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Einsteinian Wisdom: Expanding Space between Non-Expanding Galaxies

August 28 2017 at 9:21 AM
Pentcho Valev 

 
The expanding universe (Big Bang) theory is one of the silliest concepts in the history of science:

Sabine Hossenfelder: "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." http://backreaction.blogspot.bg/2017/08/you-dont-expand-just-because-universe.html

In the discussion "Ambi Valent" is trying to draw the attention to the idiotic implications of "Expanding space between non-expanding galaxies" but Sabine Hossenfelder, a brave but desperately silly Einsteinian, is unable to understand anything:

Ambi Valent: "Could you explain which circumstance decides whether there is or isn't expansion? Spacetime wouldn't know whether it's inside or outside a galaxy. There are a lot of situations: first, two stars in the same galaxy. Then, the second star is in a globular cluster in the halo. Then it's in a dwarf galaxy orbiting the first galaxy. Then in another galaxy in the same cluster. Then in a galaxy in the neighboring cluster within the same supercluster. I think Laniakea is accelerated to a common center, but will never meet there since the expansion is already stronger. So, what decides whether there can be expansion?"

Sabine Hossenfelder: "Ambi Valent, I did explain it. It expands if the average matter density is so small that the gravitational self-attraction becomes smaller than the outward pull from the expansion. That's a rough estimate. To be precise you'd have to do a numerical calculation with the exact matter distribution of some region of space-time and there's no general statement that can be made. But since galaxies are stable, we know they're gravitationally bound and don't expand. It's somewhere beyond the scale of galaxy clusters that expansion takes over."

Ambi Valent: "Sabine, my brain seems to be in a knot... Either I think expansion and attraction between masses are independent from each other, in which case space inside a galaxy would expand (but only a little). Or I accept that the attraction between masses can counteract expansion, and then I get non-expansion only at a thin borderline, and inside that borderline I would get contraction (that wouldn't make much sense either)."

Sabine Hossenfelder: "Ambi Valent, I don't know what you mean. Look, there are a lot of things that space-time can do. What it does depends on the distribution of masses and pressures and momentum flows and all that. General Relativity tells you what space-time does if you put in matter. Some of these solutions have an expanding space (properly defined), some don't. The Schwarzschild solution, for example, is non-expanding. It just doesn't expand. Now, galaxies aren't spherically symmetric, but disk shaped, but to some approximation you can think of it this way. You take the local non-expanding solutions, then you need some boundary condition to stich them to the global expanding solution. It is a reasonable interpretation then that space does not expand in the galaxy, but between the galaxies. Though, again, keep in mind that this depends on how you define space. Really if this causes you brain knot, forget all the stuff about expanding space and merely talk about things that can be measured."

Ambi Valent: "Sabine, it would seem to me that if you feed into the math that a galaxy hasn't expanded in the past, then it would result in the galaxy not expanding in the future as well. That's just math. But can I be sure this non-expanding galaxy is an accurate representation of the Milky Way? I think if you started with a galaxy in which space expands only very little while attraction between masses is very dominant and feed it into the math, then it would continue to do so - and our measurements aren't yet good enough to tell whether the galaxy expands very little or not at all. But I'm just a layman."

Sabine Hossenfelder: "Ambi, This isn't how general relativity works. You don't get to chose what space-time does. You put in matter and the equations that govern the behavior of matter, and this tells you what space-time does. You could of course assume that you have a galaxy that hasn't yet reached a quasi-stable equilibrium, one that has, say, recently undergone a collision or something like that, and in this case pretty much all bets are off - can't solve the equations other than numerically. But take the simplest case as example, a stable spherically-symmetric distribution of matter (and pressure - it won't be stable without pressure), and it will not expand, at least not in the most intuitive space-time slicing. That's still so in the presence of a cosmological constant. As I emphasized above, however, you can chose some other space-time slicing as you please and then space can do a lot of other things."

Ambi Valent: "Sabine, could it be said this way? The model of a galaxy as stable and isolated is a very good approximation of the physical reality, so the calculated expansion resulting from this model (zero) is a very good approximation to what could be expected to be measured in the actual universe on the local level. The further out one would get, the less the approximation would apply. That way, the local expansion inside a galaxy could be approximated to zero for all practical purposes, but there wouldn't be an actual border between expanding and non-expanding regions."

Sabine Hossenfelder: "AmbiValent, No, there's no actual "border". I suspect that there must be closed hypersurfaces on which the two forces exactly cancel though. Don't know if anyone has calculated details."

Pentcho Valev

 
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Anonymous

Re: Einsteinian Wisdom: Expanding Space between Non-Expanding Galaxies

August 28 2017, 9:58 AM 

The problem is drawing spacetime and General Relativity into the disussion when a mcuh simpler explanation is possible. Just accept, or assume that there is gravity which increases the closer the objects are together, and a repulsive force which increases the further the objects are apart. Then there is no inconsistency, it's a non-issue. Both forces are acting, what happens depends on which force is dominating.

 
 
Pentcho Valev

Re: Einsteinian Wisdom: Expanding Space between Non-Expanding Galaxies

August 28 2017, 2:43 PM 

"A tired light scenario assumes that the photon loses energy owing to some unknown photon-matter process or photon-photon interaction, when it travels some distance: the distance is long if we consider all the intergalactic space between the object and the earth, or short, for instance taking into consideration only the coronae enveloping the object. Indeed, it is not so much a theory as a possible phenomenological approach to explain the loss of the energy of the photons in a putative static Universe that could be explained by different theories. [...] But there are two problems... [...] Vigier[23] proposed a mechanism in which the vacuum behaves like a stochastic covariant SUPERFLUID aether whose excitations can interfere with the propagation of particles or light waves through it in a dissipative way. This avoids the two former difficulties of blurring and frequency dependence." https://arxiv.org/pdf/1701.08720.pdf

Actually the essence of the tired-light idea is popular in Einstein's schizophrenic world - one can easily publish research on it, provided one doesn't mention the words tired, redshift, Hubble, static universe. Note that Vigier's "superfluid" quoted above is long forgotten but the same "superfluid", now politically correct, is enthusiastically discussed in Nature:

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. [...] If it is true that spacetime is a SUPERFLUID and that photons of different energies travel at different speeds or dissipate over time, that means relativity does not hold in all situations. One of the main tenets of relativity, the Lorentz invariance, states that the speed of light is unchanging, regardless of an observer's frame of reference. "The possibility that spacetime as we know it emerges from something that violates relativity is a fairly radical one," Jacobson says. It does, however, clear a potential pathway toward rectifying some of the problems that arise when trying to combine relativity and quantum mechanics. "Violating relativity would open up the possibility of eliminating infinite quantities that arise in present theory and which seem to some unlikely to be physically correct." http://www.nature.com/news/superfluid-spacetime-points-to-unification-of-physics-1.15437

What does "political correctness" mean in this case? Photons are slowed down as they travel but this should not be associated with the Hubble redshift. The discussion should always go to "photons of different energies travel at different speeds":

Sabine Hossenfelder: "It's an old story: Quantum fluctuations of space-time might change the travel-time of light. Light of higher frequencies would be a little faster than that of lower frequencies. Or slower, depending on the sign of an unknown constant. Either way, the spectral colors of light would run apart, or 'disperse' as they say if they don't want you to understand what they say. Such quantum gravitational effects are miniscule, but added up over long distances they can become observable. Gamma ray bursts are therefore ideal to search for evidence of such an energy-dependent speed of light." http://backreaction.blogspot.fr/2017/01/what-burst-fresh-attempt-to-see-space.html

Any thought transition from "slowed light" to "Hubble redshift" should be prevented by crimestop:

"Crimestop means the faculty of stopping short, as though by instinct, at the threshold of any dangerous thought. It includes the power of not grasping analogies, of failing to perceive logical errors, of misunderstanding the simplest arguments if they are inimical to Ingsoc, and of being bored or repelled by any train of thought which is capable of leading in a heretical direction. Crimestop, in short, means protective stupidity." http://ebooks.adelaide.edu.au/o/orwell/george/o79n/chapter2.9.html

Pentcho Valev

 
 
Pentcho Valev

Re: Einsteinian Wisdom: Expanding Space between Non-Expanding Galaxies

August 29 2017, 4:09 AM 

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

Photons are slowed down because vacuum exerts a force equivalent to friction:

"Vacuum has friction after all. In quantum mechanics, the uncertainty principle says we can never be sure that an apparent vacuum is truly empty. Instead, space is fizzing with photons that are constantly popping into and out of existence before they can be measured directly. Even though they appear only fleetingly, these "virtual" photons exert the same electromagnetic forces on the objects they encounter as normal photons do."
https://www.newscientist.com/article/mg20927994.100-vacuum-has-friction-after-all

"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

"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

Vacuum friction slows down photons coming from distant stars - so the Hubble redshift is produced, in a STATIC universe. Assume that, as the photon travels through space (in a STATIC universe), it bumps into vacuum constituents and as a result 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. It can be shown that this provides an alternative explanation of the observations that brought the 2011 Nobel Prize for Physics to Saul Perlmutter, Adam Riess and Brian Schmidt.

Pentcho Valev

 
 
Anonymous

Re: Einsteinian Wisdom: Expanding Space between Non-Expanding Galaxies

August 29 2017, 3:14 PM 

" It can be shown that this provides an alternative explanation of the observations that brought the 2011 Nobel Prize for Physics to Saul Perlmutter, Adam Riess and Brian Schmidt."

Show it then.

 
 
Anonymous

Re: Einsteinian Wisdom: Expanding Space between Non-Expanding Galaxies

September 7 2017, 5:44 PM 


if space is constantly expanding, what is it expanding into? As it turns out, there are two possible answers to these question, depending on what assumptions we make. We can assume that the universe is infinite or we can assume that the universe has a finite size. If we assume the universe is infinite, then it's not really expanding into anything. Because the universe's size is already infinite, its size can't increase. So essentially, if the universe is of infinite magnitude, it cannot possibly be expanding into anything. Rather, it's stretching (it's a fine distinction, but an important one). Simply put, every region of the universe, every distance between every pair of galaxies, is being “stretched,” pulled apart like taffy.https://futurism.com/questions-on-dark-energy-the-expansion-of-the-universe/

 
 
roger

Re: Einsteinian Wisdom: Expanding Space between Non-Expanding Galaxies

September 7 2017, 6:30 PM 

>>>We can assume that the universe is ... blah blah ... or we can assume that the universe has a ...blah ...blah....

i.e. assume anything

 
 
Johannes Harder Andersen

Re: Einsteinian Wisdom: Expanding Space between Non-Expanding Galaxies

September 7 2017, 7:44 PM 

But don't confuse the above website with science.
There is space (as in 'room') and there is matter.

Matter which can interact with us is definitely finite ~10^53 Kg.
Space is infinite, unless it is folded around somehow to become finite but without borders. I.e. in both cases there is no 'edge' of the universe.

 
 
Anonymous

Re: Einsteinian Wisdom: Expanding Space between Non-Expanding Galaxies

September 7 2017, 8:58 PM 

>>>We can assume that the universe is ... blah blah ... or we can assume that the universe has a ...blah ...blah....

>>i.e. assume anything

Exactly. Just follow the observations. And they tell that the universe is expanding. Pentcho is confused because, being of mediocre intelligence and very under educated, he is unaware that it is quite common in physics to have different forces dominating at different length scales.

 
 
roger

Re: Einsteinian Wisdom: Expanding Space between Non-Expanding Galaxies

September 8 2017, 5:52 AM 


>>Exactly.

ok

>>Just follow the observations. And they tell that the universe is expanding.


BUT... the problem now recognized in Philosophy of Science "is" that observations/data can be interpreted by numerous different theories!

 
 
 
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