Some questions are timeless, innocent yet penetrating in their simplicity. Why is the sky blue? Why do things fall? How hard must one hit a chicken to cook it? It is this last mystery of the universe that we discuss today.
There’s a classic solution in which someone calculated that, if you slap a chicken at 3726 mph, it will be cooked. However, this analysis just calculates how hard you’d have to hit a chicken to get it to cooking temperature; you need to keep it at that temperature for it to cook. One slap won’t work unless you get it so hot that it cooks while it’s cooling.
A real answer to this vital conundrum needs to consider how fast a chicken cools. A body at a nonzero temperature is constantly radiating energy as blackbody radiation; this is what you see in incandescent lightbulbs or when glass glows during glassblowing. To keep an object at a given temperature, you have to continuously give it the same energy it’s radiating away. A typical-sized chicken at 165 F is radiating away roughly 2000 watts of power, around 300 times the power used in a fluorescent lightbulb. To avoid losing any heat to contact with the air, let’s assume we dangle the chicken from a string in a large vacuum chamber. Let’s also assume you and a few friends are hitting the chicken with baseball bats like a pinata. In order to keep the chicken at 165 F for the minutes needed to cook it, it would be enough to have four people each hitting it once a second with a bat swung at 75 mph, about the speed with which a pro swings. Four major-league baseball players wearing pressure suits in a vacuum chamber each hitting a dangling chicken with a baseball bat once a second could cook it in a few minutes.