Robert Oppenheimer: A Life Inside The Center, Ray Monk, c. 2012

In my notes on Sidney and Violet I mentioned that the book makes me want to re-read Proust or biographies of him.

How coincidental, then, to find references to Proust in Monk's biography of a theoretical physicist, Robert Oppenheimer.

On p. 114:

"Once when the topic of cruelty came into the conversation, Chevalier recalled , Oppenheimer surprised him by quoting from memory, word for word, a passage from Proust's novel. The passage comes in the first volume of Du cote de chez Swann, when Mademoiselle Vinteuil goads her lesbian lover to spit on a photograph of her recently departed father. In describing this scene, Proust emphasizes to his readers that there is something theatrical about Mlle. Vinteuil's "sadism." She is not really evil; rather, she finds it erotic to pretend to be so. In fact, Proust writes, it is precisely because she is not really evil that she can derive orgasmic pleasure form the grotesque performance of her lover. In the passage Oppenheimer memorized and recited to Chevalier, Proust writes:

Perhaps she would not have considered evil to be so rare ... had she been able to discern in herself, as in everyone, that indifference to the sufferings one causes ... is the terrible and permanent form of cruelty.

Why did this passage mean so much to Oppenheimer that he learned it by heart? And why was reading it one of hte great experiences of his life?

The passage by Proust, by the way, is much longer, I left much of it out, to make it easier to follow.

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When I re-read the book and add more notes, I will come back to this theme. It seems to be a recurring them in Oppenheimer's life that he consistently arrives in the right place at the right time. It was purely serendipity how Ernest Lawrence came upon the idea of a particle accelerator sometime between 1927 (when he first noted the problem) and 1929 when he began to build his first cyclotron (as it came to be called). "During Oppenheimer's first year at Berkeley, Lawrence began to build his cyclotron, which in January 1931 successfully accelerated hydrogen ions up to energies of 80,000 volts." -- p. 173
************************* In 1930, still convinced that Dirac's theory of electrons was wrong, he suggested that for Dirac to be correct, positively-charged electrons ("positrons") had to exist. Oppenheimer was too stubborn to accept that Dirac's equations were correct, and take the next logical step: to claim that positrons exist. In fact, Dirac, instead did that. Dirac, based on that discussion, said that experimentalists should be able to observe positrons. "When, shortly later, experimental evidence for the existence of positrons was announced, it was Dirac, not Oppenheimer, who got the credit for having correctly predicted it." -- p. 181.

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Beta decay, from wiki:

In nuclear physics, beta decay (β decay) is a type of radioactive decay in which a beta particle (an electron or a positron) is emitted from an atomic nucleus. Beta decay is a process which allows the atom to obtain the optimal ratio of protons and neutrons.
Beta decay is mediated by the weak force. There are two types: beta minus and beta plus. In the case of beta decay that produces an electron emission, it is referred to as beta minus (β⁻), while in the case of a positron emission as beta plus (β⁺).

A proton (a hadron: a particle composed of quarks): two UP quarks and one DOWN quark.
A neutron (a hadron: a particle composed of quarks): one UP quark and two DOWN quarks.

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Chapter 9, "Unstable Cores,"  is composed of two sub-chapters: one dealing with Oppenheimer's affiliation with the Communist Party in the 1930's; and, b) one dealing with his incredible work in astrophysics. For now I will post on the latter, the astrophysics.

Oppenheimer's great papers were overlooked at the time they were published due to two events. "Oppenheimer's paper with Volkoff was written in the very month that it was announced that  scientists in Germany had discovered nuclear fission; his paper with Snyder, meanwhile, was published on the very day that the Second World War began."

The papers, starting on p. 252.

"Those these papers received little attention at the time, they are now generally considered to be his greatest work. Many think that if he had lived a little longer, Oppenheimer would have received the Nobel Prize for these papers.

• Oppenheimer-Volkoff paper, 1938
• one of a series of three
• each of the three with a different co-author
• subject: neutron stars
• the concept of a neutron star had been introduced just five years earlier; one year after the discovery of the neutron
• neutron star concept: Zwicky (Caltech); Baade (Mount Wilson Observatory) -- both in Pasadena (?)
• "supernova" introduced as a word by Zwicky and Baade in the early 1930's
• "supernova" -- the death-throes of a star
• the neutron star is described, pp. 253 - 254
• 1931: Chandrasekhar -- white dwarfs; gravitational collapse
• Oppenheimer ready to publish; trumped by Hans Berthe's Nobel-Prize-winning work on the subject
• first of his three papers: a letter jointly written with Serber: "On the Stability of Stellar Neutron Cores"; that paper determined a minimum mass for a neutron mass to remain stable, rather than maximum mass as previously done
• the second paper in the series: jointly written with Volkoff; "On Massive Neutron Cores"; January 3, 1939; expanded on the Serber letter; now often credited with presenting the first serious theory of neutron stars; from it came the "Oppenheimer-Volkoff limit" -- an upper limit for a stable neutron core, which they calculated to be 0.7 solar masses (the present estimate is between 3 and 5 solar masses); very difficult calculations; despite these difficulties, Oppenheimer-Volkoff laid out the basic theory of neutron starts -- nearly thirty years before there were any empirical grounds for believing that such things really exist; the paper was probably written by Volkoff alone
• even to have raised the question of indefinite gravitational collapse required impressive boldness and imagination, but in the third of the three papers, Oppenheimer went one better: he answered the question
• the third paper: ignored for 30 years; has now become the most respected of them all; "one of the great papers in twentieth-century physics"; co-written with Harland Snyder; "the best mathematician of the Berkeley group"; "On Continued Gravitational Contraction"; the paper is celebrated for predicting the existence of what are now, and have been since the 1960s, called "black holes" -- and all this time, I thought it was Stephen Hawking, that great self-promoter who "discovered black holes" (I may have to read Hawking's On The Shoulders of Giants; whenever I see blurbs about this book I see references to Copernicus, Newton, and Einstein, but never any mention of Oppenheimer; it will be interesting to see if this British physicist gives the credit due to the American physicist)
• in four pages, mostly filled with the imposing equations of relativistic gravitational theory, Oppenheimer and Snyder provided a way of understanding the collapse of a neutron star into a black hole, the implications of which are still being explored today
• pick up a popular book on black holes now and the chances are that what you will see is a description extending over several pages, even several chapters, aof hte physical realities that correspond to the equations of Oppenheimer and Snyder. 
• almost certainly, the book will also attempt to convey the nature of black holes using the device adopted by Oppenheimer and Snyder of imagining two observers
• their papers were ignored until 1967 with the discovery of "pulsars" that year -- it was realized that "pulsars" are rotating neutron stars; the following year it was discovered that what had been known for a long time as the crab Nebula was in fact the remnant of the 1064 A.D.  supernova and that in the middle of it was a neutron star
• since then, neutron stars have even been photographed
• John Archibald Wheeler is credited with coining the term "black hole" and credits Oppenheimer's theoretical work in the 1930's as laying the groundwork

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The history of mesons, etc., were also discussed in Chapter 9, "Unstable Cores." 

• cosmic-ray research confirmed Yukawa's hypothesis of particle bigger than an electron, but smaller than a proton
• it took about 12 years, starting in 1935, to sort out this confusing issue
• the penetrative particle in cosmic rays is not the carrier of the "strong nuclear force" -- that is another particle, somewhat like it
• the confusion can be seen in the changing nomenclature
• first, they were called "mesotrons" before it was realized they were different; the name was not changed to "mesons" until after the war
• "mesotrons" was changed to "mesons" for reasons of linguistic probity (the Greek word for "middle" being "mesos" rather than "mesotros")
• to distinguish them from each other, the one that is a component of cosmic rays was called a "u-meson" (mu-meson), and the one that is the carrier of the strong nuclear force was called the "pi-meson"
• then it was decided that mesons are by definition carriers of the strong nuclear force and therefore that the mu-meson is not a meson at all; renamed the "muon"
• the other was renamed the "pion"
• playing a leading role in both the creation and the clearing up of these confusions, and thus being there at the birth of what has grown into (for most people) the utterly bewildering new discipline of particle physics, were Oppenheimer and his students
• the Standard Model helps a lot to sort this out

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Chapter 10: Fission

By this time Oppenheimer was losing interest in research; a new phase in life was beginning for Oppenheimer.

Frisch at the center of fission. First to see the implications (p. 261). Frisch working with Bohr in Copenhagen; working with Lise Meitner in Sweden by phone; then, "for the second time in just under two years Frisch found himself one of only two people in possession of a shattering piece of information: a bomb could be built with as little as a few kilograms of U-235 instead of tons of "raw" uranium (which holds very little U-235). -- p. 301.

Frisch and Peierls even explained how such a bomb could function: two subcritical lumps of U-235 could be brought together, thus forming a critical mass. "Once assembled," they remarked, "the bomb would explode within a second or less, since one neutron is sufficient to start the reaction and there are several neutrons passing through the bomb every second, from the cosmic radiation." This was, essentially, the design of the bomb that exploded over Hiroshima some five years after it was conceived by Frisch and Peierls (though, in the Hiroshima bomb, a neutron initiator -- a mixture of polonium and beryllium -- was used, rather than relying on passing cosmic rays. -- p. 301.

It was the Brits who knew what was happening; the bureaucrats in Washington, DC, were completely clueless, less by Briggs (makes me think of Harry Reid, senator, Nevada).

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Chapter 11: In On The Secret

How and why the FBI got interested in Oppenheimer as a possible spy for the Soviet Union. Fascinating story; echoes what is going on in the NSA in 2013.