There have been plenty of feuds in science. Usually they're petty. Nearly always, they're depressing. This one is more depressing than most. It resulted in two different scientists being expelled - in different ways - from the scientific community.
During World War II, Edward Teller and J Robert Oppenheimer worked together on the development of the atomic bomb. A decade later, one was in self-imposed exile on an island, and the other was materially successful but cast out of academic society.
During their work on the Manhattan Project, Oppenheimer was in the senior position. Although it was the first major project he'd managed, he was probably accustomed to being at the top of any group. Born both rich and smart, he cultivated the qualities of hard work and passionate interest, and his work in physics was always exemplary. Teller had had, comparatively, a harder time of it. Although he'd been born into a prosperous family, he'd fled the anti-Semitism in Hungary, only to find it rising up in Germany. He left Germany for England, and England for America - eventually becoming an American citizen.
Although the two men didn't seem to personally clash during the project, as soon as it became clear a fission bomb which split the atom was possible, Teller lost interest. He transferred his interest to a bomb involving the fusion of atoms. Eventually, Teller became so distracted by his research on the hydrogen bomb that Oppenheimer cut him loose from the core team, though not from the overall project, to pursue his own interests.
After the end of the war, Teller remained focused on the fusion bomb, which could be made bigger and more powerful. Oppenheimer wanted to take the concept of nuclear bombs and make them smaller. He wanted to use them as weapons against invading armies. We know now that Oppenheimer's suggestion would not have been practical. Smaller bombs would help little in the wars that followed World War II, but would have been ecological disasters. Still, at the time, they were a real possibility. Scientists spent much of the fifties through the seventies looking at small nuclear bombs as tools for construction or energy production. Either making the bomb huge or miniaturizing it were possibilities - it was only a matter of which model would get the most support. Oppenheimer and Teller were competing, actively, for the same resources from the same government. Then Oppenheimer got word that he was a suspected communist, and the Atomic Energy Commission had suspended his security clearance. Oppenheimer asked for a security hearing, and, there, Teller testified.
When asked about Oppenheimer's actions and affiliations, Teller stated, "In a great number of cases, I have seen Dr. Oppenheimer act – I understand that Dr. Oppenheimer acted – in a way which for me was exceedingly hard to understand. I thoroughly disagreed with him in numerous issues and his actions frankly appeared to me confused and complicated. To this extent I feel that I would like to see the vital interests of this country in hands which I understand better, and therefore trust more." This could be interpreted multiple ways. Either Teller was making the blandest possible accusation of collaboration with foreign communists, or he was explaining, in the most suspicious possible way, that Oppenheimer and he disagreed on matters of military strategy. In the end though, he testified that he believed that Oppenheimer should not be given security clearance.
Oppenheimer's security clearance was revoked. He left the United States for the Virgin Islands, and left nuclear research to take part in the anti-proliferation movement. Teller stayed in the scientific community for quite some time, but his unofficial reputation never recovered. Some biographers refer to his treatment by other scientists as yet another "exile."
The post-war communist paranoia left its stain on a lot of people, but arguably Teller bears too large a proportion of it. Although it's not possible to defend his words, his testimony most likely wasn't what got Oppenheimer kicked out of the AEC. Oppenheimer had been a casual attender of communist meetings - then again so had many academics in the 1930s. More serious was the fact that Oppenheimer had been approached by someone who broached the subject of moving secrets to the USSR. He'd kept it secret for months, and then lied about it. When Leslie Groves, the military head of the Manhattan Project, drilled the scientists about possible security leaks, Oppenheimer claimed that three different scientists had been contacted by a Soviet agent. Under more pressure he admitted that, to his knowledge, only he had been contacted. The "agent" was a French literature professor at UC Berkeley. Thinking that, if he admitted that he alone had been contacted the communist would be quickly found, Oppenheimer adlibbed a story.
Oppenheimer lived only a little over a decade longer, and was shut out of his chosen field of work. Teller, on the other hand, had a long career in his chosen field. In the end, it is Teller who wears the horns when it comes to this particular feud. (It didn't help that he went on to a few more feuds, including trying to blame a heart attack on Jane Fonda and Ralph Nader, and their protests of nuclear energy after Three Mile Island.) A few words, which may very well have been useless, and two reputations were damaged.