Author: Haroon Khalil
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The Photon
The application of the scientific method. There was a problem, he formulated a hypothesis, tested it against an experiment, and then concluded that he was on to something. After chalking up a few more successes, which we won’t go into here, it appeared that his hypotheses were consistent with all relevant observations of the photoelectric…
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The Heuristic Light-Quanta
What the heck is going on here? These findings were in stark contradiction to classical prediction, and they puzzled physicists for many years. The world had to wait for the one-and-only Albert Einstein to solve the problem. In a 1905 article that was nothing short of luminary, he proposed an elegant solution that explained everything,…
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Maxwell Stumbles Again
We know that Planck was a great physicist because Planck’s constant is named after him. Likewise, the strength of forces is measured in units named after Newton. So you shouldn’t be surprised to learn that the physicists’ unit for the frequency of light waves is named after the man who first demonstrated that light really…
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Introduction
We explore a second important case of quantization, this time in the form of light quanta, and learn how it provides an elegant interpretation of Max Planck’s blackbody radiation solution. We’ll also learn how the discovery of light’s particle nature can be traced back to the very experiment that proved it was a wave. We’ll…
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Energy Quantization and You
Though it wasn’t fully recognized during Planck’s time, his quantum hypotheses can be generalized beyond oscillating charges in blackbodies to any oscillating system, be it a little girl on a backyard swing, a sloshing wave of seawater, or a retired thrill-seeker dangling from a bungee cord. In contrast to our artificial “quantum staircase” from the…
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Trombones, Trumpets, and Triples
Before we go into that, though, it’s worth exploring Planck’s hypotheses and their implications a little bit further. As we will see over the course, blackbody radiation is not the only case where energies are restricted to certain, discrete levels. This concept shows up over and over again in the wacky world of quantum physics.…
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Planck’s Hypotheses
To arrive at his result, Planck followed many of the same steps, which we described above, that other physicists had taken. He, too, assumed the emitted radiation came from thermally excited charges, each oscillating at a particular frequency. In addition, he assumed that the energy emitted at any particular frequency was given by the number…
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Catastrophe Averted
Just as this controversy was heating up, a revolutionary solution was found by a German physicist named Max Planck. One Sunday afternoon in 1900, he was entertaining a fellow physicist named Heinrich Rubens at his Berlin home. A highly accomplished experimenter, Rubens spent the afternoon explaining some of his most recent measurements and how they…
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The Ultraviolet Catastrophe
We mentioned that one of the few electromagnetic phenomena that was not nicely explained by Maxwell’s classical equations had to do with heated solid materials. What exactly was the problem, and how serious was it? Let’s return to our humble fireplace poker to see. First, we need a little bit of terminology. The fancy scientific…
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Introduction
We pull at one of the loose threads that emerged and in so doing unravel the fabric of classical physics. We will see that despite classical physicists’ ability to explain and predict many extraordinary things, they were utterly incapable of explaining why fireplace pokers glowed as they did. We will meet Max Planck, a true…