Wired reports on the Enriched Xenon Observatory 200, a particle detector scientists hope will answer the question of why there is significantly more matter than antimatter
in the universe. Quoting:
"The new detector will try to fill in the picture, determining basic features of [neutrinos], like their mass and whether or not they, unlike almost all other particles, are their own antiparticles. That quirk is why some scientists believe neutrinos could be the mechanism for the creation of our matter-filled universe. Almost all other particles have an antiparticle twin that, if it comes into contact with the particle, immediately annihilates it. But if neutrinos are their own antiparticles they could conceivably be knocked onto matter's 'team,' thereby causing the cascading win for matter over antimatter that we know occurred. As the Indian theoretical physicist G. Rajasekaran put it in a speech [PDF] earlier this year, neutrinos that are their own antiparticles would explain 'how, after [the] annihilation of most of the particles with antiparticles, a finite but small residue of particles was left to make up the present Universe.'"