German professor discusses scientist who aided Einstein

Peter Kauffner

Although many biographers claim that Albert Einstein was so confident in his theory of general relativity that he was never troubled by conflicting experimental results, letters he wrote at the time and his relationship with his assistant Erwin Freundlich tell a different story, Professor Klaus Hentschel told a seminar held Friday at the University.
Hentschel, a professor at the University of Goettingen in Germany, is the author of “The Einstein Tower.” The book will soon be published in an English edition by Stanford University Press.
The theory of general relativity, first proposed in 1911, holds that gravity curves space and slows time. Light follows the curvature of space, and is therefore deflected when it passes near a massive object such as the sun. The theory also says that acceleration has effects on space and time equivalent to those of gravity.
Hentschel has chronicled Einstein’s frustrations with the scientific community while waiting for his theory to be confirmed, and his relationship with the astronomer Freundlich.
“(Freundlich) is today largely unknown, and many of his colleagues would say properly so. He was not one of those exceptional scientists like Einstein, but rather a typical, normal scientist,” Hentschel said.
As an assistant to Einstein, as well as an early and vigorous supporter of relativity, Freundlich was the focus of bitter personal attacks by those skeptical of the theory.
Confirming general relativity required some very subtle and precise astronomical measurements.
“Collection of the most precise data has become an end in itself (for German astronomy), and in general leading astronomers have quite poor theoretical physics backgrounds,” wrote Einstein in one letter. Freundlich was one of the few astronomers who recognized the importance of making measurements for the purpose of testing theories proposed by scientists in other fields.
Freundlich opened himself to criticism by including a serious mistake in a 1913 paper that purported to provide experimental confirmation of general relativity. Criticism was so intense that Freundlich lost his position at the Berlin Observatory as a result.
Although Einstein’s association with Freundlich cost him credibility within the German scientific establishment, Einstein used his influence to find Freundlich another position at the Kaiser Wilhelm Institute for Research.
A solar eclipse is the only time starlight that has passed near the sun is clearly visible from Earth. Therefore, eclipses provide an ideal opportunity to observe the deflection of light predicted by general relativity.
Freundlich put together an expedition to observe a solar eclipse in August 1914 in the Crimea. The timing proved to be most unfortunate; he was interned and deported by Russian police when World War I broke out.
General relativity finally gained wide acceptance in 1919, when British astronomer Arthur Eddington made the necessary measurements during a solar eclipse in West Africa. These measurements confirmed predictions made by general relativity.
Freundlich took advantage of Einstein’s new fame to raise money to build a solar observatory named for Einstein. The Einstein Tower, designed by expressionist architect Erich Mendelsohn, stands in Potsdam.