The laws of physics can be said to obey certain symmetries. Symmetry C is when the laws for particles are the same as their anti-particles, P is when the laws are the same in the mirror image of any situation, and T is when the laws remain the same if time were reversed.
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Symmetry Term Timeline in A Brief History of Time
The timeline below shows where the term Symmetry appears in A Brief History of Time. The colored dots and icons indicate which themes are associated with that appearance.
Chapter 5
The laws of physics can obey certain kinds of symmetries. Symmetry C refers to the laws applying to particles and anti-particles in the same way....
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...1956, Tsung-Dao Lee and Chen Ning Yang found the weak nuclear force does not obey symmetry P. This was proven true by Chien-Shiung Wu, who caused radioactive atoms to spin in...
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The weak nuclear force also does not obey the symmetry C, meaning it would cause a universe of anti-particles to not behave like our own....
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As the universe expands and cools, forces that do not obey the symmetry of T cause more anti-electrons to become quarks than electrons to become anti-quarks, creating the...
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Chapter 9
Scientific laws obey the combined symmetries of C, P, and T. C refers to particles acting as anti-particles do. P refers...
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Chapter 10
...allows time travel on a miniscule scale. As particles follow the C, P, and T symmetries, a particle going backward in time could be considered an anti-particle going forward in time....
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