#338 Baryonic acoustic oscillations (BAOs)
Can tired light or static models account for these? I’m thinking that if a statistical spacing pattern of 150 Mpc is seen in galaxies today, then most likely a similar spacing must have existed in galaxies 13.8 billion years ago. But what would be the size of that spacing?
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The cosmology calculator gives the angular scale for any redshift you type in. E.g. galaxies at z = 1.84 (or $\ln (1+z) \approx 1$) are at a distance of 13.8 Gly, the tired light scale is 20.5 kpc/arcmin, so 150 Mpc would be seen as an angle of
$$ 150000 \mbox{ kpc} / (20.5 \mbox{ kpc/‘’}) = 2.0 \mbox{ degrees}. $$
Interesting that the first CMB peak is at one degree. The “temperature fluctuations” on the graph below is calculated from “peak-to-trough”. That means the peak-to-peak fluctuation on the CMB is twice as large, or 2 degrees, just like the number calculated above…
Indeed, tired-light seems to account for the so-called “BAO” :smirk: Good discovery @ExpEarth !
Thanks @RedshiftDrift , but if anyone has made a discovery here it’s you! I am still trying to understand these issues of the CMB temperature fluctuations and the BAOs and how they fit in with the LCDM model. There they relate them to some hypothetical oscillations of plasma concentrations before light was released. What is the origins story in a static model (or in my case, a static or oscillating black hole universe model)? I read that the BAOs serve as an extra ruler to measure cosmic expansion at different times. But if the BAOs are just a spatial pattern in galaxy distribution, how can this be superior (for the LCDM model) to just using the angular diameters of the galaxies themselves? Also, would there not also be the peculiar pattern that the LCDM predicts for galaxy sizes, the one that Lerner and others found counter evidence for? It would be nice if there was some paper that put all these arguments together, explaining what the predictions and observations are for both the LCDM model and some static models. I am very late to the game as I had discounted these things as irrelevancies of the LCDM imagination.
Is TL becoming a panacea for everything? Name me one thing where tired-light does not account for.
Since the appearance of humanity, cosmology has always been an “origins story” (e.g. ‘creationism’, ‘religion’, ‘aboriginal narratives as living traditions’, etc.) Breaking with this primitive human tradition, there is no “origins story” in a static model. A “beginning of the universe” is scientifically meaningless, since an origin of the universe is beyond what science can tell us: it is not observable, not testable, and not flasifiable. Only things ‘inside the universe’ can have a beginning, an evolution, and an end. Because there is an energy density in the static model, it makes matter and light “bustling with activity” in the ever-changing patterns we observe.
“BAO scale” and “galaxy diameters” are measurements of two very different things. See below.
The book titled “The Cosmic Revolutionary’s Handbook” has most of what “latecomers to cosmology” need to know about the Big Bang model.
@ExpEarth you should write that paper on ACG github for everybody to review; you would learn a lot from that. Like every epicycle is important to Ptolemaic cosmology, these “things” are not “irrelevancies of the ΛCDM imagination” but instead at the core of Big Bang cosmology.
I am not motivated to explain ΛCDM in detail, why waste my time on “Big Bang Bull Sh*t”? As a starting point, I asked Gemini to write a brief explanation and edited it to remove inaccuracies and make it more relevant to this discussion. This must be complemented with a book on introductory cosmology.
<<The term “BAO” in the context of the ΛCDM model refers to Baryon Acoustic Oscillations. These oscillations are the sound waves that traveled through the early universe before the universe became transparent (when it was a hot, dense plasma). The BAO froze in place when the universe cooled enough for the plasma to become neutral hydrogen and for these sound waves to stop propagating due to the lack of radiation pressure. This occurred around 379,000 years after the Big Bang.
In cosmology, “decoupling of radiation” and “baryonic acoustic oscillations freeze” are two closely related events that happen simultaneously and are driven by the same underlying physical process: the cooling and expansion of the early universe. While they refer to the same moment in cosmic history, they describe two different aspects of what occurred.
Decoupling of Radiation (origin of CMB)
Baryonic Acoustic Oscillations (BAO) Freeze
It’s as if winter came suddenly and instantly froze the waves on a pond.
[*Clarification: the “frozen length scale of BAO” is the “Comoving Distance” that uses coordinate system that expands with the universe (and matches the coordinate system of a static model). 150 Mpc (comoving) today was also 150 Mpc (comoving) 13.8 Gyears ago. The “Physical Distance” is the distance we would actually measure today, equal to the comoving distance multiplied by the scale factor $a(t)$ of the expanding universe. 150 Mpc (physical) today was only 75 Mpc (physical) 5.9 billion years ago, when the universe was half its size and $a(t) = 0.5$, because the density scale of the BAO follows the “Hubble flow” and expands with the universe.
Today, the universe has expanded and the physical size of BAO is larger.
By contrast, “galaxy diameters” refer to a physical size of galaxies which does not follow the Hubble flow. If galaxies had all the same size, today and in the past, their physical size would not be a function of their distance from us.*]
Summary of the Difference
Comoving and physical distances
This is central to the Big Bang model, and must be understood.
<<When discussing the vast distances in our expanding universe, cosmologists use two different ways of measuring: comoving distance and physical distance (or proper distance). The distinction is a little like measuring a length on a balloon that is being inflated.
Imagine you draw two dots on a balloon. The comoving distance is the distance between those two dots measured on the balloon’s surface at a specific, unchanging scale defined by the distance between those two dots. Think of it as a coordinate system that expands along with the balloon. In cosmology, comoving distance is the distance between two galaxies if you “factor out” the expansion of the universe. It’s a static measure that helps us track the positions of galaxies relative to each other over cosmic history without the complication of space itself stretching.
The physical distance, on the other hand, is the actual distance between the two dots on the balloon’s surface at any given moment, measured with a ruler that does not stretch with the balloon. As the balloon inflates, the physical distance between the dots increases, even though the dots themselves haven’t moved on the balloon’s surface. In cosmology, physical distance is the distance you would measure with a giant ruler at a specific moment in time. This distance changes over time because of the expansion of the universe. For example, the physical distance to a distant galaxy is constantly increasing as the space between us and that galaxy expands.
The crucial link between these two concepts is the scale factor $a(t)$, a number that describes how much the universe has expanded since a particular time. At the present day, we define the scale factor to be $a(today) = 1$, which means that the comoving and physical distances are the same. In the past, the scale factor was smaller than 1, so the physical distance between two galaxies was less than their comoving distance. In the future, the scale factor will be greater than 1, and the physical distance will be greater than the comoving distance. This scale factor is the key to converting between the two types of distance. If we know the redshift $z$ at a certain time $t$, the scale factor is $a(t) = 1/(1+z)$. For example, at a redshift $z = 9$ we have $a(t) = 1/10$, and we see the universe when it was $1+z = 1+9 = 10$ times smaller.
The primary goal of a cosmology is to give the exact equation for $a(t)$. In ΛCDM cosmology, a simplified equation is
$$ a(t) = (\Omega_m/\Omega_\Lambda)^{1/3} \ \sinh^{2/3}(t/t_\Lambda) $$
where $t_\Lambda \equiv 2/(3H_0{\sqrt{\Omega_\Lambda}}),$ $H_0$ is the Hubble constant, $\Omega_m$ is the mass density of the universe, and $\Omega_\Lambda$ is the dark energy density.>>
[In a static cosmology, there is no expansion and $a = 1$.]
Tired-Light does not explain how the Moon formed.
Tired-light explains everything relevant to redshift (tautology!) Give me one cosmology paper that does not involve a redshift measurement?
What if Ptolemy could have asked Newton: “Name me one thing gravitation does not account for?”
$$ a(t) = (\Omega_m / \Omega_\Lambda)^{1/3} \sinh^{2/3}(t/t_\Lambda) $$
@RedshiftDrift . I cannot reproduce that formula. When looking up in Wikipedia, the most likely candidate for the cosmic scale factor is the one for the so-called Dark-energy-dominated era. Which according to standard theory is the era we currently live in. This is in concordance with the Variable Mass theory. With the latter in mind, the cosmic scale factor is always given by the same formula though, namely
$$ d = c.(-t) = \frac{c}{H_0}\ln(1+z) \quad \Longrightarrow \quad a(t) = \frac{1}{1+z} = e^{H_0 t} $$
where $t=$ atomic time, $H_0=$ Hubble parameter, $z=$ cosmic redshift, as usual.
The problem with the term tired light is it doesn’t mean anything unless it specifies the cause of the light getting tired. A redshift inherently implies energy loss and “tired light” implies an energy loss. Without a causal explanation for that energy loss it’s just a semantic distinction without a difference. The expanding universe mechanism is just the consensus explanation for the observed redshift (tired light) effect.
@RedshiftDrift . It still escapes me how Baryonic Acoustic Oscillations - the so-called “BAO” - in a static cosmology are relevant to redshift and explained by Tired Light eventually.
@budrap00 There is a causal explanation for how light loses energy, and a semi-classical calculation based on condensed-matter physics is available as well, although the result is not as accurate.
@HanDeBruijn Like galactic diameters, BAO have a ‘size’ which is believed to be uniform across large distances. That makes those ‘standard rulers’. Distance measurements are directly related to redshift measurements (the second equation on your coment)..
Thanks so much @RedshiftDrift for that wonderful summary of the BAO/CMB origins and relationships that you did with Gemini. On a side note, I have noticed that Gemini and ChatGPT have a vastly greater ability to discuss cosmology topics and hypotheses than a year ago. They make mistakes, but their depth of explanation and crunching out of ideas is really quite astonishing. I can’t always do the math, but they sure can!
It’s not clear what those spherical shells are in the galaxy patterns they observe today. Is it rings of galaxies, galaxy clusters or just what? Also, the appearance of dark matter in their explanation has the effect of undermining the physical mechanism they propose, since as we know dark matter is a suspect concept.
That’s an interesting idea. Maybe I’ll give it a shot! It would be nice if we could first nail down what’s causing those crop circles in a static framework. I tend to link this to my shell universe model, naturally, and so I’m thinking they arose at the time the shell first formed. It seems there were smaller baryonic shells which arose at that time also and left their pattern. On the other hand, the spacing could arise from a totally different phenomenon. Still, if the same pattern is visible in the CMB temperature fluctuations as exists in the BAOs, as your figure and first reply suggest, then perhaps there is some truth to the idea that acoustic waves in a plasma are actually involved. Maybe in the formation of the first black holes, which could have been much larger.
@RedshiftDrift The point was that there are lots of tired light models, yours included, but if you just say tired light without specifying which model you aren’t saying anything meaningful; it’s just handwaving - like saying dark matter.
@RedshiftDrift >…BAO have a ‘size’ which is believed to be uniform across large distances. That makes those ‘standard rulers’.
The people who believe that are the same folks who believe in the Big Bang. Making standard rulers out of beliefs is not good science. How is the BAO or whatever it is (if it is anything more than the by-product of a data massaging exercise) related to redshift in a non-expanding Cosmos? I think that’s what @HanDeBruijn is asking. The Big Bang cultists believe it is a standard ruler isn’t a very compelling answer in the hot-bed of non-belief that is ACG.
@RedshiftDrift I know that summary was written with assistance of AI, but the theory behind it seems to have been concocted by a child. Again, showing that ΛCDM is incapable of self-correction, but tries to adapt every observation to its flawed fundamental, and making it worse instead of better. I do not understand how one might ‘freeze’ a wave without freezing the medium. Yes, waves can be frozen on a pond, but to do so the pond must be frozen too. Is there a mechanism by which you can rob the wave of its energy, yet the wave is still there? It seems counter-intuitive. Either the wave dissipates (iow it’s completely gone) or the pond is frozen. Neither of these can apply here. My opinion is the wave is still there, and the real source is overlooked.
@ExpEarth if you’re looking for a mechanism to cause the waves, the arms in galactic disks may offer a clue. As for galactic arms, the consensus appears that these are ‘rotational waves’. Not impossible I guess, but I wrote a very naive paper some long time ago that the arms are result of the central bars - gravitational acoustic waves - if you like, but they are moving radially outward from centre - not rotational in the disk. The curved arms are a result of the rotating bar. BAO may be larger versions of the same and may therefore not be ‘frozen’ but detecting movement from our scale may prove difficult. Finding a potential source may prove less difficult if patterns can be consolidated.
@ExpEarth What they measure is a “two-point correlation function”. Ask Gemini, its explanation of it is not bad…
@budrap00 but only one TL is correct. I’ll be careful to specify STz next time.
@budrap00 of course. What they see is a characteristic scale of density fluctuations in a static universe. The non-Big-Bang explanation is that galaxies cluster cannot exist “near” each other because they would “fall” into each other. The minimum distance appears as a charactic length scale in the distribution of galaxies and clusters. Because the laws of physics and galaxies are the same nearby and far away, it is safe to assume that this characteristic scale is the same everywhere.
@Francois-Zinserling ΛCDM was concocted by a “team” of paid scientists, which produces more or less the same output as a child. Ever noticed the best theories are built by individuals?
@Francois-Zinserling It’s a figure of speech. Sound waves do not propagate in vacuum or in a rarefied medium. Big Bangers claim that BAOs stopped propagating when the intergalactic medium was too diluted to support any “compression waves”. (That’s the simplified explanation, the pressure of light also has some effects…)
@Francois-Zinserling I completely agree with your energy argument. Remember that in the Big-Bang delusion, acoustic waves lose energy as the universe “expands”, in the same way an expanding gas cools. For Big Bangers, even light loses energy, as observed from the redshift of light. The space expansion hypothesis is very convenient - not only it “explains” redshift, but cooling gases in the IGM, BAOs, galaxy population evolution, the appearance of a decrease of $T_{CMB}$ with time, etc.
The distorted images we observe (spectrally and geometrically), a distortion caused by tired-light (STz), are incorrectly interpreted by Big-Bangers as expansion of space. That hypothesized expansion then conveniently “explains” every other observed distortion. Big-Bangers are walking through a cosmological hall-of-mirrors, believing that the distorted images they see are real. Then they confirm their delusion with other distorted images observed by bigger telescopes.
@RedshiftDrift It is an observed fact that both galaxy clusters and galaxies collide. Supposedly the Milky Way is going collide with Andromeda in the distant future though I believe the alleged time of that event has been modified of late.
In other words there is no minimum distance observed in the Cosmos. Is there some minimum distance between any two near-by galaxies that determines whether they will collide or not? Of course there is but that distance is entirely dependent on the masses and relative motion of the galaxies - not on some “universal” characteristic length scale. The two point correlation function is just a statistical method misapplied to an imaginary “universe”. The result is meaningless - there is no need to account for it.
BTW, I know that you use the term static universe to mean non-expanding universe but the Cosmos is anything but static just because the “universal” condition of expansion doesn’t apply: https://www.nasa.gov/universe/untangling-a-knot-of-galaxy-clusters/
I never wrote “universal length scale”, I wrote “characteristic length scale”. The two point correlation function is not misapplied, it does measure something real. The dynamics that produces these characteristic distances is known to produce patterns, as Ilya Prigogine showed dissipative structures of a characteristic size in non-equilibrium systems.
Patterns are an observable universal phenomenon (not universal size!) Rain droplets are mostly of a certain size, snow flakes have a characteristic size, when snow falls there is a more probable distance between snowflakes, bubbles in boiling water have a characteristic diameter, stars are mostly between 1 and 10 times the solar size, star clusters are 10 to 30 light-years across, etc. These characteristic sizes are everywhere, as long as you are willing to observe (and understand the method used to measure that size, which you don’t).
The BAO also depends on masses and relative motion of the galaxies (not the Big Bang), and since these properties are the same everywhere, BAO size can be used as a ‘standard ruler’ in astrophysics.
@RedshiftDrift There are patterns in noise. Look at all the people pawing the minute temperature variations of the CMB looking for signs and portents. All the pattern examples you cite entail a range of values. There is no characteristic size of snowflakes (look at the picture!) - there is a range of sizes - of snowflakes, stars, etc.
A standard ruler has by definition a fixed value and can be arbitrarily chosen for convenience. The “BAO” observations are an instantaneous snapshot from our particular cosmological viewpoint that presents a unified cosmological volume from our point of view, one that otherwise has no particular physical significance and does not constitute a closed, unified physical system.
Whatever instantaneous pattern might be observed over that volume is likely just noise - to determine if it is a cosmologically significant pattern would require eons worth of observations. You do not have enough information to make that determination using some laboratory math based on closed systems analysis. The Cosmos is not analogous to any laboratory system. In physics scale matters.
@RedshiftDrift
Putting these arguments together, I take it that you are attributing the temperature fluctuations to the same spacing effect of galaxies in a static universe. You are suggesting that they are caused by something like your Stz mechanism and totally discount the plasma pulsation idea of the LCDM. In both your model and the LCDM model the same thing that causes the CMB fluctuations also causes the galactic spacing depicted as BAOs in the LCDM.
@Francois-Zinserling
The mechanism sounds good, but the scale is too small to account for the BAOs, which seem to extend for 150 Mpc. I think we also need to think of where the cosmic filaments came from. I assume the BAOs reflect a spacing of the filaments. This most likely affects the CMB, possibly in the manner @RedshiftDrift suggests.
For the spiral galaxies, as another possibility, the arms may have been ejected from the central SMBH at the time the SMBHs were formed. Some of the distant objects seen by Webb seem to be supermassive black holes without the arms. Now suppose a SMBH is contracting during its formation. If it contracts below its Schwarzschild radius it would have to shed mass, presumably outwards radially in two arms.
@ExpEarth
Yes, I’m not proposing galactic nuclei are responsible for BAO, also not trying to sell my idea too much, but my point was that explanations must make sense, as you also offer a logic alternate for galactic arms.
BAO as ‘frozen waves’ makes no sense unless the entire region is frozen - which it isn’t. So, either it’s still in motion or it’s not a wave. On the other hand, a lot of physics since early 1900 has lost the ‘sense’ part from its vocabulary altogether. Imagine the number of orgasms a BAO wavefunction would produce …
I’ve not come across this before. Is it a thing? How would it shed mass from below $R_s$?
@Francois-Zinserling
I admit it’s hard to make much sense of it. I think that’s why I always ignored it. But maybe it’s something like this. Suppose you have a bowl of water (the cosmos) and there is a temperature-sensitive dye in the water (charged particles) which prevents light from travelling very far. Because the light can’t travel, the dye molecules are the only means of energy transmission and due to this energy transport the dye molecules form standing wave patterns in the water. You can’t see these patterns yet because the temperature is still high. But when the water and dye molecules cool down, the dye does not absorb anymore and the light now moves freely through the bowl. You can now see the dye molecules (now ‘cooled’ to baryons) and lo and behold they are still in the patterns they had before. How does this fly?
It relates to the mass-energy relationship in black holes. There is a strict relationship Rs = 2GM/c^2. For a black hole to expand or contract it must lose or gain mass to remain a black hole. So let’s suppose the first objects to form gravitationally are supermassive black holes (without spiral arms). In the initial gravitational infall, the SMBH might overshoot the Schwarzschild radius Rs corresponding to its mass M. In that case it would have to eject mass to remain a black hole. Maybe the galaxy arms started off like that. This is probably the same reason that the SMBHs in spiral galaxies later eject jets. If too much matter falls into them, they may not be able to grow in radius fast enough to maintain the mass-radius relationship. So they eject the jets. The jets are ejected in the vertical plane, however, probably for electromagnetic reasons.
@ExpEarth
It flies pretty well! You almost have me subscribed to BB now. Just kidding. It is a good analogy and I can now see how some variations of that could have the same ‘frozen wave’ relic effect.
As for $R_s$ I don’t think that’s plausible. $R_s$ is not a physical surface or shell around a black hole, but an area of effect. The $2GM/c^2$ is the distance at which gravitational infall equals the speed of light. In other words, nothing can fall out. Let’s say the BH starts with mass m and thus $R_{sm}=2Gm/c^2$. Now some mass is accumulated to reach M where M>m, there is no point at which the $R_s$ remains as $R_{sm}$, but in the time that m grew to M, the new $R_{sM}=2GM/c^2$ from which, again, nothing can escape. Even trying to paint a relativistic picture, where say, mass fall in on one side causing mass to be ejected on the other side, cannot happen faster than the speed of light. Since gravity ‘updates’ at the speed of light, $R_{sm}$ would expand to $R_{sM}$ at the speed of light. What happens in a black hole, stays in a black hole. Like Vegas.
Yet there are jets, vertical, as you point out. These are perpendicular to the accretion disk (<- I don’t like this term either, as if galactic discs are only there to be absorbed over time. Is our solar ecliptic an accretion disk for the sun? I digress …) but we don’t know yet what those jets are or how they are formed. @RedshiftDrift would argue they are falling inward. I would agree that it must be an electromagnetic process which we know to be much stronger than gravity.
@Francois-Zinserling
Thanks - that analogy needs a lot of fine tuning though!
That’s the way it has been traditionally thought of, but there is also a very strong possibility that black holes have shell structures and that the universe is also a shell black hole universe, as I have talked about here. In that case the space on the interior and exterior of the shell (which is rather thick) can be viewed as sort of mirror images of each other. As well, because it’s a thick shell, the speed of light does not actually drop so low as it approaches and passes through the shell. It falls off gradually and in the mid-point of the shell it levels off, since there is mass on each side.
The value RsM would increase immediately, yes, but it takes the mass time to move to that new radius. If there is not enough time, the physics inside the black hole could break down. We already have two instances of energy or mass escaping black holes (three, if we want to count Hawking radiation, but I think that one is shaky). There are the jets we already mentioned plus there are the gravitational waves thought to be released when black holes collide. The current view is that up to 5% of the mass of two colliding black holes is radiated away as gravitational waves.
Now this GW mechanism might possibly link up with your idea of gravitational acoustic waves around the galaxy cores giving rise to spiral arms of galaxies. Suppose we have a primitive supermassive black hole without arms. If it collapses too far to be within its Rs, some of the now excess mass could be radiated away as gravitational waves but some also as straight baryonic mass. After all, the points at which GWs are emitted would have to be regions where the spacetime of the SMBHs has been really disrupted, so that the usual rules don’t apply.