研究人员解决牛顿的三体问题了吗?

研究人员解决牛顿的三体问题了吗?

If you thought that Issac Newton made physics simple, think again. The laws of motion might themselves be simple equations, but the actual motions of objects according to these laws can get complicated fast.

如果你认为是艾萨克·牛顿使物理学变得简单，那你就错了。运动定律本身可能是简单的方程，但根据这些定律，物体的实际运动很快就会变得复杂起来。

Our solar system contains far more than just three bodies, which makes the three-body problem particularly embarrassing. (Photo: NASA)

For instance, imagine a universe with just two objects in it: say, two stars. Newton's laws are reasonably sufficient for helping us to understand how these gravitationally bound objects will interact with each other. But add a third object — a third star, perhaps — and our calculations become dicey.

例如，想象一个只有两个物体的宇宙:比如说，两颗星星。牛顿定律足以帮助我们理解这些受引力束缚的物体之间是如何相互作用的。但是再加上第三个物体——也许是第三颗星——我们的计算就变得不可靠了。

This problem is known as the three-body problem. When you have three or more bodies interacting according to any inverse square force (like gravity), their interactions conflict in a chaotic way that makes their behavior impossible to predict precisely. This is a problem because, well ... there are a lot more than three bodies in the universe. Even if you just narrow the universe down to our own solar system, it's a mess. If you can't even account for three bodies, how are you supposed to predict the motions of a sun, eight planets, dozens of moons, and the countless other objects that make up our solar system?

这个问题被称为三体问题。当你有三个或更多的物体根据任何反方力(如重力)相互作用时，它们的相互作用以一种混乱的方式发生冲突，使得他们的行为无法准确预测。这是个问题，因为宇宙中有三个以上的物体。即使你把宇宙缩小到我们自己的太阳系，也是一团糟。如果你连三个物体都没有考虑，你应该如何预测太阳以及组成太阳系的八个行星、几十颗卫星和无数其他物体的运动?

Because you only need three bodies to make it a problem, even if you just try to analyze the motions of the Earth, sun and moon, you can't do it.

因为你只需要三个物体就能把它变成一个问题，即使你只是试图分析地球、太阳和月球的运动，你也做不到。

The two-body answer

双体答案

Physicists get around this problem by instead treating all systems like two-body systems. For instance, we analyze the interactions of the Earth and the moon alone; we don't factor in the rest of the solar system. This works well enough because the Earth's gravitational influence on the moon is way stronger than anything else, but this cheat can never truly get us 100 percent there. There's still a mystery at the heart of how our complicated solar system all factors in.

物理学家们通过把所有的系统都看成是两体系统来回避这个问题。例如，我们单独分析地球和月球的相互作用;我们不考虑太阳系的其他部分。这已经足够好了，因为地球对月球的引力影响比其他任何东西都要大得多，但这种欺骗不可能真正让我们百分之百地到达那里。在我们复杂的太阳系中，所有因素是如何形成的，其核心仍然是个谜。

Needless to say, it's an embarrassing conundrum for physicists to have, especially if our goal is to make perfect predictions.

不用说，这对物理学家来说是一个尴尬的难题，尤其是如果我们的目标是做出完美的预测。

But now, an international team of researchers, led by astrophysicist Dr. Nicholas Stone of Hebrew University of Jerusalem's Racah Institute of Physics, think they might finally have made progress on a solution, reports Phys.org.

但是现在，一个由耶路撒冷希伯来大学拉卡物理研究所的天体物理学家尼古拉斯·斯通博士领导的国际研究小组认为，他们可能终于在解决方案上取得了进展，Phys.org报道。

In formulating their solution, the team looked at one guiding principle that seems to apply across certain types of three-body systems. Namely, centuries of research has revealed that unstable three-body systems all eventually expel one of the trio, and inevitably form a stable binary relationship between the two remaining bodies. This principle provided a crucial clue for how this problem might be solved in a more general way.

在制定他们的解决方案时，该团队着眼于一个指导原则，似乎适用于某些类型的三体系统。也就是说，几个世纪以来的研究表明，不稳定的三体系统最终都会排斥其中的一个，并不可避免地在剩下的两体之间形成稳定的二元关系。这一原则为如何以更普遍的方式解决这一问题提供了重要的线索。

So, Stone and his colleagues crunched the math and came up with some predictive models that could be compared against computer modeling algorithms of these systems.

因此，斯通和他的同事们分析了这些数学问题，并提出了一些可与这些系统的计算机建模算法相比较的预测模型。

"When we compared our predictions to computer-generated models of their actual movements, we found a high degree of accuracy," shared Stone.

斯通说:“当我们将预测结果与电脑生成的它们实际运动的模型进行比较时，我们发现它们的准确率很高。”

He added: "Take three black holes that are orbiting one another. Their orbits will necessarily become unstable and even after one of them gets kicked out, we're still very interested in the relationship between the surviving black holes."

他补充道:“以三个相互环绕的黑洞为例。它们的轨道必然会变得不稳定，即使其中一个被踢出，我们仍然对幸存的黑洞之间的关系非常感兴趣。”

While the team's success represents progress, it's still not a solution. They've only shown that their model lines up against computer simulations in special case scenarios. But it's something to build on, and when it comes something as chaotic as three-body systems, that scaffolding goes a long way in helping us to understand how our theories might be used to more accurately construct models of reality.

虽然团队的成功代表着进步，但它仍然不是一个解决方案。他们只展示了他们的模型在特殊情况下与计算机模拟一致。但它是建立在一定基础上的，当它涉及到像三体系统这样混乱的东西时，支架在帮助我们理解如何将我们的理论用于更准确地构建现实模型上大有帮助。

It's a critical step toward a fuller understanding of how our universe operates.

这是全面了解我们的宇宙如何运作的关键一步。