The Nature of Time, by Ulrich Meyer.

Abstract

In 1908 Hermann Minkowski began an address to a congress of German natural scientists and physicians with the following now-famous words: ‘Henceforth space by itself and time by itself are doomed to fade away into mere shadows, and only a kind of union of the two will preserve an independent reality’. This union is known, reasonably enough, as space–time , and the investigation of the nature and structure of space–time has been central to the development of the general theory of relativity, one of the two foundational theories of current physics. In the other foundational theory, quantum mechanics, space and time generally appear quite distinct, and even in the context of relativity theory some physicists still maintain that time (independently of space) is the bedrock reality while others claim time is a mere emergent phenomenon. Minkowski’s prophecy has not as yet been fully vindicated, even on its home turf. In other fields, like philosophy, space and time are still considered separately. We have a Philosophy of Time Society, for instance, but not a Philosophy of Space Society. Philosophical investigations of time are typically pursued quite independently of any consideration of space. One might think that philosophers are just retrograde in this respect, but one remarkable line of thought in Ulrich Meyer’s book, The Nature of Time ( NT ), is a series of arguments with the upshot that space and time must be considered quite distinct. Space is a manifold or collection of three-dimensional points but time is something else entirely. Time, or the set of times, is in Meyer’s view more like the set of possible worlds of modal logic than the set of time points that Minkowski imagined would be folded into space–time.