The ultraviolet catastrophe

Two British scientists, Lord Raleigh and Sir James Jeans suggested that a hot object or body, such as a star, must radiate energy at an infinite rate. According to the laws known at that time, a hot body ought to give off electromagnetic waves (such as radiowaves, visible light, or X-rays) equally at all frequency ranges. For example a hot body should radiate the same amount of energy in waves with frequencies between one and two million waves a second as in frequency between three and four million million waves a second and so on. Now since the number of frequencies is unlimited, the total radiated energy should be infinite.
In order to avoid this obviously ridiculous result, the brilliant yet cautious and conservative German physicist Max Planck postulated in 1900 that light X-rays, and other waves (i.e. energy) can only be emitted or absorbed in discrete amounts which he called quanta (the plural of "quantum", the Latin word for "how much"). The energy quantum is related to the frequency of the wave by a new fundamental constant h.
When a hot body is heated, its radiated energy in a particular frequency range is, according to classical theory, proportional to the temperature of the body. With Planck's hypothesis, however, the radiation can only occur in quantum amounts of energy. So at high enough frequency, the emission of a single quantum would require more energy than is available. The radiation at high frequencies would be reduced, and the rate at which the body looses energy would be finite.(Story of the rich man)

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