Scientists nail down the total amount of matter in the universe

Sep 11, 2020
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Oh dear what can the matter be.
it’s taking so long, it’s not fair.

They promised a basket of MACHO’s
a garland of WIMP’s, a gift of Axions
the last straw was neutrinos
at least we know baryons

Oh dear what can the matter be.
it’s taking so long it’s not fair
 
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Aug 14, 2020
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So less than a third of the universe's surface is matter. And less than a third of the Earth's surface is land. Very roughly, about 31% in the first case and 29% in the second (though we can far better measure the second case than the first since the second case is far more observable than the first). Altogether, an infinite, or boundaryless, 31% of a total surface infinity, or surface boundarylessness, of the Universe (U) would seem about right.

Of course they aren't going to measure the Big Crunch underneath; deepest inside hub; farthest outside rim. They aren't going to measure an infinitesimal-infinite. They can attempt to census the finitely relative local this side of breakdown, this side of collapse in horizon, but only in a fevered mind would someone attempt to measure the infinitely non-relative non-local inside that horizon / the other side of that horizon down and in, up and out.

Again, surface-wise, even across an infinity of finite universes, an average of 31% of the surface being matter would still seem just about right. Maybe even the perfect proportion.
 
This is a great example of how the recent BOSS galaxy survey crushed the cosmology, since this new type of survey - albeit but also importantly low-z to start with - further strengthens the BOSS model.

"Because present-day galaxy clusters have formed from matter that has collapsed over billions of years under its own gravity, the number of clusters observed at the present time is very sensitive to cosmological conditions and, in particular, the total amount of matter. ... Finally, they compared the number of clusters in their new catalog with simulations to determine the total amount of matter in the universe.

"We have succeeded in making one of the most precise measurements ever made using the galaxy cluster technique," said coauthor Gillian Wilson, a professor of physics and astronomy at UCR in whose lab Abdullah works. "Moreover, this is the first use of the galaxy orbit technique which has obtained a value in agreement with those obtained by teams who used noncluster techniques such as cosmic microwave background anisotropies, baryon acoustic oscillations, Type Ia supernovae, or gravitational lensing.""

[ https://news.ucr.edu/articles/2020/09/28/scientists-precisely-measure-total-amount-matter-universe ]

They measure matter density Ω_m and structure clustering parameter σ_8, and they fall on top of Planck (Ω_m) and BOSS (σ_8), with another factor 3 lowered uncertainty [ https://arxiv.org/abs/2002.11907 ].

Now they need to expand and check for robustness (especially since earlier similar methods did not do well), but meanwhile this is encouraging.
 
Oh dear what can the matter be.
it’s taking so long, it’s not fair.
😀 Yes.

Thermal WIMPs seemed like such a slam dunk since that is presumably the way elementary particle are generated during the hot big bang and their mass and number range would fit dark matter. But that range has been eliminated by many observations by now [direct searches, particle accelerators, electron sphericity and cosmological constraint].

Axions were always more of a solution looking for a problem - there are more promising ways to solve matter/antimatter asymmetry and thus the so called "strong CP problem", as was standard matter MACHOs, and both have been eliminated in direct searches and cosmological constraints [MACHOs long since, in fact].

So for whatever reason, the easier to detail non-gravitationally interacting dark matter doesn't seem to exist, and there will be a presumably much longer route to find out more on the dark matter we all know and love.
 
So less than a third of the universe's surface is matter.
I think you mean energy content by volume (average energy density).

Of course they aren't going to measure the Big Crunch underneath;
The universe will only continue to expand by the observed process - dark energy density suffice to ensure that.

Your comment reads like a stream-of-consciousness text, more so from this part on, so it is difficult to respond to.
 
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Aug 14, 2020
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I go along with the stated 6 hydrogen atoms per cubic meter volume as stated in the article, but only within the limiting factor of the relativity of the universe to these measurers, these observers' census estimates. A self-propelled, accelerating, fast traveler in the universe, in a more elastic 4-dimensional space-time and mass-energy expansionist-contractionist, inflationary-deflationary, relativity could find himself dealing in a universal average density of 12, or 24, or 48, or..... hydrogen atoms per cubic meter volume (as measurable by him). In other words, he could be turning a certain observation on its head. He could very well be shrinking the universe around him. And instead of dealing in just one observer in his 4-dimensional space-time environmental balloon at one and the same time, he could be dealing in dozens across a shrunken [relative] universe in that same moment in time.

Of course in any deceleration his universe would reverse from a steadily contracting universe to a steadily expanding universe (as he drops from plane of universe to plane of universe). And, likely, from many hydrogen atoms per cubic meter volume back to the very few as stated.

The universe traveler's relative 'local' universe is not the Earth's observers' relative 'local' universe. Separation in space-time results in separation of universes. Relativity will breakdown. What the Earth observer, astronomer, physicist, claims for the distant universe (u), or the Universe (U) at large, may not be what [is] concerning the distant universe (or for the Universe at large). That figure of 31% average for matter just seems to me to be right for an average. My clumping it, producing an analogy to Earth's surface division between land surface and sea surface was just my analogy concerning "surface".
 
Aug 16, 2020
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Not a scientist or professor myself but, I can't help thinking the one theory that explained our existence and universe that made sense to me was the one that someone brought up that we are living in a virtual universe. It is generated by some greater being or beings. I guess much like being in a virtual reality game. I know I will probably be mocked for saying this. But, it would explain why dark matter and dark energy cannot be found or measured. Why? Well it's because they are generated mathematical algorithms or just constants. I am a computer programmer in many languages this is why it intrigues me about dark matter and energy.
 
I go along with the stated 6 hydrogen atoms per cubic meter volume as stated in the article, but only within the limiting factor of the relativity of the universe to these measurers, these observers' census estimates.
General relativity ensures that physics laws can be universal. The matter density is one such universal density parameter, since it is part of the general relativistic LCDM model that describes our universe.

Again, these comments are very hard to respond to.


Not a scientist or professor myself but, I can't help thinking the one theory that explained our existence and universe that made sense to me was the one that someone brought up that we are living in a virtual universe. It is generated by some greater being or beings.
This is a bit easier, since it reads as a combination of superstitions of philosophy and religion.

- The usual response to unrealistic models is that kicking a stone would convince anyone of reality. For simulation ideas specifically, there is also a problem of resolution (remember the recurring cat in Matrix?).

- Since 2018 we are fairly ensured that space is flat, and that we can therefore observe any activity of omnipotent (or large local) 'gods' against the zero energy density (and spontaneous expansion) of the universe. There is no such putative magic acting on the universe in its history, or acting now or can be in its future (since general relativity is self conssistent closed).
 
Aug 14, 2020
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General relativity ensures that physics laws can be universal. The matter density is one such universal density parameter, since it is part of the general relativistic LCDM model that describes our universe.

Again, these comments are very hard to respond to.




This is a bit easier, since it reads as a combination of superstitions of philosophy and religion.

- The usual response to unrealistic models is that kicking a stone would convince anyone of reality. For simulation ideas specifically, there is also a problem of resolution (remember the recurring cat in Matrix?).

- Since 2018 we are fairly ensured that space is flat, and that we can therefore observe any activity of omnipotent (or large local) 'gods' against the zero energy density (and spontaneous expansion) of the universe. There is no such putative magic acting on the universe in its history, or acting now or can be in its future (since general relativity is self conssistent closed).
How far into 'space' can you look? Can anyone look? Using any kind of instrumentation? How far?
 
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How far into 'space' can you look? Can anyone look? Using any kind of instrumentation? How far?
I don't see the relevance for our cosmology science - the models covers the local universe in detail and we may have good handle on the rest as well.

We can study the local universe many orders of magnitude of expansion into inflation before the later hot big bang (which, admittedly, isn't much in terms of time due to the high rate of expansion) [see the description in Planck collaboration cosmology parameter paper 2018, Planck Legacy Archive].
 
Jul 17, 2020
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Scientists have conducted a new cosmos-wide matter census, finding that the stuff makes up 31% of our universe.

Scientists nail down the total amount of matter in the universe : Read more
Some scientists ? ! Perhaps they mean the observable universe ? As far as I know nobody has found the end of the universe because, there appears to be no end to the universe . In which case the mathematics about matter content are meaningless if they are speaking of the greater universe. It cannot be measured, therefore, there are no mathematics to describe it
 
Perhaps they mean the observable universe ? As far as I know nobody has found the end of the universe because, there appears to be no end to the universe . In which case the mathematics about matter content are meaningless if they are speaking of the greater universe. It cannot be measured, therefore, there are no mathematics to describe it
You can of course argue how much of our universe we have modeled and how much we have measured. Everything else alike, in a flat universe, space would be infinite in extent and with exponential expansion (as the current dark energy expansion tend towards) in time as well. Notably this gets a bit problematic with inflation since it tend to make local universes while still continue expanding elsewhere, but that is more about the local inner state than our models and measurements.

Or you start locally and see how far it takes you.

- Cosmic variance - the longest wavelength variation in densities and other cosmological parameters - gives you a local universe which is at least 10^2 times larger in volume than the easily observed "observable universe". [The larges modes we can see has ~5 times larger wavelength than the observable universe, so a ~ 10`2 factor in volume.

- The uncertainty of the latest observation of flatness gives you that the local universe may be 10^8 times larger in volume. [The uncertainty in flatness is ~ 10^-4, so curvature would give a ball - for the positive vacuum energy that we see ~ (10^4)^2 = 10^8 times larger in volume.]

- The inflation process results in local universes depending on the size of the inflation conditions, which gives you a guesstimate that our local universe could be 10^75 times larger than the observable universe in volume. [Still without explaining the physics here - you can ask me - to keep it short, what conditions that decided the local universe size was the typical size of the quantum field fluctuation that kicked the local slow roll over the hill. The birth statistics of local universes would look like a stochastic Poisson process due to the fluctuations, so I guess we consistently could assume the local universe originates where the Planck collaboration see the field potential hill top [as of 2018]. If I take the largest visible fluctuations as we can observe them in the resulting cosmic web of galaxies and gas in filaments (caused by fluctuations which was sent outside the horizon but came back), and multiply them with the smallest possible expansion factor of 10^26, I get ~ 1 Gpc*10^26 or 10^33 Gpc radius for inflaton fluctuations of the early universe. So a guesstimate is that our local universe could be 10^75 times larger than the observable universe in volume.]
 
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Some scientists ? ! Perhaps they mean the observable universe ? As far as I know nobody has found the end of the universe because, there appears to be no end to the universe . In which case the mathematics about matter content are meaningless if they are speaking of the greater universe. It cannot be measured, therefore, there are no mathematics to describe it
If the big bang started with a finite size, then with finite rates of expansion and a finite age, the whole contents of the big bang must also have a finite size now.

I'm using the words big bang and 'contents of big bang' instead of the word universe. There's widespread misuse of the word universe, including among scientists and publications. You will often see phrases such as 'the universe started with a big bang' etc. However, the dictionary definition of 'universe' is "everything that exists". I find it wholly unscientific to assume the big bang was the beginning of the universe, ie the beginning of 'everything that exists', because 'everything that exists' can't be known.

So what most people and scientists call our universe, I like to call the 'contents of our big bang'. So we have the observable 'contents of our big bang' and the whole 'contents of our big bang'. I also say 'our' because it would be very strange if it was a one-off phenomenon. I personally think there are infinite 'contents of big bangs' spread over an infinite space.

Also, the second widespread misuse of the word universe is to make it plural ie universes. Since the universe is 'everything that exists' there can't be a plural word for it. Top scientists including Stephen hawking used the word 'universes', we all know what they mean but it's incorrect. Torbjorn Larsson also does above, quote - "Notably this gets a bit problematic with inflation since it tend to make local universes".
there appears to be no end to the universe .
I would agree with that, but I would say there is an end or edge to the whole 'contents of our big bang. :)
 

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