full transcript

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

Unscramble the Blue Letters

In medieval times, alchemists tried to achieve the seemingly impossible. They wanted to transform lwloy lead into gleaming gold. History portrays these people as aged eccentrics, but if only they'd known that their dreams were actually acbevahile. Indeed, tadoy we can maauurcntfe gold on Earth thanks to mdreon inventions that those medieval alchemists missed by a few centuries. But to understand how this precious metal became eemebddd in our plaent to start with, we have to gaze upwards at the stars. Gold is extraterrestrial. Instead of arising from the planet's rocky csrut, it was actually cooked up in sacpe and is present on Earth because of cataclysmic stellar explosions cllaed supernovae. Stars are mostly made up of hydrogen, the simplest and lightest element. The enormous gravitational pressure of so much material compresses and tirgegrs nuclear fsiuon in the star's core. This porcses 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 raech iron and nkicel. 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 psrsruee of a collapsing star is so high, that sobuitamc protons and electrons are frceod together in the core, forming neutrons. Neutrons have no repelling elicretc cahgre so they're easily cpeartud by the iron gurop elements. Multiple neutron cpauerts elnabe the formation of heavier elements that a star under normal circumstances can't form, from selivr 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 scdoens. But what becomes of the gold after the explosion? The exnnadpig supernova shockwave peprlos its elemntael 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 aiitcvty. Billions of years later, we now extract this pcioures 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 pirtlcae arrcacteleos, we can mimic the complex nuclear reactions that cteare 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 edcxeineg the current value of gold. So that's not a very good suloiotn. 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 hlods an estimated 20 million tons of dlosviesd gold but at extremely miniscule concentrations making its recovery too costly at present. Perhaps one day, we'll see gold resuhs to tap the mineral weatlh of the other planets of our solar system. And who knows? Maybe some future svpnuoera will occur close enough to shower us with its treasure and hopefully not eradicate all life on Earth in the process.

Open Cloze

In medieval times, alchemists tried to achieve the seemingly impossible. They wanted to transform _____ lead into gleaming gold. History portrays these people as aged eccentrics, but if only they'd known that their dreams were actually __________. Indeed, _____ we can ___________ gold on Earth thanks to ______ inventions that those medieval alchemists missed by a few centuries. But to understand how this precious metal became ________ in our ______ to start with, we have to gaze upwards at the stars. Gold is extraterrestrial. Instead of arising from the planet's rocky _____, it was actually cooked up in _____ and is present on Earth because of cataclysmic stellar explosions ______ supernovae. Stars are mostly made up of hydrogen, the simplest and lightest element. The enormous gravitational pressure of so much material compresses and ________ nuclear ______ in the star's core. This _______ 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 _____ iron and ______. 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 ________ of a collapsing star is so high, that _________ protons and electrons are ______ together in the core, forming neutrons. Neutrons have no repelling ________ ______ so they're easily ________ by the iron _____ elements. Multiple neutron ________ ______ the formation of heavier elements that a star under normal circumstances can't form, from ______ 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 _______. But what becomes of the gold after the explosion? The _________ supernova shockwave _______ its _________ 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 ________. 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 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 ________ ____________, we can mimic the complex nuclear reactions that ______ 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 _________ the current value of gold. So that's not a very good ________. 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 _____ an estimated 20 million tons of _________ gold but at extremely miniscule concentrations making its recovery too costly at present. Perhaps one day, we'll see gold ______ to tap the mineral ______ of the other planets of our solar system. And who knows? Maybe some future _________ will occur close enough to shower us with its treasure and hopefully not eradicate all life on Earth in the process.

Solution

  1. subatomic
  2. space
  3. process
  4. charge
  5. captured
  6. holds
  7. create
  8. precious
  9. solution
  10. crust
  11. reach
  12. supernova
  13. achievable
  14. embedded
  15. forced
  16. nickel
  17. captures
  18. silver
  19. elemental
  20. propels
  21. today
  22. wealth
  23. modern
  24. electric
  25. planet
  26. accelerators
  27. activity
  28. pressure
  29. group
  30. manufacture
  31. enable
  32. expanding
  33. fusion
  34. called
  35. exceeding
  36. seconds
  37. dissolved
  38. lowly
  39. rushes
  40. particle
  41. triggers

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

  1. accelerators
  2. achievable
  3. achieve
  4. activity
  5. age
  6. aged
  7. alchemists
  8. arising
  9. atom
  10. billions
  11. bouncing
  12. buried
  13. burning
  14. called
  15. captured
  16. captures
  17. carbon
  18. cataclysmic
  19. center
  20. centuries
  21. charge
  22. circumstances
  23. close
  24. collapse
  25. collapsing
  26. commodity
  27. complex
  28. compounded
  29. compresses
  30. concentrations
  31. condenses
  32. construct
  33. contrast
  34. cooked
  35. core
  36. cost
  37. costly
  38. coveted
  39. create
  40. creation
  41. crust
  42. current
  43. dance
  44. day
  45. debris
  46. delivered
  47. denser
  48. dissolved
  49. dreams
  50. dust
  51. earth
  52. easily
  53. eccentrics
  54. electric
  55. electrons
  56. element
  57. elemental
  58. elements
  59. embedded
  60. enable
  61. energy
  62. enormous
  63. eradicate
  64. estimated
  65. exceeding
  66. expanding
  67. expensive
  68. explodes
  69. explosion
  70. explosions
  71. extract
  72. extraterrestrial
  73. extreme
  74. extremely
  75. fact
  76. faster
  77. forced
  78. form
  79. formation
  80. forming
  81. fusion
  82. future
  83. gas
  84. gaze
  85. geothermal
  86. gleaming
  87. gold
  88. good
  89. gram
  90. gravitational
  91. group
  92. heavier
  93. heaviest
  94. helium
  95. high
  96. history
  97. holds
  98. hydrogen
  99. hypothetical
  100. impossible
  101. injection
  102. interstellar
  103. inventions
  104. iron
  105. kneaded
  106. layers
  107. lead
  108. life
  109. lightest
  110. longer
  111. lot
  112. lowly
  113. machines
  114. making
  115. manufacture
  116. mass
  117. material
  118. medieval
  119. medium
  120. metal
  121. million
  122. millions
  123. mimic
  124. mined
  125. mineral
  126. mining
  127. miniscule
  128. missed
  129. modern
  130. multiple
  131. neutron
  132. neutrons
  133. nickel
  134. normal
  135. nuclear
  136. occur
  137. ocean
  138. outer
  139. oxygen
  140. particle
  141. people
  142. peters
  143. piled
  144. place
  145. places
  146. planet
  147. planets
  148. point
  149. pools
  150. portrays
  151. precious
  152. present
  153. pressure
  154. process
  155. produce
  156. product
  157. propels
  158. protons
  159. rarity
  160. reach
  161. reactions
  162. recovery
  163. releases
  164. repelling
  165. represents
  166. rocky
  167. rushes
  168. seconds
  169. seemingly
  170. shine
  171. shockwave
  172. shower
  173. silver
  174. simplest
  175. solar
  176. solution
  177. space
  178. star
  179. stars
  180. start
  181. stellar
  182. subatomic
  183. subsequent
  184. sudden
  185. supernova
  186. supernovae
  187. swimming
  188. swirling
  189. system
  190. takes
  191. tap
  192. times
  193. today
  194. tons
  195. transform
  196. transformation
  197. transforms
  198. treasure
  199. triggering
  200. triggers
  201. understand
  202. universe
  203. uranium
  204. vastly
  205. veins
  206. wanted
  207. water
  208. wealth
  209. year
  210. years