Re: O'Barr: What is the real velocity of light in Frame A?

"Gerald L. O'Barr" <globarr@xxxxxxxxx> wrote in
news:1180669062.619215.248260@xxxxxxxxxxxxxxxxxxxxxxxxxxxx:

On May 31, 11:22 am, bz <bz+...@xxxxxxxxxxxxxxxxxxxx> wrote:
"Gerald L. O'Barr" <glob...@xxxxxxxxx> wrote
innews:1180631424.932229.154000@xxxxxxxxxxxxxxxxxxxxxxxxxxxx:

<delete by O'Barr>

O'Barr comments:
Every SR frame can theoretically extend to every
other point in our reality. It can extend to the
moon, to the sun, to every star that we see.
Therefore, we can make, speaking theoretically, local
SR measurements everywhere.

Yep.

In this SR frame, we can
take (record) data of the exact position of the moon
at time x on an inertial line z, and then at time y,
and we can take the distance between these two
points, and find it to be L1.

Yep.

At these same times,
we can take the position of a pulse of light moving
on this same line at time x, and again at time y, and
we can record the distance between these two points
as L2. The relative velocity between the moon and
this light pulse is therefore (L2-L1)/(y-x).

Yep. These are 'measurements' in OUR FoR.

Such a measurement did not require the direct
measurement of the speed of light or the speed of the
moon. It only consisted of the change of distance
between these two objects over a known time period.

Yep. This consititues a measurement in OUR iFoR (assuming that OUR motion
during the time that we take such measurements approximates inertial motion
and that the objects under study are in inertial motion. For many objects
these are a sufficiently true approximations.)


Now of course I have not been to the moon, but in
our frame, we have to know very exactingly the rate
at which the moon is moving at all points within our
earth's frame.

The Earth's motion is not inertial. Neither is the moons.

And such knowledge is known and it is
relativistically correct.

Approximately correct for most purposes but not exactly correct.

And we must know the speed
of light, and this is relativistically correct.

theoretically. But confirming this knowledge (or falsifying the theory)
requires actually measurement, not theoretical knowledge.

And
thus we do know that in general, a light pulse that
is moving in any direction that includes a component
of the moon's motion in the earth's frame will not be
going relative to the moon with a velocity of c.

Closing velocity is not the velocity 'relative to the moon'. If you want to
measure(calculate) the closing velocity IN THE EARTHS FoR, then you are
doing so in the EARTHS iFoR(an approximation because the earths motion is
not inertial). You have just a closing velocity.

WHen you say 'relative to the moon', then you are actually talking about
'in the moon's iFoR' and SR allows you to calculate that. It will be c.


I have worked in Aerospace for over 29 years.

Good for you.

I
have used lasers to measure both time and distances.

Then you understand that such measurements are two way measurements and
make certain assumptions. Such measurements are approximations of 'proper
SR measurements' and are only approximately correct.

I was at times the one to check the Air Force Blue
Book, to insure that the tests they were going to do
in space were correct. And thus, although I have not
personally done all of these things, I am intimately
aware of how a space ship is able to take an
electromagnetic signal from the earth, and tell
exactly how fast it is moving relative to this
signal.

Then you also understand that for most velocities and measurements,
Newtonian physics gives 'sufficently accurate' results. Relativistic
corrections are minimal over the short times and distances involved with
the speeds involved.

And a space ship can use this data to
determine how to correctly enter a moon's orbit, or
an earth's orbit. And to do this, it is required
to know its velocity relative to the object it is
approaching.

Right. For motions of objects such as Jupiters moons, over the distances
involved, relativistic corrections on the order of half a second may be
required. Significant. Measurable. Enough to make an orbital correction
firing necessary at times, but pertibation due to gravity is sufficient to
produce larger effects, as is variation in fuel feed rates.

To be able to know your relative velocity with
respect to light that has a velocity of c in the
earth's frame is a great blessing, and for anyone on
this net not to allow such thoughts only show that
you have never had a real job.

We have been trying to tell you that the light travels at c in ANY inertial
FoR. We have been trying to tell you that closing velocities need not be c
but they are in OUR (or some single FoR).

You need to be very careful in how you use 'relative to' because, if you
are not careful, you begin to think that light 'actually' travels at the
closing velocity and that the travel time can be predicted based upon that
travel time.

I feel sorry for you people.

When you step out of discussing science into attacking people, you invite
counter attack.

But even more sorry
because there are people on this net who just might
believe you.

Hopefully, they will study the situation and arrive at the correct
conclusion, taking all facts into account.

But you will not prevail. We are going
to start to do things right, and it cannot be
prevented.

Please DO change your approach and 'start to do things right'.

SR is math perfect, it makes correct math
measurement predictions, but it is a sick physical
theory, and we are going to have to understand
some of these simple things.

You just stepped out of science and into Philosophy again.
But you still think you are speaking science. THAT is your problem.






--
bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

bz+spr@xxxxxxxxxxxxxxxxxxxx remove ch100-5 to avoid spam trap
.

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