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Matter, Anti-Matter, and a New Subatomic Particle?
sciencehabit writes "Physicists may have finally figured out why the universe contains more matter than antimatter. The key lies in a flaw in the relationship between the two and a potentially new subatomic particle. 'Other researchers, however, say the results, published today in Nature, should be interpreted cautiously. It could all be an effect produced by run-of-the-mill particles'."
Sigs are too short to say anything truly profound so read the above post instead.
If there was antimatter floating in the universe we would see it via the annihilation of anti-matter with matter where they meet. In particular, an electron and positron annihilate into two gamma rays of a very specific energy, and we have space telescopes looking in that energy range. We just don't see them. You could postulate antimatter stars/galaxies, but their solar wind would run into other stars in the interstellar medium, and create these gamma rays along a boundary plane between them. We just don't see that. We've also put detectors in space looking for anti-protons (AMS). We do see some, but not very many. For more info, google "baryon asymmetry" which is the modern name of the anomaly, and is quite precisely measured.
-- Bob
1^2=1; (-1)^2=1; 1^2=(-1)^2; 1=-1; 1=0.
Very good question...
I do work on theoretical particle physics at CERN, so I would be the kind of person to take Garrett's paper and make predictions for colliders/astrophysics from it. (and hence, find methods to prove/disprove it) I'm not currently working on his theory, nor do I know of anyone who is. I only looked carefully at his paper when I posted the above comment (though I knew about it). I previously understood that he claimed the Standard Model was contained inside E8. If that is true then there are essentially no new predictions, just an interesting coincidence. However I see now that his theory is not the Standard Model, but a SU(2)xSU(2)xSU(4) Pati-Salam model. This implies several new particles that could be seen at the LHC. Garrett claims several things which are not totally justified and require some more calculations to find out (for instance...that the gauge groups unify).
The Pati-Salem model is well-studied (though not currently -- it was popular in the 80's). It is often known as a "leptoquark" theory. However I do not see in Garrett's paper the particle content necessary to make leptoquarks, nor the particles (higgses) to break the SU(2)xSU(2)xSU(4) to the Standard Model's U(1)xSU(2)xSU(3).
I think the problem is sociological. Garrett made a big splash in the gravity community, but I haven't heard a peep from any of my colleagues in particle physics. I will ask around at CERN next week. I know of no good reason why people are not studying it more carefully and making predictions (though, I'm sure Garrett is, but his background is gravity, not colliders).
Flash in the pan? Lots of stuff in the popular press is. For instance TFA is probably an effect of non-gaussian errors, but by making a splashy title they've gotten themselves a Science magazine article. Garrett got his flash partly because of his non-traditional lifestyle. Moral of the story is that the things that appear in the popular press are usually "hero" or "eureka!" stories. But science is full of neither heroes nor daily eureka's. I could complain further about the state of science reporting...
Keep in mind that there are literally hundreds of theories capable of explaining TFA (assuming it's not a statistical fluctuation), and you won't hear about them in the popular press because they're not sexy and hard to explain. For instance, a 4th generation of quarks or a complex higgs sector. Garrett's theory might be one of them, we don't know yet. We don't usually explain these theories to the public because explaining 100 different complicated theories, 99 of which must be wrong...is probably a waste of the public's time. Instead, we'll turn on the LHC this year, which will undoubtedly generate tons of popular articles, and hopefully at least one mostly-correct theory. ;)
-- Bob
1^2=1; (-1)^2=1; 1^2=(-1)^2; 1=-1; 1=0.
No, it couldn't. One thing that is definitely known is that the dark matter is not made of regular atoms (baryonic matter). Baryonic matter is known to comprise no more than about four percent of the total density of stuff in the universe, versus about 25 percent for dark matter. If the universe were 25 percent baryonic, all sorts of measurements would come out differently than they do:
(1) The primordial abundance of elements, which is observed to be about 76 percent hydrogen and 24 percent helium and a trace of lithium, would be very different. See here
(2) The signatures of acoustic oscillations in the Cosmic Micrwave Background would be much larger than they are observed to be. See here
(3) Any extra baryons would show up in the hot gas between galaxies in large clusters, which is very accurately measured by X-ray satellites. See here.
(4) Dark matter consisting of small condensed objects like Jupiter-sized planets would show up in gravitational microlensing surveys. They don't.
We don't know what dark matter is, but we sure as hell know what it's not, and it is not ordinary matter that just happens to be dark. There are multiple, independent lines of evidence which support this conclusion.
Glad I could be of service. BTW I think your "periodic table" comment is an apt description of the situation. I think what's missing is dynamics.
Rather than google, if you want to keep up with Lisi (or anyone else's) papers, I suggest the SLAC Spires database. For instance, this is Lisi's "exceptionally simple" paper. Click on the "Cited..." to get a list of citations. This is updated daily from journal sources, and more importantly arxiv.org. This database generally has topics of relevance to high-energy physics, astrophysics, and gravity. Another good database is the NASA Astrophysical Data Service, here's Lisi's "exceptionally simple" paper on ADS. I warn you however, everything retrieved this way will be technical in nature.
This is what the web was invented for, by the physics community at CERN no less, and now days all our papers are freely available before they are sent to journals, and the public is welcome to read them. Indeed, I despise the "ivory tower" perception and think we are much better off by having outsiders look at what we're doing. I just with the popular press would wrap their heads around the idea of citing primary sources with a hyperlink....but I digress.
-- Bob
1^2=1; (-1)^2=1; 1^2=(-1)^2; 1=-1; 1=0.
For example? Can you list some of these please?
Wikipedia has a concise and complete list of hypothetical and theoretical particles:
Hypothetical particles
Photino - superpartner ofthe photon
Gluino - superpartner ofthe gluon
Gravitino - superpartner of the graviton
Neutralino - superpartner of other neutral particles
Charginos - partners of charged bosons
Sterile Neutrinos - needed to explain LSND results
Sleptons and Squarks - supersymmetric partners of fermions
Tachyons - particles which travel faster than light
Higgs Boson - the origin of mass
Graviton - mediates gravity
Preons - substructure for quarks and leptons
Graviscalar and Graviphoton
Axion - Peccei-Quinn theory to solve the strong CP problem
Axino and Saxion - form together with the axion a supermultiplet
Supermultiplet - supersymmetric extensions of Peccei-Quinn theory
Branon
X and Y bosons - predicted by GUT theory
Magnetic photon
Majoron - predicted to understand neutrino masses
These are all theories. Maybe there should be an X-prize for someone who can come up with a desktop experiment that can prove or disprove one or more of these theories.
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