<human>:  When did the idea of a unified theory of physics first come about?
<bot>: The idea of a unified theory of physics was first proposed by Einstein in 1905. The first step towards unifying the forces of nature was taken by Einstein in his famous paper, "On the Electrodynamics of Moving Bodies." In this paper, Einstein showed that the electromagnetic force is the same as the gravitational force. This was a big step towards unification.