Mirror Image

I'm sitting in a chair right now. If I could zoom in to the chair, I would see that it appears to be made of molecules; zooming in further, atoms; zooming in further, electrons swirling around a nucleus.

What keeps the electrons together, and not flying off in all directions? It's much like a magnet, or a relationship. Electrons have a negative charge, the nucleus has a positive charge. Opposites attract, and the bubbly electrons stick around the stodgy nucleus.

Every particle has a fraternal twin: an antiparticle, exactly alike except for a different charge. Electrons have a negative charge, so their twins, anti-electrons, have a positive charge. Protons have a positive charge, antiprotons have a negative charge. Regular particles combine to make matter, antiparticles combine to make antimatter.

Antimatter is not a science fiction fantasy, but something regularly produced in laboratories, and routinely used in hospitals to create PET scans of patients' brains.

However, all is not well when matter and antimatter collide. If a particle of matter meets its antiparticle twin, both are instantly converted entirely into energy. For comparison, one kilogram of active material in a nuclear bomb would devastate about twenty square miles; one kilogram of matter-meeting-antimatter would devastate several thousand square miles. Fortunately, humanity has not yet figured out how to produce enough antimatter to light a match -- but they're working on it.

When antimatter was discovered, scientists fit it into their existing theories. They predicted that equal amounts of matter and antimatter should have been produced in the early universe, and that matter and antimatter should behave exactly alike. Anti-water would be wet, anti-gold would glitter, and an anti-sun would shine.

Two big problems present themselves: we don't see very much antimatter anywhere we look in the universe, and subtle differences have been detected in how one particular particle behaves in regular form and antimatter form.

Antimatter breaks current theories in an important way. Current theories assume that natural processes are perfectly reversible. Antimatter violates this assumption, and does so in a way that implicates a culprit that science has never really understood: time. The difference between matter and antimatter is linked to the direction of time's arrow. Figuring out antimatter might shed some light on the nature of time.

Scientists are busily experimenting to solve these puzzles. Until they do, they find themselves in a situation much like their classical physics predecessors: their sophisticated theories seem to explain almost everything -- but the little bits that aren't explained are a wound that won't stop bleeding with traditional medicine.

Antimatter poses several problems for humanity. How do we unlock the secrets of antimatter, which could fill in some gaps in our understanding of the universe? More importantly, will our leaders use it peacefully or destructively?

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