As it did, angular momentum became important.

随着它的坍缩，角动量变得重要起来。

That's called conservation of angular momentum.

这称为「角动量守恒定律」。

But the original star's angular momentum is preserved.

但原始恒星的角动量被保留了下来。

What's neat is that they can maintain angular momentum indefinitely.

最酷的是它可以永久性地保持角动量。

It's a physics toy that demonstrates angular momentum, potential energy, and kinetic energy.

是个物理学家的玩具可以演示角动量还有动能和势能。

Since the angular momentum doesn't change, when the distance increases the velocity has to decrease.

由于角动量不变，当距离增加时，速度就会减小。

More angular momentum means she can make more turns before needing to replenish what was lost to friction.

更多的角动量意味着 她可转更多圈 ──在因摩擦力损失动量，需再补充之前。

Take quantum vortices, which are basically whirlpools of angular momentum in materials like superconductors and superfluids, giving them strange properties.

以量子涡旋为例，它基本上是超导体和超流体等材料中角动量的漩涡，使它们具有奇特的性质。

And except for what's lost to friction, that angular momentum has to stay constant while the dancer is on pointe.

除了摩擦损耗的动量之外，当舞者踮起脚尖时 角动量必须保持不变。

That's called the conservation of angular momentum.

- 这就是所谓的角动量守恒。