Quote (bentherdonethat @ Nov 26 2010 04:11pm)
They're not all penetrating, though. Many radioactive substances can't even hurt you unless you swallow them, because alpha radiation (like what is inside of all smoke detectors) has too low of energy to pass through even a sheet of paper, let alone human skin.
also, i believe radio waves and what not are only able to cause rotation of bonds and vibrations as well... anything over UV can then excite electrons to next state. then a few steps past end of visible light, they are able to break bonds which is what you dont really want.