$ Mathematically speaking, a vacuum is ZERO particle COUNT.
Experimental MEASUREMENTs in AiR vary with AMBiENT particle COUNT.!!
(EinsteiN SPECiFiED ZERO particle-COUNT, for the VELOCiTY of light.)
(And, STP&g AiR is 26 Orders-of-Magnitude LESS EMPTY than "vacuum".)

SPECiFiCALLY ..EinsteiN's ((focus)) is on a *ZERO particle-COUNT*.!!
(Light VELOCiTY v VARiEs ..inversely, WiTH the PATH-particle-COUNT.)
Light-VELOCiTY c is, NOW, a MATHEMATiCAL constant ..just as is pi.!!

Light-VELOCiTY v "constancy", is ONLY per *CONSTANT particle-COUNT*.
Light VELOCiTY v *DECREASES*, inversely, with PATH-particle-COUNT.!!

$ CONCLUSiON:
Light VELOCiTY v *iNCREASES*, inversely, with PATH-particle-COUNT.!!
(Note, VARiOUS vacu ONLY exist in squeezed-SWiSS-cheese-LiKE minds.)

Brian A M Stuckless
^

jem wrote: Harry wrote: "jem" wrote in message
news:B2hlf.3958$fz5.1074@dukeread04... [John Kennaugh wrote earlier:
3/ It cannot be the speed relative to the observer because -=-

insert ..see top of PAGE, dooOPs.!!

-=- there is no causality whereby an observer's speed can effect
the speed at which light leaves the source besides which light
leaves the source when there is no observer so it can only be a
function of the source.] SNIP

Your claim was that the speed at which light is measured to leave
its source can't depend on the speed of the measurer, but the
*fact* that it *does* in a logically consistent theory (e.g. SR),
means that your claim is wrong. It's as simple as that.

What a big mistake!

but *whose* mistake?

Instead, in SRT it does not depend on the speed of either the
source, the receiver, or the measurer. It is measured to be
constant (in vacuum and at constant gravitational potential)
relative to any calibrated inertial coordinate system. This
system may be virtual, and all three may be moving
arbitrarily relative to it.

So at what speed does an SR observer measure light to leave its
source, when the observer is approaching that source at speed v?
(Read carefully this time). Is that speed independent of v?
Zero particle-count-error-bars.!! (i.e. in-vacu) by Uncle Tom.

You know, the idea behind written communication is to use the tool not
for your own satisfaction, but rather to convey your message.

Oh, but you did that, didn't you? Your message, having more to do with
you than the speed of light, IS clear.

Joe Fischer wrote: General Relativity has a stress-energy
tensor, which includes not only mass but also energy and -=-
PROFOUNDLY, there is NO "mass" ..in General Relativity (gtr).
PROFOUNDLY, iRONiCALLY, there's NO GR "space-time-curvature".
(The GR, G_uv = T_uv CANNOT be DEFiNED, in TERMs of "mass".!!)
possibly other factors relating to density and momentum, -=-
There is NO "mass -=- density and momentum", in GEOMETRY, duh.

This is NOT fluffy-level math ..it's whole-wheat arithmetic.!!

G*Mp*{mph} C1*(C2a*C2b) C1
-- --- -- = -- -- -- -- = -- = 4*pi*Vu*{e}*lo = 4*pi*#*{e}*c ;
(n - 1) C2^2*c c

C1*(p1*p2)*c C1*({e}^2*c^2)*c C1(q1*q2)*c^3 C1*{e}*c
= -- --- -- -- = -- -- ---- -- -- = -- - --- - -- = -- -- --
C2^2 C2^2 C2^2 C2 .

GENERAL GUESS photon mass [mph] = nA*{mph}*ls / rA = m1 = mD / n.
PARTiCULAR iSS photon mass {mph} = 2*pi*h / tp*c^2 = hbar / ls*c
= hbar / ts*c^2 = h / 2*pi*ls*c.

$ Planck common-centre-of-mass (c.c.m.) orbitals
GRAViTY acceleration g = (g1 + g2) = G*(M1 + m2) / (n - 1)*d^2:

|G*(M1 + m2)| |4*(pi)^2*d| | 4*(pi)^2*r1 4*(pi)^2*r2 |
|-- -- -- --| = |-- -- - --| = |(-- -- -- --) + (-- -- -- --)|
|(n - 1)*d^2| | T^2 | | T^2 T^2 |

| | |4*(pi)^2*(r1 + r2)|
= |-- -- -- --| = |-- -- --- -- -- --| = (g1 + g2) = gravity g.
| | | T^2 |

Note therefore, as radii r1 & r2 vary and/or M1 & m2 vary, etc,
then, BOTH, M1 & m2 can *TOUCH down* ON each other's SURFACE.!!
Depending, of course, on M1's & m2's SiZE, SHAPE, DENSiTY, etc.

Note, the dimension "d" = (r1 + r2) ..is "separation" distance;

$ M1*v1^2 m2*v2^2
Also, note that -- - -- = -- - -- = M1*r1 = m2*r2. FiNALLY..
$ g1 g2

NOTE: Mp*lp = {mph)*ls = me*wls = Moo*loo / 4*pi = hbar / c.

Brian A M Stuckless
^