All of Einstein's major papers are his alone. However, over the years he had a remarkably large number, more than thirty, of co-workers. Einstein did not like crowds, never cared for teaching classes, and did not create a school. But he loved to talk physics, as was illustrated in such delightful ways during the session of the Einstein symposium in Princeton devoted to 'working with Einstein' [W1]. The four men who reminisced on that occasion had all worked with him during the 1930s and 1940s. Their respective collaborative efforts all dealt with general relativity and unified field theory, Einstein's exclusive interests during that period. All of them were men much younger than Einstein who had come to him in the formative stages of their development.
It was not quite like that in earlier times. Along with the younger physicists who came even in those days, Einstein also had collaborators who belonged to his own generation, men like Laub, the Habicht brothers, Grossmann, Ehrenfest, Bucky, Mühsam, and Tolman. Pauli, though twenty years younger than Einstein, was already a mature physicist when he and Einstein wrote a joint paper. Furthermore, in the early days, even though relativity was already a main topic of concern, there was a greater variety of research subjects that interested Einstein. For example, he is the co-author of experimental papers dealing with refrigerators, a hearing aid, gyromagnetism, and the permeability of membranes for colloids. It would appear that in the early years Einstein had more fun.
To understand Einstein the physicist, it would be of some interest to organize a reunion, albeit on paper only, of all his collaborators.* It is the purpose of this appendix to do so. The format will be a series of thumb-nail sketches in which the nature of the various collaborations are stated and in which it is indicated what became of the people who worked with Einstein.**____________________