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Alternatively, if gravitons are massive at all, the analysis of gravitational waves yielded a new upper bound on the mass of gravitons. The graviton's Compton wavelength is at least 1.6 × 10 16 m , or about 1.6 light-years , corresponding to a graviton mass of no more than 7.7 × 10 −23 eV / c 2 . [ 18 ]
Quantum gravity (QG) is a field of theoretical physics that seeks to describe gravity according to the principles of quantum mechanics.It deals with environments in which neither gravitational nor quantum effects can be ignored, [1] such as in the vicinity of black holes or similar compact astrophysical objects, as well as in the early stages of the universe moments after the Big Bang.
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 into dark energy. [56] Another class of theories that unifies dark matter and dark energy are suggested to be covariant theories of modified gravities.
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 ...
Scientists studying the earliest black holes may have found an answer to dark matter, putting Stephen Hawking’s theory on the subject back into the spotlight.
For example, in regions of high dark matter density (e.g., the centre of the Milky Way) two dark matter particles could annihilate to produce gamma rays or Standard Model particle–antiparticle pairs. [143] Alternatively, if a dark matter particle is unstable, it could decay into Standard Model (or other) particles.
For those theories that incorporate or aim to replace dark energy, the supernova brightness results and the age of the universe can be used as tests. Another test is the flatness of the universe. With general relativity, the combination of baryonic matter, dark matter and dark energy add up to make the universe exactly flat.
Dark matter is a mysterious, invisible substance makes up more than 80 percent of all matter in the universe Science has found its first candidate for a dark-matter detector. It’s a really old rock