Paul Dirac’s PhD Thesis
Recently my grandfather’s PhD thesis has found its way onto the Internet. You can view a PDF of it here, courtesy of Florida State University:
This fascinating document is significant in the history of science. Its two-word title, “Quantum Mechanics” demonstrates how fundamental it was in opening up a new branch of science. For those of you who have written doctoral theses, imagine if the title of your thesis was exactly the title of a required undergraduate class.
The document’s journey to the Internet was slow. It had been sitting in my mother’s cluttered house for decades, before she passed it along to Graham Farmelo, who delivered it to FSU, who scanned it and published it online. Now it has a permanent home in their Dirac Collection at the Dirac Science Library.
The first thing you’ll notice about the document is that it is entirely hand-written. It doesn’t take long to realize that in 1926 this was the only practical option for a document of this type. Of course type-setting was technologically possible at that time, even for documents with complex mathematical formulae like this. But the cost of preparing a document in this manner was huge, and thus only done for works that were expected to be broadly distributed. Then as today, the primary audience for a typical PhD thesis was the handful of professors guiding the doctoral student. At the time, nobody knew that just 6 years later Dirac would be honored with the Lucasian Professorship of Mathematics, a highly prestigious academic post once held by Isaac Newton and until recently by Stephen Hawking. So of course this document was hand-written.
The thesis is also visually wonderful. There are scribbles in margins, neat parts and sloppy parts, crossed-out sections, derivations, questions marks of uncertainty, hand-drawn graphs, arrows of re-arrangements, and torn sheets of paper. The document is difficult to follow, and its completeness is not obvious — the table of contents does not seem to line up with the contents, and the pages which do have numbers aren’t even in order. Its utility to science is clearly eclipsed by later works, but seeing aspects of the original thought process laid out in both pen and pencil invites so many questions. What is that sudoku-like grid of numbers in the top margin of page 25? Why is there a hand-drawn candle on a page otherwise filled with equations going in different directions? Somebody who is well-versed in the topic would be more qualified to speculate than me. Obviously I’m biased, but I find it a joy to browse.
I am personally deeply grateful to Dr. Farmelo for his work to preserve my family’s history, while recognizing that our personal gains are entirely tangential to the vastly more important scholarly efforts which motivate him. Dr. Farmelo is himself a physicist by training, and has become a family friend while researching the most recent biography of Paul Dirac, appropriately titled The Strangest Man. This excellent book follows my grandfather’s life in great detail, describing both personal and scientific aspects. It provides great insight into a man who cared a lot more about equations than people, and was thus able to make incredible contributions to science. Some have assumed that I would take offense at Farmelo’s conclusion that my grandfather was probably autistic. Quite the contrary — I appreciate his boldness in offering a straightforward explanation of the famously odd behavioral patterns which have inspired generations of jokes, and that still have ripples in my own life today.