There is another point. Although retarded signals from us r = 0 center vertical world line in above modified Fig 1.1c T.Davis 2004 PhD redshift to essentially zero frequency at our future horizon, static LNIFs near that horizonr ~ /^-1/2 need enormous off-geodesic accelerationg(r) ~ c^2/^1/2(1 - / ^2)^-1/2 ---> infinityfrom rocket engines in order to stay at fixed r, hence they see very hot Unruh radiation, which should not be confused with the very cold black body Hawking radiation of temperature /^1/2 coming from the horizon itself seen by all observers inside the horizon (with suitable Lorentz & GCTs). (h = c = G = kB = 1). This is analogous to the black hole case, but we need to be careful. We are inside our future cosmic horizon and can never get retarded signals from it. We are outside black hole horizons and can get retarded signals from in-falling matter outside it (e.g. accretion disk).

On Mar 22, 2010, at 8:20 PM, JACK SARFATTI wrote:

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.html

I 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 = absorptione = emissionz > 0 redshiftin dS metricQ(t) = e^t/^1/2= e^t(dark energy density)^1/2in 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 ther = 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:JamesYou 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 representationg00 = - 1/grr = 1 - / ^2where 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 calculationsthat center on processes. This does come up on a couple of occasionsthough. For example, on page 126 at the end of the first full paragraphthey 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 ofthe first column on page 140, they allow that "l" has to go to infinityto provide perfect absorption.In any event, it is clear that in the action at a distance picture EMwaves propagate through horizons if the absorption events that providethe advanced component needed to produce a fully retarded interactionlies beyond the horizon.I see nothing in HN's paper that suggests that they were on the verge ofasserting accelerating expansion. It seems not to have been an issue forthem at all. I suppose that it may have occurred to them -- and Narlikarmight be able to shed some light on this. But their chief concern seemsto have been to show that the action at a distance picture could accountfor EM processes encompassed by classical and quantum EM -- with theadded bonus of a cutoff due to a future horizon that obviates the needfor 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 thebook), the membrane was never intended to be taken as physically real.It was merely a way of sidestepping complicated internal processes thatmade the math intractable. As such, it is an explicitly fictitiousdevice to simplify calculations.The reason why I have asserted that those taking the WF (or TI picture ofJohn Cramer) seriously should have predicted accelerating expansion stemsfrom a different consideration than those issues addressed in theHNpaper. It is a consequence of the fact that horizons for normalretardedinteractions do not act as cutoffs for retarded-advanced (RA)interactions. The problem with this is particularly easy to seein thecontext of gravity and inertial (as opposed to EM) -- especiallyinDennis Sciama's vector approximation to GR where he shows theconditionthat obtains for inertial reaction forces to be produced by thegravitational action of chiefly distant matter. That depends onthegravitoelectric field having, in analogy with EM, two terms. Oneis theusual gradient of the scalar potential. The other is the timederivativeof the vector potential (with suitable coefficient). The vectorpotential is the integral of the matter current density,presumably outto the particle horizon. Sciama used a trick to avoid a messycalculation involving retarded Green's functions, and got thatthe vectorpotential is just the scalar potential times the velocity of anaccelerating test particle where the inertial reaction force isto beevaluated. And since the vector potential thus goes as 1/r,Sciamaidentified this as a radiational process.If the process is radiational, and if inerital reaction forcesareinstantaneous (as they are), then clearly a WF process must beinvolved.But WF processes do not respect horizons (particle, event, orotherwise).So cutting off the interaction at the particle (or other) horizonissomething you have to do to get a reasonable result, even if youhaven'tgot a compelling physical reason for doing so (other than itworks).This is what I was getting at in Killing Time.As an experimentalist chiefly interested in building stuff andtrying toget it to work, I assumed that there must be a plausibleexplanation forthis problem and went on with my experimental program. Only whenreadingBrian Greene's Fabric of the Cosmos (in which Mach's principlefeaturesprominently) did I happen upon the explanation of the cutoff Ihadassumed must exist: accelerating expansion -- as explained in afootnoteby Greene here attached.It may be possible to write down a consistent WF action at adistancetheory that encompasses classical and quantum EM withoutacceleratingexpansion. Though, if you are right, then this isn't so. Iexpect it isimpossible to get Mach's principle to work, however, withoutacceleratingexpansion to cut off the gravitational interaction at a finiteupperbound. While gravity and EM are analogous in many ways, gravityis notjust 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 isexponential scale functionQ(t) = e^/^1/2tand constant density / = (area of future horizon)^-1Hawking temperature of horizon = /^1/2(using h = c = G = kB = 1)Kip Thorne shows that horizons are electrical membranes -peculiarquantum effects at horizons - the Hawking mechanism pullsvirtualelectron positron pairs out of the vacuum - one charge goesbehindthe horizon the other in front of it - these charges both canabsorbphotons.Horizon complementarity may play a role here - for LIFs fallingthrough the horizon the explanation you give here may beappropriate, however for us at r = 0 the electrical membranepicturemay be the appropriate explanation.However, this is the key point, it's only because there is suchanobserver-dependent horizon with dark energy density / that wehaveretarded radiation without any net advanced radiation. If / = 0then we would see advanced signals.IOn Mar 18, 2010, at 10:37 PM, james f woodward wrote:Lots of diversions, so I'm still reading, but almost done. Itseemsclear though that HN, while allowing that there is a futureeventhorizon, understand that the perfect absorber need not belocatedwithinor at the horizon. That is, EM waves, or photons, canpropagatebeyondthat horizon and that their absorption beyond the horizon willnonetheless produce the requisite advanced disturbance requiredfor theaction at a distance theory to work.James what precise text in HN lead you to conclude that?That is correct. Anywhere an EMdisturbance can get to, no matter what horizons crossed, theadvancedwave produced by absorption processes make it back to theoriginof thedisturbance. So, NH's lone photon propagating at/near adeSitterhorizon-- which nearby inertial observers (NInOs) see tooling along atspeed c-- if the principle of mediocrity is correct (and spacetime ismuch thesame everywhere allowing for large scale evolution) -- will notencountera material absorber at the horizon and likely pass on through--notwithstanding that a distant inertial observer (DInO) nearthepoint ofemission will "see" the photon infinitely redshifted at thehorizon.When it is eventually absorbed, the advanced disturbancepropagates timereversed down its worldline to the source.I'm going to finish the paper before commenting on acceleratingexpansion. :-)Q(t) = e^/^1/2t means accelerating expansion - necessary fornetretarded causality.Let me clarify - whether or not there is a quantum electricaltotalabsorber relative to us at the horizon is not the point - myonlyclaim is that it is AS IF there is one there.The key here is that different observers in GR do notnecessarilyhave the same quantum vacuum - unitarily inequivalent vacua.However, your argument requires the multiverse of Max Tegmark'slevels 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(equivalenthere to the steady state) can explain retarded radiation."Einstein-de Sitter" is not the "de Sitter" solution - look attheQ(t) functions in the table as well as the density functionrho(t).The key formulas are Q(t) = e^Ht & rho(t) = constant = /(G=h=c=1)_