Why does time speed up as you get older?

The short answer Time speeds up because the days stop being new. A child’s summer is endless because almost everything in it is a first time, and first times are how the mind marks the road going by; wear the same groove in every day and the mind, with nothing to flag, files a whole year under one heading—and the year is simply gone. The cure was never to do more; doing more, faster, is what smooths the groove. It’s to do a few things slowly enough to notice them.

The longer answer

You’ve had this happen: you drive home along a road you drive every day, pull into the drive, switch off the engine—and realize you remember none of it. Not one moment of the journey. Your hands did the whole thing, the turns and the lights and the roundabout, while you were somewhere else entirely, and the drive itself has left no trace at all, as if it never happened. Twenty minutes of your one life, gone, unrecorded, because there was nothing new in it for the mind to write down.

That vanished drive is what’s happening to the years. The mind marks time by novelty—it lays down memory where something is new, unexpected, first. A child’s summer runs long because it’s nearly all first times, each one flagged and stored, the days thick with the new and therefore long in the remembering. Live the same day enough times, though—same route, same work, same evening, the groove worn smooth—and the mind, finding nothing worth flagging, stops laying down track. And a stretch of life with no memory laid down in it isn’t recalled as full and quick; it’s recalled as nearly empty, and so as having taken almost no time at all. The year drove itself home while you were elsewhere, and left no trace.

Which means the usual remedy is exactly backwards. Feeling life speed up, we try to cram it—do more, faster, fit more in—and every bit of that deepens the groove, automates another stretch of road, and hands still more of the year to the hands while the mind checks out. Speed is the disease, not the cure. You cannot outrun the vanishing by driving faster into it.

The only thing that slows the road is novelty and attention—doing a few things newly, or slowly enough to actually be there for them. Take the different way home. Do the familiar thing as if you hadn’t done it a thousand times, which, if you attend, you’ll find you never quite have. The clock spends down at exactly the rate it always did; a year is a year. What changes is how much of it you were present for—how much got written down instead of driven home in a trance. Attention is the only thing that ever made time long.

Whether a life fully attended would feel longer at the end, or only richer, I can’t tell you—no one gets to run it twice. But I know which of my years I can still find, and they aren’t the fast ones. It may be so. It may not.