Physics offers explanation to why time flies as we get older

DURHAM, N.C. — For many of us, when we think back to childhood summers or seemingly endless days spent in the classroom, these periods of time feel as though they stretched on forever. In comparison, our more recent years of adulthood often feel like they’ve passed us by in a flash. This is usually just chalked up as another one of the many peculiarities that come with growing older. Now, a fascinating study offers up a more scientific explanation: as we age, the speed in which our brains obtain and process images gradually slows, resulting in this temporal discrepancy in memories.

Simply put, this slowing of the brain’s imaging speed causes perception of time to speed up.

“People are often amazed at how much they remember from days that seemed to last forever in their youth,” says study author Adrian Bejan, a professor of mechanical engineering at Duke University, in a release. “It’s not that their experiences were much deeper or more meaningful, it’s just that they were being processed in rapid fire.”

As we mature, the nerves and neurons in our brains also mature, growing in size and complexity. Consequently, new neural signals (memories), are faced with a longer path to travel than when we were young. Our nerves also deteriorate as we age, slowing down the flow of electrical signals throughout our minds.

These developments mean that it takes longer for new mental images and memories to be obtained and processed. One piece of evidence Bejan noted to back up his theory is how much more often infants’ eyes move in comparison to adults; children process images much faster than adults, leading to quicker eye movements and a rapid integration of information.

So, because older people are processing far fewer images within a given amount of time than they used to in their youth, it feels like time is passing at a faster rate.

“The human mind senses time changing when the perceived images change,” Bejan concludes. “The present is different from the past because the mental viewing has changed, not because somebody’s clock rings. Days seemed to last longer in your youth because the young mind receives more images during one day than the same mind in old age.”

The study is published in the scientific journal European Review.

This article was first published November 21, 2019