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Importantly, the theory also explains (without invoking the existence of dark matter and tweaking of its new free parameters) why galactic rotation curves differ from the profile expected with visible matter. The theory of entropic gravity posits that what has been interpreted as unobserved dark matter is the product of quantum effects that can ...
Induced gravity (or emergent gravity) is an idea in quantum gravity that spacetime curvature and its dynamics emerge as a mean field approximation of underlying microscopic degrees of freedom, similar to the fluid mechanics approximation of Bose–Einstein condensates. The concept was originally proposed by Andrei Sakharov in 1967.
In physics, gravity (from Latin gravitas 'weight' [1]) is a fundamental interaction primarily observed as a mutual attraction between all things that have mass.Gravity is, by far, the weakest of the four fundamental interactions, approximately 10 38 times weaker than the strong interaction, 10 36 times weaker than the electromagnetic force, and 10 29 times weaker than the weak interaction.
He further argues that this entropy modifies emergent gravity, introducing residual forces when the acceleration due to gravity is very weak. [14] The result provides a candidate explanation for dark matter similar to the Modified Newtonian Dynamics (MOND) proposal and explains the empirical relationship between dark matter and the Hubble constant.
The famous singularity theorems, proved using the methods of global geometry, say otherwise: singularities are a generic feature of general relativity, and unavoidable once the collapse of an object with realistic matter properties has proceeded beyond a certain stage [169] and also at the beginning of a wide class of expanding universes. [170]
Examples of intensive properties include temperature, T; refractive index, n; density, ρ; and hardness, η. By contrast, an extensive property or extensive quantity is one whose magnitude is additive for subsystems. [4] Examples include mass, volume and Gibbs energy. [5] Not all properties of matter fall into these two categories.
Geoid undulations based on satellite gravimetry. Gravimetry is the measurement of the strength of a gravitational field.Gravimetry may be used when either the magnitude of a gravitational field or the properties of matter responsible for its creation are of interest.
According to QFT the universe is made up of matter fields whose quanta are fermions (e.g. electrons and quarks), force fields whose quanta are bosons (i.e. photons and gluons) and a Higgs field whose quantum is the Higgs boson. The matter and force fields have zero-point energy. [2]