full transcript

From the Ted Talk by James Gillies: Dark matter The matter we can't see

Unscramble the Blue Letters

The ancient Greeks had a great idea: The universe is simple. In their mndis, all you needed to make it were four elements: earth, air, fire, and water. As theories go, it's a beautiful one. It has simplicity and eclgneae. It says that by combining the four basic elements in different ways, you could produce all the wonderful distiervy of the uevirnse. Earth and fire, for example, give you things that are dry. Air and water, things that are wet. But as theories go, it had a problem. It didn't predict anything that could be measured, and meamsruenet is the basis of experimental science. Worse still, the theory was wrnog. But the gekres were great scientists of the mind and in the 5th century B.C., Leucippus of Miletus came up with one of the most enduring sfeicntiic ideas ever. Everything we see is made up of tiny, indivisible bits of stuff called atoms. This theory is simple and elegant, and it has the anadvgtae over the earth, air, fire, and water trehoy of being right. Centuries of scientific thought and experimentation have ehsislbated that the real enetemls, things like hydrogen, carbon, and iron, can be broken down into atoms. In Leucippus's theory, the atom is the smallest, indivisible bit of stuff that's still recognizable as hydrogen, carbon, or iron. The only thing wrong with Leucippus's idea is that atoms are, in fact, divisible. Furthermore, his atoms idea turns out to eplixan just a small part of what the universe is made of. What appears to be the ordinary stuff of the universe is, in fact, quite rare. Leucippus's atoms, and the things they're made of, actually make up only about 5% of what we know to be there. Physicists know the rest of the universe, 95% of it, as the dark universe, made of dark matter and dark energy. How do we know this? Well, we know because we look at things and we see them. That might seem rather simplistic, but it's actually quite profound. All the stuff that's made of atoms is visible. Light bounces off it, and we can see it. When we look out into space, we see stars and galaxies. Some of them, like the one we live in, are beutfaiul, spiral shapes, siinpnng gracefully through sapce. When scientists first measured the motion of groups of galaxies in the 1930's and wiheegd the amount of matter they contained, they were in for a surprise. They found that there's not enough visible stuff in those groups to hold them together. Later mreuesmaents of individual galaxies conmfried this puzzling relsut. There's smiply not enough vliisbe stuff in gixleaas to pdviore enough gravity to hold them together. From what we can see, they ought to fly apart, but they don't. So there must be stuff there that we can't see. We call that stuff dark matter. The best evidence for dark matter today comes from measurements of something called the cosimc microwave barncokugd, the afterglow of the Big Bang, but that's another story. All of the evidence we have says that dark maettr is there and it accounts for much of the stfuf in those beautiful spiral galaxies that fill the heavens. So where does that lveae us? We've long known that the heavens do not rvvolee around us and that we're residents of a fairly ordinary panelt, orbiting a fairly ordinary star, in the sripal arm of a fairly ordinary gxlaay. The discovery of dark matter took us one step further away from the center of things. It told us that the stuff we're made of is only a small fraction of what makes up the universe. But there was more to come. Early this crunety, scientists studying the outer reaches of the universe confirmed that not only is everything moving apart from everything else, as you would expect in a universe that began in hot, desne big bang, but that the universe's expansion also seems to be accelerating. What's that about? Either there is some kind of energy pushing this acceleration, just like you provide energy to accelerate a car, or gravity does not behave exactly as we think. Most scientists think it's the former, that there's some kind of ergeny driving the acceleration, and they cellad it dark energy. Today's best measurements allow us to work out just how much of the universe is dark. It looks as if dark energy makes up about 68% of the universe and dark matter about 27%, laniveg just 5% for us and everything else we can actually see. So what's the dark stuff made of? We don't know, but there's one theory, called supersymmetry, that could explain some of it. Supersymmetry, or SUSY for short, predicts a whole range of new particles, some of which could make up the dark matter. If we found evidence for SUSY, we could go from understanding 5% of our universe, the things we can actually see, to around a third. Not bad for a day's work. Dark energy would probably be harder to understand, but there are some suaevlictpe theories out there that might point the way. Among them are triehoes that go back to that first great idea of the aennict Greeks, the idea that we began with several minutes ago, the idea that the universe must be simple. These theories predict that there is just a single element from which all the universe's wonderful diversity stems, a vibrating string. The idea is that all the pcareitls we know today are just different harmonics on the string. Unfortunately, sitnrg theories tadoy are, as yet, untestable. But, with so much of the universe waiting to be explored, the stakes are high. Does all of this make you feel slaml? It shouldn't. Instead, you should marvel in the fact that, as far as we know, you are a member of the only species in the universe able even to begin to grasp its wonders, and you're living at the right time to see our udnsnatirdneg explode.

Open Cloze

The ancient Greeks had a great idea: The universe is simple. In their _____, all you needed to make it were four elements: earth, air, fire, and water. As theories go, it's a beautiful one. It has simplicity and ________. It says that by combining the four basic elements in different ways, you could produce all the wonderful _________ of the ________. Earth and fire, for example, give you things that are dry. Air and water, things that are wet. But as theories go, it had a problem. It didn't predict anything that could be measured, and ___________ is the basis of experimental science. Worse still, the theory was _____. But the ______ were great scientists of the mind and in the 5th century B.C., Leucippus of Miletus came up with one of the most enduring __________ ideas ever. Everything we see is made up of tiny, indivisible bits of stuff called atoms. This theory is simple and elegant, and it has the _________ over the earth, air, fire, and water ______ of being right. Centuries of scientific thought and experimentation have ___________ that the real ________, things like hydrogen, carbon, and iron, can be broken down into atoms. In Leucippus's theory, the atom is the smallest, indivisible bit of stuff that's still recognizable as hydrogen, carbon, or iron. The only thing wrong with Leucippus's idea is that atoms are, in fact, divisible. Furthermore, his atoms idea turns out to _______ just a small part of what the universe is made of. What appears to be the ordinary stuff of the universe is, in fact, quite rare. Leucippus's atoms, and the things they're made of, actually make up only about 5% of what we know to be there. Physicists know the rest of the universe, 95% of it, as the dark universe, made of dark matter and dark energy. How do we know this? Well, we know because we look at things and we see them. That might seem rather simplistic, but it's actually quite profound. All the stuff that's made of atoms is visible. Light bounces off it, and we can see it. When we look out into space, we see stars and galaxies. Some of them, like the one we live in, are _________, spiral shapes, ________ gracefully through _____. When scientists first measured the motion of groups of galaxies in the 1930's and _______ the amount of matter they contained, they were in for a surprise. They found that there's not enough visible stuff in those groups to hold them together. Later ____________ of individual galaxies _________ this puzzling ______. There's ______ not enough _______ stuff in ________ to _______ enough gravity to hold them together. From what we can see, they ought to fly apart, but they don't. So there must be stuff there that we can't see. We call that stuff dark matter. The best evidence for dark matter today comes from measurements of something called the ______ microwave __________, the afterglow of the Big Bang, but that's another story. All of the evidence we have says that dark ______ is there and it accounts for much of the _____ in those beautiful spiral galaxies that fill the heavens. So where does that _____ us? We've long known that the heavens do not _______ around us and that we're residents of a fairly ordinary ______, orbiting a fairly ordinary star, in the ______ arm of a fairly ordinary ______. The discovery of dark matter took us one step further away from the center of things. It told us that the stuff we're made of is only a small fraction of what makes up the universe. But there was more to come. Early this _______, scientists studying the outer reaches of the universe confirmed that not only is everything moving apart from everything else, as you would expect in a universe that began in hot, _____ big bang, but that the universe's expansion also seems to be accelerating. What's that about? Either there is some kind of energy pushing this acceleration, just like you provide energy to accelerate a car, or gravity does not behave exactly as we think. Most scientists think it's the former, that there's some kind of ______ driving the acceleration, and they ______ it dark energy. Today's best measurements allow us to work out just how much of the universe is dark. It looks as if dark energy makes up about 68% of the universe and dark matter about 27%, _______ just 5% for us and everything else we can actually see. So what's the dark stuff made of? We don't know, but there's one theory, called supersymmetry, that could explain some of it. Supersymmetry, or SUSY for short, predicts a whole range of new particles, some of which could make up the dark matter. If we found evidence for SUSY, we could go from understanding 5% of our universe, the things we can actually see, to around a third. Not bad for a day's work. Dark energy would probably be harder to understand, but there are some ___________ theories out there that might point the way. Among them are ________ that go back to that first great idea of the _______ Greeks, the idea that we began with several minutes ago, the idea that the universe must be simple. These theories predict that there is just a single element from which all the universe's wonderful diversity stems, a vibrating string. The idea is that all the _________ we know today are just different harmonics on the string. Unfortunately, ______ theories _____ are, as yet, untestable. But, with so much of the universe waiting to be explored, the stakes are high. Does all of this make you feel _____? It shouldn't. Instead, you should marvel in the fact that, as far as we know, you are a member of the only species in the universe able even to begin to grasp its wonders, and you're living at the right time to see our _____________ explode.

Solution

  1. background
  2. energy
  3. stuff
  4. greeks
  5. space
  6. universe
  7. called
  8. confirmed
  9. measurement
  10. wrong
  11. galaxy
  12. theory
  13. result
  14. particles
  15. visible
  16. advantage
  17. century
  18. elegance
  19. revolve
  20. measurements
  21. scientific
  22. spiral
  23. understanding
  24. dense
  25. simply
  26. planet
  27. minds
  28. weighed
  29. theories
  30. speculative
  31. galaxies
  32. small
  33. spinning
  34. diversity
  35. today
  36. elements
  37. leaving
  38. matter
  39. beautiful
  40. ancient
  41. string
  42. leave
  43. established
  44. provide
  45. cosmic
  46. explain

Original Text

The ancient Greeks had a great idea: The universe is simple. In their minds, all you needed to make it were four elements: earth, air, fire, and water. As theories go, it's a beautiful one. It has simplicity and elegance. It says that by combining the four basic elements in different ways, you could produce all the wonderful diversity of the universe. Earth and fire, for example, give you things that are dry. Air and water, things that are wet. But as theories go, it had a problem. It didn't predict anything that could be measured, and measurement is the basis of experimental science. Worse still, the theory was wrong. But the Greeks were great scientists of the mind and in the 5th century B.C., Leucippus of Miletus came up with one of the most enduring scientific ideas ever. Everything we see is made up of tiny, indivisible bits of stuff called atoms. This theory is simple and elegant, and it has the advantage over the earth, air, fire, and water theory of being right. Centuries of scientific thought and experimentation have established that the real elements, things like hydrogen, carbon, and iron, can be broken down into atoms. In Leucippus's theory, the atom is the smallest, indivisible bit of stuff that's still recognizable as hydrogen, carbon, or iron. The only thing wrong with Leucippus's idea is that atoms are, in fact, divisible. Furthermore, his atoms idea turns out to explain just a small part of what the universe is made of. What appears to be the ordinary stuff of the universe is, in fact, quite rare. Leucippus's atoms, and the things they're made of, actually make up only about 5% of what we know to be there. Physicists know the rest of the universe, 95% of it, as the dark universe, made of dark matter and dark energy. How do we know this? Well, we know because we look at things and we see them. That might seem rather simplistic, but it's actually quite profound. All the stuff that's made of atoms is visible. Light bounces off it, and we can see it. When we look out into space, we see stars and galaxies. Some of them, like the one we live in, are beautiful, spiral shapes, spinning gracefully through space. When scientists first measured the motion of groups of galaxies in the 1930's and weighed the amount of matter they contained, they were in for a surprise. They found that there's not enough visible stuff in those groups to hold them together. Later measurements of individual galaxies confirmed this puzzling result. There's simply not enough visible stuff in galaxies to provide enough gravity to hold them together. From what we can see, they ought to fly apart, but they don't. So there must be stuff there that we can't see. We call that stuff dark matter. The best evidence for dark matter today comes from measurements of something called the cosmic microwave background, the afterglow of the Big Bang, but that's another story. All of the evidence we have says that dark matter is there and it accounts for much of the stuff in those beautiful spiral galaxies that fill the heavens. So where does that leave us? We've long known that the heavens do not revolve around us and that we're residents of a fairly ordinary planet, orbiting a fairly ordinary star, in the spiral arm of a fairly ordinary galaxy. The discovery of dark matter took us one step further away from the center of things. It told us that the stuff we're made of is only a small fraction of what makes up the universe. But there was more to come. Early this century, scientists studying the outer reaches of the universe confirmed that not only is everything moving apart from everything else, as you would expect in a universe that began in hot, dense big bang, but that the universe's expansion also seems to be accelerating. What's that about? Either there is some kind of energy pushing this acceleration, just like you provide energy to accelerate a car, or gravity does not behave exactly as we think. Most scientists think it's the former, that there's some kind of energy driving the acceleration, and they called it dark energy. Today's best measurements allow us to work out just how much of the universe is dark. It looks as if dark energy makes up about 68% of the universe and dark matter about 27%, leaving just 5% for us and everything else we can actually see. So what's the dark stuff made of? We don't know, but there's one theory, called supersymmetry, that could explain some of it. Supersymmetry, or SUSY for short, predicts a whole range of new particles, some of which could make up the dark matter. If we found evidence for SUSY, we could go from understanding 5% of our universe, the things we can actually see, to around a third. Not bad for a day's work. Dark energy would probably be harder to understand, but there are some speculative theories out there that might point the way. Among them are theories that go back to that first great idea of the ancient Greeks, the idea that we began with several minutes ago, the idea that the universe must be simple. These theories predict that there is just a single element from which all the universe's wonderful diversity stems, a vibrating string. The idea is that all the particles we know today are just different harmonics on the string. Unfortunately, string theories today are, as yet, untestable. But, with so much of the universe waiting to be explored, the stakes are high. Does all of this make you feel small? It shouldn't. Instead, you should marvel in the fact that, as far as we know, you are a member of the only species in the universe able even to begin to grasp its wonders, and you're living at the right time to see our understanding explode.

Frequently Occurring Word Combinations

ngrams of length 2

collocation frequency
dark matter 7
dark energy 4
wonderful diversity 2
visible stuff 2

Important Words

  1. accelerate
  2. accelerating
  3. acceleration
  4. accounts
  5. advantage
  6. afterglow
  7. air
  8. amount
  9. ancient
  10. appears
  11. arm
  12. atom
  13. atoms
  14. background
  15. bad
  16. bang
  17. basic
  18. basis
  19. beautiful
  20. began
  21. behave
  22. big
  23. bit
  24. bits
  25. bounces
  26. broken
  27. call
  28. called
  29. car
  30. carbon
  31. center
  32. centuries
  33. century
  34. combining
  35. confirmed
  36. contained
  37. cosmic
  38. dark
  39. dense
  40. discovery
  41. diversity
  42. divisible
  43. driving
  44. dry
  45. early
  46. earth
  47. elegance
  48. elegant
  49. element
  50. elements
  51. enduring
  52. energy
  53. established
  54. evidence
  55. expansion
  56. expect
  57. experimental
  58. experimentation
  59. explain
  60. explode
  61. explored
  62. fact
  63. feel
  64. fill
  65. fire
  66. fly
  67. fraction
  68. galaxies
  69. galaxy
  70. give
  71. gracefully
  72. grasp
  73. gravity
  74. great
  75. greeks
  76. groups
  77. harder
  78. harmonics
  79. heavens
  80. high
  81. hold
  82. hot
  83. hydrogen
  84. idea
  85. ideas
  86. individual
  87. indivisible
  88. iron
  89. kind
  90. leave
  91. leaving
  92. leucippus
  93. light
  94. live
  95. living
  96. long
  97. marvel
  98. matter
  99. measured
  100. measurement
  101. measurements
  102. member
  103. microwave
  104. miletus
  105. mind
  106. minds
  107. minutes
  108. motion
  109. moving
  110. needed
  111. orbiting
  112. ordinary
  113. outer
  114. part
  115. particles
  116. physicists
  117. planet
  118. point
  119. predict
  120. predicts
  121. problem
  122. produce
  123. profound
  124. provide
  125. pushing
  126. puzzling
  127. range
  128. rare
  129. reaches
  130. real
  131. recognizable
  132. residents
  133. rest
  134. result
  135. revolve
  136. science
  137. scientific
  138. scientists
  139. shapes
  140. short
  141. simple
  142. simplicity
  143. simplistic
  144. simply
  145. single
  146. small
  147. smallest
  148. space
  149. species
  150. speculative
  151. spinning
  152. spiral
  153. stakes
  154. star
  155. stars
  156. stems
  157. step
  158. story
  159. string
  160. studying
  161. stuff
  162. supersymmetry
  163. surprise
  164. susy
  165. theories
  166. theory
  167. thought
  168. time
  169. tiny
  170. today
  171. told
  172. turns
  173. understand
  174. understanding
  175. universe
  176. untestable
  177. vibrating
  178. visible
  179. waiting
  180. water
  181. ways
  182. weighed
  183. wet
  184. wonderful
  185. wonders
  186. work
  187. worse
  188. wrong