Cycles and orbits

The first clocks were the cycles of daily life, notably the diurnal cycle of light and dark. These continued apparently without end and so provided a measure of change, of ceaseless movement and return. Since ancient times the day has been divided into 24 hours, and since medieval times an hour has been divided into 60 minutes. An old fashioned circular clock mimics these cycles, dividing a day into hours, minutes, and seconds measured by the angular movement of pointers called hands.

Orbits are like raceways with their fixed path for repeated travel over a distance. For a race the goal is to achieve the shortest time to travel the allotted distance. But an orbit continues without apparent end. The distance a planet or satellite travels keeps increasing, providing a consistent movement to compare with other movements. An orbit is like a clock but the distance traveled is the circumferential movement, not the angular movement.

Because cycles were measured in angles first, angular movement was associated with ceaseless movement, which was called time. But circumferential or linear movement can just as well be associated with cycles, especially orbits, whose space could be equally well associated with ceaseless change. But it is change, not time or space, that these ceaseless movements are really about.

Consider the sayings that might result. “Change flies.” “Change and movement wait for no man.” “Change is of the essence.” “A waste of change.” “Change cures all.” “Change is money.” “Change works wonders.”