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← Why Is There Something Instead of Nothing?

Lawrence Krauss is the director of the Origins Project at Arizona State University, a theoretical physicist and author of "A Universe from Nothing."

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Showing Revision 3 created 04/16/2014 by Linnygapa.

  1. Hello Spacelab, I'm Lawrence Krauss,
  2. Director of the Origins Project at Arizona State University,
  3. a theoretical physicist and also the author of "A Universe From Nothing".
  4. And I'm here today to answer the following question:
  5. "Why is there something rather than nothing"
  6. Well, the question, "why is there something rather than nothing?",
  7. has been around as long as people have been asking questions,
  8. and it's gotten a lot of different answers.
  9. First, as a scientist, I should say that really
  10. "why" isn't a a good question.
  11. When we say "why", we really mean "how".
  12. Because "why" implies that there is some purpose,
  13. and there may be no purpose to the universe.
  14. In deed, as far as we can tell from all the evidence,
  15. there's no evidence of purpose.
  16. So when you say "why does something happen"
  17. you really mean "how does it happen".
  18. So, the question is "how does something come from nothing?".
  19. It seems to violate the laws of physics.
  20. But in fact the answer is quite interesting,
  21. because, it turns out, the simplest answer may be
  22. that nothing is unstable.
  23. You will always produce something.
  24. In deed, once you combine quantum mechanics and relativity
  25. empty space, which apparently of course is nothing,
  26. is not so simple.
  27. It's actually a boiling, bubbling brew of virtual particles
  28. popping in and out of existence,
  29. in a time scale so short you can't see them.
  30. And in fact, if you wait long enough,
  31. and allow gravity to operate,
  32. empty space will eventually start producing particles.
  33. And in fact, therefore, the answer to the question
  34. "why is there something rather than nothing" or
  35. "how is there something rather than nothing"
  36. is nothing is unstable.
  37. You're guaranteed if you wait long enough
  38. to have something.
  39. And if you want to ask the question
  40. you'll always be the places with something.
  41. So actually, empty space can produce enough particles
  42. to account for all hundred billion galaxies in all,
  43. and a hundred billion stars in each galaxy.
  44. Now, you might say, well empty space isn't nothing.
  45. But, if quantum mechanics actually applies to gravity,
  46. then space and time themselves become
  47. quantum mechanical variables.
  48. And whole universes can pop into existence.
  49. Spaces and times and matter and energy
  50. can pop into existence without violating any laws of physics.
  51. In fact, the total energy of our universe may be zero.
  52. In fact, when we look out, it looks like
  53. it is zero.
  54. And that gives us good evidence
  55. that perhaps it popped into existence
  56. from nothing.
  57. Because no energy to begin with
  58. and zero total energy in the end,
  59. because the positive energy associated
  60. with the mass of elementary particles
  61. is countered by the negative energy of gravity.
  62. Now, the question is of course
  63. what happened before our universe came into existence.
  64. Was there anything at all?
  65. And the answer is we don't know.
  66. A simple answer is, that the question about
  67. what happened before may not be a good question,
  68. because since space and time are tied to matter,
  69. when space and time pop into existence
  70. time itself pops into existence,
  71. and therefore, there may have been no before.
  72. The question may simply not be a good question.
  73. So there may have been no sense
  74. in which you can even ask
  75. what happened before our universe began.
  76. Alternatively, current ideas from physics suggest
  77. that perhaps our universe may be one
  78. of potentially an infinite number of universes
  79. which are popping into existence at various times.
  80. There may be universes being created right now
  81. and other universes ending.
  82. And if that's the case,
  83. then it's possible that the characteristics of our universe
  84. are precisely those that allowed us to evolve.
  85. So when we ask why does the universe have
  86. the properties it does,
  87. the answer is simply
  88. well if it didn't we wouldn't be here to answer the question,
  89. or ask the question.
  90. Now, I should say finally
  91. the question itself is really rather arrogant
  92. because it assumes the universe will always have something in it,
  93. but in fact, in the far future
  94. as far as we can tell, all the galaxies
  95. we can now see are moving away from us
  96. faster and faster and faster.
  97. And that means eventually the entire universe
  98. that we can now see will disappear.
  99. When those galaxies are moving away from us
  100. faster than light, which is allowed in general relativity.
  101. So in the far future there may just be one galaxy
  102. in which we live in, and then the stars will burn out
  103. and the universe become cold, dark, and empty.
  104. And then the simple answer to the question
  105. "why is there something rather than nothing?" is
  106. just wait, there won't be for long.
  107. Thanks for the great question.
  108. If you have a question, leave it in the comments below.
  109. The question with the most likes will be answered
  110. in the next round by another expert.
  111. Hello SpaceLab, I'm Emily Rice
  112. a professor of astronomy at the college of Staten Island
  113. and I'm here today to answer your questions.
  114. The first question is:
  115. If I was able to stand on a neutron star
  116. would I become extremely dizzy?
  117. What effect would this extreme rotational speed have on the body?