Over the coming decades there will be increasing discussion about sending robotic interstellar probes to nearby stars.
The discovery and cataloging of inhabited planets within just a few light-years of Earth will provide the motivation; we'll want to see how Darwinian evolution has played out on other worlds.
Remote sensing from huge space telescopes may never definitively prove that life is elsewhere - we'll want to see it squirming under a microscope or, better yet, walking on all six legs.
But how to get to the stars? Both scientists and science fiction writers have long favored matter-antimatter propulsion. In the Star Trek TV series, antimatter fuel is discussed as casually as buying a propane cylinder for the barbecue grill.
Antimatter is the mirror image of the electrical charges found in normal matter. It was abundant after the Big Bang. But when it came into contact with normal matter, *poof!* The Ying-Yang forms of matter annihilated with each other in a powerful burst of gamma rays.
Fortunately for us, there was a very slight excess of normal matter in the early universe to make stars, planets, and people. This is called a CP violation: the breakdown of the predicted symmetry between the number of particle and antiparticles made in the Big Bang.
The problem is that God doesn't make half the universe out of antimatter any more. And even if there were whole antimatter galaxies out there you'd want to stay far away from them.
But as a source of fuel, antimatter can't be beat, as Jennifer Ouellette describes in her recent article.