I am starting a new thread because many parts of the post this is in response to are concerned with Albert Einstein and what he chose to do with his time and life, which I find less interesting than the cosmological arguments. This post will only be concerned with the cosmology as that is my area of expertise.
The thread by psyreporter that this post responds to can be found here: viewtopic.php?f=12&t=18050
I'm not sure whether or not there is a character limit on these forums, so I should note ahead of time that I have a lot of ground to cover and will likely have to break my response up into a series of parts. Since there is no edit function, I won't be able to guess how many parts or edit them in later (it would be convenient to be able to say "Part one of five" or something like that, but I simply can't know how many posts it will take ahead of time).
I will try to give layperson explanations where things get technical when possible. Please note that many distances in astrophysics and cosmology are given in parsecs (pc), particularly kiloparsecs (kpc) and megaparsecs (Mpc). Redshift is usually denoted by the character z, and will often have a number such that z=0 means the local universe while z=5 is extremely distant (extremely redshifted).
It should be made clear from the start that cosmological redshift is not the Doppler effect (I suppose this quote gets a pass for saying "Doppler-effect based." This is important in understanding why redshift is interpreted as an expansion of the universe. There is a Doppler effect in redshifting and blueshifting, but it's negligible after a certain distance. Why?psyreporter wrote:Big Bang theory a religion?
The Big Bang theory and the idea of an expanding universe is solely based on the Doppler-effect based interpretation of red-shift.
The status quo of science claims that the Universe began in a Big Bang while many scientists are complaining that the Big Bang theory is a religion.
Because the actual Doppler effect in redshifting/blueshifting of galaxies comes from their actual motion in space relative to one another (called peculiar motion), much like the sounds of traffic coming and going are shifted. However, redshift from cosmological expansion isn't due to galaxies moving with respect to one another; it's due to the space between them expanding: it's fundamentally different from the Doppler effect caused by peculiar motion.
Why does this matter? Because it's a major clue as to why cosmological redshift indicates an expansion: cosmological expansion should become greater and greater with increasing distance. Since peculiar motion of galaxies has an upper speed limit (~2000 km/s), there should be a point where cosmological redshift (NON-Doppler) overpowers peculiar redshift (Doppler effect) if it's caused by an expansion, and that's exactly what we see:
This is a plot of the Hubble constant against galaxies observed at particular distances. In a perfect universe, they would all fall along the blue line representing galaxies moving away from us at ~68 km/s/Mpc (note that this figure is old, and goes as high as 72, we've mostly been using ~70 km/s/Mpc, but that's splitting hairs). Why are galaxies falling elsewhere on this plot other than the blue line?
It's because of their peculiar velocities -- their actual motion with respect to the Milky Way. Andromeda, for instance, is gravitationally bound to the Milky Way and so falls below zero on the y-axis (it's blueshifted). It's close enough that its peculiar motion overpowers expansion, though it's actually moving quite slowly.
Now, if I were teaching this to one of the undergrads I would have removed the text and asked them, "Ok, why are galaxies scattered all over the place on this plot in the blue oval?" It's a good conceptual check to understand this: they're scattered very far from the Hubble line because of all the mass in the Virgo Cluster (more mass = faster galaxy motion, which is greater peculiar velocity). Despite being ~15 Mpc out from the Milky Way, their peculiar velocity is very large in comparison to the expansion, so (just as we expect) we see large deviation from the Hubble flow as their peculiar motion blueshifts or redshifts them respectively from the expansion trend.
The further out you go, though, the more powerful redshifting from expansion gets; and the more negligible peculiar motion becomes: at a certain point you can begin to neglect peculiar motion entirely as all that matters is the redshift. This is in fact one of the major reasons why we look at very high z galaxies to try to constrain the Hubble constant (because then we don't have to worry about their peculiar velocity).
First I want to note that I've found this paper (https://iopscience.iop.org/article/10.1 ... 012017/pdf). It should be noted that while it's not everything in the world, one important measure of how good a scientific paper might be is by how many times it's been professionally referenced.psyreporter wrote:Boriev, I. A. (Russian Academy of Sciences) mentioned the following in Journal of Physics in 2018:
"Such red shift (and reduction of energy) may be simply explained by natural dissipation of energy of electromagnetic waves while they are propagating through the filled by DM space, which is real material medium. As clear, such dissipation must increase with increasing space distance, what logically explains the observed red shift increase with space distance. This materialistic explanation of observed red shift, known as concept of tired light, is natural and evidently true since it eliminates both obviously mysterious ideas about Universe inflation, induced by physically queer assumption of Big Bang, and about physically unexplained reason of dark energy."
I can find exactly zero other authors that reference this paper. Since it came out all the way back in 2018, that's not a good sign to have zero citations. (For instance, go to Google Scholar or something and type any random surname you can imagine and you will see that papers have citations. This paper has not been cited even once).
I think I can see why: this paper is actually about trying to explain ball lightning (of all things) using dark matter, which is just so much absolute nonsense. In other words, this paper you've cited is pseudoscience. Nevertheless, let me address the quote.
In the first sentence, the paper asserts that EM waves propagate through "filled by DM space, which is real material medium." However, dark matter doesn't permeate space in an isotropic and homogeneous way on scales smaller than 100 Mpc. This is due to early-universe anisotropies in the CMB (cosmic microwave background) that led to clumping, forming the seeds of large scale (and galactic!) structure. I'll actually talk about this a lot more in one of the next parts of this series when I discuss the CMB and BAO (baryon acoustic oscillations), as it'll be necessary to discuss dark matter structure to address some of these points.
Suffice to say for now that even if we leave whether the universe is expanding or not as an open question, dark matter is not homogeneously and isotropically distributed; so there is not such a "medium" through which light can "tire."
Here we have a paper that's at least been cited 10 times, that's a start. It's behind a $40 paywall but I'm able to get it through my university.psyreporter wrote:An example study (2014):
Observations of distant galaxies provide stunning new evidence that the Universe is not expanding
Oxford University societies hosted two presentations by LPPFusion President and Chief Scientist Eric Lerner in May. The Oxford University Space and Astronomy Society also invited Lerner to speak about his and his colleagues’ new paper on the non-expansion of the universe.
In a startling challenge to the widely-popular Big Bang theory, new evidence, published online May 2 in the International Journal of Modern Physics, D, (and posted to Arxiv) indicates that the universe is not expanding after all. The evidence, based on detailed measurements of the size and brightness of hundreds of galaxies, adds to a growing list of observations that contradict the predictions of the increasingly complex Big Bang model.
Therefore if the universe is not expanding, the redshift of light with increasing distance must be caused by some other phenomena-something that happens to the light itself as it travels through space. "We are not speculating now as to what could cause the redshift of light," explains Lerner.
https://www.worldscientific.com/doi/abs ... 1814500588
Allow me to paste from it:
All the authors have done is carefully adopted a static universe model with consistent surface brightness across cosmological distances. This is ad hoc and uninteresting, and as the authors themselves note, doesn't really do anything other than say the Tolman test doesn't rule out one aspect of their carefully crafted model. In fact, for their "static" model to work, it requires an explanation for observed redshift: this is a solution in search of a question.Lerner et al. 2014 wrote:Based on the analysis of the UV SB of luminous disk galaxies from HUDF and GALEX datasets, reaching from the local universe to z ~ 5, we show that the SB remains constant as expected in a static universe.
A re-analysis of previously published data used for the Tolman test at lower redshift, when treated within the same framework, confirms the results of the present analysis by extending our claim to elliptical galaxies. We conclude that available observations of galactic SB are consistent with a SEU model.
We do not claim that the consistency of the adopted model with SB data is sufficient by itself to confirm what would be a radical transformation in our understanding of the cosmos. However, we believe this result is more than sufficient reason to examine this combination of hypotheses further.
The answer for why there aren't more blueshifted galaxies was covered during the top portion of this post: blueshift comes from peculiar motion, and expansion overpowers peculiar motion at a certain distance. In fact, perhaps you can see that the very fact that you don't see blueshifted galaxies further out strongly favors expansion over so-called "tired light" hypotheses. That's because it's exactly what we'd expect in an expanding universe.psyreporter wrote:Another clue that the Doppler-effect based interpretation of redshift is questionable is the fact that there is no blue-shift.
"There are about 100 known galaxies with blueshifts out of the billions of galaxies that have been observed. The blue-shifted galaxies are in our own local group and are all bound to each other by gravity. Most are dwarf galaxies."
http://curious.astro.cornell.edu/observational-astronomy/97-the-universe/galaxies/cosmology/539-why-are-there-blue-shifted-galaxies-intermediate
It raises the following questions:
considering that blue shifted galaxies are all in the 'local group' of the solar system within the Milky Way and appear to apply to a specific category of galaxies within that group, wouldn't that imply that the observed blue shift effect is likely tied to a specific type of galaxies in a nearby condition?
why would scientists who are expert on the matter claim that tired light theory is the valid theory to explain red shift? They don't mention anything about blue shift in the articles that I found (including a publication in Journal of Physics, 2018).