COSMOLOGY WITH INVARIANT COMMUNICATION TIMES.

If t represents the usual cosmic time parameter, with t sub o being the present epoch, a tau-time is defined by the relation d tau Rt sub odtRt where Rt is the radius of the universe at time t. Assuming that the results of special relativity hold at each epoch with respect to tau-time, it is shown that any two co-moving bodies that can be connected by light signals have an invariant communication time with respect to tau-time, and the velocity of light is given by Ct cd tautdt. Even though this result necessitates certain basic changes, it is shown that the same relations hold among distance, red shift, luminosity, and the Hubble parameter as obtained in classical cosmology, and that observations at the present epoch do not differentiate between tau-time and t-time. Basically, the results show that tau-time is a natural dynamical time for cosmological investigations and its use rearranges the line element in such a way that the time-wise pathology occurs only through a conformal factor.