7/26/2019 In Medieval Times

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In medieval times,

alchemists tried to achieve the seemingly impossible.

They wanted to transform lowly lead into gleaming gold.History portrays these people as aged eccentrics,

but if only they'd known that their dreams were actually achievable.

Indeed, today we can manufacture gold on Earth

thanks to modern inventions

that those medieval alchemists missed by a few centuries.But to understand how this precious metal

became embedded in our planet to start with,

we have to gae upwards at the stars.

!old is e"traterrestrial.

Instead of arising from the planet's rocky crust,it was actually cooked up in space

and is present on Earth because of cataclysmic stellar e"plosions

called supernovae.

#tars are mostly made up of hydrogen, the simplest and lightest element.

The enormous gravitational pressure of so much materialcompresses and triggers nuclear fusion in the star's core.

This process releases energy from the hydrogen,

making the star shine.

$ver many millions of years,

fusion transforms hydrogen into heavier elements%helium, carbon, and o"ygen,

burning subse&uent elements faster and faster to reach iron and nickel.

However, at that point nuclear fusion no longer releases enough energy,

and the pressure from the core peters out.

The outer layers collapse into the center,and bouncing back from this sudden inection of energy,

the star e"plodes forming a supernova.The e"treme pressure of a collapsing star is so high,

that subatomic protons and electrons are forced together in the core,

forming neutrons.(eutrons have no repelling electric charge

so they're easily captured by the iron group elements.

)ultiple neutron captures enable the formation of heavier elements

that a star under normal circumstances can't form,

from silver to gold,past lead and on to uranium.

In e"treme contrast to the million year transformation of hydrogen to helium,

the creation of the heaviest elements in a supernova

takes place in only seconds.

But what becomes of the gold after the e"plosion*The e"panding supernova shockwave propels its elemental debris

through the interstellar medium,

triggering a swirling dance of gas and dustthat condenses into new stars and planets.

Earth's gold was likely delivered this waybefore being kneaded into veins by geothermal activity.

Billions of years later, we now e"tract this precious product by mining it,

an e"pensive process that's compounded by gold's rarity.

In fact, all of the gold that we've mined in history

could be piled into ust three $lympic+sie swimming pools,although this represents a lot of mass

because gold is about - times denser than water.

#o, can we produce more of this coveted commodity*

ctually, yes.

/sing particle accelerators, we can mimic the comple" nuclear reactionsthat create gold in stars.

But these machines can only construct gold atom by atom.

#o it would take almost the age of the universe to produce one gram

at a cost vastly e"ceeding the current value of gold.

#o that's not a very good solution.But if we were to reach a hypothetical point

where we'd mined all of the Earth's buried gold,

there are other places we could look.

The ocean holds an estimated - million tons of dissolved gold

but at e"tremely miniscule concentrations making its recovery too costly atpresent.

0erhaps one day, we'll see gold rushes to tap the mineral wealth

of the other planets of our solar system.

nd who knows*

to shower us with its treasureand hopefully not eradicate all life on Earth in the process.

En la Edad )edia,

los al&uimistas trataron de llegar a lo &ue parec1a imposible.

2uer1an transformar el humilde plomo en oro reluciente.3a historia retrata a estas personas como vieos e"c4ntricos,

&ue nunca llegaron a ver sus sue5os hechos realidad.

0ero de hecho, hoy podemos fabricar oro en la Tierra

gracias a inventos modernos

a los &ue los al&uimistas medievales no tuvieron acceso durante siglos.0ara entender c6mo este metal precioso

apareci6 antes &ue todo, incrustado en nuestro planeta,

tenemos &ue mirar hacia arriba en las estrellas.

El oro es e"traterrestre.

En lugar de &ue sura de la cortea rocosa del planeta,en realidad fue cocinado en el espacio

y est7 presente en la Tierra a causa de e"plosiones estelares violentas

llamadas supernovas.

3as estrellas se componen principalmente de hidr6geno,

el elemento m7s simple y ligero.3a enorme presi6n gravitacional causada por dicho elemento

comprime y desencadena una fusi6n nuclear en el n8cleo de la estrella.

Este proceso libera energ1a del hidr6geno,

lo hace brillar la estrella.

9urante muchos millones de a5os,la fusi6n convierte el hidr6geno en elementos m7s pesados%

helio, carbono y o"1geno,

y &uema otros elementos cada ve m7s r7pido hasta llegar al hierro y n1&uel.

#in embargo, la fusi6n nuclear llegada a este punto ya no libera suficiente

energ1a y la presi6n del n8cleo se apaga.3as capas e"ternas colapsan hac1a el interior,

y recuperada ef1meramente de esta repentina inyecci6n de energ1a,la estrella e"plota formando una supernova.

la presi6n e"terna de una estrella en disoluci6n es tan alta,

&ue los protones y los electrones subat6micos se meclan en el n8cleo,formando neutrones.

3os neutrones no tienen carga el4ctrica

&ue una estrella en circunstancias normales no ser1a capa de formar,

desde la plata al oro,

pasando por el plomo hasta el uranio.:rente a los millones de a5os necesarios

para &ue el hidr6geno se transforme en helio,

la creaci6n de los elementos m7s pesados en una supernova

se producen en cuesti6n de segundos.

;0ero &u4 pasa con el oro despu4s de la e"plosi6n*3a onda de cho&ue de la supernova en e"pansi6n

emite los restos de los elementos a trav4s del medio interestelar,

desencadenando un remolino de gas y polvo&ue se condensa en nuevas estrellas y planetas.

0robablemente el oro terrestre lleg6 de la misma maneraantes de ser amasado en venas por la actividad geot4rmica.

)iles de millones de a5os m7s tarde,

e"traemos este metal precioso a trav4s de la miner1a,

un proceso costoso compensado por la rarea de oro.

9e hecho, todo el oro e"tra1do en la historiapodr1a apilarse en solo tres piscinas ol1mpicas,

aun&ue esto representa una gran cantidad de masa

ya &ue el oro es - veces m7s denso &ue el agua.

s1 &ue, ;podemos producir m7s de este codiciado producto*

En realidad, s1.

7/26/2019 In Medieval Times

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