Given the collapse hypothesis (CH) of quantum measurement, EPR-type co
rrelations along with the hypothesis of the impossibility of superlumi
nal communication (ISC) have the effect of globalizing gross features
of the quantum formalism making them universally true. In particular,
these hypotheses imply that state transformations of density matrices
must be linear and that evolution which preserves purity of states mus
t also be linear. A gedanken experiment shows that Lorentz covariance
along with the second law of thermodynamics imply a non-entropic versi
on of ISC. Partial results using quantum logic suggest, given ISC and
a version of CH, a connection between Lorentz covariance and the cover
ing law. These results skew that standard quantum mechanics is structu
rally unstable, and suggest that viable relativistic alternatives must
question CH. One may also speculate that some features of the Hilbert
-space model of quantum mechanics have their origin in space time stru
cture.