Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Malamute Lover on 08/07/2020 22:58:02
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First let me make it clear that I am asking a question concerning physics as presently known and have no theory of my own to present here. I am openly inviting constructive criticism on my perceptions here even if it amounts to Man, you really blew it!
Oh and please excuse the use of Excel style math expressions. That is all my fingers know how to do.
Normal matter and antimatter are produced in equal proportions in particle collider events. Why then does the universe at large consist of normal matter? Should not the two kinds have existed in equal proportions in the early universe? And since normal matter and anti-matter annihilate each other, producing photons, why does the universe today not consist entirely of photons with no matter? The peculiar behavior of the B meson has been proposed as the answer, giving a slight advantage to normal matter.
In accordance with the Standard Model the B meson is not only its own antiparticle, it oscillates between normal matter and antimatter states. Furthermore, the B meson spends a bit more time as normal matter than as antimatter. This has been experimentally confirmed at Fermilab and with the LHCb detector. Fermilab reported a 1% advantage of matter over antimatter, far in excess of the Standard Model prediction of near zero. LHCb obtained a result much closer to the value predicted by theory.
Due to their opposite quantum numbers, matter/antimatter collisions of the same type result in energetic photons. These photons can decay into particles but again of matter/antimatter pairs. More collisions, more photons. Ultimately there are only photons. But introduce a slight bias toward normal matter and in the end only normal matter will be left. Plus a lot of photons.
Side note: Notice that this would require all matter/antimatter to ultimately pass through the B meson phase because that is the only way to generate excess normal matter. With annihilations creating photons that decay into particles that is possibly feasible over time. It is another question whether a rigorous model of this would yield the preponderance of heavy particles that we see today, that is, whether the B meson decays would be energetic enough to make all these protons and neutrons. But that is way out of my league.
If we take the 1% figure reported by Fermilab, then 99% of the original matter mass of the universe (both types) has become energy in the form of photons. This is primordial photons, not the output of stars or the like.
Being a newbie, I cannot link to sources for the following figures but they are readily available on an internet search.
The mass of the matter in the observable universe is estimated at 10^53 kg, excluding dark matter or dark energy.
The estimated volume of the observable universe (assuming it is approximately Euclidean) is 4*10^80 cubic meters.
By E=mc^2, the energy content of a kilogram of matter is 9*10^16 Joules/kg.
Fermilab estimates that 1% of the original matter mass survived as normal matter. That is the 10^53 kg of the observable universe. That leaves 99% turned into photons.
Combining these figures gives a primordial photon energy of over 10^71 joules compared to a volume of 4*10^80 m^3 or a density greater than 10^(-9) J/m^3
By comparison the energy density of the Cosmic Microwave Background (CMB) is 4 x 10^(-14) J/m^3. The amount calculated above from primordial matter annihilation is roughly 5 orders of magnitude higher than that. Seems that something 100,000 times as strong as the CMB would have been noticed.
And recall that both theory and LHCb provide values much lower than Fermilab’s 1%. I have not been able to find a source that quantifies ‘near zero’ but it must be at least a few more orders of magnitude added on to the expected energy density.
One might invoke red shifting to explain the lack of expected but undetected energy. But that is already accounted for in the math above. At some time in the past, what is now the observable universe occupied a much smaller volume, with a certain amount of CMB energy. All of that CMB energy is still there, it is simply at a much lower density. The math above generated the total expected amount of energy from primordial matter/antimatter annihilation based on existing mass of matter versus the present volume. The original density would have been much higher and now it is lower just like with CMB. No energy just up and vanished.
Alternatively, one might say that the excess energy heated the matter. But that is the CMB, the heat radiation that was able to get uncoupled from matter when the density dropped enough. If heat energy is going to be invoked to make the photon energy go away, then the CMB energy density (temperature) should be much higher.
If I have had my head on straight in all of the above, it would appear that the peculiar properties of the B meson cannot account for the universe of today being (virtually) all normal matter.
So what did I get wrong? :)
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Why matter should dominate has certainly been one of the mysteries of modern cosmology & physics!
I'm certainly not going to solve it, but here are some random thoughts...
a volume of 4*10^80 m^3
It is important to note at what epoch the universe had this volume.
The CMB was emitted when the temperature of the universe dropped below 3000K, causing hydrogen and helium to become transparent. The average thermal energy at this time was around kT = 0.26 eV. The volume had increased enormously in the 300,000 years or so since the Big Bang.
A temperature high enough to produce B Mesons in large volumes would have been much higher, at least 5GeV (the various B mesons have mass around 5.2GeV/c2). This would have occurred when the universe was much more compact than for the CMB. But these reactions would have been most common as the universe cooled down from a quark/gluon plasma into something that allows particles like diquarks (eg B mesons), triquarks (eg protons, neutrons) and other, more exotic combinations to condense, at least transiently. This plasma occurs at temperatures that can be reached by the LHC, at around 10 TeV.
See: https://en.wikipedia.org/wiki/B_meson
Fermilab reported a 1% advantage of matter over antimatter, far in excess of the Standard Model prediction
The above wikipedia article has this to say:
On 14 May 2010, physicists at the Fermi National Accelerator Laboratory reported that the oscillations decayed into matter 1% more often than into antimatter, which may help explain the abundance of matter over antimatter in the observed Universe.[6] However, more recent results at LHCb with larger data samples have suggested no significant deviation from the Standard Model.[7]
...but reference [7] is old (2011) and quoting preliminary data from a conference.
See: https://en.wikipedia.org/wiki/Baryon_asymmetry
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Why matter should dominate has certainly been one of the mysteries of modern cosmology & physics!
I'm certainly not going to solve it, but here are some random thoughts...
a volume of 4*10^80 m^3
It is important to note at what epoch the universe had this volume.
The estimate of the volume of the observable universe I used is based on is the same epoch as the estimate of the mass of matter in the observable universe I used, that is, the epoch currently being observed. The calculated current size of the universe that we observe, based on the consideration that the most distant objects we see have receded further since they emitted the light we see, is not relevant. (If that is what you meant?) If we were to observe photonic energy from the matter/antimatter annihilation period it would be from the portion of the universe currently observed and its energy density would be as calculated from the matter mass and volume estimates based on the universe as currently observed.
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The CMB was emitted when the temperature of the universe dropped below 3000K, causing hydrogen and helium to become transparent. The average thermal energy at this time was around kT = 0.26 eV. The volume had increased enormously in the 300,000 years or so since the Big Bang.
A temperature high enough to produce B Mesons in large volumes would have been much higher, at least 5GeV (the various B mesons have mass around 5.2GeV/c2). This would have occurred when the universe was much more compact than for the CMB. But these reactions would have been most common as the universe cooled down from a quark/gluon plasma into something that allows particles like diquarks (eg B mesons), triquarks (eg protons, neutrons) and other, more exotic combinations to condense, at least transiently. This plasma occurs at temperatures that can be reached by the LHC, at around 10 TeV.
See: https://en.wikipedia.org/wiki/B_meson
It was not the prevalence of B meson production that concerned me. I was misreading the mass of the B meson. It is ten times as massive as I thought. Considerably more than the proton and neutron. With the high ambient energy levels of the very early universe, producing the particles we commonly observe would not be a problem. However, that was a side topic and not related to the expected but not observed energy density.
Fermilab reported a 1% advantage of matter over antimatter, far in excess of the Standard Model prediction
The above wikipedia article has this to say:
On 14 May 2010, physicists at the Fermi National Accelerator Laboratory reported that the oscillations decayed into matter 1% more often than into antimatter, which may help explain the abundance of matter over antimatter in the observed Universe.[6] However, more recent results at LHCb with larger data samples have suggested no significant deviation from the Standard Model.[7]
...but reference [7] is old (2011) and quoting preliminary data from a conference.
See: https://en.wikipedia.org/wiki/Baryon_asymmetry
The link to the FermiLab 1% statement (6) in the B_meson wiki article is to a New York Times article. Within that article is a link to the paper submitted to Physical Review. The end of section XIV gives the asymmetry figure of 0.00957, in Eq. (65). This is about 40 times as large as the Standard Model figure given in Eq. (4). (Sorry I can’t do links yet.)
In lieu of a link, combine lhcb-public dot web dot cern dot ch
Find 9 May 2016:
In any case, I used only the FermiLab 1% in developing the very high values for the expected (but not observed) energy density.
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OOPS time!
In calculating the expected energy level of the photons arising from matter/antimatter annihilation in the early universe, I neglected to account for the consequences of red shift due to universal expansion.
Consider the Cosmic Microwave Background. This is the remnant of the flood of photons when the density and therefore temperature dropped low enough for electrons to combine with nucleons and form atoms and stop blocking photons. The expansion of the universe since then has stretched the wavelength of those photons causing them to have less energy, by about 3 orders of magnitude. This energy loss has been compensated by the corresponding loss of negative energy in the gravitational field as everything got further apart. The net energy did not change. (A gravitational field has negative energy, which is why it ‘pulls’ instead of ‘pushing’.)
In calculating the present expected energy level of the photons arising from matter/antimatter annihilation in the early universe, I used the original photon energy level expected from 99% of the original matter/antimatter mass becoming energy, as per the FermiLab figure. Since the universe has expanded considerably since then, the present energy level of these primordial photons would be much lower than my calculations would indicate.
Matter/antimatter annihilation would have happened considerably earlier than CMB creation at a time when the universe was much denser. Since the CMB energy has declined by three orders of magnitude since creation, the energy decline of the primordial photons would have declined substantially more than that. I (mistakenly) came up with a figure for the primordial photon energy level as 5 orders of magnitude greater than the observed level for CMB. Going back in time to the era of CMB creation would already account for 3 levels of magnitude. How much further back in time, i.e., how much denser must the universe have been at the matter/antimatter annihilation era to make its present level sufficiently below CMB to escape notice? As I said, that annihilation period must have been very early indeed so quite a few decimal places could be applied.
In short, my argument has NOT ruled out B meson oscillation as a viable explanation for the predominance of normal matter. :(