Abstract

Galileo was the first person to attempt to measure the velocity of light. Einstein was remarkable in 1905 in recognizing that a postulate on the velocity of light was necessary. But only two years later in 1907 he found it necessary to revise his original postulate. The very next year in 1908 Ritz proposed a radically different postulate. It was nearly half a century later that the universal time postulate was first proposed by Moon and Spencer in 1956. It was not until 1990 that the general formulation of the universal time postulate was developed by Moon, Spencer and Moon. Today we know that electromagnetic signals from moving sources can be synchronized. The paper reviews the experimental evidence for accepting the universal time postulate.