During the last years of World War II the U.S. government recruited many physicists to work intensely on developing a nuclear bomb. The problem's complexity and novelty, plus the camaraderie of a huge team of some of the world's best physicists and also the urgency given by military challenges and government backing, absorbed everyone's interest and supplied excitement and dedication. It was an adventure. Many of those physicists later explained that they were so excited about the breakthrough and loved their community problem solving so much that they didn't stop to think about the morality of the weapon which they were developing for the United States. It was only as the bomb was nearing completion that these natural philosophers became philosophical about things and began to have second thoughts. They later emphasized that the leadership role, moral weight, and international import of the Manhattan project had been a new thing for them. The move to ascendancy was exceedingly brief, they were not prepared for it, did not realize what had happened until years had passed, and were surprised at themselves afterwards. Who had ever told them that their work could have such moral weight and inspire such awe and terror?
Even today, physicists in the United States generally do not seem comfortable seeing themselves as power brokers or political or moral leaders. There are few American physicists who are syndicated for nationwide publication or who hold political office. (Internationally there is an exception: Dr. Abdul Kamal, "Missile Man of India," held office as India's President from 2002 until 2007. This is primarily a figurehead role; his tenure was known more for idealism and technological enthusiasm than for government. Perhaps the exception proves the rule.)
In other words, there is a distinct tendency for physicists to cast themselves in a role as absent minded professors, geeks, specialists, experts who understand the universe but not society and power structures. This casting choice allows physicists to absolve themselves of responsibility for society, government, and human issues. The accounts of the Manhattan project physicists are just a convenient example of this attitude: during the war most of them simply did not even consider taking this sort of responsibility, and after the war they excused themselves for this lapse by saying they were not prepared, new to the game, etc. This excuse making was exceptional, since in most cases physicists never reach the point of reconsidering whether they might have taken greater responsibility for their influence on society at large. They are so very sure of their self-casted roles. They see no connection between themselves and the fact that modern society is incredibly power hungry and often uses its power over nature and over people in destructive ways.
Yet we have seen that some of the first natural philosophers were obsessed with power, and that a physicist's goal is a certain kind of knowledge that involves a huge amount of power over the thing known. Even in the years since World War II physicists have been very glad to receive privileges and pride of place from society in return for the great contributions they had made to military power (radar, the bomb, jets, rockets, submarines) and economic power (semiconductors, LCDs, the Internet). No one could accuse the physics community of being aloof to power; in fact in the current years we seem to be running ever faster to convince power brokers that we still belong on their team. It's just that we want to play the game our way, in the role of specialists and professors who are not responsible for the use and abuse of power in the world at large. Far be it from us to be power brokers or politicians!