The Great Conversation: Time
By Gabriel Blanchard
"Do you have a moment?"
"Literally always. But never more than one."
Time is arguably our single most persistent—indeed, incessant!—experience, but it is hard to describe or define. St Augustine wryly remarked, “If no one asks me, I know what time is; if I wish to explain it to one who asks me, I do not.”
Time is usually called a dimension, like space. Duration is for time what extension is for length, breadth, and depth. This prompts some questions. Can time exist without things to occupy it (rather like the question of whether a perfect vacuum can exist)? Are there multiple dimensions of time, as there are of space? And if so, is it possible to travel through time?
Well, before we all get our hopes up, time travel has not made any major advances recently. Current scientific ideas about time are based principally on the work of Albert Einstein, only a century old. Einstein’s theory of relativity suggests that time itself is actually warped by gravity, and even by motion. As an object approaches the speed of light, its “experience” of time slows down, compared to a stationary observer. This is expressed in the famous twins paradox. Put one of a pair of identical twins in a rocket and send it on a trip at the speed of light. When the rocket returns to earth, the twin who stayed on earth will be older than the twin who went on the rocket. (This is discussed in Minute Physics’ excellent video series on relativity—which is, slightly, less bewildering than it sounds!)
Philosophy, art, and religion also address time. Change and decay, whether as lamentable or a divine plan, are recurring themes in literature and painting. The old Latin expression Memento mori, “Remember death,” was a favorite trope of Medieval and Renaissance literature, especially devotional literature. Visual depictions of the theme employed skulls and hourglasses. The West conceived of time and history as driving humanity onward, individually toward death and universally toward the Last Judgment. On the other hand, in the Far East, the doctrine of reincarnation that Hinduism and Buddhism embraced gave a different quality to time. They viewed its endless cycles as a major source of suffering, part of the curse of the half-real material realm.
The relationship of time to eternity provoked a set of philosophical questions, akin to the scientific. The difference between direct experience and memory is a key example. We only ever experience the present, so how are the future or the past real? Some philosophers have denied that they are. But most classical theists have argued that, while human knowledge and choice are defined by our experience of time, all time is equally present to the mind of God. As an eternal being, he enjoys direct knowledge of, and freedom in, every point in time, something we experience only in the present moment—hence Shakespeare’s line calling time “thou ceaseless lackey to eternity”.