h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Quantum thery has been proven, and has many practical implications and uses. Without quantum theory there would be no lasers! Practical uses for entanglement are still under development, but researchers have transmitted some Mozart across a desk at 4 times the speed of light.

Not to mention the microelectronics industry, which employs hundreds of thousands of people on all major continents and handles billions and billions of dollars a year and has irrevocably changed the face of society forever, would not be possible without the quantum theory of the electron and of electromagnetism. You wouldn't have a computer to write your article on if not for the practical application of quantum theory. And as far as proof, among all scientific theories ever proposed, only General Relativity has been shown to be more accurate (to fourteen decimal places)than quantum theory (to nine or eleven decimal places, I think, although I don't remember exactly). (Possibly ten )