Feynman diagram here
The mystery behind why there is an imbalance between matter and antimatter in the universe could be one step closer to being solved. First, let's kick off with some gentle particle physics to set the scene. Scientists are hunting for something called neutrinoless double beta decay: in normal double beta decay, two neutrons …
In the early stages of the universe when matter first began to condense out of the soup of energy, some really high energy particles (maybe so high energy we have no hope of ever creating them in a particle accelerator) that are their own antiparticle could have been created. If those preferentially decayed into 'matter' rather than 'antimatter' that would neatly explain why matter appears to be the majority in the universe.
Unfortunately, if this is true we won't ever have any way of proving it. However, the existence of Majorana particles that are created only in accelerators and don't exist in nature proves that this is a possible explanation.
"Wish I could think of an analogy to illustrate the point..."
The standard model feels like it's likely to be analogous to the geocentric model of the solar system. Sure the equations accurately predict the results, but that's because they've been finessed until they fit the data. They don't explain the underlying phenomena.
It's nothting to do with physics at all.
All the anitmatter in the universe got used up making Antipopes.
Wikipedia (I know, I know, but I'm too lazy to do the research properly) lists 41 of them over the years.
Since we've not had an antipope since the 16th Century and we can't see any antimatter (except that we create ourselves), this proves that there's none left. QED.
F**k yes. I walked away from High Energy Physics (as an electronic eng doing H/W and S/W for it) in the early 80's thinking I'd earn more spondoolicks in the commercial world.
Biggest regret of my life. Even bigger than my first marriage. Could have been working on the LHC. And had a decent pension, thanks to USS (the UK Academic scheme). Only prob, I'd probably have become an alcoholic.
My first proper job after big school was chip designing. Running automated checks on the computers that were around then used to take several days. Several days spent researching things related to work that may or may nor help in my job. Never a must-see supernatural event but the flashes of recognition of other peoples brilliance were fireworks enough for me. Admittedly working with people at the pinnacle of any 'discipline' can give you imposter syndrome but if you cant get a buzz out of learning you should move into management and abuse people instead.
In trying to create a charge-free environment, have they considered siting the experiment in a room without a woollen carpet? Plus, the scientists should avoid rubbing balloons against their jumpers. And wearing polyester-mix trousers.
It seems obvious, but it's best to double-check these things.
Let's be clear here: identifying a neutrino-less decay could be seen as a matter of not detecting something that you can't detect anyway. A neutrino, or in this case an antineutrino, has a 50% chance of making it through half a light-year of solid lead.
But of course I'm sure they've thought of that.
"But of course I'm sure they've thought of that."
Yes, they have. Because they know what they are doing, and have decades of experience with this thing. Some of them will have produced the factoid you are quoting.
"A neutrino, or in this case an antineutrino, has a 50% chance of making it through half a light-year of solid lead."
But there's loads of them.
After a little thought, it comes out like this:
The neutrino was originally discovered because, after physicists added up the bits after a nuclear reaction and compared them with the bits they started with, there was something lost, so something undetectable must have sneaked away.
So to detect a neutrino-less event, you look for ones where the before and after bits all add up to the same.
Which means that instead of knowing something was there because there was something was missing, they will know that nothing is there because nothing is missing.
If the neutrino is its own antiparticle, wouldn't this be more easily be detected by studying neutrino/neutrino decay directly?
What we seem to have is the study of a theoretical decay chain which in itself requires a theoretical decay mechanism ... To me that smacks of Nobel Prize or little hope of success ...
I seem to remember watching some US based physicist on TV not that long ago who stated that bananas are a (comparatively) rich source of anti-matter - something to do with the potassium 40 they contain. Apparently a banana will emit a positron approximately once every 75 minutes.
Instead of spending money on flash kit they need to get down to the local supermarket with a halfway decent knife and start slicing.
Severe thunderstorms also seem to produce antimatter naturally -- or at least, they produce hard gamma rays at energy levels that we only know how to explain as matter-antimatter reactions. This is one of those things we discovered by accident while looking for something else -- a satellite intended to study cosmic gamma ray sources was getting hit by occasional short bursts so close by that they overwhelmed all of its detectors.
I'm very very much not a scientist, but this has always appealed to me...
If space is n-dimentional, why couldn't the big bang have gone in two directions down one one those dimensions, with *most* of the matter being flung one way, and most of the anti-matter being flung the other way?
The bonus to that is that you get two universes which would explode if they ever came into contact with each other, which makes science fiction much more fun.
I've got all the extra antimatter. It's in my shed. Sorry. I didn't realise it was causing a problem. I was going to sell it on eBay.
If someone posts an address here, I'd be glad to return it all, providing I can afford the postage.
AC - because there's nothing more dangerous than a herd of irate theoretical physicists.
Neutrinos and anti-neutrinos are neutral, no charge hence the name. So how does the theoretical lack of a neutrino or anti-neutrino (or two) impart a positive charge to the inside of the chamber?
Neutron (no charge) decays producing a proton (positive charge), an electron (negative charge) and an anti-electron-neutrino (no charge). Charge is conserved as the proton and electron cancel each other's charge. Do it twice still no net charge.
Must be fucking magic! Unless some how the energy the anti-neutrino would normally have carried away from the decay (neutron being slightly heavier than a proton plus an electron) gives the electrons enough extra velocity to escape the germanium thus leaving a positive charge.
Paragraph 2: "in normal double beta decay, two neutrons convert to protons and two electrons"
Same thing happens in the neutinoless version...
(Mine's the one with the Physics degree ... OK - it was a Third: if only I'd proved there was a Black Hole under the Department of Physics at Birmingham...)
Funny I typed this last night but maybe it was in positrons and annihilated itself. Anyhoo - here goes - again.
How do we know that distant galaxies aren't antimatter. Maybe "where the hell is it" - is all around us?
I still haven't had a decent explanation of why this can't be the case.
We are quite close to being able to measure the spectrum of antihydrogen, although it should be the same as normal hydrogen, if there do turn out to be some subtle differences then we will know what to look for out there.
We have observed the spectrum of antihydrogen, just before christmas. It is identical to hydrogen :(
Biggest reason why other galaxies can't be antimatter is that intergalactic space isn't completely empty, only nearly so. The boundary between matter and antimatter would glow with a characteristic gamma energy. it doesn't, so it isn't there.
I've heard this assertion before about the glow from annihilation events. So I started looking into what we should be looking for.
Of course you are only going to get this effect between am/m pairs, not m/m or am/am.
Proton/antiproton annihilation results in a pair of gamma rays of around 938MeV. These may be red-shifted if the galaxies are far away, so we could be looking for a spectrum maybe between 90-900MeV.
What about the intensity of this radiation (if it were there) what would we expect? Would all the gas have mixed and annihilated aeons ago, or do you expect to see gas streaming out of the galaxies still? If so, at what rate?
Finally, looking at various observations from gamma ray observatories, these are currently at low resolution and show some radiation that may overlap with the expected spectrum. So I don't think the matter is settled, unless you can come up with specific research sources that can demonstrate the negative result with some certainty.
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