Discussion:
Sweeping Revolution in Cosmology
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Pentcho Valev
2017-10-21 16:48:07 UTC
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In my view, the following dialog marks the beginning of a sweeping revolution in cosmology:

http://backreaction.blogspot.bg/2017/10/space-may-not-be-as-immaterial-as-we.html
Sabine Hossenfelder: "Is Space-Time Fluid? We have known at least since Einstein that space and time are inseparable, two hemispheres of the same cosmic brain, joined to a single entity: space-time. Einstein also taught us that space-time isn't flat, like paper, but bent and wiggly, like a rubber sheet. Space-time curves around mass and energy and this gives rise to the effect we call gravity. That's what Einstein said. But turns out... [...] That space itself isn't fundamental but made of other things is one way to approach the problem. Not everyone likes the idea. What irks physicists most about giving substance to space-time is that this breaks Einstein's bond between space and time which has worked dramatically well - so far. Only further experiment will reveal whether Einstein's theory holds up."

Arun: "How does a fluid analog of general relativity avoid having a preferred reference frame?"

Sabine Hossenfelder: "Arun, it doesn't. It's why I write it breaks the union between space and time." [END OF QUOTATION]

Sabine Hossenfelder is on the right track. Not exactly space but what is called vacuum is "made of other things". The "other things" slow down light - this explains the Hubble redshift (in a STATIC universe):

"...explains Liberati. "If spacetime is a kind of fluid, then we must also take into account its viscosity and other dissipative effects, which had never been considered in detail". Liberati and Maccione catalogued these effects and showed that viscosity tends to rapidly dissipate photons and other particles along their path, "And yet we can see photons travelling from astrophysical objects located millions of light years away!" he continues. "If spacetime is a fluid, then according to our calculations it must necessarily be a superfluid. This means that its viscosity value is extremely low, close to zero"." https://phys.org/news/2014-04-liquid-spacetime-slippery-superfluid.html

Nature: "As waves travel through a medium, they lose energy over time. This dampening effect would also happen to photons traveling through spacetime, the researchers found." http://www.nature.com/news/superfluid-spacetime-points-to-unification-of-physics-1.15437

"Some physicists, however, suggest that there might be one other cosmic factor that could influence the speed of light: quantum vacuum fluctuation. This theory holds that so-called empty spaces in the Universe aren't actually empty - they're teeming with particles that are just constantly changing from existent to non-existent states. Quantum fluctuations, therefore, could slow down the speed of light."
https://www.sciencealert.com/how-much-do-we-really-know-about-the-speed-of-light?perpetual=yes&limitstart=1

The "preferred reference frame" does not affect the validity of the principle of relativity in its traditional usage but of course orcs will be raging for some time:

Lubos Motl: "Take Backreaction's newest blog post - something promoting the aether. She has totally ignored the LIGO+EM discovery of the golden binary. One of the things it implies is that the speed of light of all frequencies and the speed of gravitational waves are the same with a huge precision. Needless to say, it kills any kind of an aether theory much more than the data available before that. Hossenfelder just chooses the moment a few days after this huge confirmation of special relativity to promote crackpot theories involving aether and doesn't even realize the irony of it. She either doesn't have the slightest clue about the link between experiments or theory; or she just totally and arrogantly chooses to ignore these links entirely." https://motls.blogspot.bg/2017/10/27-cheers-for-shut-up-and-calculate.html

Pentcho Valev
Pentcho Valev
2017-10-22 07:23:33 UTC
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The transition from expanding to STATIC universe is unavoidable because the implications of the expanding universe theory are too idiotic:

Sabine Hossenfelder: "If The Universe Is Expanding, Then Why Aren't We? The solution of general relativity that describes the expanding universe is a solution on average; it is good only on very large distances. But the solutions that describe galaxies are different - and just don't expand. It's not that galaxies expand unnoticeably, they just don't. The full solution, then, is both stitched together: Expanding space between non-expanding galaxies." https://www.forbes.com/sites/startswithabang/2017/07/28/most-things-dont-actually-expand-in-an-expanding-universe/

"The Multiverse Is Inevitable, And We're Living In It. Alan Guth: "It's hard to build models of inflation that don't lead to a multiverse. It's not impossible, so I think there's still certainly research that needs to be done. But most models of inflation do lead to a multiverse, and evidence for inflation will be pushing us in the direction of taking [it] seriously." The Multiverse itself may not give rise to any observable, testable predictions, but arises as a direct consequences of other physical theories that have already been validated." http://scienceblogs.com/startswithabang/2017/10/12/the-multiverse-is-inevitable-and-were-living-in-it-synopsis/

Pentcho Valev
Pentcho Valev
2017-10-22 19:37:38 UTC
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"The accelerating expansion of the Universe may not be real, but could just be an apparent effect, according to new research published in the journal Monthly Notices of the Royal Astronomical Society." https://phys.org/news/2017-09-supernova-analysis-reframes-dark-energy.html

Yes it is an apparent effect but caused by events in a STATIC universe. Vacuum friction slows down photons coming from distant stars - so the Hubble redshift is produced - but at the end of their journey photons redshift less vigorously than at the beginning. This has wrongly been interpreted as accelerating expansion:

"In the mid 1990s two teams of scientists, one led by Brian Schmidt and Adam Riess, and the other by Saul Perlmutter, independently measured distances to Type 1a supernovae in the distant universe, finding that they appeared to be further way than they should be if the universe's rate of expansion was constant. The observations led to the hypothesis that some kind of dark energy anti-gravitational force has caused the expansion of the universe to accelerate over the past six billion years."
https://cosmosmagazine.com/physics/dark-energy-may-not-exist

The redshifting occurs in a STATIC, not expanding, universe, and varies EXPONENTIALLY with time. The "finding that they appeared to be further way than they should be" is an illusion due to using an approximation to the exponential function.

Assume that, as the photon travels through space (in a STATIC universe), a factor equivalent to vacuum friction (see relevant references below) slows it down so that the photon loses speed in much the same way that a golf ball loses speed due to the resistance of the air. On this hypothesis the resistive force (Fr) is proportional to the speed of the photon (V):

Fr = - KV

That is, the speed of light decreases with time in accordance with the equation:

dV/dt = - K'V

Clearly, at the end of a very long journey of photons (coming from a very distant object), the contribution to the redshift is much smaller than the contribution at the beginning of the journey. Light coming from nearer objects is less subject to this effect, that is, the increase of the redshift with distance is closer to LINEAR for short distances. For distant light sources we have:

f' = f(exp(-kt))

where f is the initial and f' the measured (redshifted) frequency. For short distances the following approximations can be made:

f' = f(exp(-kt)) ~ f(1-kt) ~ f - kd/λ

where d is the distance between the light source and the observer and λ is the wavelength.

The approximate equation, f' = f - kd/λ, is only valid for short distances and corresponds to the Hubble law.

The original equation, f' = f(exp(-kt)), shows that at the end of a very long journey (in a STATIC universe) photons redshift much less vigorously than at the beginning of the journey. This means that photons coming from very distant objects have undergone some initial "vigorous" redshifting which is unaccounted for by the Hubble law. This explains why the very distant objects "appeared to be further way than they should be if the universe's rate of expansion was constant".

Is there "vacuum friction" that slows down photons? Yes there is:

"This leads to the prediction of vacuum friction: The quantum vacuum can act in a manner reminiscent of a viscous fluid."
http://philpapers.org/rec/DAVQVN

New Scientist: "Vacuum has friction after all."
https://www.newscientist.com/article/mg20927994.100-vacuum-has-friction-after-all

"So how can a vacuum carry force? One of the first things we learn in classical physics is that in a perfect vacuum - a place entirely devoid of matter - friction can't exist, because empty space can't exert a force on objects traveling through it. But, in recent years, quantum physicists have shown that vacuums are actually filled by tiny electromagnetic fluctuations that can interfere with the activity of photons - particles of light - and produce a measurable force on objects."
http://www.businessinsider.com/casimir-effect-vacuum-space-nanoparticles-2017-4

Pentcho Valev

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