IMAGINE the thoughts going through the minds of the captain and crew of the world's first nuclear-powered submarine, USS Nautilus, when it put to sea for the very first time — 50 years ago this morning. Not only did they have to take a new submarine to sea, but also they had to control the splitting of the atom in a small space aboard a submerged submarine — in constant danger from the nuclear fission's tremendous heat and life-threatening radiation. So it's likely that Nautilus' crew didn't give much thought to the fact that they were ushering in the atomic...