Dear James
Yes, you are raising points that must be addressed.
However, it is clear to me, that the future r = 0 observer-dependent dS horizon is the nearly WF perfect absorber (long wave limit). I suspect Kip Thorne's electrical membrane picture of the horizon as well as the Hawking mechanism need to be invoked to get a more complete conceptual picture of exactly how the total absorber works relative to the r = 0 observers in the static LNIF representation
g00 = - 1/grr = 1 - / ^2
g00 = 0 when / ^2 = 1
Note, this is not the representation where Q(t) = e^t/^1/2.
I hope to clean up these unresolved conceptual issues in the next few weeks.
On Mar 22, 2010, at 7:54 PM, james f woodward wrote:
With accelerating expansion it seems that the cosmic horizon becomes the boundary for retarded signals within, so one need not be concerned about horizon crossings and whether events beyond the horizon can affect events within the horizon via advanced signals. From my perspective, that's the neat thing about accelerating expansion, for it cuts off interactionswith a finite upper bound. From the HN and WF point of view, this may be problematic if insufficient absorbers lie along future light cones within the horizon.
It might be a good idea to await John Cramer's retrocausal signaling experiment results. Should that produce curious results, the issue of perfect future absorption will become a bit more complicated. :-)
http://www.seattlepi.com/local/292378_timeguy15.htmlI am not sure if Cramer's experiment can resolve this issue which exists even on the classical level without entanglement? - says Jack
On Mon, 22 Mar 2010 01:13:58 -0700 JACK SARFATTI <This email address is being protected from spambots. You need JavaScript enabled to view it.>
writes:
Actually my original thought on all this about two years ago was very simple.
1 + z = ke/ka = Q(ta)/Q(te)
a = absorption
e = emission
z > 0 redshift
in dS metric
Q(t) = e^t/^1/2
= e^t(dark energy density)^1/2
in the accelerating expanding universe retarded radiation toward the future is redshifted, advanced radiation toward the past is blue shifted.
The redshift at our future dark energy horizon a finite distance from us is infinite - this is effective absorption - vanishing of the real photon to almost zero frequency ( actually 10^10/10^28 ~ 10^-18 Hz).
In microscopic terms, the Hawking mechanism - effective geometrodynamical field ionization of virtual electron-positron pairs into real pairs with one particle beyond the
r = 0 observer-dependent horizon and other particle inside it - effective plasma charge neutrality on both sides of the horizon - cause the return advanced signals back to the r = 0 emitter inside the cosmic horizon.
From the principle of horizon complementarity we don't give a hoot what an LIF at r ~ /^-1/2 crossing the horizon sees. What only matters is what we see at r = 0. We each see a consistent picture, but it is not the same picture.
On Mar 21, 2010, at 12:18 PM, JACK SARFATTI wrote:
James
You are raising valid points to be squarely addressed I will study in coming weeks.
However, the key point to remember in all this is that the fact that we only see retarded EM waves and not advanced waves implies that we have a future perfect absorber and an imperfect past absorber in the context of the Wheeler Feynman QED. Therefore, our future dark energy de Sitter horizon must be in effect a kind of lumped parameter perfect future horizon since we cannot ever get any retarded signals from it - unlike the black hole case. Only advanced signals from beyond our future horizon can get to us as you point out correctly - and they come from future absorbers in other regions of the (Max Tegmark) Level 1 inflation bubble perhaps.
The fine points of Hoyle-Narlikar - e.g. the high k cutoff related to /, vacuum polarization are not easy to follow in detail. H-N assert they can do all zero point energy vacuum QED & radiative corrections from the FUTURE absorber influence functional in which the de Sitter horizon plays the key role. The light cone structure at the observer-dependent null-geodesic horizon is invariant for all observers LIF & LNIF at r = 0 in the static LNIF representation
g00 = - 1/grr = 1 - / ^2
where we are at r = 0 - note r = 0 is degenerate LIF = LNIF like static LNIF --> LIF at r ---> infinity in the Schwarzschild case.
Clearly quantum gravity Hawking mechanism needs to be included, i.e. all r = 0 observers see the horizon temperature /^1/2. Kip Thorne's electrical membrane picture of horizons clearly is needed as some kind of lumped parameter model - the horizon being an effective barrier (hence its entropy) except for advanced signals.
On accelerating expansion - had they realized de Sitter is essentially same as Steady State in terms of future absorber they might have predicted dark energy. However, my main point is that since dark energy has w = -1 it is zero point vacuum virtual bosons therefore FROM THE FUTURE in the Wheeler-Feynman ---> H-N ---> Cramer type paradigm - no question of that, and the fact of only retarded EM means our dark energy de Sitter future event horizon is an AS IF effective perfect future absorber and our past particle horizon is imperfect.
More anon - have out of town guest for next few days.
On Mar 21, 2010, at 2:31 AM, james f woodward wrote:
Well, going through HN's paper, the issue of how far EM waves (or photons) propagate seems only incidental to most of their calculations
that center on processes. This does come up on a couple of occasions
though. For example, on page 126 at the end of the first full paragraph
they talk of "a future absorber of constant density and infinite extent"
being needed to get perfect absorption and fully retarded interactions.
And in their discussion of a "cutoff at the absorber", at the bottom of
the first column on page 140, they allow that "l" has to go to infinity
to provide perfect absorption.
In any event, it is clear that in the action at a distance picture EM
waves propagate through horizons if the absorption events that provide
the advanced component needed to produce a fully retarded interaction
lies beyond the horizon.
I see nothing in HN's paper that suggests that they were on the verge of
asserting accelerating expansion. It seems not to have been an issue for
them at all. I suppose that it may have occurred to them -- and Narlikar
might be able to shed some light on this. But their chief concern seems
to have been to show that the action at a distance picture could account
for EM processes encompassed by classical and quantum EM -- with the
added bonus of a cutoff due to a future horizon that obviates the need
for the renormalization program of QED.
As for the membrane picture, as I have understood it from my late friend,
Ron Crowley (who was a coauthor with Thorne on one of the chapters in the
book), the membrane was never intended to be taken as physically real.
It was merely a way of sidestepping complicated internal processes that
made the math intractable. As such, it is an explicitly fictitious
device to simplify calculations.
The reason why I have asserted that those taking the WF (or TI picture of
John Cramer) seriously should have predicted accelerating expansion stems
from a different consideration than those issues addressed in the
HN
paper. It is a consequence of the fact that horizons for normal
retarded
interactions do not act as cutoffs for retarded-advanced (RA)
interactions. The problem with this is particularly easy to see
in the
context of gravity and inertial (as opposed to EM) -- especially
in
Dennis Sciama's vector approximation to GR where he shows the
condition
that obtains for inertial reaction forces to be produced by the
gravitational action of chiefly distant matter. That depends on
the
gravitoelectric field having, in analogy with EM, two terms. One
is the
usual gradient of the scalar potential. The other is the time
derivative
of the vector potential (with suitable coefficient). The vector
potential is the integral of the matter current density,
presumably out
to the particle horizon. Sciama used a trick to avoid a messy
calculation involving retarded Green's functions, and got that
the vector
potential is just the scalar potential times the velocity of an
accelerating test particle where the inertial reaction force is
to be
evaluated. And since the vector potential thus goes as 1/r,
Sciama
identified this as a radiational process.
If the process is radiational, and if inerital reaction forces
are
instantaneous (as they are), then clearly a WF process must be
involved.
But WF processes do not respect horizons (particle, event, or
otherwise).
So cutting off the interaction at the particle (or other) horizon
is
something you have to do to get a reasonable result, even if you
haven't
got a compelling physical reason for doing so (other than it
works).
This is what I was getting at in Killing Time.
As an experimentalist chiefly interested in building stuff and
trying to
get it to work, I assumed that there must be a plausible
explanation for
this problem and went on with my experimental program. Only when
reading
Brian Greene's Fabric of the Cosmos (in which Mach's principle
features
prominently) did I happen upon the explanation of the cutoff I
had
assumed must exist: accelerating expansion -- as explained in a
footnote
by Greene here attached.
It may be possible to write down a consistent WF action at a
distance
theory that encompasses classical and quantum EM without
accelerating
expansion. Though, if you are right, then this isn't so. I
expect it is
impossible to get Mach's principle to work, however, without
accelerating
expansion to cut off the gravitational interaction at a finite
upper
bound. While gravity and EM are analogous in many ways, gravity
is not
just EM in disguise.
On Fri, 19 Mar 2010 11:24:42 -0700 JACK SARFATTI
<This email address is being protected from spambots. You need JavaScript enabled to view it.>
writes:
The key mathematically is
exponential scale function
Q(t) = e^/^1/2t
and constant density / = (area of future horizon)^-1
Hawking temperature of horizon = /^1/2
(using h = c = G = kB = 1)
Kip Thorne shows that horizons are electrical membranes -
peculiar
quantum effects at horizons - the Hawking mechanism pulls
virtual
electron positron pairs out of the vacuum - one charge goes
behind
the horizon the other in front of it - these charges both can
absorb
photons.
Horizon complementarity may play a role here - for LIFs falling
through the horizon the explanation you give here may be
appropriate, however for us at r = 0 the electrical membrane
picture
may be the appropriate explanation.
However, this is the key point, it's only because there is such
an
observer-dependent horizon with dark energy density / that we
have
retarded radiation without any net advanced radiation. If / = 0
then we would see advanced signals.
I
On Mar 18, 2010, at 10:37 PM, james f woodward wrote:
Lots of diversions, so I'm still reading, but almost done. It
seems
clear though that HN, while allowing that there is a future
event
horizon, understand that the perfect absorber need not be
located
within
or at the horizon. That is, EM waves, or photons, can
propagate
beyond
that horizon and that their absorption beyond the horizon will
nonetheless produce the requisite advanced disturbance required
for the
action at a distance theory to work.
James what precise text in HN lead you to conclude that?
That is correct. Anywhere an EM
disturbance can get to, no matter what horizons crossed, the
advanced
wave produced by absorption processes make it back to the
origin
of the
disturbance. So, NH's lone photon propagating at/near a
deSitter
horizon
-- which nearby inertial observers (NInOs) see tooling along at
speed c
-- if the principle of mediocrity is correct (and spacetime is
much the
same everywhere allowing for large scale evolution) -- will not
encounter
a material absorber at the horizon and likely pass on through
--
notwithstanding that a distant inertial observer (DInO) near
the
point of
emission will "see" the photon infinitely redshifted at the
horizon.
When it is eventually absorbed, the advanced disturbance
propagates time
reversed down its worldline to the source.
I'm going to finish the paper before commenting on accelerating
expansion. :-)
Q(t) = e^/^1/2t means accelerating expansion - necessary for
net
retarded causality.
Let me clarify - whether or not there is a quantum electrical
total
absorber relative to us at the horizon is not the point - my
only
claim is that it is AS IF there is one there.
The key here is that different observers in GR do not
necessarily
have the same quantum vacuum - unitarily inequivalent vacua.
However, your argument requires the multiverse of Max Tegmark's
levels 1 & 2 in order to work, which is also interesting.
On Thu, 18 Mar 2010 11:19:08 -0700 JACK SARFATTI
<This email address is being protected from spambots. You need JavaScript enabled to view it.>
writes:
The point of the paper is that only the deSitter solution
(equivalent
here to the steady state) can explain retarded radiation.
"Einstein-de Sitter" is not the "de Sitter" solution - look at
the
Q(t) functions in the table as well as the density function
rho(t).
The key formulas are Q(t) = e^Ht & rho(t) = constant = /
(G=h=c=1)
_
