Anti matter containment achieved...kinda

June 5, 2011 4:11 PM

We've observed antimatter being created in thunderstorms(previously) and we've created antimatter at CERN.(previously) and (previously) The first experiments, announced last November, were able to trap antimatter for about 1/10th of a second; not long enough to study and analyze it properly. Now the Alpha experiment at CERN has announced that they have successfully trapped anti-hydrogen for 1000 seconds. Nature article preprint from arxive.org
posted by AElfwine Evenstar (57 comments total)

And they let them escape!!?!
posted by IndigoJones at 4:16 PM on June 5, 2011 [5 favorites]

Table 1 also has a "detected event" of 2000 second confinement time.
posted by vidur at 4:22 PM on June 5, 2011

And they let them escape!!?!

Supposedly it had held from the notorious gas Oxygen.
posted by Brandon Blatcher at 4:32 PM on June 5, 2011

Seriously? THE ALPHA EXPERIMENT?

Do they want to create a rogue memetic anti-god, that lays waste to half the continent before a liberterian engineer saves the world.
posted by Greald at 4:38 PM on June 5, 2011 [2 favorites]

Short news article that give a bit more information for us lay readers.
posted by Brandon Blatcher at 4:44 PM on June 5, 2011 [2 favorites]

Just today I was reading about the hypothesis of anti-Particles by Dirac. Nice sync, universe.
posted by symbioid at 4:46 PM on June 5, 2011

The big news here is just that humans have managed to form and hold antimatter long enough to be able to study it, nothing else?
posted by Brandon Blatcher at 4:51 PM on June 5, 2011

The big news here is just that humans have managed to form and hold antimatter long enough to be able to study it, nothing else?

Yeah, just that. Nothing, y'know, important.
posted by ixohoxi at 4:53 PM on June 5, 2011 [17 favorites]

The big news here is just that humans have managed to form and hold antimatter long enough to be able to study it, nothing else?

I'm not a professional physicist, but from what I understand that's pretty big news.
posted by AElfwine Evenstar at 4:54 PM on June 5, 2011 [2 favorites]

...but from what I understand that's pretty big news

Because now they can actually study it and possibly learn a few things?
posted by Brandon Blatcher at 5:00 PM on June 5, 2011

Can any physics-inclined folks weigh in here? Now that we can get more than a fleeting glimpse of antimatter, what can we learn from it? Will it allow us to test any specific theories? Will the data we glean from these experiments shed light on any particular questions or areas of research?

They say they're planning to do spectroscopy on it—what might we learn from that?
posted by ixohoxi at 5:01 PM on June 5, 2011 [1 favorite]

Holy shit!

Thanks for this post, AElfwine Evenstar.
posted by likeso at 5:06 PM on June 5, 2011

Yeah and if matter and antimatter annihilate on contact, wouldn't it make sense that they aren't in equal portions in the universe? Otherwise there would be constant annihilation.

How can antimatter exist at all in a universe full of matter?
posted by Brandon Blatcher at 5:08 PM on June 5, 2011

I'm hoping physicsmatt, edd and the usual suspects drop in here, so I'm asking pre-emptively: did the Big Bang produce equal amounts of matter and anti-matter? If no, why not? If yes, why has matter mostly stuck around and anti-matter mostly vanished?
posted by Quietgal at 5:08 PM on June 5, 2011

"By simply leaving the magnetic atom trap on, we can easily make measurements for longer times."

I officially am no longer interested in whether or not we get jet packs.
posted by Lipstick Thespian at 5:12 PM on June 5, 2011 [1 favorite]

How can antimatter exist at all in a universe full of matter?

In part (and I'm definitely not a physicist), because certain high-energy events (such as thunderstorms and CERN experiments) can create antimatter.

It's not quite accurate to say that matter and antimatter are destroyed when they collide. That would violate the law of conservation of matter (or conservation of energy, which is just the other side of the same coin). Rather, the particle and the antiparticle are converted into energy. Energy, particles, antiparticles—it's all the same stuff, in different forms.
posted by ixohoxi at 5:13 PM on June 5, 2011

Quietgal, until they show up, you might enjoy reading about the Baryon asymmetry problem.
posted by Nonsteroidal Anti-Inflammatory Drug at 5:15 PM on June 5, 2011

They say they're planning to do spectroscopy on it—what might we learn from that?

IANAP, but we know a lot about hydrogen spectroscopy. So if we can do anti-hydrogen spectroscopy, any differences will point us in fruitful directions to investigate further, to understand why there's so much matter, and (apparently) so little antimatter. (And by "us," I mean "physicists who are smarter than me.")
posted by spacewrench at 5:18 PM on June 5, 2011 [1 favorite]

So, when do we get warp drive?
posted by shii at 5:19 PM on June 5, 2011 [4 favorites]

ixohoxl, according to our current understanding, atoms and anti-atoms should be identical except for that whole being made of antimatter bit. Which is to say, the energy levels of the electrons in atoms should be the same as the energy levels of the positrons in anti-atoms.

A bit of background on this: when you excite the electrons in an atom, say by heating them or via an electric current, they jump from their "home" orbital or energy level to a higher one (or escape completely). At some later point, they de-excite and fall back down, releasing energy in the form of light. Since these orbitals are well defined and thus the same for all atoms of a certain element, all the light released has the same wavelength (within the uncertainly limits of quantum mechanics). We can use this in a lot of different ways: to measure the composition of stars, to measure the speed of stars and galaxies through their redshift (how much the observed spectral lines are moved in energy from the known elements), and lasers, computers, and many many other material science applications. Plus, the yellow light of sodium lamps is due to the strong spectral line in yellow of sodium.

Ok, that's an aside. The point is, we've never tested the spectral lines of anti-atoms. Now, they MOST likely will be the same as atoms, and that'll be nifty and a great achievement, and we'll learn something very important. What we'll learn is that there isn't an additional source of charge-parity (CP) violation that occurs on the level that can affect the positron-anti-proton interaction. CP is the symmetry that must be violated in order for there to be more matter than antimatter in the Universe. We know that the weak interaction (responsible for nuclear decays) violates CP, but there doesn't seem to be enough CP violation in the Universe to explain the matter-antimatter asymmetry. That's not 100% clear, and I see a lot of talks from people trying to figure out if the Standard Model of particle physics has enough CP violation or not, but it's a nasty calculation and we just don't know quite yet. However, I doubt that the weak interaction would give an observable spectroscopic shift, so measuring one would be a huge deal, and entirely unexplainable in the Standard Model (which is wonderful, since we know there must be more out there than that).

As to the early Universe, we know that there is no antimatter in the visible Universe: there isn't any nearby, and we would see the annihilation lines (photons again) from the interface if half the Universe was one and the other half the anti-version. So what happened? CP violation!

In the early Universe, space was filled with a "thermal bath:" every particle that exists was being created and then hitting an antiparticle and turning into photons or gluons or some other particle-antiparticle pair and then continuing to interact ad infinitum. However, since the Universe was expanding, it was cooling, so as the temperature of the bath dropped, and things that were much heavier than the current temperature (both are units of energy, so use E=mc^2 for the comparison) fall out of thermal equilibrium. They can only annihilate, so their number density drops until the remenants are so far apart that they can't efficiently "find" each other (that is, the probability of a particle and ant-particle interacting and destroying each other is tiny). This leaves a "thermal relic," along with a predicted background of photons, once the whole story finishes. We see this Cosmic Microwave Background today, giving a lot of weight to the whole idea.

We can predict then how many protons and antiprotons should be around today then (electrons and positrons are harder to keep track of in the Universe today, so we ignore them. Charge conservation will give us enough at the end of the day). The thermal number density is 10^-10 (that is, one 10 billionth) of the observed density. So, there must have been some very slight CP violation, that created a very, very slight preference in the Universe for matter: annihilations in the thermal bath then created 1 extra proton for every 10^10 proton-antiproton pairs. That's enough to build a Universe of stars out of, crazily enough. Whether the known CP violation is sufficient is the question that I was talking about before.

Also, on a personal level, I want to know whether antimatter falls down in a gravitational field: if it doesn't, we'd have some questions. (There's absolutely no reason whatsoever to think it would fall up, but hey, wouldn't it be fun?)
posted by physicsmatt at 5:27 PM on June 5, 2011 [28 favorites]

shii, I'll settle for a compact proton-proton fusion reactor. I hope I'm not too old to realize my childhood dream of being killed by an AI while in orbit around Jupiter.
posted by physicsmatt at 5:37 PM on June 5, 2011 [5 favorites]

Because now they can actually study it and possibly learn a few things?

Indeed. Also, one step closer to antimatter propulsion sending us to the stars.
posted by floam at 6:19 PM on June 5, 2011

Because of charge conservation, whenever photons are converted into matter, there always needs to be equally positively and negatively charged particles created.

There's no reason (AFAIK) that it HAS to be only anti-matter/matter pairs, but for some reason, that's all we've ever observed. If energetic photons create an electron, they also create a positron with it -- never a proton.

If that were the case in the early universe, then there would have been exactly equal amounts of anti-matter and matter, and thus, no universe as we know it, because they would have annihilated themselves into photons immediately after being created.

The fact that matter exists at all implies that at very, very high energies (higher than we've been able to reproduce so far, or we would have detected it by now), photons can produce matter/matter pairs (like an electron and a proton).
posted by empath at 6:22 PM on June 5, 2011 [1 favorite]

...successfully trapped anti-hydrogen for 1000 seconds.

What?

That's almost as long as one period in hockey!

Oh, ok then. Stupid science units.
posted by bonehead at 6:27 PM on June 5, 2011 [2 favorites]

So, when do we get warp drive?

Well before we get a warp drive we'll probably get some intermediate antimatter propulsion methods like this or this.
posted by AElfwine Evenstar at 6:44 PM on June 5, 2011

empath, the reason we only see annihilation into matter-antimatter pairs is that interactions such as the ones you describe would violate both lepton (electron and it's heavier brothers, the muon and tau along with the neutrinos) and baryon (proton and neutron) numbers. Such interactions would allow for proton decay unless very highly suppressed. From experiments, we know that the proton halflife is longer than 10^32 years. There are actually ways for the Standard Model to violate B and L numbers (but not B-L) through something called a sphaleron process, but such processes are non-perturbative and so they are HIGHLY energy dependent and so absent in the world around us today (your buzzword here is "non-trivial topology from the non-abelian gauge structure of SU(2)_L." I love science).

One way to imagine how we get an excess of matter over antimatter (and remember, it's only protons we care about, there could be a lot more antineutrinos floating around and we wouldn't care) is think about some particle X that can decay to two sets (A and B) of final states. One of those states (say A) might contain quarks that can make a proton, the other (B) can't. The anti-particle \bar{P} must be able to decay into both sets of \bar{A} and \bar{B}, and the total lifetime of \bar{P} must be the same as P, otherwise the symmetry charge-parity-time (CPT, I think I talked about this in a previous thread) would be violated. P can decay to A some percentage p of the time and into B the remained of the time (probability 1-p). However if CP is violated, than \bar{P} can decay into \bar{A} a different percentage of the time (\bar{p}). Then, even if you start with equal amounts of P and \bar{P}, after they decay, you'll end up with a non-zero number of protons (it will be p - \bar{p}). The trick is CP violation, and a more than one set states you can decay into (otherwise the CP violation doesn't matter).
posted by physicsmatt at 6:58 PM on June 5, 2011 [2 favorites]

So, when do we get warp drive?

Sooner than you think perhaps.
posted by Poet_Lariat at 7:00 PM on June 5, 2011

Wee, anecdotal and totally tangential story time derail! I like telling this story because I nearly (kind of, almost) witnessed a Radioactive Boy Scout-grade incident.

When I was in HS I had an exceptionally nerdy friend. I mean exceptionally nerdy even by my standards. Like same pair of jeans and jean jacket every day for weeks with a pocket protector nerdy. Like screaming arguments and physical scuffles in the middle of AP physics nerdy. And this guy is a bit high strung and quick to offend. This becomes important as you'll see as the story unfolds.

So he hears some unsubstantiated rumor that the DoD or US Army is offering a bounty for anyone who can produce, contain and deliver antimatter for study. This bounty is something on the order of billions of dollars for a gram of antimatter. This is, as we know even today, not really feasible. It was even less feasible around 1990 when this was happening.

But he wants this money. It is truly a giant pile of "fuck off" money. So he wants to build a cyclotron. He wants to smash particles... in his garage. OK. Sure, the first cyclotrons could fit in the palm of your hand, but accelerating particles to relativistic speeds and hunting for antimatter requires either a much larger circumference or impossibly strong magnetic densities to bend the beamline. This is why the LHC is so huge. Even at that massive diameter they're using extremely strong magnets to focus and constrain the beamline. Not to mention he's going to have to have a suitable power source, and the AC delivered to his house isn't going to cut it.

He's starting to tell his high school AP Physics classmates about it and they're laughing at him because it's impossible, really. But I'm laughing at/with him and egging him on and trying to help out with planning and logistics. Hey, maybe he'll come up with some clever new way of doing things, and if not it's still fun to think about. I point out that he's going to need a lot of high grade wire for electromagnets, and a lot of capacitors and accurate timing to help pulse and time the electromagnets, and he's going to need a lot of electrical power.

So he's starting to collect the parts. He's scrounging monster capacitors the size of a small human torso from surplus electronics and electrical supply warehouses. He's accumulating spool after spool of telephone wire from who knows where, which would indeed make fine electromagnets but probably wasn't good enough for a large cyclotron/particle accelerator.

And then he stumbles on the solution for power. Somewhere off the coast of Santa Barbara during the Cold War the Navy dumped a bunch of high grade radioactive waste. So he's developing an interest in SCUBA diving to go get it. He wants to build a nuclear electrical power generation station in his backyard to power the cyclotron in the garage. I think he was thinking about a radioisotope thermoelectric generator since a steam turbine model would be too noisy and costly, not to mention bulky. But an RTG is fairly small and quiet. It just happens to also be very dangerous even when they're built properly.

Around this point his AP classmates are mercilessly ridiculing him. I don't think he realized he could just not tell anyone and avoid that ridicule, but he was argumentative and stubborn, and he's getting increasingly frustrated that his real world skills and experience aren't matching what he can think up on paper. Knowing that this is going to hinder building this thing in his garage with any probability of success is driving him crazy.

After X number of months of being taunted he snaps. He's changed the entire plan. He doesn't care about the antimatter bounty any more. He just wants revenge on the nerds that were laughing at him.

So he wants to build a coil gun in his garage. A very large one. His garage is about 2.5 miles from the HS campus in question and is actually ideally suited if someone wanted to, say, want to shell the school with an artillery piece, or even a low/flat trajectory shot as though from the main gun on a tank. The line of sight and field of fire is just about right.

I discover this news when I show up at his house one day after school and he's sitting in the garage fuming and sputtering and more pissed off than I've ever seen him while he hand-winds electromagnets and cores. He has it all planned out. He'll build smaller models at first and eventually work his way up to something capable of throwing an eight foot long bundle of welded rebar at an appreciably high double-digit MACH number which would indeed leave a massive, smoking furrow up to a half of a mile long where the high school once stood. Sure, he's going to vaporize his own house and probably several of his neighbors houses if he accomplishes this and successfully fires it off just from the hypersonic shockwave alone, but that doesn't matter at this point.

It was at this point I actually became scared. My house was about a half mile directly behind the campus from the line of sight and angle of fire from his house. I didn't really care if he vaporized the school, but not if I was standing behind it while he fired this theoretical Hammer of the Gods at it. And a very large coil gun and a capacitor bank is something someone could - theoretically - make in their garage.

Thankfully due to a heady mix of ADD, a lack of electrical and mechanical engineering and hands on skill and the fact that the internet/web as we know it didn't exist yet - none of these things ever actually happened. If I recall he did make some crude working electromagnets and solenoids, but it never went much beyond that.

But the fact that he was collecting wire, surplus electronics and was generally very serious about the antimatter bounty - and then later - the giant coilgun, that was scary enough.


Anyway, I want an anti-gravity skateboard. That would be cool. Cheap/free transport and levitation would be pretty sweet, too.
posted by loquacious at 7:10 PM on June 5, 2011 [31 favorites]

And I just searched for him and it looks like he might actually have accomplished a PhD in Electrical Engineering and/or Physics and he may be working at or involved with the ATLAS detector at the LHC and/or CERN.

I'm simultaneously proud and a little bit frightened.
posted by loquacious at 7:16 PM on June 5, 2011 [18 favorites]

.One way to imagine how we get an excess of matter over antimatter (and remember, it's only protons we care about, there could be a lot more antineutrinos floating around and we wouldn't care) is think about some particle X that can decay to two sets (A and B) of final states. One of those states (say A) might contain quarks that can make a proton, the other (B) can't. The anti-particle \bar{P} must be able to decay into both sets of \bar{A} and \bar{B}, and the total lifetime of \bar{P} must be the same as P, otherwise the symmetry charge-parity-time (CPT, I think I talked about this in a previous thread) would be violated. P can decay to A some percentage p of the time and into B the remained of the time (probability 1-p). However if CP is violated, than \bar{P} can decay into \bar{A} a different percentage of the time (\bar{p}). Then, even if you start with equal amounts of P and \bar{P}, after they decay, you'll end up with a non-zero number of protons (it will be p - \bar{p}). The trick is CP violation, and a more than one set states you can decay into (otherwise the CP violation doesn't matter).

Okay, so you have a particle P, which can decay into either A or B.

You have an anti-particle \bar{P} which can decay into either anti particles \bar{A} or \bar{B}

If \bar{P} and P have exactly matched decays, you end up with equal numbers of A and \bar{A} and B and \bar{B} and they all annihalate.

But if they decay in different percentages, so that they don't mutually annihilate, wouldn't you still end up with equal amounts of matter and anti-matter?

Because even if we have access protons we're still short a lot of anti-matter, aren't we?

Granted, i was half falling asleeping watching this susskind lecture, but I swear he was talking about the possibility of proton/electron pairs being created...
posted by empath at 7:17 PM on June 5, 2011

(access=excess)
posted by empath at 7:19 PM on June 5, 2011

Poet_lariat, the Alcubierre drive is almost certainly functionally impossible. Sadly. Not only do you need exotic matter to form the wave-packet that will propel your ship, there's no way to get out of it safely once you've started. Also, you probably need more energy than exists in the Universe. So there's that problem. Plus, I read a very fun paper about a year ago noting that the Hawking radiation off the space-time horizon you've built around your spaceship would not only probably vaporize anything inside, but might have enough energy density to disrupt the warp field itself.

I love the idea though, and I like typing "warp field" in a semi-serious context. However, it's just never going to happen in my lifetime unless the Outsiders come and sell us a prototype.

empath: the point is we only care about the proton-antiproton excess (and somewhat the electron-positron, though as you pointed out, charge symmetry means if we figure one out we figure out the other), not any other form of antimatter floating around out there (it'd most likely be in the form of neutrinos, and seriously, fuck those guys). So in my toy example, I can get a proton excess along with some excess of another (anti)particle, but I only care about the former. I'm trying to remember some of the details of electroweak baryogenesis right now (the one that might work for the Standard Model), but it's a bit more complicated and I have to think a bit before I try to explain it to a general audience. It's got bubble nucleation though, and that's cool. I have a ridiculously long flight coming up in a few hours, so if I get really bored over the Pacific, I'll see about writing something up. No promises though.
posted by physicsmatt at 7:25 PM on June 5, 2011 [1 favorite]

christ, and my biggest revenge fantasy was getting in a fight with my rusty rambo knife. which my grandpa gave me (it wasn't rusty when he gave it to me). the same grandpa who ended up dying from a case of botulism contracted by ... stepping on a rusty nail.

ok, back to the antimatter at hand.
posted by symbioid at 9:29 PM on June 5, 2011

metafilter: most likely in the form of neutrinos, and seriously, fuck those guys.
posted by symbioid at 9:33 PM on June 5, 2011

There's absolutely no reason whatsoever to think it would fall up, but hey, wouldn't it be fun?

Dammit, loquacious beat me to it. I was going to say that, with this discovered in 2011, that puts us right in time to have hoverboards developed by 2015.
posted by hippybear at 9:42 PM on June 5, 2011

Ooooh, free wifi in the airport!

I want to put on the serious-scientist hat and say there is absolutely no way antimatter will fall up in a gravitational field, for reasons like energy conservation and that I can't imagine we wouldnt have already noticed the violations of general relativity that this would imply (before anyone asks, no, this can't have anything to do with dark matter/energy). However, it's one of those things that should be checked because that's what we do in science, which is why I brought it up. Also: it's fun.

I'm being a total buzzkill today, aren't I? No warp drive and no hoverboards. Blame the neutrinos, it's all their fault somehow.
posted by physicsmatt at 10:58 PM on June 5, 2011

Yeah, but those nerds at Carnegie Mellon are working on the flying cars for us.

I love nerds.
posted by XhaustedProphet at 11:10 PM on June 5, 2011

Oh, on reread, empath, I'm guessing Susskind was thinking of the electroweak sphaleron operator, which can create protons and electrons (other operators can as well, but they tend not to shut off quickly enough at low energies, and so are tightly constrained from proton decay). I can't watch the lecture right now, so I can't confirm that. The interesting thing about the sphaleron is that it can turn lepton number into baryon. So maybe the asymmetry in the universe came from electrons due to some new physics, and then got turned into protons by the Standard Model physics. We still don't know, but with all these new results coming out in the next few years, stayed tuned.
posted by physicsmatt at 11:12 PM on June 5, 2011

Poet_lariat, the Alcubierre drive is almost certainly functionally impossible. Sadly.

I know. But the fact that Physicists can now publish papers in peer reviewed journals on such subjects and be taken seriously in combination with several working theories of trans-light travel (even if they are practically impossible) leads me to believe that we may be within 100 years of a working solution (if there is one) . Considering I remember a time when serious scientists were saying that manned space flight to the moon was impossible and I remember a time when planetary systems beyond our own were considered highly unlikely and I remember a time when any physicist would have been drummed out of the business for suggesting (let alone publishing a paper) that trans light travel might be possible in theory --- well all that leads me to believe that the next 50 years may bring more surprises.

Now back to anti-matter :)
posted by Poet_Lariat at 1:08 AM on June 6, 2011

And I just searched for him and it looks like he might actually have accomplished a PhD in Electrical Engineering and/or Physics and he may be working at or involved with the ATLAS detector at the LHC and/or CERN.

I'm simultaneously proud and a little bit frightened.

You forgot the best part of that story loquacious.

"...and his name was Lex Luthor."
posted by The Whelk at 2:20 AM on June 6, 2011 [2 favorites]

Fascinating thread.

Is it possible that, rather than CP violation, the matter/anti-matter imbalance could just be a result of an early universe with an uneven mass distribution expanding so quickly that not all of the matter had a chance to run into anti-matter? So somewhere out there is a giant region of space where everything is anti-matter?
posted by A Thousand Baited Hooks at 3:43 AM on June 6, 2011

Is it possible that, rather than CP violation, the matter/anti-matter imbalance could just be a result of an early universe with an uneven mass distribution expanding so quickly that not all of the matter had a chance to run into anti-matter?

The horizon problem discusses this:

Contrary to this expectation, the universe is in fact extremely homogeneous. For instance, the cosmic microwave background radiation (CMB), which fills the universe, is almost precisely the same temperature everywhere in the sky, about 2.725 K. The difference in temperature is so slight that it has only recently become possible to develop instruments even capable of measuring it. This presents a serious problem; if the universe had started with even slightly different temperatures in different areas, then there would simply be no way it could have evened itself out to a common temperature by this point in time. Quantum physics demands that this initial temperature difference should have actually existed at the Big Bang because of the uncertainty principle, such that there is no way that the universe could have formed with precisely the same properties everywhere.

posted by Blazecock Pileon at 4:18 AM on June 6, 2011

Is it possible that, rather than CP violation, the matter/anti-matter imbalance could just be a result of an early universe with an uneven mass distribution expanding so quickly that not all of the matter had a chance to run into anti-matter? So somewhere out there is a giant region of space where everything is anti-matter?

Maybe in some other universe, but not the observable one. It's the same everywhere we've looked.
posted by empath at 5:20 AM on June 6, 2011

So you can still continue to use that General Products #4 Hull then?
posted by longbaugh at 5:23 AM on June 6, 2011

It's the same everywhere we've looked.

How do we distinguish matter and antimatter astronomical objects? Would a distant antimatter star appear any different than one made of matter?
posted by ryanrs at 5:54 AM on June 6, 2011

How do we distinguish matter and antimatter astronomical objects? Would a distant antimatter star appear any different than one made of matter?

There would be a shitload of x-rays at the boundary of anti-matter and matter space.
posted by empath at 5:59 AM on June 6, 2011 [1 favorite]

It's true that a major mystery about the universe is the apparent lack of anti-matter. Matter is everywhere in the universe, and given that the universe is probably around 13-14 billion years old, physicists have long expected a matter backlash. Yet matter is still extremely popular - even those small particles accused of being anti-matter often claim that this is untrue, and in fact some of their best friends are matter.

The material bias pervades all aspects of our culture, and the media in America has never even claimed to take a disinterested approach to the matter/anti-matter controversy. Now the scientific establishment wants to contain anti-matter, supposedly to "study it", but we all know that rounding up anti-matter in containment camps is but the final stage in the fascist materialist project.

In that context, I propose we take up the fight for tolerance - modern America should be accepting of ALL particles, whether pro- OR anti-matter.

Except for neutrinos, of course. Seriously, fuck those guys.
posted by the quidnunc kid at 6:51 AM on June 6, 2011 [3 favorites]

Yeah and if matter and antimatter annihilate on contact, wouldn't it make sense that they aren't in equal portions in the universe? Otherwise there would be constant annihilation.

Crackpot theory interjection time: Maybe it is constant annihilation, and that's what accounts for the linear, directionally preferential arrow of time. As the universe fizzes out of one state, it fizzes into another as new virtual particles emerge and asynchronously annihilate each other. Suppose virtual particle pairs are distributed randomly in space and time and don't decay (meaning, in this case, annihilate each other) at the same rate, so that some pairs still exist even as other new pairs are created. Those slowly decaying pairs might be what account for past events exerting an influence on present events and the persistence of matter and cause and effect over time. All the partnered virtual particles eventually annihilate each other, but by the time they all have, other pairs decaying at different rates have replaced them, and the physical continuity of the universe over time is preserved. Since new virtual particle pairs still have to physically interact with any remaining, legacy particle pairs that have not yet decayed, information about the past is preserved and transmitted through the interaction of new virtual particle pairs and old ones.
posted by saulgoodman at 7:13 AM on June 6, 2011 [1 favorite]

Where's this neutrino hate coming from? I'm kinda fond of the little fellows, myself.
posted by warbaby at 7:36 AM on June 6, 2011 [1 favorite]

Neutrinos, they are very suck
They have no style and have no class
They're little balls of clusterfuck
They taste like puke and smell like ass
Each one is just a stupid schmuck
Uncouth, ignorant and crass
When children see them, they say "Yuck!
Did somebody just let off gas?
That smell is worse than a dump truck!"
So, don't give them a free pass -
They're dirty, filthy, ugly muck.
My favourite lepton to harrass.
posted by the quidnunc kid at 8:40 AM on June 6, 2011 [3 favorites]

I don't know about everyone else, but the reason I hate neutrinos is they never call, they never write, and when they come to town they're always just passing through and never stop for a visit.
posted by hippybear at 8:47 AM on June 6, 2011 [3 favorites]

I hate Kaons more. They're either up or down, but they're always strange. And they're always violating CP, whoever he is. Some say they have a mean lifetime of 1/51800000th of a second, but I say their lifetime is a LOT meaner than that.
posted by the quidnunc kid at 9:41 AM on June 6, 2011

Interesting theory Saulgoodman :)... But it still doesn't explain why we still have a preponderance of matter vs antimatter. If the matter and antimatter were constantly destroying each other, we'd be shining a lot more light? I guess it's a question of what degrees of destruction... The little bit I know is just the electron/positron interaction and radiation of photons. Do other particle/anti-particle pairs emit other things, or is it always light? What happens when an anti-atom collides with an atom. Is it a huge bang?

And the more I read about physics, damn is symmetry and duality fucking awesome and amazing. So many things tied together: space/time... position/momentum... I know supersymmetry must be behind it all, but do we have to wait to figure that out?
posted by symbioid at 10:51 AM on June 6, 2011

Eh, mostly I was playing off the fact that the cosmic neutrino background (similar to the cosmic microwave background, coming from the thermal bath after the Big Bang) would be such a wonderful thing to be able to measure directly. We'd get a snapshot of the Universe at 1 second old (as opposed to 300,000 years, the picture we get from the CMB). If there was a neutrino-antineutrino asymmetry there, we'd get information about whether some models of the baryon asymmetry were correct (many leptogenesis models, for example). The CNB is just sitting there, mocking experimentalists and annoying theorists. Thus: those bastard neutrinos.

So if you want solve the matter-antimatter problem by just splitting the Universe in half and putting the matter in one bit and the antimatter in the other, you've just introduced a HUGE charge-parity asymmetry anyway. Matter and antimatter shouldn't self-segregate. In order to do so, there would have to be a new interaction that distinguished between the two in a way that's CP-violating. That's before worrying about the gamma ray emission from the interface (which I suppose you could solve by postulating a void between the two, but now you're coming up with solutions that involve a high degree of fine-tuning, which are possible but frowned upon).

This idea reminds me of a story from The Galaxy Zoo project, which is a very cool idea that's probably worth a FPP on it's own. The idea is to crowd-source searches through the Hubble photos: they give online training to people who want to play along at home, then have you look at photos of galaxies and identify their properties (spiral, elliptical, etc). They've found a lot of very interesting oddities in there as well, and I think in at least one case, the non-scientist who found one of them got to be on the paper about it.

Anyway, one of the things they had people do was identify whether the spiral galaxies were right- or left-winding. They reported a very slight right-handed preference, and there was some minor speculation about whether this could be due to the handedness preference in the weak nuclear force (this force couples differently to matter with left- and right-angular momentum, so it's at least vaguely possible that it could leave an imprint on such large structures). It was unlikely, but the idea is really fun. Sadly (or, interestingly in a different way), they then flipped the photos and ran them past the Galaxy Zoo participants, and the asymmetry disappeared. It seems the human visual system has a slight preference for right-winding objects over left.
posted by physicsmatt at 6:18 AM on June 7, 2011 [2 favorites]

On actually using the search function, I see that metafilter already has several posts on the Galaxy Zoo. Aw, you guys really are the best of the web.
posted by physicsmatt at 6:23 AM on June 7, 2011

It seems the human visual system has a slight preference for right-winding objects over left.

That's very cool. Is there an arXiv link somewhere, where this experiment is discussed?
posted by Blazecock Pileon at 3:06 PM on June 8, 2011

Here's the arxiv paper, I seem to have remembered things a bit wrong: the preferred handedness was left, not right. They didn't conclusively identify why people were seeing a preferred direction: they speculate that it's a cognitive bias, and cite some research on that. You should always be skeptical when physicists wander that far off the reservation though. We like to think we're experts in everything. Googling "Galaxy Zoo Handedness" gives a bunch of press releases from 2008 that talk about this, most report the observed bias without commenting on the mirroring technique.
posted by physicsmatt at 7:15 PM on June 8, 2011