This quantity is raised to the negative fourth power in the definition of Einstein’s gravitational constant. The slope (-5[1])of a 45 degree line on a Minkowski diagram (10[1]-5[1])equals this quantity because Minkowski time is scaled by this quantity. The ratio of velocity to this quantity is denoted by beta. By comparing interference patterns, (-5[1])this quantity was found not to depend on the direction of measurement in the Michelson-Morley experiment. (10[1])The mass-energy equivalence states (read slowly) rest energy equals mass times (-5[1])this (10[2])quantity squared. For 10 points, (10[1])name this universal (10[1])speed (10[1])limit equal to about three times ten to the eight meters per (10[3])second. ■END■