Fistly, apologies for my earlier version of this writeup, if you didn't see it, well and good.
Any time I refer to c let us take it that it is in vacuo.
Ok the whole rod thing, what actually happens
when you move a rod is that you send a compression wave
down the rod. We are used to having rods
which seem to be rigid but that is because in the domain
of use the speed at which it is pushed is usually a
lot less than c. If you have a very long rod
moving one end is sending the information along
the rod as a compression wave. This wave can't
move faster than c. A wave in a rod of 4.3 light
years in length will probably dissipate into
heating parts of the rod and the distant end will
probably not move at all.
You can't create a perfectly rigid rod,
if from nothing else
the uncertainty principle so enough with the rods
Quantum entanglement does indeed exist. It is
known as the Einstein Podolsky Rosen paradox
(or EPR for short). It is not a paradox as no information
can be sent using this method.
This was explained by Bell with Bell's theorm
you may measure an entangled particle and instantaneously
know what state it's partner is in this is not a transmission of information. Let us say that
I want you to feed my goldfish if you measure spin up
and I spin down. The information is really the code
of action to take as a function of the measurement.
That code has to be prearranged. It is the passing of the
code which is the passing of the information and that cannot
be done using the entangled particles.
About the Cesium gas experiment,
Tiefling's comment says it all.
Ok I have just had a look at the "The Speed of
Gravity" stuff. It looks like pseudo-scientific garbage to me. It calims that gravity acts instantaneosly because
of the way n which we treat the time retarded potentials
(The Lenerd-Wicheard Potentialls. If you learn
a little about these fellows you discover that rediation
is due to the scceleration of chargesand
is the observational effect that this paper claims
is absent from gravitatijonal experiments.
To claim that binary pulsars orbits decay due to
non radial photon pressure is ridiculous. They
decay due to the emission of gravitational
, radiatioin which is travelling
I might add. Hmmmm.
you make a very nice point,
If you don't do physics then perhaps you should.
The argument is not correct, at least
in the framework of particle physics.
In particle physics the particles
which transmit, or mediate a force do
not have the smae properties as the
particles between whoom they communicate.
The best example is electromagnetisim.
The electromagnetic force acts between
charged particles. If we took your argument and applied
it to charged partices we would invoke two mediating
particles, one the communicate "attraction"
and the other that communicates "repulsion".
We woul suppose that this mediating particle has some
property of either "attractivness" or
"repulsiveness". In fact the particle
that carries the electromagnetic force
is the photon. It has no charge. The tecnical
name for such an object is an intermediating vector boson.
(more intersting than proton or electron eh!).
I can't tell you why it does what it does,
It comes out of the way we describe the
electromagnetic field. The process
is analagous to when you quantize the simple harmonic
oscillator in a second year quantum mechanics course.
If i knew my field theory better i might do a better
job at explaining, but i am a simple
My point is that the particle that mediates the graviational field is proabably massless and applying
notions of momentum to it is not a valid thing to do.
The particle is a manifestation of a field
and the test particles dynmics are determined
by the shape of the field they find themselves in.
(often physics seems like a magical place).
I know that this has not been a very clear explanation,
I apologise. I will endeavour to do
better in the future. The most elegant
description of gravity is through
(Einsteins general theory).
All of the decriptions, geometric,
field, particle, wave, codify the same physcis
and are physically equivalent.
When thinking about it, it's nice to have many
approaches to the problem.
Dear no comply
I can see how I might have pissed you off earlier and I apologise. You did however make a false statement,
To date there is no evidence for superluminal communication.
You are right, things might change. The most promising
idea on the scence is M-theory. An implication of M-theory
is that the global topology of the universe might
have extra-dimensions which are foliated onto
one another. In this scenario gravity propgates through
this higher-dimensional bulk,, while the other
forces are constrained the the lower dimensional
sub-manifold, (called a brane after membrane).
Gravity can effect objects that are not
within each others causal light cones. This theory
remains just that. Currently experiments are beginning
to test it. I may work on some aspect of this in the current year, If I do I will let you know.