Abstract

The photons the 2.7˚ Cosmic Background Radiation can provide and absolute rest frame in which all photons move at exactly c, as well as a frame in which all clocks run at the same rate. Time is usually thought of either as a separate entity that either exists independently from mass and space or as an integral part of an entity called space-time. Although many different kinds of clocks have been devised for measuring the passage of time, a careful look at them reveals that there are, in fact, two different arrows of time that are quite distinct from one another and can even be said to flow at different rates. It is shown that every clock records that passage of either inertial time or gravitational time. Several experiments demonstrate that the rates of inertial clocks are affected by both changes in motion and changes in gravity. Thought experiments are presented to show that the effects on the rate of clocks from both changes in motion and changes in gravity are caused by changes in the mass of the clock. The conclusion is reached that there is really no physical entity called time that is more than a metaphysical idea that is used to quantify different types of motion.