Dark matter - Evidence for dark matter

edit In cosmology, dark matter refers to hypothetical matter particles, of unknown composition, that do not emit or reflect enough electromagnetic radiation to be detected directly, but whose presence can be inferred from gravitational effects on visible matter such as stars and galaxies. The dark matter hypothesis aims to explain several anomalous astronomical observations, such as anomalies in the rotational speed of galaxies (the galaxy rotation problem). Estimates of the amount of matter present in galaxies, ...

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• Dark matter - Evidence for dark matter
• Dark matter - Galactic rotation
• Dark matter - Structure formation
• Dark matter - Composition
• Dark matter - Alternative explanations
• Dark matter - Dark matter in popular culture

Read more here: » Dark matter: Encyclopedia - Dark matter

In 1913, Norwegian explorer and physicist Kristian Birkeland may have been the first to predict that space is not only a plasma, but also contains "dark matter". He wrote: "It seems to be a natural consequence of our points of view to assume that the whole of space is filled with electrons and flying electric ions of all kinds. We have assumed that each stellar system in evolutions throws off electric corpuscles into space. It does not seem unreasonable therefore to think that the greater part of the material masses in the universe is found, not in the solar systems ...

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Dark matter, Dark matter - Evidence for dark matter, Dark matter - Galactic rotation, Dark matter - Structure formation, Dark matter - Composition, Dark matter - Alternative explanations, Dark matter - Dark matter in popular culture

Read more here: » Dark matter: Encyclopedia II - Dark matter - Evidence for dark matter

Data from a number of lines of evidence, including galaxy rotation curves, gravitational lensing, structure formation, and the fraction of baryons in clusters and the cluster abundance combined with independent evidence for the baryon density, indicate that 85-90% of the mass in the universe does not interact with the electromagnetic force. This "dark matter" is evident through its gravitational effect. Several categories of dark matter have been postulated. Hot dark matter Warm dark matter Cold dark ...

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Dark matter, Dark matter - Evidence for dark matter, Dark matter - Galactic rotation, Dark matter - Structure formation, Dark matter - Composition, Dark matter - Alternative explanations, Dark matter - Dark matter in popular culture

Read more here: » Dark matter: Encyclopedia II - Dark matter - Composition

Data from galaxy rotation curves indicate that nearly 90% of the mass of a galaxy cannot be seen. It can only be detected by its gravitational effect. Several categories of dark matter have been postulated. Hot dark matter Warm dark matter Cold dark matter Baryonic dark matter Hot dark matter consists of particles that travel with relativistic velocities. One kind of hot dark matter is known, the neutrino. Neutrinos have a very small mass, do not interact via either the electromagnetic or ...

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Dark matter, Dark matter - Evidence for dark matter, Dark matter - Galactic rotation, Dark matter - Structure formation, Dark matter - Composition, Dark matter - Alternative explanations, Dark matter - Dark matter in popular culture

Read more here: » Dark matter: Encyclopedia II - Dark matter - Composition

An alternative to dark matter is to suppose that the inconsistencies are due to an incomplete understanding of gravitation. One task could be given through the need of conciling gravitation with quantum mechanics and to explain mass and its creation (Higgs) within gravitation, as in some scalar-tensor theories, which couple scalar fields like the Higgs field to the curvature given through the Riemann tensor or its traces. In many of such theories, the scalar field equals the inflaton field, which is needed in some theories for explaining the inflation of the universe after the Big Bang, as t ...

See also:

Dark matter, Dark matter - Evidence for dark matter, Dark matter - Galactic rotation, Dark matter - Structure formation, Dark matter - Composition, Dark matter - Alternative explanations, Dark matter - Dark matter in popular culture

Read more here: » Dark matter: Encyclopedia II - Dark matter - Alternative explanations