Cosmological Constant

Jun 1, 2020
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Scientific American has an article suggesting the "Cosmological Constant is Physic's Most Embarrassing Problem."

However, the hard, measured evidence for its value -- it's not super accurate given the difficulty of needing billions of lightyears distance to determine a non-linear average value -- isn't what they are questioning or saying is the embarrassment. The article is showing that particle physics predicts a value that is 120 orders greater than that which is observed.

It is indeed a remarkable and embarrassing, perhaps, issue for quantum physics. The Vacuum energy calculated from theory is what is having so much trouble trying to explain it with a physical answer. The BBT has no real problem with the constant being a s it that I'm aware.

There are a few other nits in the article that may interest some:

1) It wasn't Hubble that discovered that galaxies are moving away from us, but Vesto Slipher. But Hubble was the first to measure the distance to the Andromeda Galaxy, thus was able to associated redshift measurements with distance.

2) Hubble never elected to claim the universe was expanding, though the Hubble Constant says just that. He left it to theorists to argue this issue. He correlated redshift amounts with distances.

3) The first one to suggest an expansion rate was in the very first paper (in French) by the author of the BBT -- Father Georges Lemaitre. He also, surprisingly, predicted it would not be linear over time in a graph he made. His value was off because the lacked the superior work that came from Hubble and Humason.

Nevertheless, there is a lot of interesting and accurate information in the article.
 
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There is a Cosmology course from the Great Courses: "Cosmology: The History and Nature of Our Universe" by Mark Whittle. Well worth the time and the work required. P.S.: I use 22km/sec per 10^6ly for the cosmological constant; the data computes , and anyway who wants to quibble about a fraction of a km/sec one way or the other. Yep! it's a fun course. Also, FermiLab.com has some videos; try those by Don Lincoln.
 
Jun 1, 2020
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There is a Cosmology course from the Great Courses: "Cosmology: The History and Nature of Our Universe" by Mark Whittle. Well worth the time and the work required. P.S.: I use 22km/sec per 10^6ly for the cosmological constant; the data computes , and anyway who wants to quibble about a fraction of a km/sec one way or the other. Yep! it's a fun course. Also, FermiLab.com has some videos; try those by Don Lincoln.
Are those free?
 
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Freebees: Your local library may have Mark Whittle's course. Also, that course MAY be available on Kanopy.com via your library card. (I got it from my library, and afterward purchased it from the Great Courses for my home library). Of course, FermiLab.com videos are free compliments of the U.S. Tax payers.
 

rod

Oct 22, 2019
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My observation. Interesting report on the Cosmological Constant problem in the expanding universe model presented by scientificamerican.com. It is still clearly a big problem and not yet solved. Comments like this from the report show the Cosmological Constant is a big deal in cosmology, while others would like to ignore the issue. “The problem with vacuum energy is that there's not enough of it. When scientists first started thinking about the concept, they calculated that this energy should be huge—it should have expanded the universe so forcefully and quickly that no stars and galaxies ever formed.” Another comment in this report “One of the first people to notice something was amiss was physicist Wolfgang Pauli, who found in the 1920s that this energy should be so strong that the cosmos should have expanded long past the point where light could traverse the distance between any of the objects in it. The whole of the observable universe, Pauli calculated, “would not even reach to the moon.” He was reportedly amused by his estimation, and no one took it seriously at the time. The first to formally calculate the value of the cosmological constant based on quantum theory's predictions for the vacuum energy was physicist Yakov Zel'dovich, who found in 1967 that the energy should make the cosmological constant gigantic.”

The Cosmological Constant is a free parameter in GR, you can set it to whatever is needed (Einstein set it so the universe was static, not expanding or steady state). It appears that BB cosmology has more problems than commonly reported, the sciam report was refreshing for me to read. When I read reports like this on cosmology and see free parameters used, I ponder how reliable the BB cosmology is when explaining the origin of the universe (the wrong value for the vacuum energy destroys the universe in the expansion or creates a steady state universe or a universe that collapses). When I encounter free parameters like this in use, I ponder other astronomical measurements, just how reliable the free parameters are. For example, in astronomy there is the changing angular size of the Sun. The Sun’s angular diameter (arcminute and arcsecond size) changes throughout the year during perihelion and aphelion, observable and measurable using telescopes. "As the distance varies, the apparent size of the sun changes, the visible diameter ranging from 32'.6 in January to 31'.5 in July.", Navigation and Nautical Astronomy, Dutton, 1926, updated 1951 US Naval Academy, p. 237.

Is the vacuum energy in the expanding universe with Cosmological Constant as well determined and verifiable as the Sun’s angular size changes? My answer is no. The Sun's arcminute size can be determined readily by telescope observations, repeatedly, thus a more secure foundation in science measurement – my opinion.
 
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Jun 1, 2020
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My observation. Interesting report on the Cosmological Constant problem in the expanding universe model presented by scientificamerican.com. It is still clearly a big problem and not yet solved. Comments like this from the report show the Cosmological Constant is a big deal in cosmology, while others would like to ignore the issue. “The problem with vacuum energy is that there's not enough of it. When scientists first started thinking about the concept, they calculated that this energy should be huge—it should have expanded the universe so forcefully and quickly that no stars and galaxies ever formed.”
Agreed, but notice what they're not saying (contrary to their misleading title). The "problem with vacuum energy", not the "problem with BBT". Vacuum energy seems to a very slippery animal. We know it exists but it doesn't let us dig very deep, apparently.

It's possible BBT is actually the problem, but that is not mainstream, IMO. When we have several lines of evidence that support any hypothesis, and no falsification of any prediction, then the hypothesis is regarded as relatively sound.

BBT theory is overarching in scope and makes many, many predictions. It started with Einstein saying it was abominable, but today it has more than a dozen lines of evidence making it more than "relatively sound". Theories are never proven, so it helps to know what is mainstream and what is ATM (Against The Mainstream).

Another comment in this report “One of the first people to notice something was amiss was physicist Wolfgang Pauli, who found in the 1920s that this energy should be so strong that the cosmos should have expanded long past the point where light could traverse the distance between any of the objects in it. The whole of the observable universe, Pauli calculated, “would not even reach to the moon.”
That's a pretty cool statement.

But, once again, the problem is with the vacuum energy level. He is showing that if the quantum equations are correct, we would not be able to see the Moon as it would be expanding much greater than the speed of light away from us. [I take this on the basis he is simply calculating the expansion rate at the level they calculated and without gravity compensation.]

The Cosmological Constant is a free parameter in GR, you can set it to whatever is needed (Einstein set it so the universe was static, not expanding or steady state).
No. It is set to match the observations. It has bounced up and down since Lemaitre made his, admittedly, crude estimate based only on Slipher's small data set. Even Hubble wasn't all that close since he assumed the wrong Cepheid Variable type in his original work with the Andromeda Galaxy.

It appears that BB cosmology has more problems than commonly reported, the sciam report was refreshing for me to read.
I think mainstream science sees it otherwise, though the 120 order variance is alarmingly interesting, yet this is something you will find particle physicists working on, not cosmologists. Or do you know of any cosmologists trying to argue that the 120 orders are there and we were just lucky we could go to the Moon?

The Sun’s angular diameter (arcminute and arcsecond size) changes throughout the year during perihelion and aphelion, observable and measurable using telescopes. "As the distance varies, the apparent size of the sun changes, the visible diameter ranging from 32'.6 in January to 31'.5 in July.", Navigation and Nautical Astronomy, Dutton, 1926, updated 1951 US Naval Academy, p. 237.
As Yogi might say, "You can observe a lot by just looking." :) It was the looking that made BBT so great as it supported that which was derived from GR.
 
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rod

Oct 22, 2019
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Helio in post #6 says about the cosmological constant, "No. It is set to match the observations." This is a free parameter in the equations then, freely adjusted to match what is observed :) Describing How the Universe works using free parameters, indicates that specific values needed to exist (or some selection process at work in the beginning) for the universe to be here today :) If folks study Allen's Astrophysical Quantities, Fourth Edition, 2000, you can see how sensitive the cosmological constant (Chapter 26 on Cosmology) is as well as many other constants used in astronomy. We do not have a solar system according to Wolfgang Pauli with the wrong value(s) here :) I was glad to see this acknowledged in the Scientific American report. As for me, when I find a free parameter that using QM for the vacuum energy density shows a 10^120 or more order of error, I will stay the course with the arcminute size measurements for the Sun as more reliable science :) It would be refreshing to see these free parameters and various constants that can rearrange everything in How the Universe works, clearly disclosed to the public. The Scientific American report was the clearest I have read on the cosmological constant showing the struggle in cosmology to explain expanding 3D space and keep the universe here :).
 
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Helio in post #6 says about the cosmological constant, "No. It is set to match the observations." This is a free parameter in the equations then, freely adjusted to match what is observed :) Describing How the Universe works using free parameters, indicates that specific values needed to exist (or some selection process at work in the beginning) for the universe to be here today.
Agreed, but those parameters are what are observed, which is why they are parameters. They each come with a margin of error and if we know exactly (to, say, 10 decimal places) the expansion rate over 99.999% of the age of the universe for any given year, we would, no doubt, be able to set those parameters nicely. That'll never happen so we keep looking for new ways to see farther, including gravity lens effects, etc.

As for me, when I find a free parameter that using QM for the vacuum energy density shows a 10^120 or more order of error, I will stay the course with the arcminute size measurements for the Sun as more reliable science :)
Right, it's always the objective evidence that is the true science as science, unlike philosophy and religion, is objective-based. But there are some that want to steer away from this to help in the acceptance of their pet views, such as parallel universes, or whatever.

Your solar measurements do all that is necessary to show that those that might claim, using hyperbole here, their solar physics equations require the Sun be larger than the orbit of Venus are patently wrong. The error in this faux case would be with those solar physicists, not your observations.

The Scientific American report was the clearest I have read on the cosmological constant showing the struggle in cosmology to explain expanding 3D space and keep the universe here :).
What specific statement in the article did you find that leads to the conclusion that the problem is in what cosmologists are claiming? I didn't see anything to suggest that the constant must be in error, only that it is in serious disagreement with the absurd result from particle physicists, who, like Pauli, see this as a real problem for quantum mechanics, and not a failure of astronomer's observations.
 
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Oct 22, 2019
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Post #8 asks, "What specific statement in the article did you find that leads to the conclusion that the problem is in what cosmologists are claiming?"

At the end of the report Helio we read, “We'll keep trying,” Gabadadze says of attempts to test cosmological constant hypotheses with experiments. “Every generation of physicists since 1960 or so has seen new solutions emerging. Maybe one day some of them will have observational predictions that can be tested, but at this point we're not there.” Despite the difficulty of the puzzle, he and other physicists still hope for a solution soon. Perhaps these efforts to understand the cosmological constant problem will reveal deeper truths about quantum physics and general relativity. Or maybe scientists will discover a simpler fix. And even while they're seeking a solution that may never materialize, many physicists revel in the quest."

*seeking a solution* - efforts continue. QM and GR do not play together well in 3D space expanding universe. Tinkering with other constants documented in nature can also rearrange our universe into something very different too.
 
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*seeking a solution* - efforts continue. QM and GR do not play together well in 3D space expanding universe. Tinkering with other constants documented in nature can also rearrange our universe into something very different too.
But the universe won't look any different, hence the constant won't be altered much. What will likely be significantly different, I suppose, is how much bigger the big picture will be if QM and GR resolve the 120 orders of discrepancy. This is a little like Newton mechanics having to become submissive to GR, though Newton's equations never needing to change except in those more extreme environments.
 
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I often wonder if the cosmological measurements we have taken (redshift, etc.) to estimate distance are correct. Seems like trying to match math with troubled observations might be a bit frustrating.

I know the methodology used to make our observations has been validated time and again. Or has it? There's a lot of "space" out there containing some "stuff" we don't understand. Perhaps the data on which we base our measurements is altered by the time it reaches our sensors.
 
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I often wonder if the cosmological measurements we have taken (redshift, etc.) to estimate distance are correct. Seems like trying to match math with troubled observations might be a bit frustrating.

I know the methodology used to make our observations has been validated time and again. Or has it? There's a lot of "space" out there containing some "stuff" we don't understand. Perhaps the data on which we base our measurements is altered by the time it reaches our sensors.
That is a big issue that has been even bigger within cosmology from the start.

IMO, the reason Hubble never claimed that his measurements of redshift and distances represented motions (ie expansion) was to avoid the debate all together. He was friends with de Sitter who was perhaps the most respected early GR physicist since his friend Einstein presented GR. His first model was able to demonstrate redshift without motions of galaxies, remarkably. But his model had one hitch -- he removed all matter from the universe. :) How's that for over simplifying! But it was a start.

Lemaitre realized that expansion would solve both the problem with Einstein's static model (no redshifts allowed, but with matter) and de Sitter's with redshift (but no matter).

Tired Light was the model proposed by others, originally by Fritz Zwicky, IIRC, to explain observed redshift and not associated with motions. It was debunked enough, apparently, to dismiss it.

It seems strange to me that a photon (photon packet as is the preferred view) can simply bleed off energy over time as it travels across the cosmos. If gravity has enough strength to hold a galaxy together during billions of year of expansion, why won't the much stronger EM force hold a photon together, so to speak?
 
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I am way out of my league here, but the concept of Tired Light does seem a bit weak to me. I am coining a new term (maybe not so new, I've not vetted - my apologies to whomever I owe an apology): Interstellar Filtering. Definition: TBD.
 
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These pages suggest different interpretations for the properties of spacetime. The page for GR shows how mathematically useless GR is as a practical matter.

The other pages suggest that spacetime is more subtle and yet far easier to mathematically understand than the Einstein Field equations.

While the actual nature of spacetime is complex it is internally self consistent. GR and QM are about as consistent as the physics in Disney’s Star Wars.


https://forums.space.com/threads/gravity-as-a-temporal-gradient.30614/

https://forums.space.com/threads/the-properties-of-blackholes-are-meant-to-confuse.33701/

A lot of “settled scientific physics” appears to be both bad and useless.

A “red shift” can also be caused by spacetime being out of equilibrium, such as when a galactic core black hole ruptures becoming a Quasar. That Quasar can cause the local spacetime gradients to be way out of equilibrium, which produces a massive red shift even though the Quasar might be right next door (astronomically speaking).

If you find that all of this institutional science is confusing and contradictory that just means you still know how to think.
 
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rod

Oct 22, 2019
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The cosmological constant is a free parameter in GR and therefore predicts nothing. There are other free parameters that can be adjusted like the neutron lifetime for BBN. I checked the NASA ADS site this morning. 2021 has 80 articles on the cosmological constant this year alone, here is an example. https://ui.adsabs.harvard.edu/abs/2021AAS...23731008G/abstract, Resolving the BBN lithium problem with varying physical constants, January 2021.

Perhaps like exoplanet studies that have sites showing all confirmed today, someday I may see a site listing all the cosmology free parameters adjusted to match observations as well as changes to vacuum energy density (i.e. the cosmological constant) from the beginning to present :). George Gamow and Ralph Alpher predictions for the CMBR, the temperature was some 50K or a bit more as well as lumpy background radiation. Much has been changed and reworked to keep cosmology moving forward :)
 
Rod (#5) "I ponder how reliable the BB cosmology is when explaining the origin of the universe (the wrong value for the vacuum energy destroys the universe in the expansion or creates a steady state universe or a universe that collapses)." (My italics)

As nobody really knows, or can prove anything, I will stick with my model (figure 8 on its side) whereby, instead of this indefensible notion of extrapolating backwards (almost?) linearly, I would favour a gentle curve approaching "t=0", tangentially approaching the 'axis' of the nexus ("BB") and passing to whatever unimaginable 'other side' there might be. Certainly some closer formulation of the word "universe" would be needed?

I believe that this idea originated with a Polish scientist, but I cannot recall the reference.

Is this really any worse than (IMHO) all this rubbish about infinitely high temperatures, pressures, etcetera? Surely these are unfounded mathematical constructs?

P.S. Isn't it time we labelled the CC the Cosmological Inconstant?

Cat :)
 
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There are many established constants that vary with conditions. The yield strength for a specific steel, for instance, is a constant, but it will vary with temperature if temperature becomes an issue. Understanding those conditions is part of engineering and science, which means that they can be treated as constants if done properly.

The universe is a big place, how it is behaving takes a lot of very deep research. Over time, this research should reveal more and more accurately each known parameter, and hopefully new parameters will come along as well.

The key feature of all the parameters goes to the importance found in establishing a model that unifies all of them. Does the BBT do this? Yes, the "Bullet List" given in other threads demonstrates this unification. More research is certainly needed, but nothing else offers any other unification close to the BBT at this time. Those who wish to dismiss it are ignoring that no science is perfect, but a work in progress --a conversation with Nature.

The CC started with a value of zero because it was assumed, given the lack of improved astronomy, that the universe was static -- no expansion or contraction.

Then Einstein realized that gravity (per GR) would cause his assumed static model to fail with contraction being inevitable, so he produced a brilliant term to his equation that was quite small in order to prevent collapse -- Einstein's CC. This was clearly an ad hoc tweak to his equation. Such tweaks are often frowned upon as there was no direct evidence for it, other than the universe must have some sort of energy keeping it afloat, so to speak.

In 1927, Lemaitre (later a church Abbot) used the idea of an expansion model, vs. a static one, to demonstrate unification. Redshifts made sense. Einstein's focus at that time, apparently, wasn't cosmology so he dismissed this idea. Friedman also had shown Einstein a mathematical interpretation that also favored expansion, but it was a math model vs. Lemaitre's math/physics model.

Eddington was active in cosmology, and it no doubt helped that Lemaitre was a former student of his. Eddington immediately realized the importance of Lemaitre's work, a work that he had not seen when published, and he quickly won deSitter over to it as well. Eventually, Einstein realized how important this new model was.

Lemiatre used crude redshift data to make a guess at the CC, but he knew that it would not be accurate, so you never hear about it, IMO.

Only when Hubble could put the new 100" at Wilson to work in finding Cephids, could they make a better determination of distance, thus correlate it with redshifts, thus allow some higher level of accuracy for the CC.

The next big step came with the use of Type 1a SN, which has produced greater accuracy for the CC. This revealed that we are currently accelerating so the CC, as suspected it would be, is time dependent. It has one value now vs. a value, say, 9 billion years ago. They aren't two different constants no more than the yield strength of steel is not a constant but with temperature dependency.

There are other techniques used as well, including the idea that certain galaxies have roughly the same size and luminosity, which helps confirm that the CC is relatively accurate.

Cosmologists keep working to improve the CC and the range of error is actually pretty small, but a great deal more must be determined accurately to find agreement and... unification.
 
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Oct 22, 2019
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Helio in post #21 presented some interesting history concerning the CC. Helio said "Cosmologists keep working to improve the CC and the range of error is actually pretty small, but a great deal more must be determined accurately to find agreement and... unification."

How much change took place in Lambda, the symbol for CC from Plank time until the formation of the CMBR in BB cosmology? It should be clear that CC, the vacuum energy density underwent enormous transformation from the present value(s) used to define Lambda and H0, the rate of expanding universe today with redshifts observed. To define Lambda, there is Allen's Astrophysical Quantities, Fourth Edition on page 649 that gives the specifics. Wikipedia has a discussion on this topic, https://en.wikipedia.org/wiki/Cosmological_constant

This gets back to what I presented in post #19, various constants become free parameters and adjusted to get certain *desirable results* for the outputs :) Here is another interesting site, https://math.ucr.edu/home//baez/vacuum.html
 
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How much change took place in Lambda, the symbol for CC from Plank time until the formation of the CMBR in BB cosmology? It should be clear that CC, the vacuum energy density underwent enormous transformation from the present value(s) used to define Lambda and H0, the rate of expanding universe today with redshifts observed.
Yes, discovery takes us to new places. The mindset for a static universe is a good example why one needs to be open to new and improved objective evidence.

Harvard has a nice historical view on the CC here. [It seems the differences in Cepheids was from Walter Baade's discovery in the 1950s of the Pop II stars. Each type creates a new Cepheid type, apparently, which is logical.]

This gets back to what I presented in post #19, various constants become free parameters and adjusted to get certain *desirable results* for the outputs :)
I'm unclear why you want to call it a free parameter? It isn't something that "cannot be predicted precisely or constrained by the model" [Free parameter]. The BBT places huge restraints on the CC. The CMBR alone does this. More accurate studies of the CMBR will necessarily tweak the CC value. Or am I wrong?
 
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Oct 22, 2019
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Helio, the CC still looks to be like a free parameter in my view. The CMBR does not constrain it, Einstein used the CC in his GR math to describe a very different universe, a universe with no CMBR and no expansion, thus steady state universe. The CC is adjusted to fit with the observations and does not predict what should be observed, e.g. the present CMBR. The CC during the Planck time, Planck length for the universe beginning, is the CC constrained the same like the CMBR constraint you claim?

CC still looks like a free parameter to me :) Post #5 shows the Sun's angular size changes. This has better and simpler constraints than the CC, free parameter :)
 
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Helio, the CC still looks to be like a free parameter in my view. The CMBR does not constrain it, ...
How does it not? The CMBR released the flood of light based on a given temperature, which came from cooling, which came from the expansion, which is calculated by knowing the CC (for that time frame).

Also, we now see this light that has redshifted into the microwave band, which is caused by the expansion, which requires a certain CC value, right?

Einstein used the CC in his GR math to describe a very different universe, a universe with no CMBR and no expansion, thus steady state universe.
Right, he admitted he was wrong. His GR was right, but his cosmological bias got the best of him as he ignored the evidence presented by Friedman and Lemaitre. Einstein knows that if he had opened his eyes and took greater interest in this that he would have discovered the BBT. This give legs to Gamov's claim that Einstein told him it was his biggest blunder.

[Nit... It was known as the Static Theory. The Steady State Theory is the name for the one presented by Hoyle, et. al. to counter BBT, but it failed.]

The CC is adjusted to fit with the observations and does not predict what should be observed, e.g. the present CMBR.
All constants are fit to match the observations. The yield strength of any one steel comes from what is observed through stress tests. The CC is much harder to put on lab instruments, so it necessarily will have varying values with improved measurements. The key, once again, is whether there is unification with all the other parameters.

The early history of the CC value struggled with the quality of the objective evidence and also with acceptance partly because cosmologists were convinced Omega must be = 1. But the CC kept making Omega closer to 0.25. But with DE, DM, and matter, it now adds to about 1, after all.

The CC during the Planck time, Planck length for the universe beginning, is the CC constrained the same like the CMBR constraint you claim?
The first Planck second is outside the realm of physics and is metaphysics, at best. The next few nanoseconds can be calculated but there is likely other mysteries that may have taken place under such extreme circumstances that can't be studied nicely at CERN or anywhere, though they seem to come pretty close.
 

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