Paul Dirac (Photo: https://www.nobelprize.org/nobel_prizes/physics/laureates/1933/dirac-facts.html)
Yesterday marked the 116th birth anniversary of the pioneering quantum physicist Paul Dirac. This year also happens to mark the 80th anniversary of his Nobel Prize winning equation that brought together quantum theory and relativity theory.
This is how the Nobel citation of 1933 described Dirac’s work: “During the intense period of 1925-26 quantum theories were proposed that accurately described the energy levels of electrons in atoms. These equations needed to be adapted to Albert Einstein's theory of relativity, however. In 1928, Paul Dirac formulated a fully relativistic quantum theory. The equation gave solutions that he interpreted as being caused by a particle equivalent to the electron, but with a positive charge. This particle, the positron, was later confirmed through experiments.”
It might be useful to remember that Dirac was just 26 when he did that.
His biography for the prize said, “The importance of Dirac's work lies essentially in his famous wave equation, which introduced special relativity into Schrödinger's equation. Taking into account the fact that, mathematically speaking, relativity theory and quantum theory are not only distinct from each other, but also oppose each other, Dirac's work could be considered a fruitful reconciliation between the two theories.”
If there ever was a physicist who was quantum mechanics, it was Dirac.
As part of my quest to get some measure of the universe as a lifelong exercise to be distilled into an upcoming book ‘What does Jupiter really do?’ I have been reading Dirac’s intensely mathematical take without understanding almost anything in it. There is something magical in trying to understand something very hard because as you keep at it, at the very least it becomes familiar, if not comprehensible. That has been my relationship with quantum physics all my life. With time the universe becomes familiar but not comprehensible.
Dirac said something rather interesting in his Nobel acceptance speech on December 10, 1933. I reproduce it here:
“There is in my opinion a great similarity between the problems provided by the mysterious behavior of the atom and those provided by the present economic paradoxes confronting the world. In both cases one is given a great many facts which are expressible with numbers, and one has to find the underlying principles. The methods of theoretical physics should be applicable to all those branches of thought in which the essential features are expressible with numbers.
I should like to suggest to you that the cause of all the economic troubles is that we have an economic system which tries to maintain an equality of value between two things, which it would be better to recognise from the beginning as of unequal value. These two things are the receipt of a certain single payment (say 100 crowns) and the receipt of a regular income (say 3 crowns a year) through all eternity. The course of events is continually showing that the second of these is more highly valued than the first. The shortage of buyers, which the world is suffering from, is readily understood, not as due to people not wishing to obtain possession of goods, but as people being unwilling to part with something which might earn a regular income in exchange for those goods. May I ask you to trace out for yourselves how all the obscurities become clear, if one assumes from the beginning that a regular income is worth incomparably more, in fact infinitely more, in the mathematical sense, than any single payment? In doing so I think you would then get a better insight into the way in which a physical theory is fitted in with the facts than you could get from studying popular books on physics.”
It is fascinating for me what hit home from this short speech. It is when he says, “a regular income is worth incomparably more, in fact infinitely more, in the mathematical sense, than any single payment.” Not being on a regular income and often even a single payment, I know precisely what that means. However, that is in the economic sense and not the physics of it.
I mentioned how with time the universe becomes familiar if not comprehensible. This morning as I stepped out to take in some air, I saw this lovely moth right above my mailbox. Looking at it I felt the same sense of incomprehension as I did with the Dirac equation which has been widely described by the scientific community as “the most beautiful equation.” The equation describes how particles such electrons behave at the speed of light.