Bohr's theory of complementarity was one of two components of the Copenhagen interpretation of quantum physics. It proposed that science will never be able to answer the question of whether light "is" a particle or a wave. Science is about the results of experiments, not about the way things really are, and the design of the experiment dictated whether the light would be measured as a particle or a wave.
The most famous scientist of the twentieth century. In 1905, Einstein introduced the theory of relativity, which overturned the classic Newtonian physics that had dominated the field for hundreds of years. This was the same year he published his paper on blackbody radiation, which reinterpreted Planck's famous equation as evidence that light was emitted in quanta, rather than waves. Einstein, a Jew, left Germany when the Nazis came to power and moved to the United States, where he lived out the rest of his life. For more information, see SparkNote on Albert Einstein.
Heisenberg's Uncertainty Principle was one of two components of the Copenhagen interpretation of quantum physics. It asserted that it was impossible for an observer to know both the exact position and the exact momentum of a subatomic particle. Heisenberg, like Planck, also stayed in Germany throughout World War II. After the war, some doubt remained as to whether Heisenberg had actively helped the Nazis develop an atomic bomb.
The leader of Germany's national socialist workers' (Nazi) party. In 1933, Hitler was elected the Chancellor of the German Reich. He carried out a ruthless campaign against the German Jews, culminating in the Holocaust. His hunger for power and territorial conquest led the country into World War II.
Planck's second wife. Planck married Marga Von Hoesslin a year after his first wife died. Planck and Marga were married for twenty-three years, and they raised four children together.
The author of Deutsche Physik, a work that proclaimed the superiority of German science. By German science, Lenard meant Aryan science–he claimed that relativity and quantum physics were perverse, non-Aryan creations, part of an international Jewish conspiracy led by men such as Einstein.
Planck's longest surviving son. Planck's other three children all died within a year after World War I. In 1945, Erwin Planck was executed for conspiring to assassinate Hitler.
A German physicist working on the blackbody radiation problem at the end of the nineteenth century. Wien developed a formula for the energy distribution that seemed to work but was eventually proven incorrect. Planck and Wien remained lifelong friends.