Untangling the question of antimatter mass

Antimatter isn't dark. Especially when it annihilates.

@Nicho

> Q1 - Where the hell does the 'mass' go ?

Matter is converted into either energy (and by this I mean “converted into photons”), or other types of matter (pions).

> Q2 - What's so special about anti-matter that enables it to unzip ordinary matter into a bazillion massless photons ?

Long story short? There isn’t anything. (In theory.) Antimatter is composed of different fundamental particles, but (in theory) these particles are completely identical to their “regular” counterparts, excepting that the charge/colour/flavour of the given fundamental particle is exactly the opposite of its antiparticle.

Thus when you get a particle and anti particle together they (and I am REALLY simplifying this here) attract eachother with such a powerful force that they obliterate eachother. (Thing car crash.) This particles to convert into other particles.

>Q3 - if everything can be converted to photons then aren't electrons, quarks etc at the same level as atoms ? ie. not really fundamental at all ?

Matter/antimatter collisions don’t produce exclusively photons. A proton/anti-proton reaction actually produces pions indeed of photons. These pions decay about 25% into high-energy photons on the one side and 75% (via a few different routes) into neutrinos on the other.

Remember that a proton and an anti-proton are not in fact annihilating eachother. Instead, the quarks and anti-quarks that are the constituent parts of these larger particles are doing the sub-atomic dance of destruction.

Remember that electrons are leptons; fundamental particles in their own right. So their path to annihilation is actually completely different than protons, as protons are in fact aggregations of quarks.) Each fundamental particle’s interaction with its antiparticle is different than the next.

Even Bosons have antiparticles. The W boson for example has a direct antiparticle (W+ and W- particles). The photon (another boson, just BTW,) also has an anti-particle: itself!

Oh, yeah, didn’t I mention the photon was a particle, not just a quanta of energy? Silly me. But because a photon’s gague symmetry doesn’t break, (i.e. it doesn’t interact with the Higgs field) it doesn’t have a rest mass.

In other words, there are indeed fundamental particles other than photons. Everything does not “convert into photons.” In fact, there are all sorts of ways for particles to convert from one into the other. But each fundamental particle acts completely differently from the other. That’s part of what makes them “fundamental.” They don’t break into smaller ones, and they all have entirely unique behaviours.

@Nicho

"3) Collide matter and anti-matter and you get photons(energy) . They have no mass."

The flaw in your theory is that photons DO have mass. See:

http://hubblesite.org/newscenter/archive/releases/2003/01/image/a/format/web_print/

For more, look up "gravitational lensing" in your favorite search engine. From there, you should be able to track down an easy reference as to why mass and energy are synonymous ... and don't actually "go away", but are converted into another form. Simplistic? Yes, at this level, in under 75 words and an URL. But it works for my nieces & nephews ...

Tabloids?

It's vastly better than in a lot of the press. Or do you actually prefer the tabloid attitude of writing as if the subject is fully understood by the journalists, when actually they know next to nothing about it and are spouting utter nonsense?

If the author had checked with the wikifiddlers he'd find that

"In physical cosmology, baryogenesis is the generic term for hypothetical physical processes that produced an asymmetry between baryons and antibaryons in the very early universe, resulting in the substantial amounts of residual matter that make up the universe today."

which is what the author thought baryogenesis meant.

This one's actually quite good

I thought Lucy was pretty good and missed her when she left. Lester wasn't a bad substitute but Richard is pretty good. He explains things clearly, lets you know where he thinks he may have a lack of understanding and manages to make readable articles.

And now back to my copy of Scientific American...

I presume you have peer reviewed evidence to back up your hypothesis? In which journals were they published? Citation?

I'd be interested to know your dealer's number.

What's hasn't been done....

Is a beam of a matter/anti-matter bound state, which is what they're doing here. Badly-worded sentence, but the distinction is made clear in the article....

I think the important point

is that this stuff is electrically neutral, so certain things such as gravitation can be more easily measured in isolation of the fields need to contain charged antimatter particles.

Sir

"Just keep to the other side of the room at parties please."

Where I think you will find they have just discovered a way to make the hostess's frock disappear and re-materialise 2 feet to her left.

The enormous difference in field strength means the errors in measuring the electric field would drown out the gravitational measurement. It's not a practical experiment. They're making electrically neutral atoms to remove the need for EM fields.

@briesmith

Except that particles never actually annihilate. What we think of as “annihilation” of a particle/anti-particle pair is in fact nothing more than the conversion of two fundamental particles into various other fundamental particles.

Think of it more like decay. (It’s not, in the physics sense, but let’s bypass that for a moment here.) Two particles are so very strongly attracted to each other because – for all intents and purposes – they are the same thing but with a different charge/flavour/colour. (Think positive and negative electromagnetic charge attraction.) They try to “become one with eachother,” which doesn’t really work all that well.

A proton or a neutron is composed of these things called quarks. Now when you get a proton and an antiproton together they shatter into a little cloud of quarks. These quarks very rapidly reassemble into pions (a pion is composed of two quarks). Pions then decay (mostly) into either photons or neutrinos.

This is an important concept. The proton/antiproton pair does not convert into energy. In fact, no energy is released during the initial collision at all! Instead, they are “smashed into little bitty bits.” The “little bitty bits” don’t like being bits – quarks are social particles, they have this weird need to hang out with eachother – and they immediately reassemble into pions.

But here there’s a problem; quarks are like you and I. They don’t do well in a two-quark relationship. It always goes sour. So these two quark pions rapidly fall apart and the quarks commit hara-kiri, choosing instead to live life as some other particle.

For the most part, they choose to be neutrinos. But some quarks want to go out with a bang and convert directly to high-energy photons. Still other quarks decide to assert their independence and choose to convert into an electron/positron pair, which promptly annihilate themselves by converting into photons.

Well.

*mostly*

You see, electron-positron annihilation is not so cut-and-dried. It really is all about “how much energy the little buggers have.” If the electron/positron pair have enough energy – say because they absorbed the high-energy photons emitted by the decay of some of the other pions – the electron-positron anhillation will not in fact produce photons. Instead, they’ll produce D mesons.

And a D-meson is…

…two quarks.

Oh, but that’s not all! Apparently, with even more energy, an electron/positron collision will actually create a W+/W- boson pair, or a Z boson! Which is interesting, because W and Z bosons are actually force carriers and not really particle sin the way you are used to thinking about it.

So…nothing is ever lost. It all just gets continually recycled. What various subatominc “annihilations” ultimately end up producing (pions, D mesons, bosons, photons, etc.) actually is down to “how much energy did the particles attempting to squish eachother into the same fragment of spacetime have?”

The more energy the particles had on contact, the weirder the resulting particle soup.