Abstract

This article is written under the presumption that the constancy of the "measured" speed of light by all observers (in vacuo) is an unresolved issue. The author favors Ritz's use of c+v relativity but with the reservation that extinction (Tolman or Ewald-Oseen), i.e., the speed of light eventually reaches a terminal speed with respect to any given medium, has to be taken into account. De Sitter's (1913) argument against Ritz is used as a theoretical springboard from which to examine currently published observations of what are thought to be radially pulsating variable stars. High-angular-resolution photographs of these variables obtained from the Hubble Space Telescope (HST), the very large array (VLA) radio telescope(s), the growing family of very large telescopes (VLTs), and/or the publication of light curves along with phase-matched spectroscopic line profiles (absorption and emission) can be used to resolve the c+v question.