Objects move through space and time. Time is not a universal quantity which exists on its own, separate from space. Rather, future and past are merely directions like up and down, left and right, forward and back in what is referred to as space-time. One can only travel in the future direction in time but one can travel on an angle. ( John Gribbin, 1990, p. 1)

Einstein made other great discoveries, such as the speed of light. How can observers moving at different speeds all measure light at the same speed? The answer is that they cannot, not if the normal ideas of space and time hold true. However, in the famous paper of 1905, Einstein stated that it is possible if they abandoned the idea of a universal time. Instead, all the observ

Some topics in this essay:
John Gribbin, Stephen Hawking, Albert Einstein, speed light, frame reference, moving speeds, particles travel, john gribbin 1990, john gribbin, measured clock, faster light, gribbin 1990, ‘time warps’, theory relativity,