Happy Birthday, Quantum Mechanics

This is the way that science works: you make observations, and you use them to explain something.

Even if the explanation isn't what you expected, or wanted, or even understand.

On this day in 1900 Max Planck published his theory of quantum mechanics. He was trying describe the behavior of light, but found that the only way he could explain his experimental observations was to assume that light travels in little packets (quanta), which made absolutely no sense to him. He published anyway, calling his theory "an act of desperation."

For a long time he believed that some future physicist would figure out where he had gone wrong, writing "My unavailing attempts to somehow reintegrate the action quantum into classical theory extended over several years and caused me much trouble." But, as it turned out, he hadn't gone wrong. His observations (as he knew) were correct, and the theory which explained them was also correct. Light is just weird that way. And building on Planck's work, physicists have been exploring and describing the strange behavior of light and subatomic particles for more than a century.

And the theory is now so well accepted (though perhaps, as Feynman once quipped, not so well understood) that Nikon can even use it in a camera ad:

Sometimes Light behaves like a wave.
Sometimes Light behaves like a particle.
And sometimes Light behaves like a spoiled, tempestuous child.