One of the most fascinating aspects of the Einstein Conference in Berlin was an exhibition at the basement of the Harnack Haus where Einstein's original manuscripts on GR were put on display. These manuscripts were loaned by the Hebrew University of Jerusalem to the Max Planck Society for the occasion. It was a joy to browse through the manuscripts and see the development of ideas that led to Einstein's discovery. It contains Einstein's explorations, false starts, mistakes, corrections, and his eventual triumphant discovery of the field equations of gravitation. It is a remarkable record of the creative process of a genius whose discovery made front-page news around the world and shook up the world of physics. The Exhibition shows Einstein having the "happiest thought of his life" when he realized that the principle of equivalence was really the reflection of a geometric property of space-time. Einstein realized that he needed new mathematics to turn his ideas into equations. Einstein had dismissed his teacher Hermann Minkowski's geometric reframing of special relativity in terms of 4-dimensional space-time and light cones as "superfluous erudition". Maybe it was because Minkowski had called him a lazy dog with a lackadaisical attitude towards Mathematics. But the problem of Gravitation made Einstein appreciate the value of the geometrical approach. In fact, it became his main approach to his attempts to unify gravitation and electromagnetism which lasted all the way until his death. The manuscripts show Einstein learning the basics of Riemannian geometry with the help of his childhood friend Marcel Grossman. His early attempts at constructing the equations of gravitation using the scalar curvature failed. He started again and as he was getting close, he realized to his alarm that the great David Hilbert was close to finding a solution to the problem. Hilbert had started working on uncovering the field equations for gravitation after listening to some lectures by Einstein in Goettingen. Hilbert's approach was based on variational principles. Einstein's realized to his dismay that his decade long mission to find new equations of gravitation would be completed by Hilbert. A lot was at stake, so he doubled down. In the end, they were both very close to each other in publishing their results. But Hilbert was gracious enough to give Einstein the full credit for the discovery. Einstein also later published a variational derivation of the field equations of gravitation. In fact, the name Einstein-Hilbert action is given in honor of both of these giants of science.
I created this slide presentation for a college reunion in 2016 in honor of a beloved Mathematics professor who was retiring that year. Several of Dr. Shobha Madan's former students who were accomplished mathematicians had gathered at IIT Kanpur to present talks in their areas of expertise. I was the only "non-academic" person and the only one to attend from outside India. And I chose to speak on an academic topic. So go figure. But it was a wonderful experience. Anyway, here is the slide deck.
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