You may have heard that William Shakespeare was born on this day in 1564. But the truth is that we don’t know. The same goes for Christopher Marlowe and Miguel de Cervantes. What we know is when they were baptized. And the convention is to assume that babies were baptized on the third day. So really all we can say is that Shakespeare was born on or before 26 April 1564.

The painter J. M. W. Turner was born in 1775. The great Russian composer Sergei Prokofiev was born in 1891. Director Ronald Neame was born in 1911. Roy Orbison was born in 1936. And American terrorist Timothy McVeigh was born in 1968.

Shirley Temple is 85 today. She is known for her political work in the Republican Party, which isn’t surprising given her marriage to businessman Charles Alden Black. Of course, that was when the Republicans weren’t quite so radical as they are now. Just the same, she was in favor of the Vietnam War after reasonable people had figured out it was bad for all involved. The great documentarian Michael Moore is 59. Judy Davis is 58. George Lopez is 52. And actor Dev Patel is 23.

But the day belongs to the father of quantum mechanics Max Planck who was born in 1858. He did a whole lot of stuff during his career but he is best remembered for solving the ultraviolet catastrophe. Of course, Planck wasn’t trying to solve the problem. Anyway, what he showed was that an object can only emit light in packets of particular energies. That energy is given by h (Planck’s constant 6.63e-34 J*s) multiplied by the frequency of the light. What I find fascinating is that Planck didn’t accept Einstein’s theory of the photoelectric effect, which is more or less an application of Planck’s theory. And it wasn’t because he didn’t like Einstein. In fact, he was a friend and champion of the younger scientist. We humans are complicated. Max Planck was a great man.

Happy birthday Max Planck!