也許外星人就在我們身邊，只是我們看不到而已

What if alien spacecraft are already in our midst – and we don't know about them because they're tiny nano-structures? That's the new idea put forward by one scientist seeking to explain the Fermi paradox.

如果外星人的太空船已經(jīng)來到我們?nèi)祟愔虚g，而我們卻不知道它們，因?yàn)樗鼈兪俏⑿〉募{米結(jié)構(gòu)呢?這是一位試圖解釋費(fèi)米悖論的科學(xué)家提出的新觀點(diǎn)。

This paradox – named after Italian-American physicist Enrico Fermi – posits that because the Milky Way is so vast and so old, the chances of alien civilisations being out there is actually pretty high... so where are they?

這一悖論——以意大利裔美國(guó)物理學(xué)家恩里科·費(fèi)米的名字命名——提出了這樣一個(gè)假設(shè):由于銀河系如此浩瀚而古老，外星文明存在的幾率實(shí)際上相當(dāng)高……那么他們?cè)谀睦锬?

Maybe they're buzzing around the Universe in micro-machines just a nanometre long, suggests astrophysicist Zaza Osmanov from the Free University of Tbilisi in Georgia. What's more, he's provided some pretty detailed calculations to go along with this slightly whacky-sounding idea.

來自格魯吉亞第比利斯自由大學(xué)的天體物理學(xué)家扎扎·奧斯馬諾夫認(rèn)為，也許它們是在一納米長(zhǎng)的微型機(jī)器里繞著宇宙飛行。更重要的是，他提供了一些非常詳細(xì)的計(jì)算，以配合這個(gè)聽起來有點(diǎn)古怪的想法。

Now it's worth mentioning that Osmanov's paper has yet to be peer-reviewed, so we can't place too much importance on it just yet – but it does open up an intriguing possibility about how other civilisations might one day reach us.

現(xiàn)在值得一提的是，奧斯馬諾夫的論文還沒有經(jīng)過同行評(píng)議，所以我們目前還不能把它放在太重要的位置——但它確實(shí)為我們提供了一個(gè)有趣的可能性，即有一天其他文明可能會(huì)如何影響我們。

The new study is based on the established idea of von Neumann probes: the thinking goes that aliens could send out self-replicating spacecraft to explore the galaxies, without having to risk leaving their home planet themselves.

這項(xiàng)新研究基于馮·諾依曼探測(cè)器的既定理念:外星人可以發(fā)射自我復(fù)制的宇宙飛船去探索星系，而不必冒險(xiǎn)離開自己的星球。

Previous attempts to figure out how von Neumann probes could function have hit a common problem – self-replication needs a steady supply of new materials, and it's not clear if deep space has enough suitable planets or rocky bodies to go around.

先前試圖找出馮·諾依曼探測(cè)器如何工作的嘗試遇到了一個(gè)共同的問題——自我復(fù)制需要穩(wěn)定的新材料供應(yīng)，目前還不清楚深空是否有足夠合適的行星或巖石體環(huán)繞。

To get around the issue, Osmanov has shrunk the scale right down. Microscopic probes would need much less in the way of materials, and could rely on hydrogen atoms floating through the interstellar dust for power.

為了解決這個(gè)問題，奧斯曼諾夫?qū)⒁?guī)模定位微型。微型探測(cè)器在材料方面的需求要少得多，而且可以依靠漂浮在星際塵埃中的氫原子來獲取能量。

These nanoscale probes would, in theory, be much more efficient than any previously imagined, and could replicate in just a few years – getting around the Universe relatively quickly. They'd also become very numerous (up to the level of trillions of billions) in a few short light-years of steady reproduction.

從理論上講，這些納米級(jí)的探測(cè)器比之前想象的要高效得多，而且可以在短短幾年內(nèi)進(jìn)行復(fù)制——以相對(duì)較快的速度環(huán)繞宇宙。它們也會(huì)在幾光年的穩(wěn)定繁殖中變得非常多(達(dá)到幾萬(wàn)億級(jí))。