Planck had always been a nationalist and vocal champion of Germany's cause, he also elected to stay out of politics as much as possible. After World War I, Planck became a member of the Deutsche Volkspartei, the German People's Party. This moderately conservative group advocated the unification of the German people and pushed for Germany to regain its position in the world. But politics was far from the top of Planck's agenda, and he disliked concerning himself with political issues. But there was no way he would be able to avoid the political issues lurking on Germany's horizon.

In the early 1930s, nothing was going well: there was an economic depression, the increasingly powerful political extremists drowned out the voice of more moderate political parties, and anti-Semitism pervaded government and academic life. Things were bad for Germany, but they were about to get much, much worse.

On January 30, 1933, Adolf Hitler became Chancellor of the German Reich.

Planck expected that once in a national office, Hitler would have to become more moderate in order to hold into his power. But the chancellor soon proved himself even more extreme than anyone had realized. His attacks on the German Jews took a speedy toll on German science. On April 7, 1933, the German government passed the Law to Restore the Career Civil Service. The law defined a non-Aryan as anyone with a non-Aryan parent or grandparent, and anyone fitting this broad definition was no longer allowed to hold a civil service job. In most cases, non-Aryan meant Jew, and the law spelled the beginning of the end for German Jewish scientists, many of whom immediately began preparing to leave the country.

The law resulted in the firing of over one thousand university teachers. Since there tended to be more Jewish theoretical physicists than applied physicists, theoretical physics programs suffered heavily from the dismissal of professors. Before 1933, there were about sixty teachers at German universities working in theoretical physics; after April of 1933, twenty-six of these left their positions. The departed academics included six Nobel laureates and eight who would go on to later win the Nobel Prize. An American scientist visiting Germany at the time observed that "[m]ost people don't give a darn; a large proportion is rather glad it all happened."

This was only the beginning. As Hitler's campaign against the Jews expanded, Germany lost twenty-five percent of its theoretical physicists, either by government-imposed dismissal or voluntary exodus. The best and the brightest of Germany's physicists left their jobs and left the country, including Edward Teller, Victor Weisskopf, Hans Bethe, and Max Born.

Recognizing that the Nazi policies were single-handedly destroying German science, Planck–who was in a position to meet with high-ranking members of the German governmentmdash;tried to caution Hitler that his policies might be damaging the national science community. Some records of the conversation indicate that Hitler did not respond well to the criticism, replying heatedly, "Our national policies will not be revoked or modified. Even for scientists. If the dismissal of Jewish scientists means the annihilation of contemporary German science, then we shall do without science for a few years!"

Hitler's repugnant policies did not escape notice by the international scientific community. As the outside world learned more about what was going on inside Germany, the German physics community began to once again find itself isolated by neighboring countries. Foreign scientists declined to visit the country, read its journals, or take part in its organizations. The German government encouraged such isolation by forbidding German scientists to take part in many international activities, believing its scientists should not sully themselves by interactions with non-Aryan outsiders.

One extreme example of this type of hostile parochialism was the growth of the Deutsche Physik, or German/Aryan Physics, movement. As extolled in physicist Philipp Lenard's 1936 work Deutsche Physik, the movement wasn't for anything, but it was very definitely against what it saw as the modern physics of the Jews: relativity and quantum physics. Lenard and his allies claimed that all real physics came from the Aryan race and that "Jewish physics," such as Albert Einstein's nonsensical theories of relativity, were nothing more than an international Jewish conspiracy designed to destroy physics and elevate the Jewish people.

There were actually very few scientists in Germany who fell for Lenard's blatantly racist propaganda, and Deutsche Physik never replaced real physics in the German universities. Even those professors who believed Einstein to be a traitorous Jew still taught his theories, though they avoided mentioning Einstein by name. There were probably no more than thirty supporters of Deutsche Physik at any given time, and the movement had died out before the early 1940s. Its true importance was that it provided yet another piece of evidence that German physics was being attacked from inside, and, to scientists such as Planck, action would need to take place soon before it was too late.

While the majority of German Jewish physicists were driven from their jobs and their country–and many fled of their own accord, fearing what might happen to them if they stayed–the non-Jewish physicists had the luxury of making their own decision. Should they too leave the country in protest of Hitler's policies? Or should they stay and live under the Nazi regime? Many left, disgusted by what their country had become. Others stayed and happily supported the new political status quo.

And then there were those like Planck. He hated what the Nazis were doing to his country, to his colleagues, and to his scientific community. But he loved Germany, he loved German physics, and he believed that it was his duty to stay and protect what he loved. When Hitler came to power, Planck had high-ranking positions at two state-sponsored scientific organizations, putting him in a position–or so he believed–to work with the government to preserve German science. In doing so, he was forced to negotiate a difficult line: if he continued to go along with the Nazis, would history judge him any better than them? But if he put up too much of a fuss, he would lose all his power and be unable to protect anyone, even himself.