# Postquantum Gravity: A New Approach to Quantum Physics and Gravity
Physicists have discovered a new approach to solving a century-old problem: combining quantum physics with gravity. This new approach, called postquantum Gravity, is proposed by Jonathan Oppenheim and his collaborators. The theory not only provides a solution to the conflict between quantum physics and gravity but also explains dark matter and dark energy.
# Conflict Between Quantum Physics and Gravity
Quantum physics and gravity are fundamentally different. Quantum physics is a non-deterministic theory with a random element and inherent uncertainty. It suggests that quantum particles can be in two places at once, but the math indicates that it doesn't make sense to say they are in any particular place.
On the other hand, gravity is described by Einstein's theory of general relativity, which is deterministic. It assigns a time and place to everything and follows a deterministic pattern where the future follows from the past.
# Previous Attempts to Unify Quantum Physics and Gravity
Many attempts have been made to unify quantum physics and gravity, leading to theories such as String Theory, Loop Quantum Gravity, and Asymptotically Safe Gravity. These theories aim to give quantum properties to gravity. However, the path less taken is to leave gravity as a non-quantum theory or to change something about quantum physics. These ideas have not been successful so far.
# Postquantum Gravity: A New Idea
Oppenheim's new idea, postquantum Gravity, combines gravity and quantum physics by giving a random element to gravity. This randomness is not derived from anything else and is a fundamental ingredient, just like the randomness of quantum mechanics.
In this theory, quantum mechanics remains non-quantum, and particles remain quantum. However, these two sectors communicate with each other because particles have gravity, and that gravity in return influences the particles. This works without contradictions because these two randomness fit together in the new framework.
# Changes to the Law of Gravity
Oppenheim and his co-author Russo say that this randomness changes the law of gravity under certain circumstances. Specifically, when the acceleration of an object is very small, the changes to the law of gravity are noticeable. This behavior is similar to Modified Newtonian Dynamics (MOND), a modification of Einstein's gravity that becomes noticeable at small acceleration.
The authors derive an equation that is similar to Newton's law of gravity for the Newtonian potential, with some unusual contributions. These extra contributions seem to be similar to those of Modified Newtonian Dynamics, which is a competitor to dark matter. For good measure, they also get a term that they say looks like dark energy.
# Criticism of the Theory
However, there is criticism of the theory. The equation used is linear in the Newtonian potential, while modified gravity requires a nonlinear equation in the potential. The authors have not yet addressed this issue, and it remains to be seen if the theory can be modified to address this criticism.
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