Search results
Results from the WOW.Com Content Network
Dark matter can refer to any substance which interacts predominantly via gravity with visible matter (e.g., stars and planets). Hence in principle it need not be composed of a new type of fundamental particle but could, at least in part, be made up of standard baryonic matter, such as protons or neutrons. Most of the ordinary matter familiar to ...
Theoretically, in order to explain relatively small-scale structures in the observable Universe, it is necessary to invoke cold dark matter or WDM. In other words, hot dark matter being the sole substance in explaining cosmic galaxy formation is no longer viable, placing hot dark matter under the larger umbrella of mixed dark matter (MDM) theory.
Dark matter is called ‘dark’ because it’s invisible to us and does not measurably interact with anything other than gravity. It could be interspersed between the atoms that make up the Earth ...
In cosmology and physics, cold dark matter (CDM) is a hypothetical type of dark matter. According to the current standard model of cosmology, Lambda-CDM model , approximately 27% of the universe is dark matter and 68% is dark energy , with only a small fraction being the ordinary baryonic matter that composes stars , planets , and living organisms.
Sub-GeV dark matter has been used to explain the positron excess in the Galactic Center observed by INTEGRAL, excess gamma rays from the Galactic Center [7] and extragalactic sources. It has also been suggested that light dark matter may explain a small discrepancy in the measured value of the fine structure constant in different experiments. [8]
As "dark matter", baryonic dark matter is undetectable by its emitted radiation, but its presence can be inferred from gravitational effects on visible matter. This form of dark matter is composed of "baryons", heavy subatomic particles such as protons and neutrons and combinations of these, including non-emitting ordinary atoms.
The presence of dark matter (DM) in the halo is inferred from its gravitational effect on a spiral galaxy's rotation curve.Without large amounts of mass throughout the (roughly spherical) halo, the rotational velocity of the galaxy would decrease at large distances from the galactic center, just as the orbital speeds of the outer planets decrease with distance from the Sun.
Faster-than-light (superluminal or supercausal) travel and communication are the conjectural propagation of matter or information faster than the speed of light in vacuum (c). The special theory of relativity implies that only particles with zero rest mass (i.e., photons ) may travel at the speed of light, and that nothing may travel faster.