In September, scientists in Europe made an incredible announcement: they had produced not one, but tens of thousands of "anti-atoms," atoms made entirely of antimatter. This result rightly generated a good amount of publicity, but I was amused at the media's reaction to the news. Whenever I saw it mentioned, either on television or in papers, there always seemed to be a picture of the starship Enterprise or some other science fiction-type image.
Of course, that seems fitting; antimatter is dramatic, exciting stuff, and is, as well, the fuel that supposedly propels the starship Enterprise across the galaxy. But there's so much more to the antimatter story. Sure, understanding antimatter and how to create it in our laboratories may very well lead us to a super-efficient, almost inexhaustible energy source to power the spaceships in our far future. But the properties of antimatter may also help us understand how we, and in fact, everything in the universe, came into being.
What exactly is antimatter? Well, antimatter wouldn't look any different to us if we could see a chunk of it flying through space. And, although this is highly unlikely, if a distant galaxy were made entirely of antimatter, we'd have absolutely no way of telling from the light it emitted. Every type of particle in the universe has a kind of evil twin, its antiparticle. The only difference between the two is that antiparticles have an opposite electrical charge than their regular-matter mates.
An antiproton is exactly like a proton, except that it has a negative charge instead of positive. An anti-electron has a positive charge, and thus is usually called a "positron." There's even an anti-neutron, which is also neutral, since the neutron has no charge. Antimatter isn't really dangerous in small amounts, as an antiparticle can only annihilate a similar amount of matter.
As it turns out, creating antimatter in a laboratory isn't that hard if you can pump a lot of energy into a small volume. The people at CERN, the European Center for Nuclear Research (the acronym is in French), have gotten quite good at producing antimatter by accelerating a stream of protons to nearly the speed of light, then ramming them into a sheet of heavy metal.