This recent posting on LinkedIn’s Theoretical Physics group led to much meandering discussion to no discernable clarity. Einstein’s admission to bafflement does not deter every Tom, Dick, or Harry from his own interpretation, of course, but maybe some clarification is possible.
With this in mind, I went to Wikipedia for guidance.
In physics, a quantum(plural: quanta) is the minimum amount of any physical entity (physical property) involved in an interaction. The fundamental notion that a physical property may be “quantized” is referred to as “the hypothesis of quantization“.This means that the magnitude of the physical property can take on only discrete values consisting of integer multiples of one quantum.
For example, a photon is a single quantum of light (or of any other form of electromagnetic radiation). Similarly, the energy of an electron bound within anatom is quantized and can exist only in certain discrete values. (Indeed, atoms and matter in general are stable because electrons can exist only at discrete energy levels within an atom.)
I tried to find experimental evidence for this last assertion, but was unsuccessful. Wikipedia goes on:
Quantization is one of the foundations of the much broader physics of quantum mechanics. Quantization of energy and its influence on how energy and matter interact (quantum electrodynamics) is part of the fundamental framework for understanding and describing nature.
So, what, then, is quantization? The best answer I can seem to find is that it is the arbitrary assignment of a numerical value to some unit of a quantity, or force , or value. And who knows what it means? It seems it can be interpreted at will, by whomever, and may or may not be agreed upon.
Again, from Wikipedia:
The word quantum comes from the Latinquantus, meaning “how great”. “Quanta”, short for “quanta of electricity” (electrons), was used in a 1902 article on the photoelectric effect by Philipp Lenard, who credited Hermann von Helmholtzfor using the word in the area of electricity. However, the word quantum in general was well known before 1900. It was often used by physicians, such as in the term quantum satis. Both Helmholtz and Julius von Mayerwere physicians as well as physicists. Helmholtz used quantum with reference to heat in his article on Mayer’s work, and the word quantum can be found in the formulation of the first law of thermodynamicsby Mayer in his letter dated July 24, 1841
In 1901,Max Planck used quanta to mean “quanta of matter and electricity”,gas, and heat.In 1905, in response to Planck’s work and the experimental work of Lenard (who explained his results by using the term quanta of electricity),Albert Einstein suggested thatradiation existed in spatially localized packets which he called“quanta of light” (“Lichtquanta”).
The concept of quantization of radiation theory was discovered in 1900 by Max Planck, who had been trying to understand the emission of radiation from heated objects, known as black-body radiation. By assuming that energy can be absorbed or released only in tiny, differential, discrete packets (which he called “bundles”, or “energy elements”), Planck accounted for certain objects changing colour when heated.On December 14, 1900, Planck reported his findings to the German Physical Society, and introduced the idea of quantization for the first time as a part of his research on black-body radiation.[As a result of his experiments, Planck deduced the numerical value of h, known as the Planck constant, and reported more precise values for the unit of electrical charge and the Avogadro–Loschmidt number, the number of real molecules in a mole, to the German Physical Society. After his theory was validated, Planck was awarded the Nobel Prize in Physics for his discovery in 1918.
The original use of the term,quantum satis(the amount which is enough) can easily have meaning in an analog universe, that is, as the quantity, level, intensity, etc., required to achieve detection. This interpretation requires a standard variable to be set and modified, upgraded as methodology improves. In a sine wave, for instance, if detection occurs only when a value achieves a certain positive level, the result can be mistakenly interpreted as a series of separated point values, which have been artificially cut off at their lower values.
Wikipedia’s list of usage examples (in physics) follows, not to speak of “quantum leap”
Introduction to quantum mechanics
Quantum cellular automata
Quantum Field Theory
(Each of these has a Wikipedia page!)
Planck’s defining of (not “discovery of”) energy quanta led to the almost immediate conflation or misinterpretation that energy only existedas quanta, that is, that it could not be considered as a continuous phenomenon. Which is where we got the photon, and the (false) truism of “wave-particle duality,” the subject of millions of words of explanation throughout the literature. But, it was convenient for the math, so it stuck, and bedevils us to this day. Understanding light as a wave phenomenon also explains in simple terms the famous double slit experiment (you can look it up here) as simple diffraction mechanics, not as mysterious particle-jumping-around behavior. Physics does not need made up mystery. There will always be enough to go around without the need to make them up out of thin air.
Who benefits from made-up mysteries? Maybe the academic programs, if you look at how many graduate students are studying string theory. When I ask these questions on the theoretical physics websites, half of what I get back are mathematical equations, which explain nothing.