Submarine Definition & Meaning

The submarine has been one of the most important inventions man has ever seen. A submarine is a vessel that can travel on the surface of the water as well as underwater. It is shaped like a cigar, and can be tightly closed from all sides. There are different types of submarines, which can travel underwater at different depths. They are usually powered by disesel-elelectric engines, but some are nuclear-powered also

Failure of Quantum Mechanics without Relativity

Philosophical questions aside, in the 1930s and 1940s quantum mechanics was like an unstoppable Mack truck barreling down a highway, flattening all the problems that had puzzled physicists for centuries. One brash young quantum physicist, Paul Dirac, ruffled the feathers of many chemists when he had the nerve to say that quantum mechanics could reduce all of chemistry to a set of mathematical equations.