After missing the first collection of essays on this brilliant recluse published soon after his death, I picked up the present version as soon as I was able. It did not disappoint.
The book is a collection of four lectures given in the subject's honor in 1995 on the tenth anniversary of his death. The final lecture and the latter part of the third are highly mathematical and technical and clearly intended for a professional audience.
But for me, the first lecture by Abraham Pais is worth the purchase price alone. Pais was not only a contemporary physicist, but also a close friend and as close to a confidant as was possible with such a reticent man.
Through Pais' eyes, we see a mathematician turned physicist who was very different from the man to whom Dirac is most frequently compared, Albert Einstein. Einstein was a physicist first, mathematician second. Dirac was exactly the opposite. Einstein became a social and political critic, Dirac never strayed far from his study. The two were similar in that both viewed mathematical beauty as primary and both hated the modern remake of quantum mechanics (after the initial theory) for very similar reasons. This last point was interesting as Dirac was the first one to combine all his contemporaries' work on this improved quantum physics into a formal mathematical structure. His resulting equation, called naturally the Dirac equation, is classic Dirac, short and sweet. It combined Einsteinian relativity with the new quantum theory and Dirac considered the result to govern most of physics and all of chemistry. Stephen Hawking, the renowned theoretical physicist, says in his introductory memorial address to the book, "If Dirac had patented the equation ... he would have become one of the richest men in the world. Every television set or computer would have paid him royalties." For this work, Dirac shared the 1933 Nobel Prize with German physicist Erwin Schroedinger. One unexpected consequence of this work was a mathematical conclusion that defined a "negative energy" matter (aka antimatter) solution. Simply put, he had discovered a universe noone had imagined. To this day, we see the effects of this discovery from medical necessities (PET scan imaging-Positron Emission Tomography) to science fiction (Star Trek).
The quotations and anecdotes Pais chooses are well placed and often very funny. They are also supported by the images of Dirac portrayed in the sketch on the cover and in the few photographs scattered through the first two lectures. They reveal his character well. He saw mathematical and physical realities so clearly that he simply could not understand why others did not see them as well. The photo of him "listening" to future Nobel Laureate Richard Feynman in Maurice Jacob's section is one of the most amusing of the collection.
In the second lecture, Jacob shows the path of discovery and effect on latter day experimental physics of antimatter. He goes too long in spots but is generally fine.