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  2. Planck units - Wikipedia

    en.wikipedia.org/wiki/Planck_units

    The Planck Units are derived from the left-most vertice of the triangle, where the schwarzchild radius meets the compton wavelength. In particle physics and physical cosmology, Planck units are a system of units of measurement defined exclusively in terms of four universal physical constants: c, G, ħ, and k B (described further

  3. List of physical constants - Wikipedia

    en.wikipedia.org/wiki/List_of_physical_constants

    While the values of the physical constants are independent of the system of units in use, each uncertainty as stated reflects our lack of knowledge of the corresponding value as expressed in SI units, and is strongly dependent on how those units are defined. For example, the atomic mass constant is exactly known when expressed using the dalton ...

  4. Planck constant - Wikipedia

    en.wikipedia.org/wiki/Planck_constant

    The Planck constant, or Planck's constant, denoted by , [1] is a fundamental physical constant [1] of foundational importance in quantum mechanics: a photon's energy is equal to its frequency multiplied by the Planck constant, and the wavelength of a matter wave equals the Planck constant divided by the associated particle momentum.

  5. Orders of magnitude (time) - Wikipedia

    en.wikipedia.org/wiki/Orders_of_magnitude_(time)

    10 −14 qs: The length of one Planck time (t P = / ≈ 5.39 × 10 −44 s) [3] is the briefest physically meaningful span of time. It is the unit of time in the natural units system known as Planck units. 10 −30: quectosecond: qs Quectosecond, (quecto-+ second), is one nonillionth of a second 10 −27: rontosecond: rs

  6. Physical constant - Wikipedia

    en.wikipedia.org/wiki/Physical_constant

    The term "physical constant" refers to the physical quantity, and not to the numerical value within any given system of units. For example, the speed of light is defined as having the numerical value of 299 792 458 when expressed in the SI unit metres per second, and as having the numerical value of 1 when expressed in the natural units Planck ...

  7. Orders of magnitude (length) - Wikipedia

    en.wikipedia.org/wiki/Orders_of_magnitude_(length)

    1 Planck length: 0.0000162 qm Planck length; typical scale of hypothetical loop quantum gravity or size of a hypothetical string and of branes; according to string theory, lengths smaller than this do not make any physical sense. [1] Quantum foam is thought to exist at this scale. 10 −24: 1 yoctometer 142 ym

  8. Time-variation of fundamental constants - Wikipedia

    en.wikipedia.org/wiki/Time-variation_of...

    In such systems, it is meaningful to measure any specific quantity which is not used in the definition of units. For example, in Stoney units, the elementary charge is set to e = 1 while the reduced Planck constant is subject to measurement, ħ ≈ 137.03, and in Planck units, the reduced Planck constant is set to ħ = 1, while the elementary ...

  9. System of units of measurement - Wikipedia

    en.wikipedia.org/wiki/System_of_units_of_measurement

    Some examples are as follows: Geometrized unit systems are useful in relativistic physics. In these systems, speed of light and the gravitational constant are among the constants chosen. Planck units is system of geometrized units in which the reduced Planck constant is included in the list of defining