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“Surely something is wanting in our conception of the universe. We know positive and negative electricity, north and south magnetism, and why not some extra terrestrial matter related to terrestrial matter, as the source is to the sink. … Worlds may have formed of this stuff, with element and compounds possessing identical properties with out own, indistinguishable from them until they are brought into each other’s vicinity. … Astronomy, the oldest and most juvenile of the sciences, may still have some surprises in store. Many anti-matter be commended to its care! … Do dreams ever come true?”Antimatter is some of the most wonderful stuff in the Universe. All of the normal matter on Earth — that you’re used to — is made up of atoms, which in turn are made of protons, neutrons, and electrons, like so.
-Sir Arthur Schuster, 1898, 34 years before the discovery of antimatter
So what is an antiparticle?
But there are a few very important differences! They have the opposite sign of charge, for instance. If a particle is positively charged (like a proton), its antiparticle (the antiproton) will be negatively charged. Neutrinos and antineutrinos, as another example, always have helicities (or spins, or intrinsic angular momentum, depending on your naming convention) opposite to one another. But the biggest one comes if you allow a particle to meet with its own antiparticle.
When a particle collides with its own antiparticle, they annihilate, and turn into pure energy via Einstein’s famous E = mc2, typically creating two ultra-high-energy photons.
It’s worth asking the question, what’s truly remarkable about this antimatter?
Let me explain, and let me start at the beginning. When you want to do something, it takes energy.
How much more efficient? If I had a million pounds of hydrogen, and I fused the entire million pounds into helium, how much would turn into energy, and how much would turn into (helium) waste? I’d get about 7,000 pounds worth of energy (which, by E=mc2, is a lot, but I’d still get 993,000 pounds of waste. 0.7% efficiency isn’t so great, all things considered.
(Yes, it takes much, much more than a million pounds of energy to make 500,000 pounds of antihydrogen, but that’s not the point.)
And that’s why creating and trapping neutral anti-hydrogen is such a big deal!
This, no doubt, is the fuel of the long-term future. And while it’s way too early to start thinking about large, practical amounts of it anytime soon, this is the start of something that’s sure to be very, very big!
So if someone asks you what the big deal about antimatter is, you know what to tell them. Most. Efficient. Fuel source. Ever. In principle. And we just successfully stored it for the first time. So don’t be afraid to dream big; I know it’s what I’ll be doing!