in the way you
imply, and no modern physicists ever claimed it was so. *You are
knocking a straw man.

Speak to the PDG or shut up.

* * *Since electromagnetic waves have inertial mass, it is pretty much
a trivial extrapolation to infer they have gravitational mass. If you
want, you can claim that A. Einstein made a trivial extrapolation from
the work of A. Lorentz. Some may think it unfair to Einstein, but it
would make more sense than your idiotic "massless photon" analogy. If
this doesn't work, you can try calling H. A. Lorentz an idiot.

Ye're all mòroi.

-Aut