- #1
jingles2005
- 2
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Under what conditions will quantum effects become important for gravity?
Under what conditions will quantum effects become important for gravity?
- Context: Graduate
- Thread starter jingles2005
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Discussion Overview
The discussion centers on the conditions under which quantum effects become significant in the context of gravity, exploring theoretical implications and experimental observations related to strong gravitational fields and high-energy interactions.
Discussion Character
- Exploratory
- Technical explanation
- Debate/contested
Main Points Raised
- Some participants propose that quantum effects are relevant in very strong gravitational fields, such as those near black holes, or in high-energy particle interactions.
- Others argue that in current particle physics experiments, such as those conducted in accelerators and colliders, gravitational effects are negligible due to the absence of a renormalizable quantum theory of gravity.
- One participant mentions that while quantum effects can be neglected in general relativity for large-scale phenomena, cosmological scenarios may present complexities that warrant further investigation.
- Another participant raises the question of what specific effects arise from strong gravitational fields and high-energy particles, suggesting gravitational redshift as one example.
- It is noted that quantum gravity effects might be responsible for inhomogeneities in the Universe, with some calculations aligning with observations of the cosmic microwave background (CMB) spectrum and large-scale structure.
- A participant highlights that differences in Earth's gravitational potential can lead to detectable phase shifts in the wavefunction of quantum particles, referencing the COW experiments as foundational evidence.
Areas of Agreement / Disagreement
The discussion contains multiple competing views regarding the significance of quantum effects in gravity, and no consensus is reached on the specific conditions or implications of these effects.
Contextual Notes
Participants express uncertainty regarding the precise conditions under which quantum effects become important, and there are references to ongoing experiments that may further elucidate these issues.
- #2
dextercioby
Science Advisor
- 13,410
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Either very strong gravity fields (see BH and all similar phenomena) or very high energy particles/interactions in particle physics...For now,in accelerators and colliders gravity effects are too small to be considered,and that fact would be impossible,because we lack a renormalizable quantum theory of gravity.Quantum effects can be neglected in GR,as long you consider large scale phenomena,like planetary/galactic motion.Once you get into cosmology,things are not that simple...
Daniel.
Daniel.
- #3
Idlemind
- 2
- 0
What would the effects be caused by the strong gravitaional fields and the energy particles?
Last edited:
- #4
Gza
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- #5
smallphi
- 436
- 2
It is believed that quantum gravity effects are responsible for the inhomogeneities in the Universe. There are even calculations in agreement with CMB spectrum and Large Scale Structure.
- #6
Creator
- 566
- 6
jingles2005 said:
It is not commonly realized that even differences in Earth's gravitational potential produce detectable phase shifts in the wavefunction of quantum particles.
This was first established experimentally in the so called COW experiments,( after the authors, Colella, Overhauser, and Werner, 1975) using neutron interferometry.(Phys. Rev. Lett. 34, p.1472 - 1474 (1975))
or
See here: http://prola.aps.org/abstract/PRL/v34/i23/p1472_1
Further 'COW' experiments are on-going.
Creator
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