Physics:Gravitationally-interacting massive particles

Gravitationally-interacting massive particles (GIMPs) are a set of particles theorised to explain the dark matter in our universe, as opposed to an alternative theory based on weakly-interacting massive particles (WIMPs). The proposal makes dark matter a form of singularities in dark energy, described by Einstein's gravitational field equations for General Relativity.

Background

Dark matter was postulated in 1933 by Zwicky, who noticed the failure of the velocity curves of stars to decrease when plotted as functions of their distance from the center of galaxies.

Since Albert Einstein’s development of General Relativity, our universe has been best described on the macroscopic scale by four-dimensional spacetime whose metric is calculated via the Einstein field equations:

[math]\displaystyle{ R_{\mu \nu} - \tfrac{1}{2}R \, g_{\mu \nu} + \Lambda g_{\mu \nu} = \frac{8 \pi G }{c^4} T_{\mu \nu}. }[/math]

Here R_μν is the Ricci curvature tensor, R is the scalar curvature, g_μν the metric tensor, G Newton’s gravitational constant, c the speed of light in vacuum, and T_μν is the stress–energy tensor. The symbol Λ represents the “cosmological constant”.

WIMPs would be elementary particles described by the Standard Model of quantum mechanics, which could be studied by experiments in particle laboratories such as CERN. In contrast, the proposed GIMP particles would follow the Vacuum Solutions of Einstein’s equations for gravity. They would be singular structures in spacetime, embedded within a geometry whose average forms the dark energy that Einstein expressed in his cosmological constant.

Implications

The proposed identification of dark matter with GIMPs makes dark matter a form of dark energy filled with singularities, i.e., “entangled” dark energy. This would roughly affirm Einstein's hope in 1919 that all particles in the universe would follow the traceless version of his equation.

If we identify all matter as the sum of dark energy plus dark matter in the form of GIMPs, his expectation would turn out to have been almost right. Matter would play a role similar to point charges in the homogeneous Maxwell equation [math]\displaystyle{ \nabla^2 E = 0 }[/math] in which delta functions are ignored. The sum of dark matter plus dark energy makes up 76% of all matter, which is sufficient to allow computer simulations to produce a good representation of the behavior of all matter.