full transcript

From the Ted Talk by Chad Orzel: What is the Heisenberg Uncertainty Principle?

Unscramble the Blue Letters

The Heisenberg Uncertainty Principle is one of a hdafnul of ideas from quantum physics to expand into ganreel pop culture. It says that you can never ssmtlluunioaey know the exact position and the exact speed of an object and shows up as a metaphor in everything from literary criticism to sports cmremoatny. Uncertainty is often explained as a result of murmneeseat, that the act of measuring an object's position changes its speed, or vice versa. The real origin is much deeper and more amazing. The Uncertainty Principle exists because everything in the universe behaves like both a particle and a wave at the same time. In quantum mechanics, the exact position and exact speed of an object have no meaning. To understand this, we need to think about what it means to bvheae like a particle or a wave. pirtalecs, by definition, eisxt in a single place at any instant in time. We can repenerst this by a graph showing the probability of fidnnig the object at a particular place, which looks like a sipke, 100% at one specific position, and zero everywhere else. waevs, on the other hand, are disturbances spread out in space, like ripples covering the surface of a pond. We can clearly identify features of the wave pattern as a whole, most importantly, its wavlntegeh, which is the distance between two neighboring peaks, or two neighboring vlyales. But we can't assgin it a snigle position. It has a good probability of being in lots of different places. Wavelength is estneasil for quantum physics because an object's wavelength is related to its momentum, mass times velocity. A fast-moving object has lots of momentum, which corresponds to a very short wavelength. A heavy object has lots of momentum even if it's not monivg very fast, which again means a very short wavelength. This is why we don't notice the wave nature of everyday objects. If you toss a baseball up in the air, its wavelength is a billionth of a trillionth of a trillionth of a meter, far too tiny to ever detect. Small things, like aomts or electrons though, can have wavelengths big enough to measure in physics experiments. So, if we have a pure wave, we can measure its wavelength, and thus its momentum, but it has no position. We can know a particles position very well, but it doesn't have a wavelength, so we don't know its momentum. To get a pracltie with both position and momentum, we need to mix the two pictures to make a graph that has waves, but only in a small area. How can we do this? By combining waves with different wavelengths, which means giving our quantum object some possibility of having different momenta. When we add two waves, we find that there are places where the peaks line up, making a bigger wave, and other places where the peaks of one fill in the valleys of the other. The result has regions where we see waves separated by regions of nothing at all. If we add a third wave, the regions where the waves ccneal out get bigger, a fourth and they get bigger still, with the wavier reingos becoming nrwoerar. If we keep adding waves, we can make a wave pkcaet with a clear wavelength in one small region. That's a quantum object with both wave and particle nature, but to ascomiclph this, we had to lose certainty about both ptooisin and momentum. The positions isn't restricted to a single point. There's a good probability of finding it within some range of the center of the wave packet, and we made the wave packet by adding lots of waves, which means there's some probability of finding it with the momentum corresponding to any one of those. Both position and momentum are now uncertain, and the uncertainties are connected. If you want to reduce the position uncertainty by making a smaller wave packet, you need to add more waves, which means a bieggr momentum uttcrnaeniy. If you want to know the momentum better, you need a bigger wave packet, which maens a bigger position uncertainty. That's the Heisenberg Uncertainty Principle, first stated by German physicist wnerer Heisenberg back in 1927. This uncertainty isn't a mttaer of measuring well or badly, but an inevitable rluest of combining particle and wave nature. The Uncertainty pnliipcre isn't just a practical limit on measurment. It's a liimt on what properties an object can have, built into the fundamental suuctrrte of the universe itself.

Open Cloze

The Heisenberg Uncertainty Principle is one of a _______ of ideas from quantum physics to expand into _______ pop culture. It says that you can never ______________ know the exact position and the exact speed of an object and shows up as a metaphor in everything from literary criticism to sports __________. Uncertainty is often explained as a result of ___________, that the act of measuring an object's position changes its speed, or vice versa. The real origin is much deeper and more amazing. The Uncertainty Principle exists because everything in the universe behaves like both a particle and a wave at the same time. In quantum mechanics, the exact position and exact speed of an object have no meaning. To understand this, we need to think about what it means to ______ like a particle or a wave. _________, by definition, _____ in a single place at any instant in time. We can _________ this by a graph showing the probability of _______ the object at a particular place, which looks like a _____, 100% at one specific position, and zero everywhere else. _____, on the other hand, are disturbances spread out in space, like ripples covering the surface of a pond. We can clearly identify features of the wave pattern as a whole, most importantly, its __________, which is the distance between two neighboring peaks, or two neighboring _______. But we can't ______ it a ______ position. It has a good probability of being in lots of different places. Wavelength is _________ for quantum physics because an object's wavelength is related to its momentum, mass times velocity. A fast-moving object has lots of momentum, which corresponds to a very short wavelength. A heavy object has lots of momentum even if it's not ______ very fast, which again means a very short wavelength. This is why we don't notice the wave nature of everyday objects. If you toss a baseball up in the air, its wavelength is a billionth of a trillionth of a trillionth of a meter, far too tiny to ever detect. Small things, like _____ or electrons though, can have wavelengths big enough to measure in physics experiments. So, if we have a pure wave, we can measure its wavelength, and thus its momentum, but it has no position. We can know a particles position very well, but it doesn't have a wavelength, so we don't know its momentum. To get a ________ with both position and momentum, we need to mix the two pictures to make a graph that has waves, but only in a small area. How can we do this? By combining waves with different wavelengths, which means giving our quantum object some possibility of having different momenta. When we add two waves, we find that there are places where the peaks line up, making a bigger wave, and other places where the peaks of one fill in the valleys of the other. The result has regions where we see waves separated by regions of nothing at all. If we add a third wave, the regions where the waves ______ out get bigger, a fourth and they get bigger still, with the wavier _______ becoming ________. If we keep adding waves, we can make a wave ______ with a clear wavelength in one small region. That's a quantum object with both wave and particle nature, but to __________ this, we had to lose certainty about both ________ and momentum. The positions isn't restricted to a single point. There's a good probability of finding it within some range of the center of the wave packet, and we made the wave packet by adding lots of waves, which means there's some probability of finding it with the momentum corresponding to any one of those. Both position and momentum are now uncertain, and the uncertainties are connected. If you want to reduce the position uncertainty by making a smaller wave packet, you need to add more waves, which means a ______ momentum ___________. If you want to know the momentum better, you need a bigger wave packet, which _____ a bigger position uncertainty. That's the Heisenberg Uncertainty Principle, first stated by German physicist ______ Heisenberg back in 1927. This uncertainty isn't a ______ of measuring well or badly, but an inevitable ______ of combining particle and wave nature. The Uncertainty _________ isn't just a practical limit on measurment. It's a _____ on what properties an object can have, built into the fundamental _________ of the universe itself.

Solution

  1. commentary
  2. single
  3. position
  4. packet
  5. assign
  6. simultaneously
  7. atoms
  8. particles
  9. waves
  10. measurement
  11. general
  12. behave
  13. spike
  14. limit
  15. exist
  16. wavelength
  17. valleys
  18. structure
  19. accomplish
  20. result
  21. moving
  22. matter
  23. finding
  24. werner
  25. cancel
  26. essential
  27. regions
  28. handful
  29. means
  30. uncertainty
  31. particle
  32. narrower
  33. represent
  34. principle
  35. bigger

Original Text

The Heisenberg Uncertainty Principle is one of a handful of ideas from quantum physics to expand into general pop culture. It says that you can never simultaneously know the exact position and the exact speed of an object and shows up as a metaphor in everything from literary criticism to sports commentary. Uncertainty is often explained as a result of measurement, that the act of measuring an object's position changes its speed, or vice versa. The real origin is much deeper and more amazing. The Uncertainty Principle exists because everything in the universe behaves like both a particle and a wave at the same time. In quantum mechanics, the exact position and exact speed of an object have no meaning. To understand this, we need to think about what it means to behave like a particle or a wave. Particles, by definition, exist in a single place at any instant in time. We can represent this by a graph showing the probability of finding the object at a particular place, which looks like a spike, 100% at one specific position, and zero everywhere else. Waves, on the other hand, are disturbances spread out in space, like ripples covering the surface of a pond. We can clearly identify features of the wave pattern as a whole, most importantly, its wavelength, which is the distance between two neighboring peaks, or two neighboring valleys. But we can't assign it a single position. It has a good probability of being in lots of different places. Wavelength is essential for quantum physics because an object's wavelength is related to its momentum, mass times velocity. A fast-moving object has lots of momentum, which corresponds to a very short wavelength. A heavy object has lots of momentum even if it's not moving very fast, which again means a very short wavelength. This is why we don't notice the wave nature of everyday objects. If you toss a baseball up in the air, its wavelength is a billionth of a trillionth of a trillionth of a meter, far too tiny to ever detect. Small things, like atoms or electrons though, can have wavelengths big enough to measure in physics experiments. So, if we have a pure wave, we can measure its wavelength, and thus its momentum, but it has no position. We can know a particles position very well, but it doesn't have a wavelength, so we don't know its momentum. To get a particle with both position and momentum, we need to mix the two pictures to make a graph that has waves, but only in a small area. How can we do this? By combining waves with different wavelengths, which means giving our quantum object some possibility of having different momenta. When we add two waves, we find that there are places where the peaks line up, making a bigger wave, and other places where the peaks of one fill in the valleys of the other. The result has regions where we see waves separated by regions of nothing at all. If we add a third wave, the regions where the waves cancel out get bigger, a fourth and they get bigger still, with the wavier regions becoming narrower. If we keep adding waves, we can make a wave packet with a clear wavelength in one small region. That's a quantum object with both wave and particle nature, but to accomplish this, we had to lose certainty about both position and momentum. The positions isn't restricted to a single point. There's a good probability of finding it within some range of the center of the wave packet, and we made the wave packet by adding lots of waves, which means there's some probability of finding it with the momentum corresponding to any one of those. Both position and momentum are now uncertain, and the uncertainties are connected. If you want to reduce the position uncertainty by making a smaller wave packet, you need to add more waves, which means a bigger momentum uncertainty. If you want to know the momentum better, you need a bigger wave packet, which means a bigger position uncertainty. That's the Heisenberg Uncertainty Principle, first stated by German physicist Werner Heisenberg back in 1927. This uncertainty isn't a matter of measuring well or badly, but an inevitable result of combining particle and wave nature. The Uncertainty Principle isn't just a practical limit on measurment. It's a limit on what properties an object can have, built into the fundamental structure of the universe itself.

Frequently Occurring Word Combinations

ngrams of length 2

collocation frequency
uncertainty principle 3
heisenberg uncertainty 2
quantum physics 2
exact position 2
exact speed 2
good probability 2
short wavelength 2
wave nature 2
quantum object 2
wave packet 2
position uncertainty 2

Important Words

  1. accomplish
  2. act
  3. add
  4. adding
  5. air
  6. amazing
  7. area
  8. assign
  9. atoms
  10. badly
  11. baseball
  12. behave
  13. behaves
  14. big
  15. bigger
  16. billionth
  17. built
  18. cancel
  19. center
  20. certainty
  21. clear
  22. combining
  23. commentary
  24. connected
  25. corresponds
  26. covering
  27. criticism
  28. culture
  29. deeper
  30. definition
  31. detect
  32. distance
  33. disturbances
  34. electrons
  35. essential
  36. everyday
  37. exact
  38. exist
  39. exists
  40. expand
  41. experiments
  42. explained
  43. fast
  44. features
  45. fill
  46. find
  47. finding
  48. fourth
  49. fundamental
  50. general
  51. german
  52. giving
  53. good
  54. graph
  55. hand
  56. handful
  57. heavy
  58. heisenberg
  59. ideas
  60. identify
  61. importantly
  62. inevitable
  63. instant
  64. limit
  65. line
  66. literary
  67. lose
  68. lots
  69. making
  70. mass
  71. matter
  72. meaning
  73. means
  74. measure
  75. measurement
  76. measuring
  77. measurment
  78. mechanics
  79. metaphor
  80. meter
  81. mix
  82. momenta
  83. momentum
  84. moving
  85. narrower
  86. nature
  87. neighboring
  88. notice
  89. object
  90. objects
  91. origin
  92. packet
  93. particle
  94. particles
  95. pattern
  96. peaks
  97. physicist
  98. physics
  99. pictures
  100. place
  101. places
  102. point
  103. pond
  104. pop
  105. position
  106. positions
  107. possibility
  108. practical
  109. principle
  110. probability
  111. properties
  112. pure
  113. quantum
  114. range
  115. real
  116. reduce
  117. region
  118. regions
  119. related
  120. represent
  121. restricted
  122. result
  123. ripples
  124. separated
  125. short
  126. showing
  127. shows
  128. simultaneously
  129. single
  130. small
  131. smaller
  132. space
  133. specific
  134. speed
  135. spike
  136. sports
  137. spread
  138. stated
  139. structure
  140. surface
  141. time
  142. times
  143. tiny
  144. toss
  145. trillionth
  146. uncertain
  147. uncertainties
  148. uncertainty
  149. understand
  150. universe
  151. valleys
  152. velocity
  153. versa
  154. vice
  155. wave
  156. wavelength
  157. wavelengths
  158. waves
  159. wavier
  160. werner