full transcript

From the Ted Talk by Netta Schramm: Why don't perpetual motion machines ever work?

Unscramble the Blue Letters

Around 1159 A.D., a mathematician called Bhaskara the Learned sketched a design for a wheel containing curved reservoirs of mecrruy. He reasoned that as the wheels spun, the mercury would flow to the boottm of each reservoir, leaving one side of the wheel perpetually heavier than the other. The imbalance would keep the wheel tnunirg forever. Bhaskara's drawing was one of the earliest designs for a pteuparel motion machine, a device that can do work indefinitely without any external energy source. imagnie a windmill that produced the beezre it needed to keep rotating. Or a lightbulb whose glow provided its own electricity. These devices have captured many inventors' imaginations because they could transform our relationship with energy. For example, if you could biuld a perpetual motion machine that included humans as part of its perfectly efficient system, it could stsiuan life indefinitely. There's just one prlbeom. They don't work. Ideas for perpetual motion machines all violate one or more fundamental laws of thermodynamics, the branch of physics that dcsrieebs the relationship between different forms of energy. The first law of thermodynamics says that energy can't be crateed or destroyed. You can't get out more eengry than you put in. That rules out a useful perpetual motion machine right away because a machine could only ever produce as much energy as it consumed. There wouldn't be any left over to pweor a car or charge a phone. But what if you just wanted the mcnahie to keep itself moving? inntoevrs have proposed ptelny of ideas. Several of these have been variations on Bhaskara's over-balanced wheel with rolling balls or weights on swinging arms. None of them work. The moving parts that make one side of the wheel heavier also shift its center of mass downward below the axle. With a low center of mass, the wheel just swings back and forth like a pendulum, then sotps. What about a different approach? In the 17th century, Robert Boyle came up with an idea for a self-watering pot. He theorized that capillary action, the attraction between liquids and surfaces that pulls wetar through thin tubes, might keep the water cycling around the bowl. But if the capillary action is strong enough to ocmveroe gviatry and draw the water up, it would also prevent it from falilng back into the bowl. Then there are versions with magnets, like this set of ramps. The ball is supposed to be pulled upwards by the mnaget at the top, fall back down through the hole, and repeat the cycle. This one fails because like the self-watering pot, the magnet would simply hold the ball at the top. Even if it somehow did keep moving, the magnet's strength would degrade over time and eventually stop working. For each of these minheacs to keep moving, they'd have to create some extra energy to nudge the system past its stopping point, bnireakg the first law of thermodynamics. There are ones that seem to keep going, but in reality, they invariably turn out to be dwnirag energy from some external source. Even if eneeingrs could somehow design a machine that didn't violate the first law of thermodynamics, it still wouldn't work in the real world because of the second law. The second law of thermodynamics tells us that energy tends to spread out through processes like friction. Any real machine would have moving parts or interactions with air or liquid molecules that would generate tiny amounts of friction and heat, even in a vacuum. That heat is energy escaping, and it would keep leeching out, reducing the energy available to move the system itself until the machine iaevtibnly stopped. So far, these two laws of tamcrnoehidyms have stymied every idea for perpetual motion and the dearms of pfcreelty efficient energy generation they imply. Yet it's hard to conclusively say we'll never dovceisr a perpetual motion machine because there's still so much we don't understand about the universe. Perhaps we'll find new exotic frmos of matter that'll force us to revisit the laws of thermodynamics. Or maybe there's perpetual mtoion on tiny quantum scales. What we can be reasonably sure about is that we'll never stop looking. For now, the one thing that seems truly perpetual is our search.

Open Cloze

Around 1159 A.D., a mathematician called Bhaskara the Learned sketched a design for a wheel containing curved reservoirs of _______. He reasoned that as the wheels spun, the mercury would flow to the ______ of each reservoir, leaving one side of the wheel perpetually heavier than the other. The imbalance would keep the wheel _______ forever. Bhaskara's drawing was one of the earliest designs for a _________ motion machine, a device that can do work indefinitely without any external energy source. _______ a windmill that produced the ______ it needed to keep rotating. Or a lightbulb whose glow provided its own electricity. These devices have captured many inventors' imaginations because they could transform our relationship with energy. For example, if you could _____ a perpetual motion machine that included humans as part of its perfectly efficient system, it could _______ life indefinitely. There's just one _______. They don't work. Ideas for perpetual motion machines all violate one or more fundamental laws of thermodynamics, the branch of physics that _________ the relationship between different forms of energy. The first law of thermodynamics says that energy can't be _______ or destroyed. You can't get out more ______ than you put in. That rules out a useful perpetual motion machine right away because a machine could only ever produce as much energy as it consumed. There wouldn't be any left over to _____ a car or charge a phone. But what if you just wanted the _______ to keep itself moving? _________ have proposed ______ of ideas. Several of these have been variations on Bhaskara's over-balanced wheel with rolling balls or weights on swinging arms. None of them work. The moving parts that make one side of the wheel heavier also shift its center of mass downward below the axle. With a low center of mass, the wheel just swings back and forth like a pendulum, then _____. What about a different approach? In the 17th century, Robert Boyle came up with an idea for a self-watering pot. He theorized that capillary action, the attraction between liquids and surfaces that pulls _____ through thin tubes, might keep the water cycling around the bowl. But if the capillary action is strong enough to ________ _______ and draw the water up, it would also prevent it from _______ back into the bowl. Then there are versions with magnets, like this set of ramps. The ball is supposed to be pulled upwards by the ______ at the top, fall back down through the hole, and repeat the cycle. This one fails because like the self-watering pot, the magnet would simply hold the ball at the top. Even if it somehow did keep moving, the magnet's strength would degrade over time and eventually stop working. For each of these ________ to keep moving, they'd have to create some extra energy to nudge the system past its stopping point, ________ the first law of thermodynamics. There are ones that seem to keep going, but in reality, they invariably turn out to be _______ energy from some external source. Even if _________ could somehow design a machine that didn't violate the first law of thermodynamics, it still wouldn't work in the real world because of the second law. The second law of thermodynamics tells us that energy tends to spread out through processes like friction. Any real machine would have moving parts or interactions with air or liquid molecules that would generate tiny amounts of friction and heat, even in a vacuum. That heat is energy escaping, and it would keep leeching out, reducing the energy available to move the system itself until the machine __________ stopped. So far, these two laws of ______________ have stymied every idea for perpetual motion and the ______ of _________ efficient energy generation they imply. Yet it's hard to conclusively say we'll never ________ a perpetual motion machine because there's still so much we don't understand about the universe. Perhaps we'll find new exotic _____ of matter that'll force us to revisit the laws of thermodynamics. Or maybe there's perpetual ______ on tiny quantum scales. What we can be reasonably sure about is that we'll never stop looking. For now, the one thing that seems truly perpetual is our search.

Solution

  1. sustain
  2. created
  3. stops
  4. engineers
  5. motion
  6. water
  7. dreams
  8. drawing
  9. energy
  10. turning
  11. build
  12. power
  13. overcome
  14. inevitably
  15. problem
  16. inventors
  17. mercury
  18. machine
  19. bottom
  20. magnet
  21. breaking
  22. imagine
  23. gravity
  24. perpetual
  25. machines
  26. forms
  27. perfectly
  28. plenty
  29. breeze
  30. discover
  31. thermodynamics
  32. falling
  33. describes

Original Text

Around 1159 A.D., a mathematician called Bhaskara the Learned sketched a design for a wheel containing curved reservoirs of mercury. He reasoned that as the wheels spun, the mercury would flow to the bottom of each reservoir, leaving one side of the wheel perpetually heavier than the other. The imbalance would keep the wheel turning forever. Bhaskara's drawing was one of the earliest designs for a perpetual motion machine, a device that can do work indefinitely without any external energy source. Imagine a windmill that produced the breeze it needed to keep rotating. Or a lightbulb whose glow provided its own electricity. These devices have captured many inventors' imaginations because they could transform our relationship with energy. For example, if you could build a perpetual motion machine that included humans as part of its perfectly efficient system, it could sustain life indefinitely. There's just one problem. They don't work. Ideas for perpetual motion machines all violate one or more fundamental laws of thermodynamics, the branch of physics that describes the relationship between different forms of energy. The first law of thermodynamics says that energy can't be created or destroyed. You can't get out more energy than you put in. That rules out a useful perpetual motion machine right away because a machine could only ever produce as much energy as it consumed. There wouldn't be any left over to power a car or charge a phone. But what if you just wanted the machine to keep itself moving? Inventors have proposed plenty of ideas. Several of these have been variations on Bhaskara's over-balanced wheel with rolling balls or weights on swinging arms. None of them work. The moving parts that make one side of the wheel heavier also shift its center of mass downward below the axle. With a low center of mass, the wheel just swings back and forth like a pendulum, then stops. What about a different approach? In the 17th century, Robert Boyle came up with an idea for a self-watering pot. He theorized that capillary action, the attraction between liquids and surfaces that pulls water through thin tubes, might keep the water cycling around the bowl. But if the capillary action is strong enough to overcome gravity and draw the water up, it would also prevent it from falling back into the bowl. Then there are versions with magnets, like this set of ramps. The ball is supposed to be pulled upwards by the magnet at the top, fall back down through the hole, and repeat the cycle. This one fails because like the self-watering pot, the magnet would simply hold the ball at the top. Even if it somehow did keep moving, the magnet's strength would degrade over time and eventually stop working. For each of these machines to keep moving, they'd have to create some extra energy to nudge the system past its stopping point, breaking the first law of thermodynamics. There are ones that seem to keep going, but in reality, they invariably turn out to be drawing energy from some external source. Even if engineers could somehow design a machine that didn't violate the first law of thermodynamics, it still wouldn't work in the real world because of the second law. The second law of thermodynamics tells us that energy tends to spread out through processes like friction. Any real machine would have moving parts or interactions with air or liquid molecules that would generate tiny amounts of friction and heat, even in a vacuum. That heat is energy escaping, and it would keep leeching out, reducing the energy available to move the system itself until the machine inevitably stopped. So far, these two laws of thermodynamics have stymied every idea for perpetual motion and the dreams of perfectly efficient energy generation they imply. Yet it's hard to conclusively say we'll never discover a perpetual motion machine because there's still so much we don't understand about the universe. Perhaps we'll find new exotic forms of matter that'll force us to revisit the laws of thermodynamics. Or maybe there's perpetual motion on tiny quantum scales. What we can be reasonably sure about is that we'll never stop looking. For now, the one thing that seems truly perpetual is our search.

Frequently Occurring Word Combinations

ngrams of length 2

collocation frequency
perpetual motion 7
motion machine 3
perfectly efficient 2
moving parts 2

ngrams of length 3

collocation frequency
perpetual motion machine 3

Important Words

  1. action
  2. air
  3. amounts
  4. approach
  5. arms
  6. attraction
  7. axle
  8. ball
  9. balls
  10. bhaskara
  11. bottom
  12. bowl
  13. boyle
  14. branch
  15. breaking
  16. breeze
  17. build
  18. called
  19. capillary
  20. captured
  21. car
  22. center
  23. century
  24. charge
  25. conclusively
  26. consumed
  27. create
  28. created
  29. curved
  30. cycle
  31. cycling
  32. degrade
  33. describes
  34. design
  35. designs
  36. destroyed
  37. device
  38. devices
  39. discover
  40. downward
  41. draw
  42. drawing
  43. dreams
  44. earliest
  45. efficient
  46. electricity
  47. energy
  48. engineers
  49. escaping
  50. eventually
  51. exotic
  52. external
  53. extra
  54. fails
  55. fall
  56. falling
  57. find
  58. flow
  59. force
  60. forms
  61. friction
  62. fundamental
  63. generate
  64. generation
  65. glow
  66. gravity
  67. hard
  68. heat
  69. heavier
  70. hold
  71. hole
  72. humans
  73. idea
  74. ideas
  75. imaginations
  76. imagine
  77. imbalance
  78. imply
  79. included
  80. indefinitely
  81. inevitably
  82. interactions
  83. invariably
  84. inventors
  85. law
  86. laws
  87. learned
  88. leaving
  89. leeching
  90. left
  91. life
  92. lightbulb
  93. liquid
  94. liquids
  95. machine
  96. machines
  97. magnet
  98. magnets
  99. mass
  100. mathematician
  101. matter
  102. mercury
  103. molecules
  104. motion
  105. move
  106. moving
  107. needed
  108. nudge
  109. overcome
  110. part
  111. parts
  112. pendulum
  113. perfectly
  114. perpetual
  115. perpetually
  116. phone
  117. physics
  118. plenty
  119. point
  120. pot
  121. power
  122. prevent
  123. problem
  124. processes
  125. produce
  126. produced
  127. proposed
  128. pulled
  129. pulls
  130. put
  131. quantum
  132. ramps
  133. real
  134. reality
  135. reasoned
  136. reducing
  137. relationship
  138. repeat
  139. reservoir
  140. reservoirs
  141. revisit
  142. robert
  143. rolling
  144. rotating
  145. rules
  146. scales
  147. search
  148. set
  149. shift
  150. side
  151. simply
  152. sketched
  153. source
  154. spread
  155. spun
  156. stop
  157. stopped
  158. stopping
  159. stops
  160. strength
  161. strong
  162. stymied
  163. supposed
  164. surfaces
  165. sustain
  166. swinging
  167. swings
  168. system
  169. tells
  170. theorized
  171. thermodynamics
  172. thin
  173. time
  174. tiny
  175. top
  176. transform
  177. tubes
  178. turn
  179. turning
  180. understand
  181. universe
  182. vacuum
  183. variations
  184. versions
  185. violate
  186. wanted
  187. water
  188. weights
  189. wheel
  190. wheels
  191. windmill
  192. work
  193. working
  194. world