He was one of his closest friends and classmate in Switzerland. He helped him with his exams and lent him his notes. Who was the mathematician Einstein admired? It was Marcel Grossman, Einstein’s “guardian angel”.

Grossmann was born in Budapest in 1878. His family was from Switzerland. He attended the Zurich Polytechnic, where he met Einstein. According to the latter, the notes made by his friend were outstanding.

### Invaluable help

It took the genius a while to find employment, hard as it is to believe. He was looking to be an assistant to some professor. Grossman’s father helped him get a job at the now famous Patent Office. There, in 1905, the 26-year-old unknown genius made history. He published his theory of special relativity. There he went on to write five scientific studies that revolutionized early 20th century physics.

Helping him get that job would be described by Einstein as “the greatest thing Marcel Grossmann did for me as a friend.” In fact, that year, the physicist dedicated his doctoral thesis to him.

And he found in his friend a great guide. “The need to go beyond the Euclidean description of space-time was first articulated by Grossman. He persuaded Einstein that this was the right language for what would become general relativity.” David McMullan, Professor of Theoretical Physics at Plymouth University, tells the story.

Grossman was an expert in tensor calculus and his explanations eventually convinced Einstein. “I am working exclusively on the problem of gravitation. I can overcome all difficulties with the help of a mathematician friend here,” wrote Einstein.

In 1913, the two friends published a paper together. They brought together the sophisticated mathematics Grossmann knew and Einstein’s physics. It is an important step on the way to the general theory of relativity.

### Part of the story

In late 1915, Einstein arrived at the final formulation of his theory. He published it and revolutionized the history of science and the way we understand the universe.

Months after publishing the theory, Einstein wrote: “I want to acknowledge with thanks my friend, the mathematician Grossmann. He not only saved me the effort of studying the relevant mathematical literature. He also helped me in my search for the equations of field gravitation.”

It would be pertinent to give him the importance he has. The mathematician Einstein admired is also part of the history of science.