czas-i-pomiary: Cosmological constant

Evidence: 100 • authority: 72

In physical cosmology, the cosmological constant (usually denoted by the Greek capital letter lambda: Λ), alternatively called Einstein's cosmological constant, is a coefficient that Albert Einstein initially added to his field equations of general relativity. He later removed it; however, much later it was revived to express the energy density of space, or vacuum energy, that arises in quantum mechanics. It is closely associated with the concept of dark energy. Einstein introduced the constant in 1917 to counterbalance the effect of gravity and achieve a static universe, which was then assumed. Einstein's cosmological constant was abandoned after Edwin Hubble confirmed that the universe wa…

Evidence: 57 • authority: 72

In physical cosmology and astronomy, dark energy is a proposed form of energy that affects the universe on its largest scales. Its primary effect is to drive the accelerating expansion of the universe. It also slows the rate of structure formation. Assuming that the lambda-CDM model of cosmology is correct, dark energy dominates the universe, contributing 68% of the total mass-energy in the present-day observable universe while dark matter and ordinary (baryonic) matter contribute 27% and 5%, respectively, and other components such as neutrinos and photons are nearly negligible. Dark energy's density is very low: 7×10−30 g/cm3 (6×10−10 J/m3 in mass-energy), much lower than the density of or…

Evidence: 45 • authority: 88

The Cosmological Constant Is Not Dark Energy. Dark Energy is one of the mysterious realities of the universe, where our technology is unable to explain its origin and properties. However observational data are consistence with Lambda-CDM model and cosmological constant, but my analysis shows a different result; Cosmological Constant can’t be the cause of expansion.<br><br>As far as observation and experiment could not have the key impact for realizing the reality of Dark Energy, and also observational data are in reach of all researchers, I wanted to have a theoretical analysis of Lambda-CDM model by using these data based on accepted principles of science and physics to see whether it can…

Evidence: 43 • authority: 92

Anisotropy in the cosmic acceleration inferred from supernovae.. Under the assumption that they are standard(izable) candles, the lightcurves of Type Ia supernovae have been analysed in the framework of the standard Friedmann-Lemaitre-Robertson-Walker cosmology to conclude that the expansion rate of the Universe is accelerating due to dark energy. While the original claims in the late 1990s were made using overlapping samples of less than 100 supernovae in total, catalogues of nearly 2000 supernovae are now available. In light of recent developments such as the cosmic dipole anomaly and the larger-than-expected bulk flow in the local Universe (which does not converge to the Cosmic Rest Fram…

Evidence: 41 • authority: 72

In astronomy and cosmology, dark matter is an invisible and hypothetical form of matter that does not interact with electromagnetic radiation, including light. Dark matter is implied by gravitational effects that cannot be explained by general relativity unless more matter is present than can be observed. Such effects occur in the context of formation and evolution of galaxies, gravitational lensing, the observable universe's current structure, mass position in galactic collisions, the motion of galaxies within galaxy clusters, and cosmic microwave background anisotropies. Dark matter is thought to serve as gravitational scaffolding for cosmic structures. After the Big Bang, dark matter clu…

Evidence: 34 • authority: 72

Zero-point energy (ZPE) is the lowest possible energy that a quantum mechanical system may have. Unlike in classical mechanics, quantum systems constantly fluctuate in their lowest energy state as described by the Heisenberg uncertainty principle. Therefore, even at absolute zero, atoms and molecules retain some vibrational motion. Apart from atoms and molecules, the empty space of a vacuum also has these properties. According to quantum field theory, the universe can be thought of not as isolated particles but continuous fluctuating fields: matter fields, whose quanta are fermions (in other words, leptons and quarks), and force fields, whose quanta are bosons (such as photons and gluons).…

Evidence: 34 • authority: 88

Dark Energy and the Riddle of the Cosmological Constant. Dark energy was created to interpret astronomical observations that the earlier standard model of cosmology could not explain. First, measurements of the pattern of cosmic background radiation revealed that the universe must be large-scale flat, corresponding to an average density greater than the "dark" and visible matter combined account for.

Evidence: 29 • authority: 72

A non-standard cosmology is any physical cosmological model of the universe that was, or still is, proposed as an alternative to the then-current standard model of cosmology. The term non-standard is applied to any theory that does not conform to the scientific consensus. Because the term depends on the prevailing consensus, the meaning of the term changes over time. For example, hot dark matter would not have been considered non-standard in 1990, but would have been in 2010. Conversely, a non-zero cosmological constant resulting in an accelerating universe would have been considered non-standard in 1990, but is part of the standard cosmology in 2010. Several major cosmological disputes hav…

Evidence: 27 • authority: 92

Galaxy Evolution with Manifold Learning.. Matter in the early Universe was nearly uniform, and galaxies emerged through the gravitational growth of small primordial density fluctuations. Astrophysics has been trying to unveil the complex physical phenomena that have caused the formation and evolution of galaxies throughout the 13-billion-year history of the Universe using the first principles of physics. However, since present-day astrophysical big data contain more than 100 explanatory variables, such a conventional methodology faces limits in dealing with such data. We, instead, elucidate the physics of galaxy evolution by applying manifold learning, one of the latest methods of data scie…

Evidence: 20 • authority: 92

The orbital dynamics of the LMC and SMC about the Milky Way.. This review summarizes the changing observational and theoretical landscape that has led to rapid developments in our understanding of the orbital history of the Milky Way's most massive satellite galaxies, the LMC and SMC. The determination of high precision center-of-mass proper motions for the Clouds and their environs, coupled with new insights into the structure of dark matter halos from cosmological simulations, indicates that the Clouds are recent additions to the Milky Way's satellite system, where the LMC was sufficiently massive at infall to induce distortions in the Milky Way's dark matter halo, and bring in satellites…

Evidence: 20 • authority: 80

Testing the Cosmological constant as a Candidate for Dark Energy

Evidence: — • authority: 80

Dynamical system analysis of logotropic dark fluid with a power law in the rest-mass energy density