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In astronomy, dark matter is an invisible and hypothetical form of matter that does not interact with light or other electromagnetic radiation. Dark matter is implied by gravitational effects which cannot be explained by general relativity unless more matter is present than can be observed.
The Dark Era is defined as "n > 101". By this era, with only very diffuse matter remaining, activity in the universe will have tailed off dramatically, with very low energy levels and very large time scales. Electrons and positrons drifting through space will encounter one another and occasionally form positronium atoms.
Vera Florence Cooper Rubin (/ ˈ r uː b ɪ n /; July 23, 1928 – December 25, 2016) was an American astronomer who pioneered work on galaxy rotation rates. [1] [2] She uncovered the discrepancy between the predicted and observed angular motion of galaxies by studying galactic rotation curves.
In physics, the special theory of relativity, or special relativity for short, is a scientific theory of the relationship between space and time. In Albert Einstein 's 1905 paper, On the Electrodynamics of Moving Bodies , the theory is presented as being based on just two postulates : [ p 1 ] [ 1 ] [ 2 ]
About 90% of all matter appears to be dark matter, which has mass (or, equivalently, gravitational influence), but does not interact electromagnetically and, hence, cannot be observed directly. [140] There is no generally accepted description of this new kind of matter, within the framework of known particle physics [ 141 ] or otherwise. [ 142 ]
At the same time, when Lorentz worked out his theory, Wien (1903) recognized an important consequence of the velocity dependence of mass. He argued that superluminal velocities were impossible, because that would require an infinite amount of energy — the same was already noted by Thomson (1893) and Searle (1897).
The results show that cold dark matter produces a reasonable match to observations, but hot dark matter does not. The sky at energies above 100 MeV observed by the Energetic Gamma Ray Experiment Telescope (EGRET) of the Compton Gamma Ray Observatory (CGRO) satellite (1991–2000). 1988 – The CfA2 Great Wall is discovered in the CfA2 redshift ...
This class of theories attempts to come up with an all-encompassing theory of both dark matter and dark energy as a single phenomenon that modifies the laws of gravity at various scales. This could, for example, treat dark energy and dark matter as different facets of the same unknown substance, [ 55 ] or postulate that cold dark matter decays ...