I guess let me begin by saying that biographies are one of my favorite genres of books, and of those I have read, this is easily the best.
Oppenheimer is best known as being the 'father of the atomic bomb' which is really the only role I knew him as prior to reading this book. Due to this, I was always somewhat skeptical about the man and held him in a pretty negative light, because quite honestly I think it's a perversion of science when it is used to find the most efficient means of wiping out civilian populations. After reading, I found that the mood of the times was that using scientific research in such a manner, while problematic, was ultimately a superior option to conceding America to the Nazis. I guess not living during the 40s, makes it hard for me to realize how large a fear this was.
I had always believed that Oppenheimer became a pariah in the scientific community post-WWII due to his position as Director at Los Alamos. While this may have been the case in some isolated events, the evidence presented in the book does not really back it up. While the generation of scientists that were reared in the post-atomic world might dislike him, at the time there seem to have been few scientists who actively opposed his participation in the project. I think the main reason, and one I had never considered, was the scope of Los Alamos and the fact that aside from Oppenheimer the majority of top American-born (and many who were not) scientists also participated in one way or another with the work carried out there.
After the war, Oppenheimer did much to try to regulate the build-up of atomic caches before they could be mass produced. He, and other top scientists, essentially envisioned the Cold War as it would play out, but a government paralyzed by fear about Communists would not listen and nuclear proliferation ruled the day (and the decade, and the one after that, and a couple of more after that). As a result, he stepped on a few toes, especially those of one extremely vitriolic bastard by the name of Lewis Strauss. Strauss was one of few who disliked Oppenheimer, but I don't think the term 'dislike' can quite sum up his feelings. He seemingly hated Oppenheimer and was hell-bent on ruining his career (which he eventually did at the cost of his own). Around 1955-56, Strauss had managed to buy his way into the position of Chairman of the Atomic Enery Commission, a board of which Oppenheimer was a paid consultant.
At this time the atomic bomb had become passe, and the new thing was the hydrogen bomb. Oppenheimer and many, many other scientists opposed this weapon on the grounds that it could have no role solely as a military weapon. This is the simple truth, as the H-bomb could easily destroy everything within it's blast radius of ~100 miles. This was a weapon that would be used for genocide, and there were quite rightly moral qualms concerning it. Oppenheimer used his status as the nations leading scientist-statesman, not to mention as a paid consultant, to actively oppose the construction of this weapon. Strauss, was incensed at this behavior and eventually managed to drag Oppenheimer before an AEC Board, questioning his loyalty to the country as a way of both public humiliation for his enemy and so that his dissenting views could be pushed to the side.
This AEC Board was no doubt the most eye-opening part of the book. The means Strauss went to from illegally wire-tapping Oppenheimer's, his lawyer's, and friend's homes so that he could see in which direction they would go about fighting the case, not providing the defense with material supplied both to the Board and the prosecutor, choosing the Board so that they would be sympathetic to his cause, and many more egregious examples of unfair and illegal practices made this little more than a show trial, reminiscent of the Soviets we were so scared of. Of course, since he was not presented with a fair and equitable way to provide a defense, Oppenheimer lost the case and his security clearance, a full day before it expired anyway.
This was essentially a public beating, designed solely to break Oppenheimer and it succeeded. Many close friends claimed he was never the same after, withdrawn and disinclined to give his opinion on most any topic. Within a few years he died as possibly the most public victim of McCarthyite hysteria (without actually having been a victim of McCarthy). They used his brain while it suited them, then kicked him to curb in the most humiliating manner possible when they were done.
All in all an excellent read, even though it does break your heart. Let me leave you with a quote about the findings of the AEC Board, concerning Oppenheimer's opposition to the the H-bomb that I just can't shake from my head: "Equating dissent with disloyalty, it called in to question the very definition of advice."