Quantum Tales: Freeman Dyson on Learning Quantum Mechanics

Freeman Dyson (1923 – 2000), American mathematician and theoretical physicist.

Freeman J. Dyson, the American mathematical prodigy who died in 2020 at the age of 96, was one of the foremost theoretical physicists of the 20th century. As a young graduate student at Cornell University in 1949, Dyson wrote a landmark paper — worthy, some colleagues thought, of a Nobel Prize — that deepened the understanding of how light interacts with matter to produce the palpable world. The theory the paper advanced, called quantum electrodynamics, or QED, ranks among the great achievements of modern science.

But it was as a writer and technological visionary that Dyson gained public renown. Known for his fertile imaginations, that extended well beyond the confines of physics, Dyson imagined exploring the solar system with spaceships propelled by nuclear explosions and establishing distant colonies nourished by genetically engineered plants.

“Life begins at 55, the age at which I published my first book,” he wrote in “From Eros to Gaia,” one of the collections of his writings that appeared while he was a professor of physics at the Institute for Advanced Study — an august position for someone who finished school without a Ph.D. The lack of a doctorate was a badge of honor, he said. With his slew of honorary degrees and a fellowship in the Royal Society, people called him Dr. Dyson anyway.

Quantum Mechanics is one of Dyson’s professional specialties. Dyson’s thought much on the subject, and on the peculiar mind transformations a student of Quantum Mechanics has to go through in order to arrive at the inevitable conclusion that they can calculate everything, yet understand nothing, at least from the standard menu of pre-Quantum Mechanical ideas.

Here is Dyson writing on his humbling experience. It is vintage Dyson.  

I have observed in teaching quantum mechanics, and also in learning it, that students go through an experience similar to the one that Serbian physicist, Mihajlo Idvorsky Pupin describes. The student begins by learning the tricks of the trade. He learns how to make calculations in quantum mechanics and get the right answers, how to calculate the scattering of neutrons by protons and so forth. To learn the mathematics of the subject and to learn how to use it takes about six months. This is the first stage in learning quantum mechanics, and it is comparatively painless.

The second stage comes when the student begins to worry because he does not understand what he has been doing. He worries because he has no clear physical picture in his head. He gets confused in trying to arrive at a physical explanation for each of the mathematical tricks he has been taught. He works very hard and gets discouraged because he does not seem to be able to think clearly. This second stage often lasts six months or longer. It is strenuous and unpleasant.

Then, unexpectedly, the third stage begins. The student suddenly says to himself, “I understand quantum mechanics,” or rather he says, “I understand now that there isn’t anything to be understood.” The difficulties which seemed so formidable have mysteriously vanished. What has happened is that he has learned to think directly and unconsciously in quantum-mechanical language. He is no longer trying to explain everything in terms of prequantum conceptions.

The duration and severity of the second stage are decreasing as the years go by. Each new generation of students learns quantum mechanics more easily than their teachers learned it. The students are growing more detached from prequantum pictures. There is less resistance to be broken down before they feel at home with quantum ideas. Ultimately, the second stage will disappear entirely. Quantum mechanics will be accepted by students from the beginning as a simple and natural way of thinking, because we shall all have grown used to it. By that time, if science progresses as we hope, we shall be ready for the next big jump into the unknown.”

~ Freeman Dyson, “Innovation in Physics” Scientific American (1958).

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