John Stachel

Towards the end of the career of many a distinguished scientist, or shortly after his or her death, an edition of the scientist's articles is published under the title: ‘The Collected Papers of…’. While not wishing to slight either the ceremonial importance or real utility of such collections, they must be clearly distinguished from the sort of editions on which theCollected Papers of Albert Einsteinis modelled. The former are primarily intended to make the published papers of a great scientist easily accessible to other scholars and students working in the same field as an aid to their research. The reader is provided with little or no help in understanding or evaluating the historical role these writings played in the development of this field, the circumstances leading to their creation, or how they fit into the life of their creator.

David Malament's (1977) well-known result, which is often taken to show the uniqueness of the Poincare-Einstein convention for defining simultaneity, involves an unwarranted physical assumption: that any simultaneity relation must remain invariant under temporal reflections. Once that assumption is removed, his other criteria for defining simultaneity are also satisfied by membership in the same backward (forward) null cone of the family of such cones with vertices on an inertial path. What is then unique about the Poincare-Einstein convention is that it is independent of the choice of inertial path in a given inertial frame, confirming a remark in Einstein 1905. Similarly, what is unique about the backward (forward) null cone definition is that it is independent of the state of motion of an observer at a point on the inertial path.