Noncommuting position variables due to quantum gravity

In summary, the conversation discusses the concept of quantizing gravity and its relationship to the Planck length. It also touches on the implications of this for measuring the position of a particle in quantum mechanics and the need for modifications in incorporating gravitational effects. The conversation then shifts to the topic of noncommutative field theory and its relevance in M theory, string theory, and quantum Hall states. The speakers note that this field has seen significant research and has led to the discovery of new phenomena. Finally, they discuss the mathematical knowledge required to understand a related paper.
  • #1
nabil0
20
1
I've read that if one wants to quantize gravity , there must be a smallest length scale " The Planck length " . If I want to measure the position of a point particle then in conventional Quantum mechanics I'll find it at the point $(x,y,z)$ at some-time $t$ with an arbitrary momentum but this can't be though in quantum gravity since the smallest length scale that can exist is the Planck scale so the particle must be at a neighbourhood of (x,y,z) of area that's equal to Planck length . So if we measured the X operator to find the eigenvalue x the particle must be spread in the eigenspace of the Y and Z operators that's X,Y,Z are not commuting operators So we must have [X,Y] not equal to zero .
Is this line of reasoning correct ? Have something of this sort been worked out ? It seems that many things in Quantum mechanics should be modified if we want to incorporate gravitational effects
 
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  • #2
http://arxiv.org/abs/hep-th/0106048
Noncommutative Field Theory
Michael R. Douglas (Rutgers, IHES), Nikita A. Nekrasov (IHES, ITEP)
We review the generalization of field theory to space-time with noncommuting coordinates, starting with the basics and covering most of the active directions of research. Such theories are now known to emerge from limits of M theory and string theory, and to describe quantum Hall states. In the last few years they have been studied intensively, and many qualitatively new phenomena have been discovered, both on the classical and quantum level.
 
  • #3
Sounds interesting . What mathematical knowledge required to be able to understand that paper ?
 
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1. What is quantum gravity?

Quantum gravity is a theoretical framework that aims to unify the theories of general relativity and quantum mechanics. It seeks to explain the behavior of gravity at the smallest scales, such as those found in subatomic particles.

2. How does quantum gravity affect position variables?

In quantum gravity, the position variables of particles do not commute, meaning they cannot be precisely measured at the same time. This is because the theory suggests that space and time are not continuous, but rather discrete and grainy, making it impossible to determine an exact position at a given moment.

3. What evidence supports the existence of noncommuting position variables?

Currently, there is no direct empirical evidence for noncommuting position variables due to quantum gravity. However, various theories and mathematical models, such as loop quantum gravity, string theory, and black hole thermodynamics, suggest their existence.

4. How do noncommuting position variables impact our understanding of the universe?

The existence of noncommuting position variables has significant implications for our understanding of the universe. It challenges our traditional notions of space and time and requires us to rethink the fundamental principles of physics. It also has potential implications for the behavior of matter and energy at the smallest scales.

5. Can we observe the effects of noncommuting position variables?

As of now, we do not have the technology or means to directly observe the effects of noncommuting position variables. However, scientists are conducting experiments and using advanced technologies, such as particle accelerators, to test the predictions of quantum gravity and potentially provide evidence for their existence.

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