When the Nazis came to power in 1933, Planck held positions of power in several state supported scientific institutions and–though it had been many years since he'd produced any scientific work of note–was one of the leaders of the German scientific community. As Adolf Hitler began to turn the country upside down, Planck had a choice: to leave or to stay. He decided, without hesitation, to stay for this was his country, and he would fight for its survival. But this left Planck with another choice: to go along with the new government's policies or protest what he believed to be wrong.
For Planck, this was a trickier decision. He didn't have the temperament for political agitation, and he felt that he could best serve his colleagues by keeping his good standing with the government. Planck originally considered resigning from his posts in protest, but he felt that he would be shirking his duty. He believed that his peers looked up to him for both practical and emotional support, no matter how much he might have liked to leave public life. So Planck decided to go with the flow, doing what he could, as quietly as he could, from behind the scenes. He advised his colleagues to do the same: stay quiet, wait things out, not speak their consciences, and hope things would soon improve.
This led Planck into many a difficult situation, as he tried to hold a balance between what he knew was right and what he thought was smart. The bolder the Nazis became, the more Planck was forced to go along with policies he disliked. One of the scientific academies that Planck headed, the Kasier-Wilhelm- Gesellschaft, was eventually forced to officially align itself with the Nazis. Its building flew a swastika, and its leaders were required to give the Hitler salute at official meetings. A witness to one of these meetings remembered Planck's reluctance to participate, and his eventual acquiescence: "Planck stood on the rostrum and lifted his hand half high, and let it sink again. He did it a second time. Then finally the hand came up, and he said 'Heil Hitler.'"
One of the more famous moments in which Planck was forced to confront his conscience and decide whether or not to go along with the ruling party was in the early 1930s, as Germany attempted to deal with its brightest star: Albert Einstein. Einstein and Planck weren't merely colleagues in a close-knit community. Planck had been one of the first reputable physicists to support Einstein's theory of relativity, and it was due in large part to this support that Einstein's work was accepted by his fellow scientists.
In the decades since then, Einstein had become the biggest star of German physics, an international figure who made it nearly impossible for the rest of the world to completely shun the German physics community. Planck knew that it was of supreme importance to keep Einstein in Germany and to keep him happy, and he did all he could to make that happen. But by 1933, Einstein, who was Jewish, had had enough of Germany's anti-Semitic policies, of those who claimed his work was nothing but Jewish pseudoscience, and of those who derided his work and threatened his life. That year, Einstein resigned his post and left Germany forever.
When this happened, the government insisted that the Berlin Academy of Sciences expel Einstein publicly to punish him for his traitorous behavior. The secretary of the Academy, Ernst Heymann complied, issuing a scathing statement about Einstein's supposed "work of agitation abroad" and expressing no sorrow that Einstein had chosen to leave. The members of the Academy voted in overwhelming majority to support the statement. Einstein responded harshly, by claiming that no good German would support Germany at such a time and that by staying in the country, he would have indirectly contributed to "the brutalization of morals and the destruction of all contemporary civilization."
Into this battlefield stepped Planck, hopeful that he could find a peaceful middle ground that would embarrass neither Einstein nor his government. In the minutes of the May 11, 1933 meeting of the Academy, he reaffirmed Einstein's tremendous scientific contributions and offering regret that Einstein had found it necessary to leave.
Planck may have felt that he had accomplished some tangible goal in moderating the situation, but the end result was the same. Germany had lost Einstein, and then the country had made itself look even worse in the eyes of the world by acting pleased that Einstein was gone. Did Planck accomplish anything with his subtle acts of resistance? Many of his colleagues agreed that he did. Thanks to his gentle interventions, the Academy was allowed to retain a much higher degree of independence than it might have otherwise. It did manage to retain its Jewish members and employees for many more years than other German organizations did. This certainly had at least something to do with Planck's efforts. But Planck could not stand in the way of history–at least, not history as determined by Hitler. In 1938, the Academy was finally forced to expel its Jewish members, and it was Planck's responsibility to request their resignation.