ABSTRACT
Public time, as we have seen, is a logical construct from private time. It is always possible that public time, and the clocks that measure it, seems to be running fast or slow by comparison with the private time of our own experience. What the Lorentz transformations show is that this must be the case if we seek to establish a public time between people at great distances from each other, moving at great velocities with respect to each other. Noon by San Francisco time is late evening by G.M.T., and occasionally this can raise difficulties. Many people have confused themselves about the implications of the Lorentz transformations. Length is not shortened nor time lengthened; but the rules for constructing a public time for different people at different—distant—places turn out to be more complicated than we had thought, if certain symmetries are to be achieved.
