外太空最黑暗的真空中是否有生命(上)

We generally imagine aliens on a vaguelyEarth-like planet circling a distant star. We do not normally think of themliving out in space itself.

我们通常想象外星人住在绕着遥远的恒星运行,隐约像地球的行星上. 我们一般不会认为他们住在太空之中.

But maybe that is not such a ridiculousidea. In April 2016, researchers reported that some of the key building blocksof life can be produced from simple substances under harsh conditions mimickingthose of interstellar space.

但或许这并非荒谬的想法. 2016年4月, 研究人员报告说, 关键的生命构件中, 有些可以从模仿星际空间的恶劣环境里存在的简单物质中产生.

Cornelia Meinert at the University of Nice,France and colleagues showed that a mixture of frozen water, methanol andammonia – all compounds known to exist in the vast "molecular clouds"from which stars form – can be transformed into a wide range of sugar moleculeswhen exposed to ultraviolet rays, which pervade space. The sugars includedribose, which is a part of the DNA-like molecule RNA.

法国尼斯大学的科妮莉亚.迈纳特及其同事证明, 冻水, 甲醇和氨气的混合物受到弥漫太空的紫外线照射时,可转化为各式各样的糖分子. 众所周知, 所有这些化合物存在于浩翰的“分子云”中– 恒星从“分子云”中形成. 糖中包含核糖, 核糖是脱氧核糖核酸(DNA)样分子核糖核酸(RNA)的一部分.

This suggests that the fundamentalmolecules of life might be formed in outer space, and then delivered to planetslike Earth by icy comets and meteorites.

这表明, 基本的生命分子或可在外太空形成, 然后由结冰的彗星和流星传送至地球这样的行星.

The finding points to an intriguingpossibility. Life itself might not have needed a warm and comfortable planetbathed in sunlight to get going. If the raw ingredients were already out therein interplanetary limbo, might life have started there too?

这个发现暗示了一种有趣的可能性. 生命本身可能并不需要沐浴在阳光中的温暖舒适的星球才能开始. 如果生命的原材料已然存在于星际间的过渡状态, 那么生命或许也从那儿开始的?

Ideas about the origins of life do notoften consider this scenario. It is hard enough to figure out how life couldhave begun on the early Earth, let alone at temperatures close to absolute zeroand the near vacuum of interstellar space. Making the basic building blocks oflife, like sugars and amino acids, is the easy part. There are lots ofchemically plausible ways to do that, starting with the simple molecules foundin young solar systems.

有关生命起源的思想常常未予考虑这个场景. 要弄清生命在早期地球是如何开始的已经够难了, 更别说在接近绝对零度和星际空间近乎真空的情况下了. 制造糖类和氨基酸等基本的生命构件是较容易的部分. 从早期的太阳系中发现的简单分子入手, 有很多种化学上可行的办法可以做到这一点.

The hard bit is persuading thesecomplicated molecules to assemble into something capable of life-sustainingprocesses like replication and metabolism. Nobody has ever done this, or comeup with a completely plausible way it might happen, in the nurturing environmentof a warm, rocky planet –let alone in space.

难点在于使这些复杂的分子组配成能够进行复制和代谢等过程的物质. 没人在温暖的岩石行星的滋养环境中做过这个, 或提出完全可行的实现方法, 更别说是在星际空间了.