I just finished an interesting lecture in my course in Quantum Mechanics. It was about a famous debate between Albert Einstein and Neils Bohr that occurred in the 1920s.
Einstein you know about, even the spell check program knew how to spell his name, and corrected me when I misspelled it. With Neils, I had to look his name up. This is because in addition to being one of the world's greatest physicists, Einstein had a knack for self-promotion. Caricatures of his weird hairdo made him instantly recognizable. Nobody knows what Bohr looked like (like an ordinary businessman). In addition, he was an adopted American, and we were glad to claim him.
However, Einstein accomplished little in the last half of his life. He got off a brilliant start and then stalled. Meanwhile Quantum Mechanics, which he helped start, became more and more successful. Einstein fought this vigorously, and in these debates he challenged Bohr over and over. Eventually, he had to admit that he couldn't find anything wrong with Quantum Mechanics. But he never liked the stuff anyway.
He said "God does not play dice with the universe" Bohr replied "Stop telling God what to do." Let me quote from the course transcript:
You can think of Einstein as the lone genius. Bohr is the leader of a movement. Einstein as a prophet. Bohr as the Pope.
But the day of the lone genius, such as Newton, was over. The era of group movements, or teams, had arrived. And Bohr was the head of the Institute for Theoretical Physics at the University of Copenhagen, where much of Quantum Mechanics was developed.
You need know only one thing about Quantum Mechanics: it is nothing like Classical Mechanics. The micro world is nothing like the macro world - but Quantum Mechanics has been completely successful in explaining it. One big difference is determinism: the macro world has it, but the micro world does not. This is what upset Einstein: Relativity is deterministic, so why shouldn't Quantum Mechanics be also?
Determinism states that if enough is known about a system at one point in time, its state at any other point in time can be determined completely. This ignores randomness, which is big part of the universe too - but is ignored by Classical Mechanics. Quantum Mechanics, in the other hand, can only predict probabilities - not exactly what is going to happen, and we have to be satisfied with that.
The reasons why the micro world is not deterministic are many, and form the subject matter for most of the course. At one point I was asking myself: "Do we really need this strange stuff?" Then I remembered semiconductors: the basis for nearly everything in modern computers - and post-modern life. Semiconductors would not have happened without Quantum Mechanics. They are part of the micro world, where things happen differently.
Some British researchers at one point were interested in the properties of ultra-pure crystalline matter - something sensible people were not interested in at all. The result we all know: a revolution in human affairs. Now these ultra-pure materials are mass-produced as a standard industrial process: the starting point for integrated circuits that can contain a whole computer.
Sometimes it pays to pay attention to the way nature really is, not to just what we think she is.