Brain Pickings

Brian Cox Explains Entropy and the Arrow of Time with Sandcastles and Glaciers


Understanding the joy and tragedy of the human condition through desert sand and polar ice.

It’s hard not to be perpetually perplexed by time and its arrow, which we’ve previously examined through a BBC documentary, a visual history of the timeline, and 7 essential books. After Minute Physics’ animated one-minute explanation of entropy and the Arrow of Time, here comes physicist Brian Cox with his penchant for using ordinary objects to explain the extraordinary: In this fantastic segment from BBC’s The Wonders of the Universe, Cox builds sandcastles in the Namib Desert to explain why, thanks to the second law of thermodynamics, entropy is the reason time flows in one direction.

Entropy always increases… because it’s overwhelmingly more likely that it will.

In another segment from the same program, Cox uses the Perito Moreno glacier in Patagonia, Argentina to explain the Arrow of Time and its unidirectional movement:

The Arrow of Time dictates that as each moment passes, things change, and once these changes have happened, they are never undone. Permanent part is a I a fundamental part of being human. We all age as the years pass by — people are born, they live, and they die. I suppose it’s part of the joy and tragedy of our lives, but out there in the universe, those grand and epic cycles peer eternal and unchanging. But that’s an illusion. See, in the life of the universe, just as in our lives, everything is irreversibly changing.

Cox’s new book, The Quantum Universe: Everything That Can Happen Does Happen, came out last month and is a mind-bender of the most stimulating kind.

The Kid Should See This

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