elusiveneutrino (user #1428)Log in for details.
I am an elementary particle with spin 1/2 (so I'm a fermion). I have very small mass and do not interact via the strong or electromagnetic forces. I come in three different flavors: the electron neutrino, the muon neutrino, and the tau neutrino. I switch between these types every now and then just on a whim. It is very difficult to find me. A piece of lead a light-year long would block about half of the neutrinos flowing through it (length-wise of course!) so if you think you'll get a chance to interact with me, well, don't count on it, bubba.