This mechanism shrinks when pulled

This little mechanism shrinks when you try to stretch it. You try to pull it apart and all of a sudden it pulls back on you. That's so weird, right? Here it is under controlled conditions.

There's a cup hanging from the mechanism. But now look what happens as you add water to it. All of a sudden, the cup shoots up. The amount it shoots up is tiny.

But the physics behind it is so counterintuitive, nobody thought it was possible. It feels like it violates physics. That's why it's fun. The paradox that controls this mechanism governs everything from mechanical systems to food chains, from traffic jams to power grids.

And to understand it, you just need to ask a simple question. What will happen to this weight if you cut the green rope? Where is this going to end up? Is it going to go up?

Is it going to going to go down? Or is it going to stay the same? Can I touch? Yeah.

Yeah. Yeah, you can try it. Nothing. You don't think anything's going to happen?

In the same place. Uh, weight is going to be right over there. Like it's going to fly off or what? No, not not too much, but probably it's going to go to this way.

If you cut the green rope, this is going to come down. It will go down. It will go down. It drops.

It'll fall down. The first thing that occurs to me is as soon as you cut that, the weight is going to drop. I imagine the weight ends up lower than it started. Here's a closer look at the setup.

You have a spring hanging from a hookup here. And then via this green rope, it's connected to another spring that's carrying this weight below them. There are two extra ropes here as well. So the red one and the black one are slack.

They're not under any tension whatsoever. So they're not actually carrying any weight. What's going to happen if you cut the green rope? You can pause the video here and try to figure it out for yourself.

Wait, what? Here it is in slow motion. So, even though the ropes on the side were slack and we cut the only rope in tension, the weight somehow went up. Okay, so if you're unconvinced that cutting the ...