Planck’s constant is 6.62606957 × 10-34 m2 kg/sec. Notice the -34 exponent. That means it is an extremely small number. To see how this plays out, we must go back to the year 1894, when Max Planck, first a gifted musician who had become a professor of physics and theoretician, focused his intellect on the problem of black-body radiation. Previous research in this area had been somewhat inconclusive, the theoretical speculation being at odds with experimental data.
By way of background, Gustav Kirchhoff (1824-1887), the German physicist who had extended Ohm’s law to clarify complex electrical circuits, had asked in 1859 how the intensity of electromagnetic radiation emitted by a black body depends upon the frequency of the radiation (the color of the light) and the temperature of the body.
Several theoretical approaches, including what became known as the “ultraviolet catastrophe” attempted to force an agreement between theoretical speculation and experimental data. But none of these were valid for both high and low frequencies.
After a false start, known as the Wien-Planck law, Planck honed his methodology. In 1900, he issued what became known as the Planck black-body radiation law. Later in the same year, he amended the theory to include the notion of quantization, which was the great breakthrough later called the Planck postulate. It stated that electromagnetic energy is emitted in quantized as opposed to continuous fashion, and this became the foundation upon which quantum mechanics was built.
The assertion, totally at odds with our experience in the everyday world, is that on a very small scale, action, relative motion and therefore space itself is granular rather than smooth. Counterintuitive as this may seem, it resolves a number of contradictions that had troubled fin de siècle (end of the 19th century) physics.
The Planck constant, h, the tiny number mentioned above, is the defining term in what became known as the Planck-Einstein relation:
E = hv
Where E is the energy of a charged atomic oscillator in a black body and v is the frequency of the emitted electromagnetic wave. Before long, the quantum came to be regarded as a particle, not exclusively describable as a wave.
Max Planck at first regarded the constant as an inconvenient fudge factor that had to be inserted into the equation to make it work. Subsequently, he realized that the constant, despite its almost infinitesimal value, was central to the view that action on a subatomic level happens in discrete jumps, not in a continuous flow. This set the stage for Niels Bohr’s highly successful depiction in 1913 of the quantum action of electrons orbiting an atomic nucleus.
Previously, it had been assumed that because an electron orbiting a nucleus should emit electromagnetic radiation, in short order it should lose energy and crash into the nucleus. Referring to the Planck constant, Bohr resolved the contradiction between theory and empirical observation by quantizing the electron’s behavior, showing it orbited the nucleus in discrete energy levels, emitting a quanta of energy when it changed from a higher to a lower energy level. This model saved electrons and therefore all atomic matter in the universe from annihilation.
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