full transcript

From the Ted Talk by Sajan Saini: What is the universe expanding into?

Unscramble the Blue Letters

The universe began its cosmic life in a big bang nearly fourteen billion years ago, and has been ednaxinpg ever since. But what is it expanding into? That's a complicated qseioutn. Here's why: Einstein's equations of general relativity describe space and time as a kind of inter-connected farbic for the universe. This means that what we know of as space and time exist only as part of the universe and not beyond it. Now, when everyday objects expand, they move out into more space. But if there is no such thing as space to expand into, what does expanding even mean? In 1929 Edwin Hubble's astronomy ovatrinbseos gave us a definitive answer. His survey of the night sky found all fwraaay galaxies redece, or move away, from the Earth. Moreover, the further the galaxy, the faster it recedes. How can we interpret this? Consider a loaf of raisin bread rising in the oven. The batter rises by the same amount in between each and every raisin. If we think of raisins as a stand-in for galaxies, and batter as the space between them, we can imagine that the stretching or expansion of intergalactic space will make the galaxies recede from each other, and for any galaxy, its faraway noirebhgs will recede a larger distance than the nearby ones in the same amount of time. Sure enough, the eoinqatus of general relativity pedrict a cmsoic tug-of-war between giavrty and expansion. It's only in the dark void between galaxies where esxonapin wins out, and space stretches. So there's our answer. The universe is expanding unto itself. That said, cosmologists are pushing the litmis of mathematical moleds to slapctuee on what, if anything, exists beyond our spacetime. These aren't wild guesses, but hypotheses that tlcake kinks in the scientific theory of the Big Bang. The Big Bang predicts matter to be distributed evenly across the universe, as a sparse gas —but then, how did galaxies and stars come to be? The inflationary model drsceibes a brief era of incredibly rapid expansion that relates quantum fluctuations in the energy of the early uisevnre, to the formation of clmups of gas that eventually led to galaxies. If we accept this paradigm, it may also iplmy our universe represents one region in a greater cosmic reality that undergoes endless, eternal inflation. We know nothing of this speculative ialinntfg reality, save for the maittaechaml prediction that its endless expansion may be driven by an unstable quantum energy sttae. In many lacol regions, however, the energy may setlte by random chcnae into a stable state, stopping iaointlfn and forming bubble universes. Each bubble universe —ours being one of them —would be described by its own Big Bang and laws of physics. Our universe would be part of a greater multiverse, in which the fantastic rate of eternal inflation makes it impossible for us to ecnneotur a neighbor universe. The Big Bang also predicts that in the early, hot universe, our fundamental feorcs may unify into one super-force. Mathematical string theories suggest descriptions of this unification, in addition to a fundamental srutrtcue for sub-atomic quarks and electrons. In these proposed models, vibrating strings are the building blocks of the universe. Competing models for sgirtns have now been consolidated into a unified dpisteocirn, and ssgeugt these structures may interact with massive, higher dimensional scfuaers called branes. Our universe may be contained within one such brane, flaintog in an unknown higher dimensional place, playfully named “the bulk,” or hyperspace. Other branes—containing other types of universes—may co-exist in hyperspace, and neighboring branes may even share certain fundamental forces like gravity. Both eternal inflation and barnes describe a muirvslete, but while uierensvs in eaetrnl inflation are itleaosd, brane universes could bump into each other. An echo of such a clliooisn may appear in the cosmic microwave background —a soup of radiation throughout our universe, that’s a relic from an ealry Big Bang era. So far, though, we’ve found no such cosmic echo. Some suspect these deirfnifg multiverse hypotheses may eventually coalesce into a common description, or be replaced by something else. As it sdtnas now, they’re speculative explorations of mathematical models. While these models are isnreipd and guided by many scientific experiments, there are very few objective etnmpexreis to directly test them, yet. Until the next Edwin Hubble comes along, scientists will likely be left to argue about the elegance of their competing models… and continue to dream about what, if anything, lies beyond our universe.

Open Cloze

The universe began its cosmic life in a big bang nearly fourteen billion years ago, and has been _________ ever since. But what is it expanding into? That's a complicated ________. Here's why: Einstein's equations of general relativity describe space and time as a kind of inter-connected ______ for the universe. This means that what we know of as space and time exist only as part of the universe and not beyond it. Now, when everyday objects expand, they move out into more space. But if there is no such thing as space to expand into, what does expanding even mean? In 1929 Edwin Hubble's astronomy ____________ gave us a definitive answer. His survey of the night sky found all _______ galaxies ______, or move away, from the Earth. Moreover, the further the galaxy, the faster it recedes. How can we interpret this? Consider a loaf of raisin bread rising in the oven. The batter rises by the same amount in between each and every raisin. If we think of raisins as a stand-in for galaxies, and batter as the space between them, we can imagine that the stretching or expansion of intergalactic space will make the galaxies recede from each other, and for any galaxy, its faraway _________ will recede a larger distance than the nearby ones in the same amount of time. Sure enough, the _________ of general relativity _______ a ______ tug-of-war between _______ and expansion. It's only in the dark void between galaxies where _________ wins out, and space stretches. So there's our answer. The universe is expanding unto itself. That said, cosmologists are pushing the ______ of mathematical ______ to _________ on what, if anything, exists beyond our spacetime. These aren't wild guesses, but hypotheses that ______ kinks in the scientific theory of the Big Bang. The Big Bang predicts matter to be distributed evenly across the universe, as a sparse gas —but then, how did galaxies and stars come to be? The inflationary model _________ a brief era of incredibly rapid expansion that relates quantum fluctuations in the energy of the early ________, to the formation of ______ of gas that eventually led to galaxies. If we accept this paradigm, it may also _____ our universe represents one region in a greater cosmic reality that undergoes endless, eternal inflation. We know nothing of this speculative _________ reality, save for the ____________ prediction that its endless expansion may be driven by an unstable quantum energy _____. In many _____ regions, however, the energy may ______ by random ______ into a stable state, stopping _________ and forming bubble universes. Each bubble universe —ours being one of them —would be described by its own Big Bang and laws of physics. Our universe would be part of a greater multiverse, in which the fantastic rate of eternal inflation makes it impossible for us to _________ a neighbor universe. The Big Bang also predicts that in the early, hot universe, our fundamental ______ may unify into one super-force. Mathematical string theories suggest descriptions of this unification, in addition to a fundamental _________ for sub-atomic quarks and electrons. In these proposed models, vibrating strings are the building blocks of the universe. Competing models for _______ have now been consolidated into a unified ___________, and _______ these structures may interact with massive, higher dimensional ________ called branes. Our universe may be contained within one such brane, ________ in an unknown higher dimensional place, playfully named “the bulk,” or hyperspace. Other branes—containing other types of universes—may co-exist in hyperspace, and neighboring branes may even share certain fundamental forces like gravity. Both eternal inflation and ______ describe a __________, but while _________ in _______ inflation are ________, brane universes could bump into each other. An echo of such a _________ may appear in the cosmic microwave background —a soup of radiation throughout our universe, that’s a relic from an _____ Big Bang era. So far, though, we’ve found no such cosmic echo. Some suspect these _________ multiverse hypotheses may eventually coalesce into a common description, or be replaced by something else. As it ______ now, they’re speculative explorations of mathematical models. While these models are ________ and guided by many scientific experiments, there are very few objective ___________ to directly test them, yet. Until the next Edwin Hubble comes along, scientists will likely be left to argue about the elegance of their competing models… and continue to dream about what, if anything, lies beyond our universe.

Solution

  1. question
  2. suggest
  3. tackle
  4. differing
  5. cosmic
  6. faraway
  7. early
  8. collision
  9. inflation
  10. chance
  11. surfaces
  12. experiments
  13. local
  14. eternal
  15. observations
  16. clumps
  17. predict
  18. describes
  19. description
  20. expanding
  21. encounter
  22. forces
  23. gravity
  24. multiverse
  25. structure
  26. branes
  27. imply
  28. strings
  29. universes
  30. isolated
  31. expansion
  32. floating
  33. equations
  34. fabric
  35. universe
  36. stands
  37. limits
  38. inspired
  39. mathematical
  40. speculate
  41. inflating
  42. neighbors
  43. recede
  44. models
  45. state
  46. settle

Original Text

The universe began its cosmic life in a big bang nearly fourteen billion years ago, and has been expanding ever since. But what is it expanding into? That's a complicated question. Here's why: Einstein's equations of general relativity describe space and time as a kind of inter-connected fabric for the universe. This means that what we know of as space and time exist only as part of the universe and not beyond it. Now, when everyday objects expand, they move out into more space. But if there is no such thing as space to expand into, what does expanding even mean? In 1929 Edwin Hubble's astronomy observations gave us a definitive answer. His survey of the night sky found all faraway galaxies recede, or move away, from the Earth. Moreover, the further the galaxy, the faster it recedes. How can we interpret this? Consider a loaf of raisin bread rising in the oven. The batter rises by the same amount in between each and every raisin. If we think of raisins as a stand-in for galaxies, and batter as the space between them, we can imagine that the stretching or expansion of intergalactic space will make the galaxies recede from each other, and for any galaxy, its faraway neighbors will recede a larger distance than the nearby ones in the same amount of time. Sure enough, the equations of general relativity predict a cosmic tug-of-war between gravity and expansion. It's only in the dark void between galaxies where expansion wins out, and space stretches. So there's our answer. The universe is expanding unto itself. That said, cosmologists are pushing the limits of mathematical models to speculate on what, if anything, exists beyond our spacetime. These aren't wild guesses, but hypotheses that tackle kinks in the scientific theory of the Big Bang. The Big Bang predicts matter to be distributed evenly across the universe, as a sparse gas —but then, how did galaxies and stars come to be? The inflationary model describes a brief era of incredibly rapid expansion that relates quantum fluctuations in the energy of the early universe, to the formation of clumps of gas that eventually led to galaxies. If we accept this paradigm, it may also imply our universe represents one region in a greater cosmic reality that undergoes endless, eternal inflation. We know nothing of this speculative inflating reality, save for the mathematical prediction that its endless expansion may be driven by an unstable quantum energy state. In many local regions, however, the energy may settle by random chance into a stable state, stopping inflation and forming bubble universes. Each bubble universe —ours being one of them —would be described by its own Big Bang and laws of physics. Our universe would be part of a greater multiverse, in which the fantastic rate of eternal inflation makes it impossible for us to encounter a neighbor universe. The Big Bang also predicts that in the early, hot universe, our fundamental forces may unify into one super-force. Mathematical string theories suggest descriptions of this unification, in addition to a fundamental structure for sub-atomic quarks and electrons. In these proposed models, vibrating strings are the building blocks of the universe. Competing models for strings have now been consolidated into a unified description, and suggest these structures may interact with massive, higher dimensional surfaces called branes. Our universe may be contained within one such brane, floating in an unknown higher dimensional place, playfully named “the bulk,” or hyperspace. Other branes—containing other types of universes—may co-exist in hyperspace, and neighboring branes may even share certain fundamental forces like gravity. Both eternal inflation and branes describe a multiverse, but while universes in eternal inflation are isolated, brane universes could bump into each other. An echo of such a collision may appear in the cosmic microwave background —a soup of radiation throughout our universe, that’s a relic from an early Big Bang era. So far, though, we’ve found no such cosmic echo. Some suspect these differing multiverse hypotheses may eventually coalesce into a common description, or be replaced by something else. As it stands now, they’re speculative explorations of mathematical models. While these models are inspired and guided by many scientific experiments, there are very few objective experiments to directly test them, yet. Until the next Edwin Hubble comes along, scientists will likely be left to argue about the elegance of their competing models… and continue to dream about what, if anything, lies beyond our universe.

Frequently Occurring Word Combinations

ngrams of length 2

collocation frequency
big bang 6
eternal inflation 4
general relativity 2
mathematical models 2
fundamental forces 2
higher dimensional 2

Important Words

  1. accept
  2. addition
  3. amount
  4. answer
  5. argue
  6. astronomy
  7. background
  8. bang
  9. batter
  10. began
  11. big
  12. billion
  13. blocks
  14. brane
  15. branes
  16. bread
  17. bubble
  18. building
  19. bulk
  20. bump
  21. called
  22. chance
  23. clumps
  24. coalesce
  25. collision
  26. common
  27. competing
  28. complicated
  29. consolidated
  30. contained
  31. continue
  32. cosmic
  33. cosmologists
  34. dark
  35. definitive
  36. describe
  37. describes
  38. description
  39. descriptions
  40. differing
  41. dimensional
  42. distance
  43. distributed
  44. dream
  45. driven
  46. early
  47. earth
  48. echo
  49. edwin
  50. electrons
  51. elegance
  52. encounter
  53. endless
  54. energy
  55. equations
  56. era
  57. eternal
  58. evenly
  59. eventually
  60. everyday
  61. exist
  62. exists
  63. expand
  64. expanding
  65. expansion
  66. experiments
  67. explorations
  68. fabric
  69. fantastic
  70. faraway
  71. faster
  72. floating
  73. fluctuations
  74. forces
  75. formation
  76. forming
  77. fourteen
  78. fundamental
  79. galaxies
  80. galaxy
  81. gas
  82. gave
  83. general
  84. gravity
  85. greater
  86. guesses
  87. guided
  88. higher
  89. hot
  90. hubble
  91. hyperspace
  92. hypotheses
  93. imagine
  94. imply
  95. impossible
  96. incredibly
  97. inflating
  98. inflation
  99. inflationary
  100. inspired
  101. interact
  102. intergalactic
  103. interpret
  104. isolated
  105. kind
  106. kinks
  107. larger
  108. laws
  109. led
  110. left
  111. lies
  112. life
  113. limits
  114. loaf
  115. local
  116. massive
  117. mathematical
  118. matter
  119. means
  120. microwave
  121. model
  122. models
  123. move
  124. multiverse
  125. named
  126. nearby
  127. neighbor
  128. neighboring
  129. neighbors
  130. night
  131. objective
  132. objects
  133. observations
  134. oven
  135. paradigm
  136. part
  137. physics
  138. place
  139. playfully
  140. predict
  141. prediction
  142. predicts
  143. proposed
  144. pushing
  145. quantum
  146. quarks
  147. question
  148. radiation
  149. raisin
  150. raisins
  151. random
  152. rapid
  153. rate
  154. reality
  155. recede
  156. recedes
  157. region
  158. regions
  159. relates
  160. relativity
  161. relic
  162. replaced
  163. represents
  164. rises
  165. rising
  166. save
  167. scientific
  168. scientists
  169. settle
  170. share
  171. sky
  172. soup
  173. space
  174. spacetime
  175. sparse
  176. speculate
  177. speculative
  178. stable
  179. stands
  180. stars
  181. state
  182. stopping
  183. stretches
  184. stretching
  185. string
  186. strings
  187. structure
  188. structures
  189. suggest
  190. surfaces
  191. survey
  192. suspect
  193. tackle
  194. test
  195. theories
  196. theory
  197. time
  198. types
  199. undergoes
  200. unification
  201. unified
  202. unify
  203. universe
  204. universes
  205. unknown
  206. unstable
  207. vibrating
  208. void
  209. wild
  210. wins
  211. years