國家地理:送給外星人的地圖(1)

A half century ago astronomers designed a map that would point to Earth from anywhere in the galaxy. Then they sent it into space, reasoning that any aliens smart enough to intercept a spacecraft could decode the map and uncover its origin. Many movies and TV shows have used variations on this theme as a plot point, but we didn't borrow it from science fiction. It's reality.

半個世紀前，天文學家設計了一幅可以從銀河系任何地方指向地球的地圖。然后他們把這幅地圖發(fā)送至太空，推論任何聰明到能攔截宇宙飛船的外星人，都有能力破解這幅地圖并找出它來自哪里。許多電影和電視節(jié)目都使用了這個主題的變體作為情節(jié)，但我們沒有從科幻小說中借用。這是現(xiàn)實。

Truth is, this tale has been part of my family's lore since before I was born. Growing up, I'd heard stories about the map and seen its depiction on multiple interstellar spacecraft, and several years ago, I found the original, penciled-in pathway to Earth where my parents had stashed it.

事實上，在我出生前，這個故事就已經(jīng)是我家族歷史中的一頁。我在成長過程中聽了關于這幅地圖的故事，也在多艘星際宇宙飛船上看到復制的地圖，在幾年前，我從父母收藏這張地圖的地方挖出這張以鉛筆繪制、通往地球路徑的最早版本。

That was an exciting find! Then came the buzzkill: This original map won't be good for much longer, cosmically speaking. The signposts it uses will disappear within tens of millions of years, and even if they don't, the map would point toward our home for only a fraction of the 200 to 250 million years it takes the sun and other nearby stars to spin once around the Milky Way.

那真是令人興奮！然后掃興的事情來了：以宇宙的時間尺度來說，這幅原始地圖即將失效。它所使用的路標將在千萬年內(nèi)消失，而就算這些路標沒有消失，這幅地圖能指向我們家園的時間，也只占太陽和其他鄰近恒星繞行銀河系一周（約需2億至2億5000萬年）的一小段時間而已。

Sure, the chances of aliens intercepting the map are astronomically improbable -- but if that did happen, an outdated map would be useless rather than helpful. And that wasn't the goal.

當然，外星人攔截到這幅地圖的機會很渺茫，但若真的發(fā)生，一幅過時的地圖將派不上用場。而這并不是本來的目標。