theories:speculative_theories:quantum_gravity
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theories:speculative_theories:quantum_gravity [2018/03/28 08:50] jakobadmin ↷ Links adapted because of a move operation |
theories:speculative_theories:quantum_gravity [2018/12/19 11:00] jakobadmin ↷ Links adapted because of a move operation |
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| <tabbox Intuitive> | <tabbox Intuitive> | ||
| - | Quantum gravity is the generic term for theories that try to combine the principles of [[theories:quantum_theory|quantum theories]] with [[theories:classical_theories:general_relativity|general relativity]]. | + | Quantum gravity is the generic term for theories that try to combine the principles of [[theories:quantum_mechanics:canonical|quantum theories]] with [[models:general_relativity|general relativity]]. |
| - | So far, no experimentally proven theory of quantum gravity exists. | + | So far, no experimentally verified theory of quantum gravity exists. |
| ---- | ---- | ||
| - | * A great book on quantum gravity for layman is "Three Roads to Quantum Gravity" by Lee Smolin | + | * A great book on quantum gravity for laypersons is "Three Roads to Quantum Gravity" by Lee Smolin |
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| <tabbox Concrete> | <tabbox Concrete> | ||
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| * [[https://arxiv.org/abs/1010.5822|Gauge Gravity: a forward-looking introduction]] by Andrew Randono | * [[https://arxiv.org/abs/1010.5822|Gauge Gravity: a forward-looking introduction]] by Andrew Randono | ||
| + | ---- | ||
| + | <blockquote>From a brief analysis of the standard Einstein-Hilbert action, we see that fluctuations of the metric at the Planck scale should become very violent, leading to potential changes in the topology of the spacetime [103, 104]. <cite>https://arxiv.org/abs/1711.00864</cite></blockquote> | ||
| <tabbox Abstract> | <tabbox Abstract> | ||
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| <tabbox Why is it interesting?> | <tabbox Why is it interesting?> | ||
| <blockquote> | <blockquote> | ||
| - | One of the big problems in physics — perhaps the biggest! — is figuring out how our two current best theories fit together. On the one hand we have the [[models:standard_model|Standard Model]], which tries to explain all the forces except gravity, and takes quantum mechanics into account. On the other hand we have [[theories:classical_theories:general_relativity|General Relativity]], which tries to explain gravity, and does not take [[theories:quantum_mechanics|quantum mechanics]] into account. Both theories seem to be more or less on the right track — but until we somehow fit them together, or completely discard one or both, our picture of the world will be deeply schizophrenic. | + | One of the big problems in physics — perhaps the biggest! — is figuring out how our two current best theories fit together. On the one hand we have the [[models:standard_model|Standard Model]], which tries to explain all the forces except gravity, and takes quantum mechanics into account. On the other hand we have [[models:general_relativity|General Relativity]], which tries to explain gravity, and does not take [[theories:quantum_mechanics:canonical|quantum mechanics]] into account. Both theories seem to be more or less on the right track — but until we somehow fit them together, or completely discard one or both, our picture of the world will be deeply schizophrenic. |
| It seems plausible that as a step in the right direction we should figure out a theory of gravity that takes quantum mechanics into account, but reduces to General Relativity when we ignore quantum effects (which should be small in many situations). This is what people mean by "quantum gravity" — the quest for such a theory. | It seems plausible that as a step in the right direction we should figure out a theory of gravity that takes quantum mechanics into account, but reduces to General Relativity when we ignore quantum effects (which should be small in many situations). This is what people mean by "quantum gravity" — the quest for such a theory. | ||
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| - | <blockquote>At the beginning of the XX century,[[theories:classical_theories:general_relativity| General Relativity]] (GR) and [[theories:quantum_mechanics|Quantum Mechanics]] (QM) once | + | <blockquote>At the beginning of the XX century,[[models:general_relativity| General Relativity]] (GR) and [[theories:quantum_mechanics:canonical|Quantum Mechanics]] (QM) once |
| again began reshaping our basic understanding of space and time and, respectively, matter, energy | again began reshaping our basic understanding of space and time and, respectively, matter, energy | ||
| and causality —arguably to a no lesser extent. But we have not been able to combine these new | and causality —arguably to a no lesser extent. But we have not been able to combine these new | ||
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| | Regge calculus | Perturbative quantum gravity | Finkelstein | Null surfaces | [[theories:speculative_theories:lqg|Loop Quantum Gravity]] | | | Regge calculus | Perturbative quantum gravity | Finkelstein | Null surfaces | [[theories:speculative_theories:lqg|Loop Quantum Gravity]] | | ||
| | Simplicial models | QFT on curved space–times | Twistors | Spin foam models | [[theories:speculative_theories:asymptotic_safety|Asymptotic Safety]] | | | Simplicial models | QFT on curved space–times | Twistors | Spin foam models | [[theories:speculative_theories:asymptotic_safety|Asymptotic Safety]] | | ||
| - | | | | | | [[theories:speculative_theories:supergravity|Supergravity]]| | + | | | | | | [[models:speculative_models:supergravity|Supergravity]]| |
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| <tabbox FAQ> | <tabbox FAQ> | ||
| + | |||
| --> What's so difficult about Quantum Gravity?# | --> What's so difficult about Quantum Gravity?# | ||
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| <-- | <-- | ||
| + | -->Why is Gravity Non-Renormalizable?# | ||
| + | see https://arxiv.org/abs/0709.3555 | ||
| + | <-- | ||
| <tabbox History> | <tabbox History> | ||
theories/speculative_theories/quantum_gravity.txt · Last modified: 2020/04/03 16:50 by 95.168.180.148
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