164: Antimatter

Matter is made out of fermions*. Fermions are made up of quarks and leptons. Atoms are mostly made out of quarks. Quarks live in pairs or triplets, no quark has been found alone or in quartets and above (or as my roller derby brain insists, quad-tet). Lone quarks are theoretically impossible because of quantum chromodynamics. Color is important to quarks… I have no idea what that means or how it relates to normal human colors. Then stuff gets weird!

Quarks in pairs are called mesons (and while they’re made out of fermions they’re categorized as bosons because they’re involved in force, not matter, although they are forces that are essential for matter to exist forces are essential, but mesons aren’t part of day to day atomic life. See the comments for more info!). One particle in a meson is a quark, the other particle is an ANTI-QUARK! The meson can still have a positive charge if the quark has a stronger charge than the anti-quark. Forces bind the quark and anti-quark together and then other forces keep them separated so they don’t annihilate each other. To get the charge of the meson particle you simply add the positive and negative charges together.

Quarks in triplets are called baryons. Baryons are wot we are made of. When someone says baryonic matter, that’s a fancy way of saying matter that exists somewhere on the periodic table. Baryons can be made of quarks and/or anti-quarks! I’ll repeat that in case you didn’t hear QUARKS and/or ANTI-QUARKS living together! A quark’s bffs for life can be anti-quarks, anti-quarks!

All of us folks made of matter have anti-particles inside us. We have baryons to give us matter and mesons generate forces that help matter hang out with matter (I think that’s the technical term, mesons are the mediating particle of the Residual Strong Nuclear Force… last I heard it was useful for neutrons and protons to hang out and form that middle bit of an atom).

Doh! This is what happens when you learn by piecing stuff together and coming to what feels like a logical conclusion on incomplete information that feels complete because you think you’re finally getting a handle on things. Mesons are all about Residual Strong Nuclear Force, but they are not the only particles playing the nuclear force game. Mesons are rare beasts that live out in space and generate gamma radiation, something that life as we know it does not enjoy. Thanks Vandana Singh, see comments for further info.

At our most fundamental level we contain the anti to our matter. That is what allows us to exist. Opposite particles that are so tightly into each other that the force of trying to pull them apart would be so violent it would cause other particles to spoing into existence. Opposite particles that would annihilate each other if they touched.

I dunno about you, but that’s pretty amazing.

In Saturday’s comic I’ll write about awesome people who have been helping me with my research. I was going to do that today, but I got carried away by the science of it all.

* Info for this excited post mostly comes from the Particle Physics Overview, from the Astronomy department at Case Western Reserve University.

4 thoughts on “164: Antimatter

  1. Hi Liz,

    Great that you are excited about this subject! I am often tempted to start babbling to strangers on the street about the subtle beauties of particle physics, so when someone actually wants to know, it is wonderful. I used to research the area and I miss it, but the great thing is that new developments and discoveries are always being made and I can keep learning.

    A couple of clarifications. Particle physics is full of jargon, so it is important to get the meanings clear. Elementary matter particles are all fermions (which only means they have spin 1/2), and they consist of 6 quarks, and 6 leptons. The leptons include our friend the electron. The quarks combine in various ways to produce matter. When a quark and an anti-quark hang out together, they form what are known as mesons. Important note: the anti-quark in the pair is not the antiparticle of that particular quark, otherwise they would annihilate! A green u-quark cannot pair with an anti-green u-anti-quark, but CAN pair with a red u-antiquark! BTW ‘color’ for quarks is just a label to describe an attribute for which we don’t have an analog at our scale of things. When three quarks come together as in a proton or neutron, they form a category of particle called baryons.

    The matter we’re made of at the very basic level consists of u and d quarks and the electron, and as they interact, they exchange ‘force field particles’ like the photon, the gluons, and the W and Z particles. The more exotic particles like mesons are not generally found in ordinary matter because they are not stable. We see them in cosmic rays and produce them in accelerator collisions. Similarly we don’t find a lot of antimatter in our universe, which is a) good because there would be a lot of annihilation going on, and b) puzzling because there is no clear reason why the universe should prefer matter over antimatter. There are various hypotheses about this.

    Endlessly fun stuff!

    1. Thanks!

      Is matter defined as stuff of substance bigger than a particle? That was something I was puzzling over. If a particle is matter then it anti-particles would be a teeny tiny piece of antimatter bounded within a system that is, overall, matter.

      Is it, particles are to atoms as matter is to molecules?

    2. Also, checking in, my impression was that baryons could contain anti-quarks as well as quarks in their triad. Is that incorrect?

    3. And thanks for the link to the particle physics overview. I went over the chart of particles with fresh eyes. Most common Baryons seem to be made entirely out of anti-quarks.

      I imagine my brain diving for the coolest thing and from an Earth centered perspective (after all most people contain trace elements of a large chunk of the periodic table… unless that understanding is wrong too) assumed that if it existed it would be in us too, rather than bearing in mind the universe as a whole has some really weird stuff in it.

      Looking through the charts, I imagine the baryons containing anti-quarks are about as rare as mesons. Doh! I’ve redrawn tomorrow’s comic given it seems like there’s a bit of BAD physics in today’s comic, even if antiparticles hanging out with particles is still completely amazing.

      My brain is still trying to come to terms with when does a photon become its antiphoton (or is it always in a wave/particle kind of way). Do we bombard them to reverse their spin, is it how we look at them? But that’s probably a conversation for another day! Oh universe, the more I look at you, the more intrigued I get. The more I think, what do these words actually mean?

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