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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 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.
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 ...
Along with dark energy, dark matter is an outlier in Einstein's relativity, and an explanation for its apparent effects is a requirement for a successful theory of everything. In 1957, Hermann Bondi proposed that negative gravitational mass (combined with negative inertial mass) would comply with the strong equivalence principle of general ...
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.
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 ]
Also Emil Cohn (1904) continued to develop his alternative model (as described above), and while comparing his theory with that of Lorentz, he discovered some important physical interpretations of the Lorentz transformations. He illustrated (like Joseph Larmor in the same year) this transformation by using rods and clocks: If they are at rest ...
Dark energy and dark matter account for most of the Universe's energy, so it is valid to ignore baryons when simulating large-scale structure formation (using methods such as N-body simulation). However, since the visible components of galaxies consist of baryons, it is crucial to include baryons in the simulation to study the detailed ...