To Sylas & Nereid: I’m growing a little weary of the thread myself, so you’re in good company

One thing keeping it afloat, however, is that there is no mainstream answer to the problem. DEILE model could be wrong, but until something better one comes along…

Adding to the difficulty in sinking DEILE model is that it is an extension, not a guess. That is, most other proposals to explain luminosity-redshift curve (i.e. “acceleration”) make a guess that “something” is not as it appears. Perhaps c is not constant…maybe G changes with time. They show that such a hypothesis produces a “pretty good fit.” Then Sylas carves up the results.

But DEILE is not a guess at what could be, it is an extension of what is. The effect of sunlight in the solar system—relative to its absence—is to cause the average distance between objects to increase…dust the most. DEILE merely extends this observation to infinity…and it is hard to prove a negative. It is hard to prove that what we see happening in solar system has nothing to do with what we see happening at infinity

DEILE also is an extension of the duality. All finite gravitational systems have dualistic tendency: the central, dense region grows denser; the spacious, outer part(s) grow more spacious. Again, it is difficult to prove the contrary that the duality does not end on expansion at infinity.

The above questions/objections revolve around the extent of the extension: Sure, radiation can push dust around; but galaxies? The skepticism may be well founded.

Frame-dragging is a good analogy of what I mean by that. I could argue that frame-dragging (from GR) is causing the moon’s orbit to expand. I would be “correct” in the sense that frame-dragging is real, and in the earth-moon system it causes moon’s orbit to expand. But I would be incorrect in stating that frame-dragging explains the observed 10E-10/yr expansion, because—as I recall—frame-dragging has an effect more than 1000 times smaller than Newtonian tidal effects. So frame-dragging is real, and it would have a small net-expansive effect in earth-moon system, but it does not explain the all of it…not even 1/10th of 1 % of it.

In like manner, the effect of radiation I am describing should produce a small, non-zero net expansion. It may not explain all of observed expansion; it may not even explain 1/10th of 1 % of it. But radiation has some small, expansive effect. This effect—whatever its magnitude—must be taken into account before we turn to other explanations.

As to how dust pushes back, as Nereid would suggest, we invoke laws of physics on an as-needed basis : conservation of linear momentum. When a photon gets absorbed by dust particle, a certain quantity of linear momentum, hv/c, or something like that, is imparted to dust particle. We can, in principle, trace the origin of this back to some other quantum system in the sun that emitted photon. It recoils; it loses the linear momentum the dust gains. The force of radiation pressure on dust is therefore equal and opposite to force exerted on sun. The sun’s radiation pushes outward with 70 trillion pounds of force, and the universe pushes back equally

Granted, 70 trillion pounds of force is “almost nothing” in the grand scheme of things. But every star in universe is doing likewise. So to model universe, you have to model infinite centers-of-gravity all “pulling” against each other gravitationally, and all are “pushing” against each other radiantly (because centers-of-gravity tend to get hot and radiate like hell). So what happens in the sea of infinite time and space, with an infinite number of centers-of-gravity all pulling and all pushing? The long-term result of this tug-of-war between push and pull is not immediately obvious, but with a little reflection, we should not be surprised at what we see: dense regions growing denser and spacious regions growing spaciouser.

And Yes, Nereid, dust is transparent to gamma and radio waves. Every substance has its “absorption spectrum.” Dust just happens to be particularly absorbent near the peak emission range of most stars, and hydrogen particularly transparent. But all-and-everything makes some contribution, at some wavelength, at some distance. It is said that it would take 10 light-years of lead to stop neutrinos. Well, between here and infinity lies 10 lys of lead. The neutrinos the sun spews forth make an impact…though it be far, far away. Space is nearly transparent to many types of radiation, but it is not perfectly so to any. Every part of the 70 trillion pounds of force the sun puts out makes an impact somewhere, sometime.

For DEILE model, the effect of this outward-directed radiation pressure is crucial. Here is an instance where DEILE model apparently flatly contradicts known laws of physics:

Typical Mainstream Description: "The star was found to have a ring of dusty debris in 1983 along with some other young stars (Jean Cote, 1987). Then, in 1991 astronomers learned that this debris ring was unusually warm and close to its parent star, unlike other disks that are farther out and so colder (Aumann and Probst, 1991, pp. 266 and 269). This dust, given its known properties, should spiral into a star within 20,000 years, according to current theories of physics and star formation. "[emphasis added]
source

I do not know what exactly they took into consideration in their “current theories,” but there are at least 3 factors at work:
1. Orbital velocity of dust
2. Size of dust
3. Radial velocity of radiation field

Number 3 is typically left out in explanations of the effect, e.g. wikipedia. When #3 is taken into consideration, conclusion is that only dust very near the star will spiral in. In the case of our sun, this condition is met only well inside Mercury’s orbit. This subtlety—that real radiation sources rotate, and therefore, their radiation fields, too—completely changes the picture.

I do not know the particulars of Zeta Leporis, the star in question in the above quote, but in general, the region close to a star where orbital velocity exceeds relative velocity of the radiation field is small and finite, whereas the region where orbital velocity is less than the velocity of the radiation field is large and infinite. Ergo, in general, of the two forces at work—outward-directed radiation pressure and inward-acting Poynting-Robertson drag—radiation pressure is going to win more often than not. Ergo, the general tendency of radiation is to push bodies away from the radiation source, as comet tails demonstrate, not towards it, as above sources suggest.

Finally, as to how it can move galaxies: I’ve already described how dust—being pushed away from any bright source—tends to gather between stars where radiation is equal in all directions. Following this logic, dust should get expelled from the galaxy…except gravitational tug of gas in the disc hauls it back in.

Thus radiation field between galaxies couples to dust within them, which is gravitationally coupled to gas, which is coupled to the stars. Ergo dust acts as a buffer, coupling reaction-force to galaxy as a whole. So all the galaxies in universe are not only pulling on each other gravitationally, they are all pushing against each other, radiantly.

In GR, radiant energy is an attractive force, like matter. As with dust, which “in theory” should spiral into the sun but is observed to spiral away, I believe there is something being overlooked. I am not sure what it is, but my understanding is that GR is a “general” theory and does not take into account specifics of electromagnetic and other types of radiation.

Cosmologists keep looking for an “anti-gravity” force. Well, virtually every visible object in the universe is a source of anti-gravity force—the sun’s contribution being about 70 trillion pounds. When the anti-gravity effect of starlight is shown to be not enough to explain observed expansion, then we look for “exotic” energy sources. Then someone can give DEILE hypothesis the coupe de grace.

But as it stands—to my understanding—radiation in GR produces an attractive force, not an expansive one, hence there must be “something else” (i.e. DE) producing the expansive force. As with the pre-1998 “slowing” of expansion, the mainstream does not even have the “direction” of radiation pressure right. I just don’t see how the effect of radiation—which under local conditions has an irrefutable expansive effect—can have the opposite effect under GR. It just does not add up.

__________________
PW -- Plant Whisperer