100 years a ago on November 25 1915 Albert Einstein presented the final version of his theory of gravitation known as the General Relativity to Prussian Academy of Sciences. The paper was published in 1916.

Why do we mention David Hilbert in the story of General Relativity? David Hilbert was the most influential mathematician of the 20’th century. You can see here and here for his wide ranging contributions to mathematics and physics. He posed the questions known as the Hilbert’s problems to challenge the 20’th century mathematicians. In 1915 Einstein was 36 years old, Hilbert was 53.

Einstein was eager to interact with Hilbert and show him his earlier version of General Relativity theory and perhaps learn from him. Einstein was struggling to find the covariant forms of his equations. I will not get into what “covariant” means but without the covariant equations his theory would not be truly general.

Einstein visited David Hilbert at the University of Gottingen in June and July 1915. Hilbert was very impressed by Einstein’s theory but Hilbert being very energetic and brilliant he raced Einstein to find the covariant forms of the equations. This created tremendous pressure on Einstein. Between June 1915 and November 25, 1915 Einstein was a driven man. He worked with superhuman intensity until he finally found the covariant forms of his equations. Hilbert came up with the covariant equations at the same time as Einstein did. This is a controversial subject. Historians are still trying to sort out the priority regarding the covariant forms of the equations but it is clear that Einstein developed the entire theory starting with Special Relativity. Einstein clearly deserves a huge credit for the development of the General Relativity as well as the Special Relativity. I would like to remind everyone that the co-author of the earlier version of general relativity (1913 version) known as the “Entwurf” was Marcel Grossman who was Einstein’s long time friend. Marcel Grossman was the chairman of the mathematics department at ETH when he worked with Einstein on the General Relativity.

In my research of the history of Einstein’s scientific contributions the most useful book for me was Hans Ohanian’s book titled “Einstein’s Mistakes.” I also recommend Walter Isaacson’s book titled “Einstein: His Life and Universe” which is the standard reference book.

Einstein has been criticized for not citing the work of other scientists in his papers and not giving enough credit to deserving physicists of his era. This is a fair criticism. Not citing the relevant work of other scientists is a big sin.

To appreciate the full scope of the drama between Einstein and Hilbert we need to remember that 1914 and 1915 were the years of turmoil in the life of Germany as a country because of the WW1. The year 1915 was particularly difficult for Einstein. He was getting divorced and he was separated from his 2 sons. Einstein was in a depressed state of mind for most of 1915.

**Note for the curious (1)**: David Hilbert supervised 69 doctoral students. This involves great personal sacrifice. Supervising PhD research takes a lot of time and energy. In contrast, Albert Einstein had no Ph.D. students.

**Note for the curious (2)**: Einstein has been my hero since my high school days but I have never studied General Relativity formally. I have learned the concepts of course but I have never learned the mathematics of General Relativity. I have never taken a course in General Relativity because it was not offered in the universities I attended. In most physics departments in the US the General Relativity is not taught. Like most physicists I have a copy of the heavy (5 pounds) textbook titled “Gravitation” by C.W. Misner, K.S. Thorne, and J.A. Wheeler. I skimmed through the book but I have not studied it. This is a rather strange!

**Centennial celebrations **

APS (American Physical Society): One Hundred Years of General Relativity

**Tutorials in relativity **

http://www.staff.science.uu.nl/~hooft101/lectures/genrel_2013.pdf (Gerard ‘t Hooft)

http://www.relativity.li/en/epstein2/read/