Lawrence Sklar

Despite over one-hundred years of effort, the origin of temporal asymmetry in the physical world still eludes us. While much has been learned about the role played by fundamental instabilities in microdynamics, by the imperfect isolation of systems and by cosmological facts in the origin of the behavior described by kinetic theory and thermodynamics, important puzzles still remain which continue to make the origins of asymmetric thermal behavior out of dynamically time symmetric underlying laws mysterious to us.

Those who think of some aspects of the world as "physically necessary" usually think of this kind of necessity as being confined to the general law of nature, initial conditions being "contingent." Tachyon theory and general relativity provide independent but related reasons for thinking that some initial states are, however, "impossible." And statistical mechanics seems to lead us to conclude that some initial conditions are, if not impossible, "highly improbable." We are then, led from these aspects of physics to wonder if initial conditions are always "freely specifiable" and in the domain of physical contingency.

It has been argued, most trenchantly by Nancy Cartwright, that the diversity of the concepts and regularities we actually use to describe nature and predict and explain its behavior leaves us with no reason to believe that our foundational physical theories actually "apply" outside of delicately contrived systems within the laboratory. This paper argues that, diversity of method notwithstanding, there is indeed good reason to think that the foundational laws of physics are universal in their scope.