科学美国人60秒 SSS 混沌轨道可能导致灾难性的碰撞（在线收听）

Chaotic Orbits Could Cause Catastrophic Collision

Isaac Newton said, “I can calculate the motion of heavenly bodies, but not the madness of people.” He meant that while people can be unpredictable, the planets are just the opposite—they glide through space in orbits defined by the laws of physics. But that view’s been changing and a new study bolsters a more complex outlook.

艾萨克?牛顿说,”我可以计算出天体的质量,但是无法计算出人的精神状态.”他的意思是, 人类是不可预知的,但是天体恰恰相反——这些天体是根据物理规律在轨道上运行的。因为一项新的研究表明，现在那个观点已经被改变。

“The big finding of this paper was the discovery of the first real firm, unambiguous geologic evidence to confirm this idea that the solar system is chaotic.”

“本论文发现的结果是首次真正实体的发现，这个明确的地质证据证明太阳系是非常混乱的。”

Stephen Meyers, a geoscientist at the University of Wisconsin Madison.

斯蒂芬·迈耶斯是威斯康辛大学麦迪逊分校的地质科学家。

By chaotic, Meyers doesn’t mean that the planets zoom around wildly on random paths. Rather, he’s referring to the mathematical meaning of the word, in which the future state of a complex system depends strongly on its initial conditions. In this case, it means that seemingly random changes in planets’ orbits can occur because of subtle gravitational interactions between objects in the solar system.

混乱，迈耶斯的意思并不是行星的运动是随机的，无规律的。相反，他指的不是这个单词的数学意义，而是，一个复杂系统最初的状态决定于其初始的条件。在这种情况下，行星轨道随机的改变，是由于太阳系之间星体微妙的引力作用。

“It’s also known as the butterfly effect. This is the exact same phenomenon. The idea that a butterfly flapping over the Indian Ocean could influence weather patterns over North America a week later.”

“人们也将之称为蝴蝶效应。这是同样的现象。蝴蝶在印度洋上空拍打着翅膀，可能会影响未来一周北美的天气。”

The idea has been proposed before, but Meyers and his team found supporting evidence in a surprising place: a rock formation in Colorado. The formation is made up of sedimentary layers deposited when a vast inland sea covered parts of North America. These layers contain a record of regularly paced climate changes that were triggered by fluctuations in the amount of sunlight hitting Earth as a result of variations in its orbit.

人们之前就提出过这种想法，但是迈耶斯和他的团队在一个令人惊奇的地方发现了支持的证据：科罗拉多州的岩层。这个岩层是在北美洲还是内陆海时，由于岩层沉积形成的。这些岩层记录了由于地球轨道的变化，引发的太阳光对地球照射的波动，而最终引发的气候变化的一些有规律的节奏。

For at least the last 50 million years or so, Earth’s orbit has cycled between a more circular shape and a more elliptical shape every 2.4 million years, producing climate changes with the same timing. However, by independently dating the rocks in Colorado with other methods, Meyers and his colleagues found that before about 85 million years ago, this cycle took 1.2 million years. The cycle time changed because Mars and Earth tugged on each other—just the kind of thing you would expect to see in a chaotic system. The findings are in the journal Nature.

至少在过去5千万年前，地球的轨道每240万年，就在圆形轨道和椭圆形轨道之间变换，而气候变化也在同样的时间产生。然而，通过对科罗拉多州岩石的进行单独的时间追溯，迈耶斯和他的同事们发现，在大约850万年前，这个循环耗费了大约120万。循环的时间变了，因为火星和地球在相互拖拽——这就是在一个混沌的系统中会发生的。该研究结果发表在《自然》杂志上。

Meyers says the results have several implications. One is that they will help scientists to date ancient rocks and understand the link between orbital changes and climate. But the other potential implication is somewhat more disturbing: billions of years from now, there’s a very small chance that Mars could crash into Earth.

迈尔斯表示，这样的结果有多重的含义。其中一个就是，这可以帮助科学家确定古代岩石的时间，同时可以了解轨道变化和气候之间的关系。但是另外一个潜在的含义有些令人不安，那就是在未来的数十亿年，有很小的几率火星会碰撞地球。

“That certainly is a rather dramatic demise to the Earth that would be a consequence of the chaos.”

这可能是混沌后果所导致的地球戏剧性的结果。

But that’s just life—or the end of it—in a chaotic solar system.

但这是生命——或者在混沌的太阳系统中生命的终结。