Any kid will undoubtedly tell you that time drags when you're bored -- but you age, the days, weeks, months and years seem to whiz by.

Adrian Bejan,  Professor of Mechanical Engineering at Duke, has a theory for that phenomenon, which will no doubt sound familiar to the computer-savvy: processing speed.

In his findings, published in the journal European Review, Bejan posits that as people age, the method by which they obtain visual information -- and how they process those images -- slows down.

The eyes of babies, for example, dart around, drinking in their environment, as their developing nervous system fires on all cylinders. As people age, however, their eye movement slows, and their expanded, adult-sized nervous system degrades.

Electrical resistance is to blame, causing the slow-down of signals and, therefore processing speed.  That makes time seem to pass faster, Bejan says.

He concludes, "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."