Title:

The arch and the scaffold: How Einstein found the field equations of general relativity (based on joint work with Jürgen Renn, Max Planck Institute for History of Science, Berlin, published recently in Physics Today)

 

Abstract:

In his later years, Einstein often claimed that he had found the generally covariant field equations of general relativity in November

1915 simply by choosing the mathematically most natural candidate. In 1912–13, he had already considered equations close to the ones he published three years later. He had given up on them back then because of difficulties with their physical interpretation. He had settled for equations constructed specifically and at the expense of general covariance to avoid such difficulties. In Einstein’s later recollections, the ensuing three years of work on the intractable covariance properties of these physically sensible but mathematically inelegant equations had largely been a waste of time. Progress, as he saw it, had resumed only when he had abandoned these equations and once again put his trust in the mathematics. Einstein’s writings at the time, we argue, tell a different story. In our reconstruction of events, the inelegant equations of 1913 served as the scaffold for the magnificent arch erected in November 1915.