ethan@utastro.UUCP (05/24/84)
[][][][][][][] I made an error in my last submission. > Now, if space is flat (like a critically bound model universe) then >there is a global coordinate system in which nobody is moving "faster than >light" i.e. there are no two points whose increase in spatial separation >per unit time is greater than the speed of light. Wrong. If space is empty (open universe, infinitesimal matter density) then such a global coordinate system exists because the space-time can be transformed to ordinary minkowski space. (flat, empty, isotropic and homogeneous, this is the space where special relativity becomes exactly true). "Cute signoffs are for Ethan Vishniac perverts" {charm,ut-sally,ut-ngp,noao}!utastro!ethan Department of Astronomy University of Texas Austin, Texas 78712