Bangs, Crunches, Whimpers, and Shrieks: Singularities and Acausalities in Relativistic Spacetimes

by John Earman

Almost from its inception, Einstein's general theory of relativity was known to sanction spacetime models harboring singularities. Until the 1960s, however, spacetime singularities were thought to be artifacts of the idealizations of the models. This attitude evaporated in the face of a series of theorems, due largely to Stephen Hawking and Roger Penrose, which showed that Einstein's general theory implies that singularities can be expected to occur in a wide variety of conditions in both gravitational collapse and in cosmology. In the light of these results some physicists adopted the attitude that, since spacetime singularities are intolerable, general relativity contains within itself the seeds of its own destruction. Others hoped that peaceful coexistence with singularities could be achieved by proving a form of Roger Penrose's cosmic censorship hypothesis, which would place singularities safely inside black holes. Whatever the attitude one adopts toward spacetime
singularities, it is evident that they raise a number of foundational problems for physics and have profound implications for the philosophy of space and time. However, philosophers of science have been slow to awaken to the significance of these developments. Indeed, this is the first serious book-length study of the subject by a philosopher of science. It features an overview of the literature on singularities, as well as an analytic commentary on their significance to a number of scientific and philosophical issues.

Genres: Philosophy

272 pages, Hardcover

First published January 1, 1995

Reviews

[Jonathan Hockey · Rating 4 out of 5]

For the earlier chapters it is worth this rating. Some good detail into the philosophical issues at the foundation of solutions to Einstein's Field Equations in relation to the emergence of naked singularities and closed time curves that can raise issues for our notions of causality. It shows how there is no clearly accepted rationale for how to distinguish a "reasonable" solution to those equations from an "unreasonable" one, only some tentative efforts and principles and conjectures, such as claims of cosmic censorship to dispense of naked singularities, and Penrose's weyl conjecture or the standard models proposed early inflationary expansion of the universe.

However, all have their own difficulties and are often motivated not by clear rationales and more by ad hoc attempts to only be left with the Einstein Field Equation solutions you wanted to be left with. However in later chapters, he tends to presume a resolution was reached in these early chapters that was never reached allowing him to have an extra confidence in general relativity than he can have in the correctness of quantum theory for instance. Earman seems keen to deflate the problem of singularities, but this was by no means achieved and instead of blaming philosophers of science for not having explored this topic enough, the fault may lay with general relativity itself as having problems, which seems to be the only option Earman is totally unable to countenance. If all we are going to do in philosophy and physics is try to defend one theory then we are dealing more with an epicycle style model of reality than the empirical reality itself, and I dont personally think that in a philosophical attempt even general relativity should be held as sacrosanct and above some, at least, tentative criticisms.

If his goal was to show that the problems in general relativity can be deflated he did not show this, but why would that be anyone's goal anyway? Surely the goal is to better understand the physical reality of the universe, and ensure our theories don't sway away from a solid grounding in physical reality. If our theories lead to paradoxes and science fiction style scenarios, it may not be these paradoxes and scenarios that are to blame, and need to be deflated, it is surely more likely to be a problem in the theory that gave rise to them.