1858-1947

German Physicist

Max Planck revolutionized physics by originating the quantum theory, which states that all radiant energy, such as light, is made up of irreducible packets called quanta. A quantum of electromagnetic radiation is called a photon. The energy a photon carries is proportional to its frequency. So, for example, an x-ray photon is more energetic than a photon of visible light, because x rays are of higher frequency than visible light. The constant of proportionality, h, has come to be called Planck's constant. Planck's particle-like model of light provided a way to explain the emission and absorption of energy by matter. He was awarded the Nobel Prize in physics in 1918.

Planck was born on April 23, 1858, in Kiel, Germany, to a distinguished family that valued scholarship. Planck had many interests; he did well in all his school subjects from...