Name: サッカー、物理学、対称性 (Football, Physics, and Symmetry)
Uploaded: 2021-01-14T05:26:45.000Z
Duration: 2 min 3 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

When people talk about the physics of American football, they normally mention force, torque,

and so on… Like how the energy from two linemen colliding is enough to power a 60W

light bulb for over a minute, or is equivalent to an average person falling two stories off

But there's another aspect of physics in football that isn't talked about as much – symmetry!

You might think symmetry is just for butterflies and rorschach tests, but it's all over the

place in football: there's translational symmetry when teams keep the same formations as they

move up or down the field, and rotational symmetry when they switch sides after a touchdown.

Even the ball has axial symmetry so it can spin smoothly through the air.

But why is symmetry useful in the first place? Symmetry makes things easier, or at least

more efficient; it gives you a guide: "same scenario, same action." That means you don't

have to reinvent the wheel all the time: to draw a straight line, you just keep drawing

in the same direction. For a circle, keep curving the same amount.

So when football players practice a play over and over, the patterns of football become

so ingrained in their reflexes they can act without thinking. Psychologists call this

"habit formation"; we call it "symmetry in time"! And when players line up on the field

the same way at the thirty, or forty, or fifty yard lines, that's "symmetry in space".

Even physics itself is symmetric – ever heard of Newton's law: "a body in motion tends

to stay in motion"? That's just nature saying "keep doing the same thing." What's more,

Newton's laws of motion are the same now as they were yesterday, and they'll be the same

again tomorrow! Doesn't that make life easy?

Ultimately, symmetry is what allows both science AND football to function - if the laws of

the universe (or the rules of football) changed from day to day, we wouldn't be able to repeat

experiments, make predictions, or know what plays to practice.

So when you reach for yet another handful of chips while watching the next football

game, know that millions across the country are doing exactly the same, in perfect symmetry.