As a university professor in Berlin, Max Planck was commissioned by electric light makers to figure out what was the maximum amount of light that could be emitted using the minimum amount of power. It was actually kind of an old question just prior to the turn of the century, but the answer had never been derived to anyone’s total satisfaction.

On December 14, 1900, Planck postulated that electromagnetic energy (such as light) can only be emitted in quantized form, where the elementary unit E=hv is Planck’s constant (the notion of Planck’s constant had already been suggested, but the concept of quantization was new).

At the time, Planck considered the concept “a purely formal assumption…actually I did not think much about it.” But others did.

He was awarded the Nobel Prize in 1918 for his theory, which today marks the birth of quantum physics. His postulate, and other new measures (Planck’s Length and Planck’s Mass) predate Einstein’s notion of quantum packets by five years.

To his great consternation, Planck was never able to fully grasp the concept of energy quanta, and the field quickly got away from him. He was, however, one of the few physicists at the time to recognize the significance of Einstein’s special theory of relativity, and did much to promote acceptance of the concept.

Planck was well respected as an instructor; he rarely used notes but observers said his calculations were always flawless. At one point in his career, he taught uncertified courses in physics to standing-room-only crowds.

Planck’s leadership in academic circles allowed him to bring Einstein to Berlin and the two scientists became close friends, but world events created great turbulence in their professional careers.

Nearly all of Planck’s writings were destroyed in an Allied air raid in February 1944. Planck’s own son Erwin was executed for his role in an attempted assassination of Adolph Hitler.  His son’s death was a crushing blow to Planck, who previously had done his best to keep Jewish scientists on government payrolls at great personal risk.

He died in October, 1947 at the age of 89. He is still regarded as the founder of quantum theory.