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

Subatomic particles often travel near the speed of light and thereby experience very large ‘time warps’. One consequence of these ‘time warps’ is that unstable particles can travel much farther before decaying than they would otherwise. For example, much of the background radiation at the surface of the Earth is caused by time-warped muons created by cosmic rays striking the upper atmosphere. The muons travel the many kilometers to ground level in spite of the fact that in their own frame of reference they exist for only about two microseconds, scarcely long enough for them to travel a few hundred meters. ( p. 2)

ers would have their own individual time, measured by a clock they each carried. The times on these clocks would measure the same if they were all moving at the same speed—but the times would differ significantly if the clocks were moving at different speeds. (Stephen Hawking, 1993, p. 73)

The amount of time dilation depends upon the speed of the trip—the closer the astronaut gets

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,