For the first two decades of the twentieth century, Planck's professional life just kept getting better and better. His most important contribution to physics–the invention of the light quantum–may have been behind him, but his importance within the physics community continued to grow. Planck's reputation as both a brilliant physicist and a likeable, principled man marked him as a natural leader for his fellow scientists.
In 1912, he was elected a standing secretary of the Berlin Academy of Science's Mathematical-Physical class, which was a significant achievement that gave him a large amount of influence over his peers. In this new position, Planck was responsible for presiding at meetings, keeping track of the academy's finances, and supervising the publication of meeting proceedings. The next year, Planck's administrative duties grew as he was made rector of the University of Berlin. But these successes must have paled in comparison to the triumph of 1919, when Planck was finally awarded the Nobel Prize.
His professional successes in these years were paired with a satisfying personal life. Widowed in 1909, Planck was married again a year later, to Marga Von Hoesslin, a niece of his first wife. Planck and Marga were married for twenty- three years, and they raised four children together. They lived in Grünewald, a pleasant suburb of Berlin filled with academics from the nearby university. Planck, who was usually rather reserved in public, apparently could only truly relax in the company of his family.
Though busy with administrative obligations and family duties, Planck did not lose his passion for the science that had brought him to such a happy point. After years of studying physics, Planck had very definite ideas of what he felt the discipline was all about; he was ready to expound his philosophy to anyone who would listen. And, thanks to his prominent position, he never lacked an audience.
In December 1908, Planck gave his first major speech outside of Germany, and he took the opportunity to explain his philosophy of science to the outside world. The lecture addressed the subject of whether physics described an objective reality or whether the results of the experiments depended on the subjective experience of the experimenters. Planck argued strongly for the former. He believed that the purpose of science was to discover universal constants, because these offered "the possibility of establishing units of length, time, mass, and temperature, which necessarily retain their significance for all cultures, even unearthly 'nonhuman ones'."
These views were in opposition to the up-and-coming philosophy of positivism. The positivists argued that scientists could only believe in facts they gained from their own direct experience with the world and that science can never teach us anything about the objective world beyond human experience. Planck was disgusted by this line of argument, believing that it eliminated the possibility of scientific laws independent from human observers.
In the years following his 1908 speech, Planck continued to echo these anti- positivist themes all over the world. In 1909, at Columbia University, he reiterated that positivism was a scientifically useless philosophy and that the paramount goal of science should be to establish a worldview independent of all human observers.
Planck had fame, prestige, a happy family, and a fulfilling professional life, but none of it was enough to insulate him from the turmoil that was to follow. For decades, Planck's Germany had been the most powerful force in international physics, but its luck was about to change, as scientific pursuits were overtaken by war.