The Topic: Practice
The Guest: David Epstein
You live in the past.
You don’t know this because your brain lies to you and then covers up the lies, which is a good thing. If your brain didn’t fudge reality, you wouldn’t be able to hit a baseball, drive a car, or even carry on a conversation.
You may have already noticed this through its absence. Sounds that come from very far away don’t get edited. Maybe you’ve been high in the bleachers at a sporting event and saw the crack of a bat or the crunch of a tackle, but the sound seemed to arrive in your head just a tiny bit later than when it should have. Sometimes there is a delay, like reality is out of sync. You can see this in videos too. If you see a big explosion or a gun shot from far away, the sound will arrive after the camera has already recorded the images so that there is gap between seeing the boom and hearing it.
The reason this occurs, of course, is because sound waves travel much more slowly than light waves. But if that’s true, why isn’t there always a lag between seeing and hearing? How come you can carry on a conversation with someone at the end of a long hallway even though the light that’s allowing you to see her mouth is arriving well before the sound of her voice?