Under what conditions will quantum effects become important for gravity?

In summary, quantum effects become important for gravity under either very strong gravity fields, such as in black holes, or in very high energy particles and interactions in particle physics. Currently, in accelerators and colliders, gravity effects are too small to be considered due to the lack of a renormalizable quantum theory of gravity. However, in cosmology, quantum effects cannot be neglected, as shown by the inhomogeneities in the Universe and agreement with the CMB spectrum and Large Scale Structure. Additionally, even differences in Earth's gravitational potential can produce detectable phase shifts in the wavefunction of quantum particles, as demonstrated in the COW experiments using neutron interferometry.
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Under what conditions will quantum effects become important for gravity?
 
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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.
 
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What would the effects be caused by the strong gravitaional fields and the energy particles?
 
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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.
 
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jingles2005 said:
Under what conditions will quantum effects become important for gravity?

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:biggrin:
 

1. What is the relationship between quantum mechanics and gravity?

The relationship between quantum mechanics and gravity is still not fully understood, and is a subject of ongoing research. However, it is believed that quantum mechanics plays a significant role in the behavior of gravity at very small scales, such as the Planck scale.

2. What is the Planck scale and why is it important?

The Planck scale is the smallest scale at which our current understanding of physics breaks down. It is approximately 10^-35 meters and 10^-43 seconds. This scale is important because it is the scale at which quantum effects are believed to become important for gravity.

3. How do quantum effects affect the behavior of gravity?

At very small scales, the uncertainty principle of quantum mechanics becomes significant. This means that the position and momentum of particles cannot be known simultaneously, and the concept of a continuous spacetime breaks down. This leads to the need for a quantum theory of gravity to fully understand the behavior of gravity at these scales.

4. Can quantum mechanics and general relativity be reconciled?

Currently, there is no widely accepted theory that fully reconciles quantum mechanics and general relativity. However, there are several theories, such as string theory and loop quantum gravity, that attempt to bridge the gap between the two. Further research and experiments are needed to determine which theory, if any, is correct.

5. What are some potential consequences of quantum effects on gravity?

If quantum effects are found to play a significant role in the behavior of gravity, it could have major implications for our understanding of the universe. It could potentially lead to a better understanding of the origin of the universe, the behavior of black holes, and the nature of spacetime. It could also have technological applications, such as in the development of quantum computers and advanced propulsion systems.

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