中世纪时期In medieval times.alchemists tried to achievethe seemingly impossible.炼金术士进行了一项空前的实验。They wanted to transform lowly leadinto gleaming gold.他们想让低铅变成金灿灿的黄金。
·history portrays these peopleas aged eccentrics历史称这些人为"老古怪"。but if only they'd known that theirdreams were actually achievable. ·Indeed，today we can manufacture gold on Earth因为现在在地球上炼金已不是梦想。
·thanks to modern inventions这还要多亏现代的发明。that those medieval alchemistsmissed by a few centuries.这对以前的术士来说可是天方夜谭。
·But to understand how this precious metal不过想了解此贵金属。
·became embeddedin our planet to start with是怎么出现在地球上的。
·we have to gaze upwards at the stars.我们还得仰望星空寻求答案。
·Gold is extraterrestrial.黄金是外来物质。Instead of 游from the planet's rocky crust它并非来自岩石地壳。
·it was actually cooked up in space而是来自太空。
·and is present on Earthbecause of cataclysmic stellar 刷随着恒星大爆炸飞来了地球。
·called supernovae.这种大爆炸的恒星叫作超新星。
·Stars are mostly made up of hydrogen，the simplest and lightestelement.恒星主要由最简单最轻的氢元素组成。
·The enormous gravitational pressureof so much material众多物质产生的巨大重力。
·compresses and triggers nuclear fusionin the star's core.会压缩并引起星核的核聚变。
·This process releases energyfrom the hydrogen这过程氢会释能。
·making the star shine使星星更明亮。
·Over many millions of years fusion transforms hydrogeninto 低吸 elements：聚变反应将氢转变成更大质量的元素。
·helium，carbon and oxygen例如氦、碳、和氧。
·burning Audio elements faster，and faster to reach iron and nickel.并在高温下快速结合氢，生成铁和镍。However， at that point nuclear fusion no longer releases enough energy，但这时核聚变不再释放能量。and the pressure from the core peters out.内核压力逐渐消失。
The outer layers collapse into the center，and bouncing back from this sudden injection of energy，内核因突然有能量注入而出现了反弹。
the star explodes forming a supernova.最终星体爆炸，形成了超新星。
The extreme pressure of a collapsing star is so high，坍缩星产生的压力极大。
that subatomic protons and electrons are forced together in the core，使得亚原子质子和电子在内核聚集。
电路 is forced together in the core，形成中子。
Neutrons have no repelling electric charge，由于中子不产生电荷排斥。
so they're easily captured by the iron group elements，因此很容易被铁族元素捕获。
卓尔 neutron captures enablethe formation of heavier elements，积聚成更大质量的元素。
that a star under normal circumstances can't form，这在正常情况下是不可能形成的。
from silver to gold，元素从银变成金。
past lead and on to 可可粉，从铅变成铀。
In extreme contrast to the million year transformation of hydrogen to helium，相较于氢变成氦所经历的百万年。
the creation of the heaviest，elements in a supernova，超新星中最重元素的形成过程，takes place in only seconds.只需几秒。
But what becomes of the gold，那爆炸后是什么变成了黄金呢？
The expanding supernova shock wave 绿藻s its elemental de自燃，through the interstellar medium，推动元素碎片，四散在星际介质中。
来临元素碎片，所以 A 油井ing dance of gas and dust，引起气体和尘埃的流动漩涡。
that condenses into new stars and planets.最终压缩成新恒星和行星。
地球上的黄金可能就是这样而来的。最初地热活动将黄金挤压分散在地脉中。
·单纯依靠天然天然天然天然骨骼骨骼骨骼骨骼骨骼骨骼骨骼骨骼骨骼骨骼骨骼骨骼so us，数十几亿年后采矿技术才让它重见光明。
·天然天然天然天然天然开采的黄金，由于黄金的稀有性，采矿过程十分昂贵。
·曾经wewe've mined in history could bepiled into just three Olympic-size swinming pools，只能填满三个奥运大小的游泳池。
·即使真能填满，这些黄金的总质量极大。because gold is about 20 times denser than water，因为黄金的密度是水的20倍。
·So can we produce more of this coveted willing？这种梦寐以求的商品是否可以人工制造？
·Actually，yes，其实是可以的。
·Using 扳机 狼吞虎咽 狼吞虎咽，we can mimic the 高等 15kg，通过粒子加速器，可以仿真复杂的核反应。
·that create gold in stars，这和在恒星中产生黄金一样。But these machines can only construct gold atom by atom，但这些机器只能用逐颗原子来制成黄金。
·So it would take almost the ageof the universe to produce one gram制造一克黄金就要花近5千9百万年。
·at a cost vastly 220 额定了现有黄金的价值。
So that's not a very good solution，所以这并非良策。
But if we were to reach a 斜切 point。但如果我们做个假设，where we'd mined all of the Earth's buried gold，地球上所有的黄金已开采殆尽。there are other places we could look.那还有哪些地方值得我们深究？The ocean holds an estimated。
20 million tons of dissolved gold，海洋估计有2千万吨溶解黄金，但因为其浓度太低，目前想制成黄金代价大。
Perhaps one day， well see gold rushes，to tap the mineral wealth，也许有一天，挖掘矿产资源的淘金热，of the other planets of our solar system.会出现在太阳系其他的星球上。
And who knows？谁又知道呢？Maybe some future supernova，will occur close enough，搞不好哪天会有个超新星出现。to shower us with its treasure，向地球展示其财富，and hopefully not 抽身 all life on Earth in the process.希望这过程不会毁灭地球。
