What’s That in the Sky?
不明飛行物
In his book Cosmos, the late scientist Carl Sagan talks about the way in which the earth is regularly struck by material from outer space. These collisions with space debris can be minor–as in a shooting star on a summer night–or amazingly destructive, as in the collision that probably killed off the dinosaurs. Thankfully, the biggies are extremely rare.
Sagan makes the point that the most dangerous collision facing us now, however, is one that might be mistaken for something else: a nuclear attack. He warned that thinking an asteroid is actually an ICBM could result in the worst possible destruction–an unintended war.
Was this just paranoid thinking? Unfortunately, no. Carl Sagan is no longer with us, but in testimony before congress just last year, a United States Air Force brigadier general warned that just such a thing almost happened in June of two thousand and two. That’s when a meteoroid entered the earth’s atmosphere over the Mediterranean and was picked up by U.S. early-warning satellites on the lookout for high-altitude explosions and incoming missiles.
The alarming object falling from the sky was recognized for what it was, this time. The generals’ point, though, was that we never know where space junk will fall. Turn the globe by just a few hours earlier on that day in June and the meteoroid would have been over the border of Pakistan and India–exactly where everyone was fearing a nuclear attack.
We’ve been lucky so far. But Carl Sagan’s warning came perilously close to becoming a prophecy and a harmless natural event in the sky, to triggering a terrible event here on earth.
已故科學(xué)家卡爾·薩根在著作《宇宙》中敘述了外太空物體如何有規(guī)律和地球發(fā)生碰撞。太空垃圾和地球碰撞的機(jī)率很小,就像夏夜劃過(guò)流星,破壞性卻很大,這種碰撞可以令恐龍滅絕。值得慶幸的是,這種機(jī)率太渺茫了。
薩根闡述的觀(guān)點(diǎn)是目前我們面臨的最危險(xiǎn)的是碰撞而非人們誤解的核戰(zhàn)。他提醒人們,事實(shí)上,行星就像洲際彈道導(dǎo)彈,可能產(chǎn)生意料外破壞性極大的戰(zhàn)爭(zhēng)后果。
這僅僅是偏執(zhí)思維嗎?不幸地是,無(wú)獨(dú)有偶。去年(本文發(fā)表于2003年),一位美過(guò)空軍準(zhǔn)將在國(guó)會(huì)的一份證詞中稱(chēng)類(lèi)似的事情發(fā)生在2002年6月。美國(guó)預(yù)警衛(wèi)星在監(jiān)測(cè)高空爆炸物和來(lái)襲導(dǎo)彈時(shí)發(fā)現(xiàn)一顆流星穿破地球大氣層,降落在地中海地區(qū)。
而這次人們確認(rèn)從天而降令人惶恐的物體究竟是什么。準(zhǔn)將指出我們無(wú)法確定太空垃圾降落在什么地方。如果六月的這天,地球轉(zhuǎn)動(dòng)退回到幾小時(shí)前,流星降落的地方就正好是巴基斯坦和印度的交界處,世人唯恐發(fā)生核戰(zhàn)的交界地。
迄今為止,我們都還很幸運(yùn)。但是,卡爾·薩根的提醒很可能是可怕的預(yù)言,本來(lái)平常的天空自然事件很可能引發(fā)地球?yàn)?zāi)難。