Einstein’s equations of general relativity (modern notation, λ → Λ): −G = Tµν κ µν curvature = mass/energy density + c.c. It generally predicts a slightly slower acceleration of the expansion of the universe than the cosmological constant. It is customary to describe dark energy as a cosmic fluid d efined by its equation of state (EOS) of the form p d =wρ d , where ρ d and p d stand for dark-energy density and pressure, respectively. A simple model of dark energy with a constant or a varying equation of state parameter is that of a barotropic fluid. This could, for example, treat dark energy and dark matter as different facets of the same unknown substance,The density of the dark energy might have varied in time during the history of the universe. Some scientists have proposed that our The simplest explanation for dark energy is that it is an intrinsic, fundamental energy of space. Inflation, occurring about 10Quintessence is from the ancient Greeks who used the term to describe a mysterious ‘fifth Depending on the ratio of the two energies and the pressure they exert, quintessence can either attract or repel. This scenario is so-called 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. He found that with only the conventional type of gravity, his solutions predicted a Universe that was either expanding or contracting. In physical cosmology, dark energy is a hypothetical form of energy that permeates all of space and tends to increase the rate of expansion of the universe.Assuming the existence of dark energy is the most popular way to explain recent observations that the universe appears to be expanding at an accelerating rate.In the standard model of cosmology, dark energy currently accounts for almost three-quarters of the total mass-energy of the universe.Two proposed forms for dark energy are the cosmological constant, a constant energy density filling space homogeneously, and scalar fields such as quintessence or moduli, dynamic fields whose energy density can vary in time and space.In fact contributions from scalar fields which are constant in space are usually also included in the cosmological constant.The cosmological constant is thought to arise from the vacuum energy.Scalar fields which do change in space are hard to distinguish from a cosmological constant, because the change may be extremely slow.High-precision measurements of the expansion of the universe are required to understand how the speed of the expansion changes over time.The rate of expansion is parameterized by the cosmological equation of state.Measuring the equation of state of dark energy is one of the biggest efforts in observational cosmology today.Adding the cosmological constant to cosmology's standard FLRW metric leads to the Lambda-CDM model, which has been referred to as the "standard model" of cosmology because of its precise agreement with observations.The exact nature of this dark energy is a matter of speculation.It is known to be very homogeneous, not very dense and is not known to interact through any of the fundamental forces other than gravity.Since it is not very dense, it is hard to imagine experiments to detect it in the laboratory.Dark energy can only have such a profound impact on the universe, making up 70% of all energy, because it uniformly fills otherwise empty space.The two leading models are quintessence and the cosmological constant.The simplest explanation for dark energy is that it is simply the "cost of having space": that is, a volume of space has some intrinsic, fundamental energy.Another possibility is that dark energy may become dark matter when buffeted by baryonic particles, thus leading to particle-like excitations in some type of dynamical field, referred to as quintessence.Quintessence differs from the cosmological constant in that it can vary in space and time.In order for it not to clump and form structure like matter, it must be very light so that it has a large Compton wavelength.Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. It is a quantum field with kinetic and potential energy. Because it is causing the universe to expand rather than contract, dark energy is said to have negative pressure, or “tension”, hence the solution to its equation of state has a minus value.
It was a Other types of dark energy have been proposed, including a cosmic field associated with inflation and a different, low-energy field dubbed “quintessence”.It is thought that the very early universe also went through a period of rapid expansion, called inflation. Depending on the ratio of the two energies and the pressure they exert, quintessence can either attract or repel. As Preposterous readers know all too well, about seventy percent of the stuff in the universe is a mysterious substance called dark energy (unless general relativity is breaking down, which is interesting but less likely).
It has an equation of state (relating its pressure p and density ρ) of p = wρ, where w is equal to the equation of state of the energy component dominating the universe. A No-Go theorem has been proven that gives this scenario at least two degrees of freedom as required for dark energy models. (2017). This is the cosmological constant, usually represented by the Greek letter Λ (Lambda, hence The cosmological constant has negative pressure equal and opposite to its There are two major advantages for the cosmological constant.