At ten, a year was forever.At forty, it is gone before you notice.

The simplest explanation Draaisma revisits is arithmetic. Subjective time is judged against the total life already lived. To a child of ten, one year is a full tenth of everything they have known. To an adult of fifty, the same year is one-fiftieth — a much quieter slice of the felt whole.

The denominator keeps growing. Each new year takes up a quieter, smaller slice of the felt whole.

Move the slider and watch the slice shrink. The numbers are small, but the implication is large: even if absolutely nothing else changed about how the brain measures time, arithmetic alone would be enough to make the years feel like they accelerate.

In 2019, Adrian Bejan — a Romanian-American engineer at Duke — published a striking paper in European Review. His claim was simple: as we age, our brains process fewer “mental images” per unit of clock time. Saccadic eye movements slow. Neural pathways grow longer. Signals degrade. The result: the same minute, but fewer perceived moments inside it.

If felt time is the count of mental frames per second, and that rate is falling, then time must feel faster — literally fewer events per real second. Slide the simulator below to see how the frame rate falls between childhood and old age.

People are not aware of this and they accuse themselves of wasting time. The cause is in their head. — Adrian Bejan

Psychology has been chasing this question for nearly a hundred and fifty years. The four theories below are the load-bearing ones for the pre-/post-thirty story. They do not replace each other — they stack.

Proportionality explains the slow drift. Memory density (the core of Draaisma’s book) explains why a routine adult year shrinks while a novelty-rich adolescent one stretches. Bejan’s frame-rate model explains the physical mechanism. Telescoping explains why the years since thirty feel like “a couple of years.”

Ask anyone over forty for their ten most vivid autobiographical memories. A strong cluster appears in late adolescence and early adulthood. First love. First job. First apartment. First grief. This is the reminiscence bump, one of the most replicated findings in memory research.

The bump exists because that decade is dense with firsts, with identity-defining decisions, and with novelty. Each first leaves a distinct, time-stamped trace. Adult years — more routine, more chunked — leave fewer. In retrospect, the decade that left more markers was longer.

Here is the most counter-intuitive finding in the entire literature. A routine week feels short while you live it (low attention to time) and short in memory (few landmarks). A novel week — a holiday, a course, a move — feels long while you live it (high attention, novelty) and long in memory (many distinct traces).

This is the holiday paradox. Lived time and remembered time usually run in opposite directions — except when novelty is present, where they finally agree. Toggle the two modes below to feel the asymmetry.

Friedman and Janssen’s 2010 review pulls together decades of evidence on a quiet, robust illusion called forward telescoping. We systematically remember public events as being closer to the present than they actually were. The 2008 financial crisis feels like “a few years ago.” The launch of the iPhone feels like “the other day.”

Telescoping matters because it explains a subtle part of the acceleration: if the past feels closer than it is, the years between then and now must feel compressed. Drag the marker below to where each event feels, and watch your own bias light up.

You cannot rewrite the arithmetic of proportionality. You cannot run your dopamine higher than your biology permits. But you can change how densely you encode the weeks. The research, taken together, suggests these six practices work — quietly, cumulatively, over years.

None of them require leaving your city or buying anything. They are about attention, novelty, and marking the passage of a week so the week leaves a mark on you in return.

I built this small assistant on top of the papers cited throughout. It is grounded only in the research listed in the Sources section — ask it about Bejan’s frame-rate model, the reminiscence bump, telescoping, scalar timing, or what any of it means for how you spend a Tuesday.

If you ask it something it does not know, it will say so instead of inventing. Try the suggestion chips to start.

Every claim on this page is grounded in one of the works below — two Cambridge University Press titles and one European Review paper. Tap any line to open the source.