TedTest

From the Ted Talk by David Lunney: Where does gold come from?

Unscramble the Blue Letters

In mvideael times, alchemists tried to aevcihe the seemingly impossible. They wanted to transform lowly lead into gleaming gold. History portrays these polpee as aged eccentrics, but if only they'd known that their dreams were actually achievable. Indeed, today we can mcufatunare gold on Earth thanks to modern ivtoennins that those medieval aschmlteis missed by a few centuries. But to uadesnrtnd how this precious mtael became embedded in our planet to start with, we have to gaze upwards at the stars. Gold is extraterrestrial. Instead of arising from the planet's rkocy crust, it was actually cooked up in space and is present on Earth because of csciayatmlc stellar esxloionps called supernovae. Stars are mostly made up of hydrogen, the simplest and lightest element. The enormous gravitational pressure of so much material compresses and triggers nuclear fusion in the star's core. This process releases energy from the hedryogn, making the star shine. Over many millions of years, fusion transforms hydrogen into heavier elements: helium, carbon, and oxygen, burning subsequent elements faster and faster to reach iron and nickel. However, at that point nuealcr fusion no longer releases enough energy, and the pressure from the core peters out. The outer layers collapse into the cenetr, and bouncing back from this sudden injection of energy, the star explodes forming a surenpvoa. The extreme pressure of a calsolinpg star is so high, that sotubimac ptoorns and encleorts are forced together in the core, forming neutrons. Neutrons have no rillenpeg electric charge so they're easily ctuperad by the iron group elements. Multiple neutron captures enable the formation of heavier elements that a star under namorl circumstances can't form, from silver to gold, past lead and on to uianurm. In extreme contrast to the mliloin 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 explosion? The expanding supernova shockwave propels its elemental dbeirs through the interstellar medium, triggering a siwlnrig dance of gas and dust that condenses into new stars and planets. Earth's gold was likely delivered this way before being kadened into veins by geothermal aticvtiy. Billions of years later, we now extract this piercuos product by mining it, an expensive process that's compounded by gold's rarity. In fact, all of the gold that we've menid in history could be piled into just three Olympic-size siimwmng pools, although this rpesertens a lot of mass because gold is about 20 times desner than water. So, can we produce more of this coveted ctodiommy? Actually, yes. Using particle accelerators, we can mimic the complex nuclear reactions that create gold in stars. But these machines can only construct gold atom by atom. So it would take almost the age of the urisenve to produce one gram at a cost vastly exceeding the current value of gold. So that's not a very good solution. But if we were to rceah 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 20 million tons of dissolved gold but at extremely miniscule concentrations making its rorcevey too costly at present. Perhaps one day, we'll see gold rushes to tap the mineral wealth of the other pnteals of our solar system. And who knows? Maybe some ftuure supernova will occur colse enough to shower us with its treasure and hopefully not eradicate all life on Earth in the poscres.

Open Cloze

In ________ times, alchemists tried to _______ the seemingly impossible. They wanted to transform lowly lead into gleaming gold. History portrays these ______ as aged eccentrics, but if only they'd known that their dreams were actually achievable. Indeed, today we can ___________ gold on Earth thanks to modern __________ that those medieval __________ missed by a few centuries. But to __________ how this precious _____ became embedded in our planet to start with, we have to gaze upwards at the stars. Gold is extraterrestrial. Instead of arising from the planet's _____ crust, it was actually cooked up in space and is present on Earth because of ___________ stellar __________ called supernovae. Stars are mostly made up of hydrogen, the simplest and lightest element. The enormous gravitational pressure of so much material compresses and triggers nuclear fusion in the star's core. This process releases energy from the ________, making the star shine. Over many millions of years, fusion transforms hydrogen into heavier elements: helium, carbon, and oxygen, burning subsequent elements faster and faster to reach iron and nickel. However, at that point _______ fusion no longer releases enough energy, and the pressure from the core peters out. The outer layers collapse into the ______, and bouncing back from this sudden injection of energy, the star explodes forming a _________. The extreme pressure of a __________ star is so high, that _________ _______ and _________ are forced together in the core, forming neutrons. Neutrons have no _________ electric charge so they're easily ________ by the iron group elements. Multiple neutron captures enable the formation of heavier elements that a star under ______ circumstances can't form, from silver to gold, past lead and on to _______. In extreme contrast to the _______ 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 explosion? The expanding supernova shockwave propels its elemental ______ through the interstellar medium, triggering a ________ dance of gas and dust that condenses into new stars and planets. Earth's gold was likely delivered this way before being _______ into veins by geothermal ________. Billions of years later, we now extract this ________ product by mining it, an expensive process that's compounded by gold's rarity. In fact, all of the gold that we've _____ in history could be piled into just three Olympic-size ________ pools, although this __________ a lot of mass because gold is about 20 times ______ than water. So, can we produce more of this coveted _________? Actually, yes. Using particle accelerators, we can mimic the complex nuclear reactions that create gold in stars. But these machines can only construct gold atom by atom. So it would take almost the age of the ________ to produce one gram at a cost vastly exceeding the current value of gold. So that's not a very good solution. But if we were to _____ 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 20 million tons of dissolved gold but at extremely miniscule concentrations making its ________ too costly at present. Perhaps one day, we'll see gold rushes to tap the mineral wealth of the other _______ of our solar system. And who knows? Maybe some ______ supernova will occur _____ enough to shower us with its treasure and hopefully not eradicate all life on Earth in the _______.

Solution

recovery
activity
people
cataclysmic
kneaded
inventions
uranium
process
medieval
represents
collapsing
denser
universe
million
repelling
explosions
swirling
manufacture
future
understand
planets
center
close
metal
normal
subatomic
swimming
achieve
supernova
protons
reach
electrons
hydrogen
precious
commodity
mined
debris
alchemists
captured
nuclear
rocky

Original Text

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 gaze upwards at the stars. Gold is extraterrestrial. 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 explosions called supernovae. Stars are mostly made up of hydrogen, the simplest and lightest element. The enormous gravitational pressure of so much material compresses and triggers nuclear fusion in the star's core. This process releases energy from the hydrogen, making the star shine. Over many millions of years, fusion transforms hydrogen into heavier elements: helium, carbon, and oxygen, burning subsequent 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 injection of energy, the star explodes forming a supernova. The extreme pressure of a collapsing star is so high, that subatomic protons and electrons are forced together in the core, forming neutrons. Neutrons have no repelling electric charge so they're easily captured by the iron group elements. Multiple 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 extreme 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 explosion? The expanding supernova shockwave propels its elemental debris through the interstellar medium, triggering a swirling dance of gas and dust that condenses into new stars and planets. Earth's gold was likely delivered this way before being kneaded into veins by geothermal activity. Billions of years later, we now extract this precious product by mining it, an expensive process that's compounded by gold's rarity. In fact, all of the gold that we've mined in history could be piled into just three Olympic-size swimming pools, although this represents a lot of mass because gold is about 20 times denser than water. So, can we produce more of this coveted commodity? Actually, yes. Using particle accelerators, we can mimic the complex nuclear reactions that create gold in stars. But these machines can only construct gold atom by atom. So it would take almost the age of the universe to produce one gram at a cost vastly exceeding the current value of gold. So 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 20 million tons of dissolved gold but at extremely miniscule concentrations making its recovery too costly at present. Perhaps one day, we'll see gold rushes to tap the mineral wealth of the other planets of our solar system. And who knows? Maybe some future supernova will occur close enough to shower us with its treasure and hopefully not eradicate all life on Earth in the process.

Frequently Occurring Word Combinations

ngrams of length 2

collocation	frequency
nuclear fusion	2

Important Words

accelerators
achievable
achieve
activity
age
aged
alchemists
arising
atom
billions
bouncing
buried
burning
called
captured
captures
carbon
cataclysmic
center
centuries
charge
circumstances
close
collapse
collapsing
commodity
complex
compounded
compresses
concentrations
condenses
construct
contrast
cooked
core
cost
costly
coveted
create
creation
crust
current
dance
day
debris
delivered
denser
dissolved
dreams
dust
earth
easily
eccentrics
electric
electrons
element
elemental
elements
embedded
enable
energy
enormous
eradicate
estimated
exceeding
expanding
expensive
explodes
explosion
explosions
extract
extraterrestrial
extreme
extremely
fact
faster
forced
form
formation
forming
fusion
future
gas
gaze
geothermal
gleaming
gold
good
gram
gravitational
group
heavier
heaviest
helium
high
history
holds
hydrogen
hypothetical
impossible
injection
interstellar
inventions
iron
kneaded
layers
lead
life
lightest
longer
lot
lowly
machines
making
manufacture
mass
material
medieval
medium
metal
million
millions
mimic
mined
mineral
mining
miniscule
missed
modern
multiple
neutron
neutrons
nickel
normal
nuclear
occur
ocean
outer
oxygen
particle
people
peters
piled
place
places
planet
planets
point
pools
portrays
precious
present
pressure
process
produce
product
propels
protons
rarity
reach
reactions
recovery
releases
repelling
represents
rocky
rushes
seconds
seemingly
shine
shockwave
shower
silver
simplest
solar
solution
space
star
stars
start
stellar
subatomic
subsequent
sudden
supernova
supernovae
swimming
swirling
system
takes
tap
times
today
tons
transform
transformation
transforms
treasure
triggering
triggers
understand
universe
uranium
vastly
veins
wanted
water
wealth
year
years