The next day, I called one of them and asked if I could come to his office to discuss the briefing. Fine with him, so off I went. I sat down and aske… - Samuel T. Cohen

Naturally, the next question was: “How accurate is the nuclear data you used in your calculation?” As only Edward Teller is capable of doing, he replied, with a smirk-smile going from ear to ear: “Well, it’s possible that the data might be off by a factor of ten.” Which way, he didn’t profess to know, but I suspect that much of the audience didn’t sleep too well that night. (If you’re beginning to worry that you might not be sleeping too well from now on, I have to tell you that as it turned out, after careful nuclear measurements and detailed calculations were made, we were safe by far more than a factor of ten. It simply couldn’t happen.)

People are people, and all people have emotions and biases, rarely understood: intellectual and emotional behavior don’t necessarily have an inverse correlation. Oppenheimer, as superhuman and wise as he was in so many ways, was still a human being. Depending upon the occasion he could be as human (dramatic, overwhelming, megalomaniacal, self-serving, and even downright dishonest, as his arch-rival Edward Teller was accused of being, and was) as most of us. Like most of us, depending upon the circumstances, he could change his personality and alleged beliefs at the drop of a hat.

Teller’s irascible behavior forced him out of the mainstream but not out of the lab, thanks to Oppenheimer who didn’t think we should be without geniuses, even those whose enormous egos caused serious friction. As bright and innovative as Teller was, his overall performance during the war left a lot to be desired. He was not content to be part of a team effort (like yours truly) and preferred to work off to the side on new and different and sometime pretty far-out ideas (like yours truly). This caused considerable resentment. After all there was a war going on and most people thought future nuclear weapon concepts should be worked on sometime in the future, after we had finished our primary assignment. Edward’s behavior was like a colonel on a planning staff during a military campaign who tells his commanding general that he’d like to plan for the next war. That would be the end of the colonel, who would be demoted and shipped off to some base in the Aleutian Islands.
Oppenheimer, however, realized that guys like Teller, despite their shortcomings, were necessary to have around; one never knows when a guy like that can be worth his weight in gold, which to the best of my recollection never happened with Teller. So an arrangement was worked out where Teller and a handful of like-minded theoretical physicists, willing to put up with his domineering ways, formed a small group dedicated to doing what they pleased, realizing their efforts stood precious little chance of impacting on the project.
The one idea dearest to Teller’s heart was the H-bomb. He and a couple of his cronies applied themselves to devising various schemes on designing such a weapon. All of them turned out to be impractical and most of them unworkable. Which never slowed him down in the slightest for reasons we’ll never know nor will he. I’ve known Edward for a very long time and although I’ve never known him well, one thing about him became clear to me from the very beginning: he was a creature possessed. By what? Again, who knows? Many, if not most, who have read about his life and what he has done, plus those who have known him directly and observed him close at hand and at great length, would say by Satan (which has been said all over the world about me). I wouldn’t go along with that and although I have seen Teller give some of the most impassioned statements morally defending his positions, some of which I have found deeply moving and thoroughly convincing, I would not say that the God I’ve been told exists has had a tight hold on him. If Edward has been possessed by anyone it’s been himself. I’d say the same for myself, and I’ve given you some reasons why, but hardly all of them. I don’t know all of them and would be ashamed to tell you if I did.