《那些古怪又让人忧心的问题》第77期:致命中微子(2)
Similarly, it's hard to produce enoughneutrinos to get even a single one of them to interact with matter; it'sstrange to imagine a scenario in which there'd be enough of them to hurt you.
同样，你甚至都难以制造出足够多的中微子让它们中哪怕只有一个和物质发生反应，要想象在什么样的场景下会有足以对你造成伤害的中微子就更难了。
Supernovae provide that scenario. tor, the Hobart and William Smith Colleges physicist who asked me thisquestion, told me his rule of thumb for estimating supernova-related numbers:However big you think supernovae are, they're bigger than that.
但超新星能够提供这样的场景。问我这个问题的霍巴特和威廉姆史密斯学院的物理学家斯佩克特博士告诉我，他推测和超新星相关的数字时的经验法则是：不管你认为超新星有多大，它们其实比你以为的更大。
Here's a question to give you a sense ofscale. Which of the following would be brighter, in terms of the amount ofenergy delivered to your retina:
让我给大家直观地比较一下。按照你的视网膜所接收到的能量来算，以下两者哪个更亮：
A supernova, seen from as far away as theSun is from the Earth, or the detonation of a hydrogen bomb pressed againstyour eyeball?
在一个日地距离以外观看一颗超新星，还是在你眼珠前爆炸的氢弹？
Can you hurry up and set it off? This isheavy.
求你快点引爆这个炸弹吧，它太重了。
Applying Dr. Spector's rule of thumbsuggests that the supernova is brighter. And indeed, it is . . . by nine ordersof magnitude.
运用那位物理学家的经验法则可知，超新星更亮一些。其实它们差了……整整9个数量级。
That's why this is a neatquestion-supernovae are unimaginably huge and neutrinos are unimaginablyinsubstantial. At what point do these two unimaginable things cancel out toproduce an effect on a human scale?
这也正是这个问题的优雅之处所在：超新星巨大到难以想象，而中微子又飘渺到难以想象。在哪个距离上这两个难以想象的事情会相互抵消，并对人体产生影响？
A paper by radiation expert Andrew Karamprovides an answer. It explains that during certain supernovae, the collapse ofa stellar core into a neutron star, 1057 neutrinos can be released (one forevery proton in the star that collapses to become a neutron).
辐射专家安德鲁•卡拉姆的一篇论文给出了答案。这篇论文指出，在某些超新星核心坍缩成中子星的过程中会放出多达1057个中微子。（每个发生坍缩的质子都会放出一个中微子。）
Karam calculates that the neutrinoradiation dose at a distance of 1 parsec would be around half a nanosievert, or1/500th the dose from eating a banana.
卡拉姆计算出在1秒差距距离上的中微子辐射剂量约为0.5纳西弗，也就是吃一根香蕉所受辐射的1/500。
A fatal radiation dose is about 4 g the inverse-square law, we can calculate the radiation dose:
致命剂量的辐射量约为4西弗。利用平方反比律，我们可以计算出辐射剂量：
That's a little more than the distancebetween the Sun and Mars.
2.3个天文单位比太阳和火星之间的距离要远那么一点。
Core-collapse supernovae happen to giantstars, so if you observed a supernova from that distance, you'd probably beinside the outer layers of the star that created it.
发生核心坍缩的超新星此前都是巨大的恒星，因此如果你在那个距离观看超新星，那么你将位于恒星的外层内部。
