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Response to The Origins of the Quantom Theory

Max Planck first introduced the element of discontinuity (or the quantum) a century ago. This was to help us better understand unusual occurrences at the microscopic level. The topic was complex for the time and could not be explained entirely. In fact, “Physicists pondered for years what a quantum theory might be.” Because of its depth, it was not easy to integrate the quantum theory into the already existing 19th century physics. Although the subject is not light, it helps account for previous unexplained phenomena.

Planck was interested in two theories: electrodynamics (the theory of electricity, magnetism, and light waves) and thermodynamics/statistical mechanics. Both theories originated from different notions and had not been related to each other. Before the 1900’s, Planck’s work was quite involved with the emission of light. The topic of “blackbodies” was contemporary at the time. These “blackbodies” were perfectly absorbing bodies of black which provided a standard for emission. What proved to be the “near-ideal blackbody” was a closed tube with a small hole because it allowed for the most accurate measurements. A model of a blackbody was found by the emitted and absorbed radiation of oscillating charges. Based on experiment data Willy Wien was able to produce a model. Planck then improved upon the deviations of Willy Wien’s formula with the use of the constant, h. The use of the equation: E=hf, reproduced experimental data well and therefore more accurately fit the model of blackbody radiation. The physical discontinuity of h was not taken into account until Einstein approached it later.

Einstein questioned if discontinuity could possibly work for light as well. James Clerk Maxwell had provided a model but it was inadequate for unusual phenomena (particularly for blackbody radiation). Einstein took a different look at the topic compared to Planck. Einstein found that the results of Wien and Planck were absolutely wrong, which is quite a statement. Einstein believed that thermodynamics forced light to behave as particles or “energy quanta,” not as waves. From there he applied thermodynamics to light to show that Planck’s work actually implied “real quanta.” If so, light could be composed of quanta. Einstein then produced the law for the photoelectric effect. His law was not confirmed until a decade later by Robert Millikan. Einstein was awarded with the Nobel Prize but it was for his discovery of the law, not the explanation.

After so many years, only a law existed to express quantum theory. The topic had slow progress because of its complexity. It also shows that work on the grand theory was not a solitary effort. Planck only got it started; Einstein improved on it. In the years after, Einstein continues to attribute light to “particle-like quantum,” or photons. Science often always builds on what we know or re-explains what we know to better suit what is happening (ie. Planck’s view on light vs. Einstein’s). Once there is something to work with, others are able to provide improvements to the theory or give feedback. In this case Einstein completely reworks Planck’s theory. So in a sense, this is how science advances.