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.

我們通常想象外星人住在繞着遙遠的恆星運行,隱約像地球的行星上. 我們一般不會認爲他們住在太空之中.

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.

但或許這並非荒謬的想法. 2016年4月, 研究人員報告說, 關鍵的生命構件中, 有些可以從模仿星際空間的惡劣環境裏存在的簡單物質中產生.

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.

法國尼斯大學的科妮莉亞.邁納特及其同事證明, 凍水, 甲醇和氨氣的混合物受到瀰漫太空的紫外線照射時,可轉化爲各式各樣的糖分子. 衆所周知, 所有這些化合物存在於浩翰的“分子云”中– 恆星從“分子云”中形成. 糖中包含核糖, 核糖是脫氧核糖核酸(DNA)樣分子核糖核酸(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.

這表明, 基本的生命分子或可在外太空形成, 然後由結冰的彗星和流星傳送至地球這樣的行星.

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?

這個發現暗示了一種有趣的可能性. 生命本身可能並不需要沐浴在陽光中的溫暖舒適的星球才能開始. 如果生命的原材料已然存在於星際間的過渡狀態, 那麼生命或許也從那兒開始的?

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.

有關生命起源的思想常常未予考慮這個場景. 要弄清生命在早期地球是如何開始的已經夠難了, 更別說在接近絕對零度和星際空間近乎真空的情況下了. 製造糖類和氨基酸等基本的生命構件是較容易的部分. 從早期的太陽系中發現的簡單分子入手, 有很多種化學上可行的辦法可以做到這一點.

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.

難點在於使這些複雜的分子組配成能夠進行復制和代謝等過程的物質. 沒人在溫暖的岩石行星的滋養環境中做過這個, 或提出完全可行的實現方法, 更別說是在星際空間了.