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Ω determines the ultimate fate of the universe. If Ω ≥ 1, the universe may experience a Big Crunch. If Ω < 1, the universe may expand forever; [22] λ ≈ 0.7: The ratio of the energy density of the universe, due to the cosmological constant, to the critical density of the universe.
This is a list of well-known dimensionless quantities illustrating their variety of forms and applications. The tables also include pure numbers, dimensionless ratios, or dimensionless physical constants; these topics are discussed in the article.
Dimensionless quantities, or quantities of dimension one, [1] are quantities implicitly defined in a manner that prevents their aggregation into units of measurement. [ 2 ] [ 3 ] Typically expressed as ratios that align with another system, these quantities do not necessitate explicitly defined units .
A physical constant, sometimes fundamental physical constant or universal constant, is a physical quantity that cannot be explained by a theory and therefore must be measured experimentally. It is distinct from a mathematical constant , which has a fixed numerical value, but does not directly involve any physical measurement.
A meaningful test on the time-variation of G would require comparison with a non-gravitational force to obtain a dimensionless quantity, e.g. through the ratio of the gravitational force to the electrostatic force between two electrons, which in turn is related to the dimensionless fine-structure constant.
The matter power spectrum describes the density contrast of the universe (the difference between the local density and the mean density) as a function of scale. It is the Fourier transform of the matter correlation function. On large scales, gravity competes with cosmic expansion, and structures grow according to linear theory. In this regime ...
Pages in category "Dimensionless quantities of chemistry" The following 4 pages are in this category, out of 4 total. This list may not reflect recent changes .
Dimensionless quantities of chemistry (4 P) Pages in category "Dimensionless numbers of chemistry" The following 26 pages are in this category, out of 26 total.