India, April 4 -- Some days ago, Zara Murao, my editor at HT Wknd, and I got into an animated conversation over WhatsApp: Why does it feel like the first quarter of the year just evaporated? Wasn't it just yesterday that we were scribbling vows to the gods about productivity and fitness?

Yet here we are, in April, staring at a to-do list that had outgrown the ecosystem it started life in. Time isn't just flying; it's evaporating. This feeling has intensified in recent years, we agreed. It ought to be investigated.

I've done some digging since then, into some of the theories that attempt to answer the question of what alters our perception of time.

Science points to the Proportional Theory. This one is simple enough: to a five-year-old,...