# 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). Dark matter was postulated by F. Zwicky in 1933 who noticed the failure of the velocity curves of stars to decrease when plotted as functions of their distance from the center of galaxies[1][2]. Since Einstein's work, our universe is described by four-dimensional spacetime whose metric is calculable by the Einstein field equations:

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

Here Rμν is the Ricci curvature tensor, R the scalar curvature, gμν the metric tensor, G Newton's gravitational constant, c the speed of light in vacuum, and Tμν the stress–energy tensor. The constant Λ is the so-called cosmological constant[3][4].

While WIMPs would be elementary particles described by the standard model that can in principle be studied by experimentalists in laboratories such as CERN, the proposed particles called GIMPs would follow the Vacuum Solutions of Einstein's equation. They are just singular structures of spacetime in a geometry whose average forms the dark energy that Einstein expressed in his cosmological constant. The identification of "dark matter" with GIMPs proposed[5] makes dark matter a form of dark energy filled with singularities, i.e., an entangled dark energy. This would roughly confirm Einstein's hope in 1919[3] 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 similar role as the point charges in the homogeneous Maxwell equation ${\textstyle \nabla ^{2}E=0}$ 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 impression of the behavior of all matter.[6]

## References

1. ^ Zwicky, Fritz (2009). "Republication of: The redshift of extragalactic nebulae". General Relativity and Gravitation. 41 (1): 207–224. Bibcode:2009GReGr..41..207E. doi:10.1007/s10714-008-0707-4. ISSN 0001-7701.
2. ^ Zwicky, Fritz (1957). Morphological Astronomy. Berlin, Heidelberg: Springer Berlin Heidelberg. ISBN 9783642875441. OCLC 840301926.
3. ^ a b Einstein, Albert (1919). "Spielen Gravitationsfelder im Aufbau der materiellen Elementarteilchen eine wesentliche Rolle?". Albert Einstein: Akademie-Vorträge. Weinheim, FRG: Wiley-VCH Verlag GmbH & Co. KGaA. pp. 167–175. doi:10.1002/3527608958.ch15. ISBN 9783527608959.
4. ^ Sauer, Tilman (2012-10-01). "On Einstein's early interpretation of the cosmological constant". Annalen der Physik. 524 (9–10): A135–A138. Bibcode:2012AnP...524A.135S. doi:10.1002/andp.201200746. ISSN 0003-3804.
5. ^ Kleinert, Hagen (2017). Particles and Quantum Fields. Singapore: World Scientific. pp. 1545–1553. ISBN 978-9814740890. OCLC 934197277.
6. ^ Springel, Volker (2016-09-27). "Hydrodynamical Simulations of Galaxy Formation: Progress, pitfalls, and promises". YouTube. Joint IAS/PU Astrophysics Colloquium. Retrieved 2018-05-25.