Time III

Understanding the relationships between space, time and motion is essential for discussing time travel. Knowing something about time dilation is essential for discussing sf about slower than light interstellar travel. We refer particularly to The Time Machine and to relevant works by Poul Anderson. Wells' Time Traveller and Anderson's mutant time travellers experience time dilation while remaining stationary on the Earth's surface. Thus, they do not accelerate anywhere.

When someone accelerates through space, his duration is stretched or dilated by contrast with that of anyone moving more slowly than he is. However, within his enclosed spaceship environment, he is not aware of any difference. There are still sixty minutes between 01:00 and 02:00 on a clock. He still experiences an hour as sixty times longer than a minute.

But each of us moves within his own particular relativistic frame of reference. Within his own frame of reference, someone can accelerate from sixty miles per hour to a hundred and twenty miles per hour but cannot accelerate from sixty minutes per hour to a hundred and twenty minutes per hour. 

Extension is measured in units of length. Endurance is measured in units of time. Velocity is measured in units of length by units of time. Thus, endurance is like extension along a fourth dimension, not like motion along the fourth dimension. The Time Traveller confuses the issues horribly in his introductory exposition!