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. (shrink)