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How Spaghetti Stumped Physicists For a Century - Video học tiếng Anh

How Spaghetti Stumped Physicists For a Century

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0:00This is super weird. Take a spaghetti

0:01noodle, hold it the ends, and try to

0:03break it like this.

0:05Did you see that? It never breaks in two

0:07pieces. Let's roll the instant replay.

0:12It always breaks into three or more

0:14pieces. And if you don't believe me, you

0:16should try it for yourself.

0:18And it's not just noodles.

0:20>> Oh my word. Look at that. The pole

0:23snapped.

0:23>> Did you catch that? Look at it again.

0:26His pole snapped not just in half, but

0:29into three pieces. But why? I mean,

0:32what's happening here? Well, spaghetti

0:34is long and skinny and flexible until it

0:37reaches its breaking point. Uh, this

0:39pasta puzzle stumped some really smart

0:42people. Even Richard Fineman, who solved

0:44some of the toughest problems in quantum

0:46physics. His noodle couldn't figure out

0:48these noodles until 2005 when a pair of

0:52MIT scientists cracked it. Literally,

0:54they built a high-tech spaghetti snapper

0:56so they can control and measure the

0:58popping pasta. When a spaghetti noodle

1:00bends, the outer side is stretched in

1:02tension while the inner sized is

1:04squeezed and compression. Well, the

1:05first break always seems to happen near

1:07the middle where its curvature is the

1:09highest. But there's all this stored

1:11energy in that bent noodle. That energy

1:13has to go somewhere and get suddenly

1:15released as this rapid recoil. The

1:18scientists found that the two halves

1:19whip back in the opposite direction as

1:21they try to straighten. It sends a shock

1:23wave down each piece that warps it so

1:26sharply that they often break in one or

1:28more other spots, too. This is called a

1:31cascading failure. And that's why you

1:34almost never get just two pieces. These

1:37same scientists also figured out that

1:39you actually can get spaghetti to break

1:41into only two pieces if you twist it

1:44before you bend it. That way, when it

1:46snaps, that unwinding motion cancels out

1:49some of the wave motion and prevents the

1:52cascading failure. Now, a pole valter

1:54isn't going to care how many pieces

1:56their pole snaps into. I mean, two's

1:58already too many, but it's still pretty

2:00awesome that a noodle can unlock a

2:02mystery of physics. Follow me for more

2:04cool science videos.

2:07So weird.