# Questions tagged [gravity-theory]

Gravity is the weakest of the four fundamental forces of physics. The standard gravity theory is Newton's law of universal gravitation and general theory of relativity (proposed by Albert Einstein in 1915, and David Hilbert, and others). Alternative formulations include string theory, entanglement and others.

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### Mach's principle, Newton's law and Hilbert sphere?

(This question has originally been posted on reddit, but I thought, that the question raised in the post above, might fit as well here on MO.) I wanted to share with you something I stumbled upon ...
271 views

### Inverse square-law as a positive definite kernel?

Newtons law for gravity states that: $$F_{12} = \frac{G m_1 m_2} {|x_1-x_2|^2}$$ The function : $$k(x,y):=\exp(-| x-y|^2)$$ is known to be a positive definite function, called the RBF-kernel. It ...
185 views

### What are the applications of spin geometry? [closed]

What are applications of spin geometry to physics? Does it have something to do with gravity?
1 vote
82 views

### How to smoothly interpolate gravitational field between trajectories in high dimension?

I'm looking for the adequate numerical interpolation technique to solve the following problem. This is probably trivial for physicists who study gravitational fields, but I didn't find clear answers ...
2k views

### Decidability of 3 body problem

Is there a result showing that something along the lines of the three body problem is undecidable? Or are they known to be decidable or neither? I mean problems along the lines of the following ...
1 vote
54 views

### What does it mean for correlation functions to be dominated by the vacuum block for a 2D CFT?

In a 2D CFT, correlation functions dominated by the vacuum block have no conical defects. You can calculate the OPE and determine the correlation function using the D-S equations and cancel out UV ...
4k views

### Euler's Master's Thesis

At the age of 16, Leonhard Euler defended his Master's Thesis, where he discussed and compared Descartes' and Newton's approaches to planet motion. I don't know anything else about it. In particular, ...
78 views

### Prerequisites/Preparation for understanding a research paper - global solutions to Einstein field in Bondi Coordinates

I would like to read this paper: João L. Costa, Filipe C. Mena, Global solutions to the spherically symmetric Einstein-scalar field system with a positive cosmological constant in Bondi ...
238 views

### Electromagnetic energy in Lovelock gravities

To fix ideas, let us recall that General Relativity describes gravitational phenomena on a 4-dimensional pseudo-Riemannian manifold $(X,g_{ab})$ with field equations that relate the energy-momentum ...
2k views

### What do physicists mean by a topological quantum gravity theory

This is a jargon-like question. The fact that this is posted here rather in a physics forum indicates two things I know too little physics. An explanation with more mathematics flavors will be ...
Given a spherically symmetric potential $V: {\bf R}^d \to {\bf R}$, smooth away from the origin, one can consider the Newtonian equations of motion $$\frac{d^2}{dt^2} x = - (\nabla V)(x)$$ for a ...