Just now, somewhere in the universe, a star exploded. There goes another one.
刚刚，在宇宙的某一处，就有一颗恒星爆炸了。接着，又有一颗爆炸了。
In fact, a supernova occurs every second or so in the observable universe,
事实上，每秒种都有超新星，在巨大的宇宙里，
and there is one on average every 25 to 50 years in a galaxy the size and age of the Milky Way.
每25至50年就会产生似银河系大小和年龄的星系。
Yet we've never actually been able to watch one happen from its first violent moments.
然而，我们从没机会目睹爆炸的瞬间。
Of course, how would we?
当然，这怎么可能呢？
There are hundreds of billions of stars close enough that we could watch the supernova explosion break through the surface of the star.
有上千亿颗恒星在我们可观察到的范围内演变超新星爆炸。
But we'd have to have our best telescopes focused on the right one at precisely the right time to get meaningful data.
但真正去取得有力的数据，首先需要一台先进望远镜，以及它精准的对焦与时间的拿捏。
Suffice it to say, the odds of that happening are astronomically low.
可以这么说，这种情况发生的几率非常低。
But what if we could anticipate a supernova before its light reached us? That may seem impossible.
或许，我们可以尝试在光线传达到地球前预测超新星的发生？这听起来不可能。
After all, nothing travels faster than the speed of light, right?
毕竟，没有力量可以超越光速，不是吗？
As far as we know, yes.
据我们所知，确实没有。
But in a race, fast doesn't matter if you take a detour while someone else beelines it for the finish line.
不过在竞赛中，速度不代表一切，相比绕路，走直径才能胜出。
For exactly that reason, photons don't win the supernova race to Earth. Neutrinos do.
同样的道理，最早往地球传达超新星的不是光子，而是中微子。
Here's why. There are two types of supernova.
这就是原因。超新星分为两类。
Type 1 is when a star accumulates so much matter from a neighboring star,
第一类是当一颗恒星从周围累积足够的物质后，
that a runaway nuclear reaction ignites and causes it to explode.
失控核反应启动并致其爆炸。
In type 2, the star runs out of nuclear fuel,
在第二类中，恒星耗尽核燃料，
so the gravitational forces pulling in overwhelm the quantum mechanical forces pushing out,
所以引力的作用压倒了量子力学的作用，
and the stellar core collapses under its own weight in a hundredth of a second.
使恒星的内核因自身重量的压力在百分之一秒内崩塌。
While the outer reaches of the star are unaffected by the collapsed core,
虽然星系的外围不受内部的影响，
the inner edges accelerate through the void, smash into the core, and rebound to launch the explosion.
但内缘在孔隙巨洞不断加速，直到核心受到重击，而以此爆炸。
In both of these scenarios, the star expels an unparalleled amount of energy, as well as a great deal of matter.
在这两类情况下，恒星将排出前所未有的能量以及大量物质。

In fact, all atoms heavier than nickel, including elements like gold and silver, only form in supernova reactions.
实际上，所有比镍重的原子，包括金和银，只能在超新星爆炸中诞生。
In type 2 supernovae, about 1% of the energy consists of photons, which we know of as light,
在第二类超新星中，大约1%的能量是由光子组成的，也就是我们所说的光，
while 99% radiates out as neutrinos, the elementary particles that are known for rarely interacting with anything.
而其中的99%以中微子放射，它们的基本粒子很少交涉。
Starting from the center of the star, the exploding matter takes tens of minutes, or even hours,
从恒星的中央，爆炸物需要数分钟，或数小时，
or in rare cases, several days, to reach and break through the surface of the star.
甚至有些时候花几天时间来抵达和突破恒星的表层。
However, the neutrinos, thanks to their non-interactivity, take a much more direct route.
相比之下，中微子的非交互性质促使它们选择更快的直径线路。
By the time there is any visible change in the star's suface,
在恒星表面发生明显变化前，
the neutrinos typically have a several hour head start over the photons.
中微子就比光子占有时间上的优势。
That's why astronomers and physicists have been able to set up a project called SNEWS, the Supernova Early Warning System.
这就是为什么天文学家与物理学家建立了SNEWS项目，全称超新星早期预警系统。
When detectors around the world pick up bursts of neutrinos, they send messages to a central computer in New York.
当探测器检测到微中子的存在时，这些信息将被传输到位于纽约的中央计算机。
If multiple detectors receive similar signals within ten seconds,
如果多个探测器在十秒内同时检测到信号，
SNEWS will trigger an alert warning that a supernova is imminent.
SNEWS会启动超新星爆炸警报。
Aided by some distance and direction information from the neutrino detectors,
从微中子探测器提供的距离、方向等信息里，
the amateur astronomers and scientists alike will scan the skies and share information
业余的天文学家以及科学家可通过扫描天空以及分享资料
to quickly identify the new galactic supernova and turn the world's major telescopes in that direction.
从而快速识别新的超新星，并且将世界最高级的望远镜转到那个方向。
The last supernova that sent detectable neutrinos to Earth was in 1987
在1987年最新探测到往地球发送中微子的超新星，
on the edge of the Tarantula Nebula in the large Magellanic Cloud, a nearby galaxy.
在大麦哲伦星云狼蛛星云边缘附近的一个星系。
Its neutrinos reached Earth about three hours ahead of the visible light.
这些中微子比可见光提前三小时抵达地球。
We're due for another one any day now, and when that happens,
现在，随时都有可能发生超新星爆炸，而当它发生的时候，
SNEWS should give you the opportunity to be among the first to witness something that no human has ever seen before.
SNEWS将给你一个千载难逢的机遇，来见证人类从未见过的场景。