Re: In emission theory, WHY is light emitted at precisely c relative to the source?

On Mon, 27 Apr 2009 00:42:47 -0700 (PDT), Jerry
<Cephalobus_alienus@xxxxxxxxxxx> wrote:

parts-per-billion level.

Yet there is no such evidence for such a spread in velocities of
emitted light. Single-attosecond pulses of XUV light have been
generated in the lab. Emission theory suggests that such tight
pulses of light should disperse over distances of just a few
centimeters. Yet dispersion is not observed, even when attosecond
pulse experiments are conducted in high vacuum chambers.

In emission theory, what forces light to be emitted at exactly c
relative to the source?

The way of avoiding the dispersion problem (and the deSitter
double-star disproof of conventional emission theory) would seem to be
to invoke velocity-dependent gravitomagnetic effects.

Observerspace arguments are useful here:
The observerspace principle says that the laws of physics shouldn't
just be //presumed// to be obeyed, but should be //seen// to be obeyed
-- in other words, the universe should not just be assumed to be
behaving consistently, but should //look// consistent, too .
The observerspace principle only gets you so far, because it breaks
down around horizons when we have classical indirect radiation effects
or quantum Hawking radiation effects acting through a horizon
region ... but as a guide before we get to those extreme situations,
the weak version of the observerspace principle can be useful as a
starting point.

[Occam's Razor] says that wherever possible we should assign the same
causes to the same effects. When two nominally-different effects have
radically different explanations, but generate apparently
indistinguishable associations of effects, we should try to apply a
single explanation to both effects, or try to make the two
descriptions [dual]. When we suceed, using sets of phenomena that were
previously considered to be different, the result is often a
breakthrough in theoretical physics (such as when Maxwell compared the
hypothetical properties of an electromagnetic wave with the properties
of light and suggested that these two "different" things were actually
the same beastie).

So ... if we set aside our usual preconceptions and apply Occam's
Razor within observerspace, we find that the set of phenomena
associated with relative velocity generate observer-effects that are
suspiciously similar to those associated with there being a
gravitational differential between the object and observer. Receding
or approaching objects seem to us to be compacted or elongated (as if
there was a relative increase or decrease in extrapolated metric
density of the viewed region, normally associated with a gravitational
field), and when we try to dismiss the idea by pointing out that if
this differential was real it'd have to be associated with a matching
gravitational redshift or blueshift, we remember that our receding and
approaching objects //do// appear frequency-shifted, thanks to the
Doppler/signal propagation effects associated with relative motion.
The shift- and length-change effects associated with relative motion
link together as we'd expect if we were really looking at a
gravitational effect.
If we try to to dismiss the idea of duality here, by pointing out that
a body seen through a gravitational gradient should also show lensing
effects, we realise that moving bodies show the counterpart of this
sort of behaviour too, thanks to the spreading and squashing of their
apparent geometry due to aberration effects, giving something that
//looks// like the lensing effects that would be associated with our
fictitious gravitational field. If the apparent geometrical
redistribution of a body's fieldlines due to relative motion has to
also apply to the body's //gravitational// fieldines (which it does),
we can then go on to derive the existence of velocity-dependent
gravitomagnetic effects from aberration principles.

At this point an SR-trained physicist is likely to jump into the
conversation and say that there's no such thing as a significant
velocity-dependent gravitomagnetic effect, because it upsets special
relativity, and if such a thing existed we'd know about it -- if a
moving object really //could// be said to appear within an
observerspace snapshot as if it was immersed in a polarised
gravitational field acting in its direction of motion, then we'd
expect to see this apparent field acting on nearby light, and dragging
it along in the body's direction of motion -- but one of the starting
points of special relativity is that we "know" that the speed of light
is constant.

Except, that, if we look at the actual physical evidence, it
disagrees. General relativity already predicts the existence of
apparent v-gm effects around moving bodies that have significant
gravitation, and when we go down to the molecular level, and shine
light between the molecules of water flowing in a tube, they get
dragged along too. The action of v-gm effects (or their equivalents by
another name) seems to be general. We tend to get around this in
special relativity by saying that these are a separate class of effect
associated with particulate media, which SR doesn't have to deal with
....
.... we say, "Oh, okay these effects //do// exist, but they're dealt
with separately by QM, and they're QM-specific, and QM cohabits very
nicely with SR, so there's not a problem" ...
.... but since every conventional physical object or observer is
technically a local particulate medium, and should drag light in its
vicinity, special relativity has based a set of laws on a principle
that //we// consider fundamental, but which Nature doesn't actually
follow.
SR's version of lightspeed constancy is an interesting idea, and
generates some fun geometry, but it isn't real-world physics. Light
around real objects does something else.

If real objects drag light (and all our experimental evidence would
seem to say that they do), then since we define the geometry of
spacetime according to the propagation of light, this means that any
problem involving signals passed between bodies with "relativistic"
relative velocities is technically a curved-spacetime problem.

So high-energy inertial physics isn't a flat-spacetime problem. The
physics of the universe that we live in doesn't use a "flat" Minkowski
metric, it uses a "warped" acoustic-style metric, and if you try to
approximate an a.m. with Minkowski spacetime, you lose key features,
and pretty much guarantee that the results (and structures based on
them), won't be compatible with quantum mechanics.


The equivalent gravitomagenetic field-differential for these
light-dragging effects can be expressed in terms of a gravitaitonal
terminal velocity, whose value seems to be the same as the actual
relative velocity of the moving body.
This turns the "curvature-based" and "velocity-based" calculations of
what we see into fully-dual descriptions. There's curvature associated
with physical relative motion between real bodies, and there's
relative motion associated with physical bodies separated by curvature
gradients. We can say that the curvature causes the velocity or that
the velocity causes the curvature (much as we say that an EM wave has
electric and magnetic components that mutually regenerate the motion
of the wave).

Once we go down this route, Wheeler's GR mantra, "Matter tells space
how to bend, space tells matter how to move", also applies down at the
level of simple inertial physics, and down at the particle level,
where the effect of projecting the curvature details of an acoustic
metric onto a flat nominal background generate the sorts of
discontinuous wierdnesses that we associate with quantum mechanics.
With this type of "more general" general theory, we eliminate the
current distinction between "gravitational" and "nongravitational"
physics ,and end up with a single set of relativistic rules operating
everywhere.

If we embrace the concept of curvature as something fundamental to
physics (Clifford), and eliminate special relativity from general
relativity as a superfluous additional theoretical layer, then we seem
to eliminate the usual disagreements between quantum theory and
general relativity. But as soon as we decided to make it a core
assumption of GR that no lightspeed effects were associated with the
simple relative motion of objects, forcing flat spacetime (and SR as a
foundation for GR), we pretty much guaranteed that the resulting
structure would be incompatible with quantum mechanics.



: ANYHOW, HAVING NOW ESTABLISHED SOME BACKGROUND,
: LET'S GET BACK TO YOUR ORIGINAL QUESTION ...

In emission theory, what forces light to be emitted at exactly c
relative to the source?


In a completely curved-spacetime model of classical physics, the
duality principle means that for an object receding at velocity "v",
its motion-shift also corresponds to the effect of an apparent
intermediate gravitational gradient between object and observer, with
an associated terminal velocity that is also "v". So by applying the
duality principle, we end up saying that if a lightsignal is emitted
at "c" w.r.t. the emitter, then by the time it leaves the emitter's
influence and enters ours, it's ridden across a gravitomagnetic
gradient that would be expected to have altered its velocity, by "v".

So the gravitomagnetic effect that's missing from current SR-based
theory regulates local lightspeed constancy, and ensures that light is
always emitted at c[emitter] and received at c[observer].

In the lab, if we then measure the speed of light between two marks,
the result should be precisely the same regardless of whether the
original lightsource was a laboratory laser, or a distant galaxy
approaching or receding from us at great speed. Gravitomagnetic
regulation generates the result that any collection of signals moving
along the same path at the same time will have precisely the same
transmission speed (disregarding nonlinear coupling effects, which'll
depend on energetics in the lab frame and won't depend on how the
different signal components ended up with those energies).

So in that respect, the speed of light (in the lab) will be
independent of the speed of the original (distant) source.

But if we consider a region sufficiently close to the source body (or
to any other body that's sufficiently near to the signal path), the
relative speed of the body will be a contributing factor to how qickly
light propagates in that region. So the //original// speed of the
signal //did// depend on the speed of the source, but the effect was
confined to a region very near the source. The relative motion of the
source should affect signal flighttimes, but the flight-time
differences will be small, and won't scale linearly with pathlength as
deSitter suggested in his disproof of emission theory. The variation
in signal flight-times from a double-star will be embedded in the
variation ofsignal flight-times that we'd usually tend to blame on
GR's predictions of gravity-waves from the double-star. DeSitter's
disproof only works if emission theory is superimposed on a flat
background. The disproof fails if gravitomagnetic effects are
fundamental.

This leads to the result that in simple inertial physics, the speed of
light should always be measured as being locally constant. If we set
aside special relativity and flat spacetime in favour of something a
little more ambitious, then intead of taking lightspeed constancy as a
"given", or as a result of Maxwell's equations, we can explain //why//
the speed of light is locally constant, and describe the mechanism
involved. Which is cool.

PS: Another result of this model is that signals emitted by "compound"
sources emerge in an orderly manner. Light emitted in the same
direction by different atoms in a star's atmosphere might initially
have different nominal velocities due to the different velocities of
their relative sources, but as the signals leave their parent atoms
and enter a common gravitaitonal environment outside the star, they
end up with the same velocity. So the signals leave their individual
//atoms// at c[atom], but they leave the //star// at c[star].

---

If you want to argue that all of this goes way beyond the scope of
hisorical emission theory, then you're right. Emission theory was
never properly finished as a research project. But if you try to fix
the problems with "historical" emission theory, and force the thing to
be compatible with wave theory, then this is where you end up - with
velocity-dependent gravitomagnetic effects, a relativistic acoustic
metric, and a classically-based interpretation of parts of quantum
mechanics.

=Erk= (Eric Baird) http://erkdemon.blogspot.com
: "Insanity in individuals is something rare - but in groups,
: parties, nations, and epochs it is the rule. "
: -- Friedrich Wilhelm Nietzsche (attrib)
.

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