Excerpted with permission from The Island of Knowledge: The Limits of Science and the Search for Meaning by Marcelo Gleiser. Available from Basic Books, a member of The Perseus Books Group. Copyright © 2014.
What goes on when you see something, say, this book you are reading? Leaving aside the whole business of how the brain processes visual information, let’s just focus on the information travel time. To make life simple, let’s also just consider the classical propagation of light, ignoring for now how atoms absorb and reemit light. Light is bouncing around the room because either the window is open or the lamp is on, or both. This bouncing light hits the surface of the book, and some of it is absorbed, while some is reflected outwards in different directions. The page and the ink used for printing absorb and emit light in different ways, and these differences are encoded in the reflected light. A fraction of this reflected light then travels from the book to your eyes, and thanks to the brain’s wondrous ability to decode sensorial information, you see the words on the book’s page.
Credit: Flickr/Alex Harries, adapted under a Creative Commons license.
It all looks ...