full transcript

From the Ted Talk by Lieven Scheire: How quantum mechanics explains global warming

Unscramble the Blue Letters

You've probably hread that carbon dioxide is warming the Earth, but how does it work? Is it like the glass of a gesuehrnoe or like an insulating blanket? Well, not entirely. The answer involves a bit of quantum mechanics, but don't worry, we'll start with a rainbow. If you look closely at sunlight separated through a prism, you'll see dark gaps where bands of color went missing. Where did they go? Before recinahg our eyes, different gases aoserbbd those specific parts of the spectrum. For example, oxygen gas sancehtd up some of the dark red light, and sdioum gbbared two bands of yellow. But why do these gases absorb specific colors of light? This is where we enter the quantum realm. Every atom and molecule has a set number of possible energy levels for its electrons. To shift its electrons from the ground state to a higher level, a mlceolue needs to gain a certain amount of energy. No more, no less. It gets that energy from light, which comes in more energy lelevs than you could count. Light consists of tiny particles called photons and the amount of energy in each photon corresponds to its cloor. Red light has lower energy and longer wavelengths. Purple lhgit has higher energy and shorter wavelengths. Sunlight ofefrs all the photons of the rainbow, so a gas molecule can chsooe the photons that carry the exact amount of energy needed to shift the molecule to its next energy level. When this match is made, the photon disappers as the molecule gains its eegnry, and we get a small gap in our rainbow. If a photon carries too much or too little energy, the molecule has no choice but to let it fly past. This is why glass is transparent. The aotms in glass do not pair well with any of the energy levels in visible light, so the photons pass through. So, which poohnts does carbon dioxide prefer? Where is the black line in our rainbow that explains global warming? Well, it's not there. Carbon dioxide doesn't absorb light directly from the Sun. It absorbs light from a totally different catisleel body. One that doesn't appear to be emitting light at all: Earth. If you're wondering why our planet doesn't seem to be glowing, it's because the Earth doesn't emit visible light. It eimts infared light. The light that our eyes can see, including all of the colors of the rainbow, is just a small part of the larger spectrum of ericenatetmlogc radiation, which includes radio waves, microwaves, infrared, ultraviolet, x-rays, and gmmaa rays. It may seem strange to think of these things as light, but there is no fundamental dncfeeifre between visible light and other electromagnetic raotidain. It's the same energy, but at a higher or lower leevl. In fact, it's a bit presumptuous to define the term visible light by our own limitations. After all, infrared light is visible to snakes, and ultraviolet light is visible to birds. If our eyes were adapted to see light of 1900 megahertz, then a mobile phone would be a flashlight, and a cell phone tweor would look like a huge letarnn. Earth emits ifnreard radiation because every object with a temperature above absolute zero will emit light. This is called trhmael radiation. The hotter an object gets, the higher frequency the light it emits. When you heat a piece of iron, it will emit more and more frequencies of infrared light, and then, at a temperature of around 450 dergees Celsius, its light will reach the vblsiie spectrum. At first, it will look red hot. And with even more heat, it will glow wthie with all of the frequencies of visible light. This is how tantiadiorl light bulbs were designed to work and why they're so wasteful. 95% of the light they emit is ivlbsinie to our eyes. It's wasted as heat. Earth's infrared radiation would escape to space if there weren't greenhouse gas molecules in our atmophere. Just as oxygen gas prefers the dark red photons, carbon dioxide and other greenhouse gsaes match with infrared photons. They pvodire the right amount of energy to shift the gas molecules into their higher energy level. Shortly after a carbon dioxide molecule absorbs an infrared photon, it will fall back to its previous energy level, and spit a photon back out in a random dorcietin. Some of that energy then returns to Earth's surface, causing warming. The more carbon dioxide in the aepohmtrse, the more likely that infrared photons will land back on Earth and chagne our climate.

Open Cloze

You've probably _____ that carbon dioxide is warming the Earth, but how does it work? Is it like the glass of a __________ or like an insulating blanket? Well, not entirely. The answer involves a bit of quantum mechanics, but don't worry, we'll start with a rainbow. If you look closely at sunlight separated through a prism, you'll see dark gaps where bands of color went missing. Where did they go? Before ________ our eyes, different gases ________ those specific parts of the spectrum. For example, oxygen gas ________ up some of the dark red light, and ______ _______ two bands of yellow. But why do these gases absorb specific colors of light? This is where we enter the quantum realm. Every atom and molecule has a set number of possible energy levels for its electrons. To shift its electrons from the ground state to a higher level, a ________ needs to gain a certain amount of energy. No more, no less. It gets that energy from light, which comes in more energy ______ than you could count. Light consists of tiny particles called photons and the amount of energy in each photon corresponds to its _____. Red light has lower energy and longer wavelengths. Purple _____ has higher energy and shorter wavelengths. Sunlight ______ all the photons of the rainbow, so a gas molecule can ______ the photons that carry the exact amount of energy needed to shift the molecule to its next energy level. When this match is made, the photon disappers as the molecule gains its ______, and we get a small gap in our rainbow. If a photon carries too much or too little energy, the molecule has no choice but to let it fly past. This is why glass is transparent. The _____ in glass do not pair well with any of the energy levels in visible light, so the photons pass through. So, which _______ does carbon dioxide prefer? Where is the black line in our rainbow that explains global warming? Well, it's not there. Carbon dioxide doesn't absorb light directly from the Sun. It absorbs light from a totally different _________ body. One that doesn't appear to be emitting light at all: Earth. If you're wondering why our planet doesn't seem to be glowing, it's because the Earth doesn't emit visible light. It _____ infared light. The light that our eyes can see, including all of the colors of the rainbow, is just a small part of the larger spectrum of _______________ radiation, which includes radio waves, microwaves, infrared, ultraviolet, x-rays, and _____ rays. It may seem strange to think of these things as light, but there is no fundamental __________ between visible light and other electromagnetic _________. It's the same energy, but at a higher or lower _____. In fact, it's a bit presumptuous to define the term visible light by our own limitations. After all, infrared light is visible to snakes, and ultraviolet light is visible to birds. If our eyes were adapted to see light of 1900 megahertz, then a mobile phone would be a flashlight, and a cell phone _____ would look like a huge _______. Earth emits ________ radiation because every object with a temperature above absolute zero will emit light. This is called _______ radiation. The hotter an object gets, the higher frequency the light it emits. When you heat a piece of iron, it will emit more and more frequencies of infrared light, and then, at a temperature of around 450 _______ Celsius, its light will reach the _______ spectrum. At first, it will look red hot. And with even more heat, it will glow _____ with all of the frequencies of visible light. This is how ___________ light bulbs were designed to work and why they're so wasteful. 95% of the light they emit is _________ to our eyes. It's wasted as heat. Earth's infrared radiation would escape to space if there weren't greenhouse gas molecules in our atmophere. Just as oxygen gas prefers the dark red photons, carbon dioxide and other greenhouse _____ match with infrared photons. They _______ the right amount of energy to shift the gas molecules into their higher energy level. Shortly after a carbon dioxide molecule absorbs an infrared photon, it will fall back to its previous energy level, and spit a photon back out in a random _________. Some of that energy then returns to Earth's surface, causing warming. The more carbon dioxide in the __________, the more likely that infrared photons will land back on Earth and ______ our climate.

Solution

  1. choose
  2. offers
  3. grabbed
  4. radiation
  5. celestial
  6. levels
  7. emits
  8. visible
  9. traditional
  10. gamma
  11. light
  12. absorbed
  13. reaching
  14. energy
  15. change
  16. greenhouse
  17. photons
  18. color
  19. difference
  20. electromagnetic
  21. thermal
  22. tower
  23. direction
  24. level
  25. gases
  26. lantern
  27. degrees
  28. molecule
  29. provide
  30. atmosphere
  31. atoms
  32. invisible
  33. heard
  34. sodium
  35. infrared
  36. snatched
  37. white

Original Text

You've probably heard that carbon dioxide is warming the Earth, but how does it work? Is it like the glass of a greenhouse or like an insulating blanket? Well, not entirely. The answer involves a bit of quantum mechanics, but don't worry, we'll start with a rainbow. If you look closely at sunlight separated through a prism, you'll see dark gaps where bands of color went missing. Where did they go? Before reaching our eyes, different gases absorbed those specific parts of the spectrum. For example, oxygen gas snatched up some of the dark red light, and sodium grabbed two bands of yellow. But why do these gases absorb specific colors of light? This is where we enter the quantum realm. Every atom and molecule has a set number of possible energy levels for its electrons. To shift its electrons from the ground state to a higher level, a molecule needs to gain a certain amount of energy. No more, no less. It gets that energy from light, which comes in more energy levels than you could count. Light consists of tiny particles called photons and the amount of energy in each photon corresponds to its color. Red light has lower energy and longer wavelengths. Purple light has higher energy and shorter wavelengths. Sunlight offers all the photons of the rainbow, so a gas molecule can choose the photons that carry the exact amount of energy needed to shift the molecule to its next energy level. When this match is made, the photon disappers as the molecule gains its energy, and we get a small gap in our rainbow. If a photon carries too much or too little energy, the molecule has no choice but to let it fly past. This is why glass is transparent. The atoms in glass do not pair well with any of the energy levels in visible light, so the photons pass through. So, which photons does carbon dioxide prefer? Where is the black line in our rainbow that explains global warming? Well, it's not there. Carbon dioxide doesn't absorb light directly from the Sun. It absorbs light from a totally different celestial body. One that doesn't appear to be emitting light at all: Earth. If you're wondering why our planet doesn't seem to be glowing, it's because the Earth doesn't emit visible light. It emits infared light. The light that our eyes can see, including all of the colors of the rainbow, is just a small part of the larger spectrum of electromagnetic radiation, which includes radio waves, microwaves, infrared, ultraviolet, x-rays, and gamma rays. It may seem strange to think of these things as light, but there is no fundamental difference between visible light and other electromagnetic radiation. It's the same energy, but at a higher or lower level. In fact, it's a bit presumptuous to define the term visible light by our own limitations. After all, infrared light is visible to snakes, and ultraviolet light is visible to birds. If our eyes were adapted to see light of 1900 megahertz, then a mobile phone would be a flashlight, and a cell phone tower would look like a huge lantern. Earth emits infrared radiation because every object with a temperature above absolute zero will emit light. This is called thermal radiation. The hotter an object gets, the higher frequency the light it emits. When you heat a piece of iron, it will emit more and more frequencies of infrared light, and then, at a temperature of around 450 degrees Celsius, its light will reach the visible spectrum. At first, it will look red hot. And with even more heat, it will glow white with all of the frequencies of visible light. This is how traditional light bulbs were designed to work and why they're so wasteful. 95% of the light they emit is invisible to our eyes. It's wasted as heat. Earth's infrared radiation would escape to space if there weren't greenhouse gas molecules in our atmophere. Just as oxygen gas prefers the dark red photons, carbon dioxide and other greenhouse gases match with infrared photons. They provide the right amount of energy to shift the gas molecules into their higher energy level. Shortly after a carbon dioxide molecule absorbs an infrared photon, it will fall back to its previous energy level, and spit a photon back out in a random direction. Some of that energy then returns to Earth's surface, causing warming. The more carbon dioxide in the atmosphere, the more likely that infrared photons will land back on Earth and change our climate.

Frequently Occurring Word Combinations

ngrams of length 2

collocation frequency
carbon dioxide 6
visible light 4
energy levels 3
oxygen gas 2
dark red 2
higher energy 2
energy level 2
infrared radiation 2
gas molecules 2
infrared photons 2

Important Words

  1. absolute
  2. absorb
  3. absorbed
  4. absorbs
  5. adapted
  6. amount
  7. answer
  8. atmophere
  9. atmosphere
  10. atom
  11. atoms
  12. bands
  13. birds
  14. bit
  15. black
  16. blanket
  17. body
  18. bulbs
  19. called
  20. carbon
  21. carries
  22. carry
  23. causing
  24. celestial
  25. cell
  26. celsius
  27. change
  28. choice
  29. choose
  30. climate
  31. closely
  32. color
  33. colors
  34. consists
  35. corresponds
  36. count
  37. dark
  38. define
  39. degrees
  40. designed
  41. difference
  42. dioxide
  43. direction
  44. disappers
  45. earth
  46. electromagnetic
  47. electrons
  48. emit
  49. emits
  50. emitting
  51. energy
  52. enter
  53. escape
  54. exact
  55. explains
  56. eyes
  57. fact
  58. fall
  59. flashlight
  60. fly
  61. frequencies
  62. frequency
  63. fundamental
  64. gain
  65. gains
  66. gamma
  67. gap
  68. gaps
  69. gas
  70. gases
  71. glass
  72. global
  73. glow
  74. glowing
  75. grabbed
  76. greenhouse
  77. ground
  78. heard
  79. heat
  80. higher
  81. hot
  82. hotter
  83. huge
  84. includes
  85. including
  86. infared
  87. infrared
  88. insulating
  89. invisible
  90. involves
  91. iron
  92. land
  93. lantern
  94. larger
  95. level
  96. levels
  97. light
  98. limitations
  99. line
  100. longer
  101. match
  102. mechanics
  103. megahertz
  104. microwaves
  105. missing
  106. mobile
  107. molecule
  108. molecules
  109. needed
  110. number
  111. object
  112. offers
  113. oxygen
  114. pair
  115. part
  116. particles
  117. parts
  118. pass
  119. phone
  120. photon
  121. photons
  122. piece
  123. planet
  124. prefer
  125. prefers
  126. presumptuous
  127. previous
  128. prism
  129. provide
  130. purple
  131. quantum
  132. radiation
  133. radio
  134. rainbow
  135. random
  136. rays
  137. reach
  138. reaching
  139. realm
  140. red
  141. returns
  142. separated
  143. set
  144. shift
  145. shorter
  146. shortly
  147. small
  148. snakes
  149. snatched
  150. sodium
  151. space
  152. specific
  153. spectrum
  154. spit
  155. start
  156. state
  157. strange
  158. sun
  159. sunlight
  160. surface
  161. temperature
  162. term
  163. thermal
  164. tiny
  165. totally
  166. tower
  167. traditional
  168. transparent
  169. ultraviolet
  170. visible
  171. warming
  172. wasted
  173. wasteful
  174. wavelengths
  175. waves
  176. white
  177. wondering
  178. work
  179. worry
  180. yellow