A nearly universal feeling
Most adults share the same impression: the years pick up speed. Summers feel shorter, weeks blur into one another, you wake up one morning and it is already December. Studies that try to measure this perception (asking people to estimate how long ago a given event happened) confirm that, with age, most of us shrink the past. What happened five years ago feels three years away.
There are several explanations for this, and they reinforce one another.
The proportional explanation
The oldest one goes back to the philosopher Paul Janet, who put it into words in 1877. The idea fits in a single sentence: each year of your life is a smaller fraction of everything you have already lived.
For a five-year-old, a year is one-fifth of a lifetime, twenty percent. That is enormous. For a fifty-year-old, the same year weighs only one-fiftieth, two percent. Ten times less. If your sense of time is sensitive to that ratio, the same year feels ten times shorter at fifty than it did at five.
This logic carries a vertiginous consequence: by the formula’s own arithmetic, half of your subjective life is already behind you by roughly the age of seven or eight. Everything after that is overtime, and it runs faster and faster.
A bored brain takes fewer photographs
The second explanation runs through memory. For a child, almost everything is new: the first day of school, the first friend, the first sight of the sea, the first scoop of pistachio ice cream. Each day prints rich, distinct memories. When the child looks back, memory is thick.
As we age, novelty thins out. Days resemble each other, the commute is familiar, gestures fall into routine. Our brain, ever efficient, compresses all of it into a single generic memory (“this year I worked, nothing special”). Look back across that stretch and there are few landmarks, and so little to weigh. The whole thing feels short.
The physicist Adrian Bejan proposed an even more radical version in 2019: with age, our neural networks process mental images more slowly. We capture fewer subjective frames per second. Fewer frames across the same real duration means a thinner memory, and the impression that the time has slipped away.
The takeaway is almost practical. If you want to slow your years down, load them with novelty. A trip somewhere unfamiliar, something new to learn, a different neighbourhood, a relationship beginning. Time does not stretch — but it remembers.