Keep it Juicy! Physics Says Time DOES Fly

Keep it Juicy! Time seems to fly as we age. The Keep It Juicy! blog author, Helen Mitternight, talks to physicist Adrian Bejan about the physics of how that happens and how to slow time.

Listen online the 17th of April 2019 by visiting Keep it Juicy! or by using this online player: Episode 65 – Time Flies with Adrian Bejan.

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The Tortoise and the Hare

41598_2018_30303_Fig9_HTML.png “The fastest animals and vehicles are neither the biggest nor the fastest over lifetime” is the subtitle of A. Bejan, U. Gunes, J. D. Charles, and B. Sahin in their Nature Scientific Report published the 27 August 2018.

Thanks to their theory, in this article, the authors explained phenomena such as the emergence of animal “outliers”:  higher speed at smaller body mass.

They show that what accounts for the animal outlier also accounts for the vehicle outlier: military jet fighter are smaller and reach speeds higher than the biggest commercial aircraft. Yet, like the cheetah, the jet fighter spends most of its active life at rest, on the ground, out of sight.  This new view gives the word ‘outlier’ a different meaning: the jet fighter is the outlier because, during its overall lifetime, it is slower than the bigger commercial aircraft, which spend most of its time flying.

This new meaning is in fact the oldest, taught by Aesop in his fable “The Tortoise and the Hare”: what matters in the life of the mover is the movement – i.e. the territory covered, the speed averaged – over the whole lifetime.