**Max Planck Formulates Quantum Theory (1900):** For several decades, physicists had been trying to understand the surprising results they continued to get from heating black bodies (a surface that absorbs all frequencies of light that hits it). Try as they might, scientists could not explain the results using classical physics.

In 1900, German theoretical physicist Max Planck (1858-1947) discovered an equation that explained the results of these tests. The equation is E=Nhf, with E=energy, N=integer, h=constant, f=frequency. In determining this equation, Planck came up with the constant (h), which is now known as "Planck's constant."

The really amazing part of Planck's discovery was that energy, which appears to be emitted in wavelengths, is actually discharged in small packets (quanta). This new theory of energy revolutionized physics and opened the way for Albert Einstein's theory of relativity.