Picturing our lives as a timeline, a threat or string running through time from beginning to end, makes a lifetime seem something like old-fashioned film, the way movies were created and shown before the digital age. One could hold a reel of film in one’s hands and have the entire experience in one place, but the film on the reel said nothing. The film had to be threaded into a projector and shown on a screen to have meaning. As a motor moved the film through the projector, a flashing light shone through each frame—twenty-four frames per second. Trial and error showed that aspect to be ideal for viewing. Seeing twenty-four images each second, a viewer saw action and motion that seemed normal—they could be filmed by a camera that took twenty-four photographs per second, or they could be a series of drawings or still photographs that were carefully arranged to imitate normal action and motion.

An average human life—we will say seventy-six years—would require many reels of film. One would need enough reels to contain over one million feet of film. Nearly 57 billion frames would need to be shown at twenty-four frames per second to cover those seventy-six years. We can take this metaphor to think about time and about living our lives in time. However, this metaphor has a simple yet important shortcoming. In spite of the successful illusion captured by film shown twenty-four frames per second, time does not move in tiny bursts the way film operates.

If time clicked along at twenty-four units per second, a photon or neutrino (or anything else moving at the speed of light) would jump 7,750 miles between each frame. Science shows no evidence of particles jumping from point to point in space. Particles appear to move at a consistent rate, existing in every inch or centimeter between any two locations. Time, then, must also operate consistently, not jumping from instant to instant with a tiny gap between instants, but flowing effortlessly through every conceivable instant.

Early philosophers questioned the geometry of points and lines and planes and three-dimensional space. If a moving object must pass through an infinite number of points to reach its goal, how can it ever arrive? It must first reach the half-way point, but before getting there it must reach a point half-way there, and on and on cutting the distance in half again and again but still having more intervening points to achieve. Now, it seems, time must do the same. We approach an instant… we reach that instant… we pass that instant… and somehow, that instant has traveled from the future into the past although it was scarcely present at all.

Experience tells us that objects indeed travel through space and through time. The problem of traveling through an infinite number of points in space and an infinite number of instants in time does not bother moving objects in the least. Change, it seems, is a constant reality in our world. But, in a world where everything continually changes, how can we hold to the belief that anything stays the same? If each of us is constantly changing, how can any of us remain the same person throughout a lifetime, or even in the course of one year? J.