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For example, Planck units, constructed from c, G, ħ, and k B give conveniently sized measurement units for use in studies of quantum gravity, and atomic units, constructed from ħ, m e, e and 4πε 0 give convenient units in atomic physics. The choice of constants used leads to widely varying quantities.
Within the first fraction of a second of the universe's existence, the four fundamental forces had separated. As the universe continued to cool from its inconceivably hot state, various types of subatomic particles were able to form in short periods of time known as the quark epoch, the hadron epoch, and the lepton epoch. Together, these epochs ...
The constants listed here are known values of physical constants expressed in SI units; that is, physical quantities that are generally believed to be universal in nature and thus are independent of the unit system in which they are measured. Many of these are redundant, in the sense that they obey a known relationship with other physical ...
The cosmological constant, which can be thought of as the density of dark energy in the universe, is a fundamental constant in physical cosmology that has a dimensionless value of approximately 10 −122. [19]
An infinite universe (unbounded metric space) means that there are points arbitrarily far apart: for any distance d, there are points that are of a distance at least d apart. A finite universe is a bounded metric space, where there is some distance d such that all points are within distance d of each other.
In particle physics, an elementary particle or fundamental particle is a subatomic particle that is not composed of other particles. [1] The Standard Model presently recognizes seventeen distinct particles—twelve fermions and five bosons .
In physics, natural unit systems are measurement systems for which selected physical constants have been set to 1 through nondimensionalization of physical units.For example, the speed of light c may be set to 1, and it may then be omitted, equating mass and energy directly E = m rather than using c as a conversion factor in the typical mass–energy equivalence equation E = mc 2.
Atomism (from Ancient Greek ἄτομον (atomon) ' uncuttable, indivisible ') [1] [2] [3] is a natural philosophy proposing that the physical universe is composed of fundamental indivisible components known as atoms. References to the concept of atomism and its atoms appeared in both ancient Greek and ancient Indian philosophical traditions.