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While scanning through items in our #rss-bot channel for today, I came upon an interesting article at phys.org CP violation or new physics?:
Over the past few years, multiple neutrino experiments have detected hints for leptonic charge parity (CP) violation—a finding that could help explain why the universe is made of matter and not antimatter. So far, matter-antimatter asymmetry cannot be explained by any physics theory and is one of the biggest unsolved problems in cosmology.
But now in a new study published in Physical Review Letters, physicists David V. Forero and Patrick Huber at Virginia Tech have proposed that the same hints could instead indicate CP-conserving "new physics," and current experiments would have no way to tell the difference.
Both possibilities—CP violation or new physics—would have a major impact on the scientific understanding of some of the biggest questions in cosmology. Currently, one of the most pressing problems is the search for new physics, or physics beyond the Standard Model, which is a theory that scientists know is incomplete but aren't sure exactly how to improve. New physics could potentially explain several phenomena that the Standard Model cannot, including the matter-antimatter asymmetry problem, as well as dark matter, dark energy, and gravity.
As the scientists show in the new study, determining whether the recent hints indicate CP violation or new physics will be very challenging. The main goal of the study was to "quantify the level of confusion" between the two possibilities. The physicists' simulations and analysis revealed that both CP violation and new physics have distributions centered at the exact same value for what the neutrino experiments measure—something called the Dirac CP phase. This identical preference makes it impossible for current neutrino experiments to distinguish between the two cases.
[...] "The trick is that the type of new physics we postulate in our paper manifests itself in the way in which neutrino oscillations are affected by the amount of earth matter through which the neutrino traverses," Huber said. "The more matter travelled through, the larger the effect of this type of new physics."
An abstract (DOI: 10.1103/PhysRevLett.117.031801 ) is available; full article is paywalled.
This is way outside my level of understanding, but I have seen references to CP violations before and find the concept fascinating Any Soylentils care to weigh in and explain what was found and what it may mean in terms that an educated but non-physicist layman might understand?
(Score: 2) by TrumpetPower! on Tuesday July 26 2016, @02:56AM
The entropic arrow of time is another way of stating the "past hypothesis." Namely, you can remember yesterday but not tomorrow because entropy was lower yesterday than it was today and it'll be higher still tomorrow. That's basic thermodynamics, which itself is simple statistics. Follow that backwards and a baker's dozen billion years ago you get to the Big Bang, which was a condition of extraordinarily low entropy, with entropy increasing ever since.
Richard Feynman described antimatter as mathematically equivalent to regular matter moving backwards in time.
If we put the two together and assume that matter and antimatter were made in equal proportions by the mechanics of the Big Bang, then we get a picture of a similar "mirror" to our own universe made of antimatter that shares our own Big Bang but with its arrow of time pointing in the opposite direction.
I've mentioned this in passing to a physicist who know his stuff and he wasn't impressed, so take this with a monstrous grain of sale.
Cheers,
b&
All but God can prove this sentence true.
(Score: 0) by Anonymous Coward on Tuesday July 26 2016, @04:30AM
But from the perspective of a sentient being within this "mirror universe" (i assume they all have goatees), time would appear to be running forward, the same as it does here, so such a thought exercise doesn't really go anywhere, except maybe in establishing that we only have a single parallel universe, the antimatter universe (which we could thus never visit or interact with), rather than an infinite number of them; this would explain where all the antimatter went though.
(Score: 0) by Anonymous Coward on Tuesday July 26 2016, @05:20AM
No, as I understand it the two interact all the time, because of the behavior of photons and virtual particles, and possibly the behavior of information around the singularity of a black hole. But that is to say, I don't understand it :P
(Score: 2) by TrumpetPower! on Tuesday July 26 2016, @01:52PM
That's basically right, though it wouldn't say anything about multiverses -- only that universes come in pairs of matter and antimatter. Maybe our is the only such pair; maybe there're innumerable such pairs; maybe only some have laws of physics that include antimatter; and maybe (much more likely) I'm nowhere near qualified to be speculating on the matter....
b&
All but God can prove this sentence true.
(Score: 2) by bob_super on Tuesday July 26 2016, @05:14PM
I'm even less qualified than you, because I don't understand how the gravity-driven collapse of all matter into a single point, which is then followed by a Big Bang spreading it again (rinse-repeat), should result into equal quantities of matter and anti-matter...
(Score: 1, Funny) by Anonymous Coward on Tuesday July 26 2016, @06:22PM
"I'm nowhere near qualified to be speculating on the matter...."
But are you qualified to be speculating on the antimatter?
(Score: 3, Interesting) by Immerman on Tuesday July 26 2016, @04:27PM
That seems somewhat unlikely. Case in point:
You can do an experiment today that generates antimatter and traps it in an inadequate magnetic bottle until all the particles individually escape and annihilate with normal matter. If the antimatter were actually "time reversed normal matter", that would imply that, from the perspective of the antimatter, each particle was individually created from a small high-energy concentration, raced directly toward the magnetic bottle, and was trapped there until its fellows achieved a peak particle density, at which point they were all destroyed in an extremely brief particle accelerator event that converted their energy into two tightly-focussed beams of normal matter that raced away in opposite directions.
Mathematically it may be consistent, but it wreaks havoc with our understanding of causality, or alternately suggests that leaky magnetic bottles should spontaneously fill with antimatter. Not every mathematically equivalent concept is equally valid for understanding the universe.