 You'll recall from our segment on distant stars that we can determine temperature from color because of our knowledge of black body radiation. You'll notice on this graph that as the frequency of the light moves into the higher frequency ultraviolet range, the spectral energy goes down. But the classical formula for radiation energy has it increasing to infinity when the frequency goes up. This dramatic inconsistency between the theory and observation became known as the ultraviolet catastrophe. It wasn't until the early 20th century that Albert Einstein and Max Planck solved this problem. In 1900, Planck came up with a solution for black body radiation that fit the observations. But he had to assume that the light emitted was discontinuous instead of continuous as universally assumed at the time. Furthermore, he calculated that the light's energy was dependent on the light frequency and described by the simple formula energy is equal to a constant times the frequency. The constant became known as Planck's constant. With this assumption, he generated equations that exactly matched the black body radiation observations. Unlike the speed of light that's a really big number, Planck's constant is a really small number. Remember that a jewel of energy was the energy needed to lift the apple? Planck's constant is 66 billion trillion trillion times smaller than that. That's why we don't see the effects in everyday life.