Physics:List of physical constants
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 constants and can be determined from them.
Table of physical constants
Symbol | Quantity | Value[lower-alpha 1][lower-alpha 2] | Relative standard uncertainty |
Ref |
---|---|---|---|---|
[math]\displaystyle{ c }[/math] | speed of light in vacuum | 299792458 m/s | 0 | [1] |
[math]\displaystyle{ h }[/math] | Planck constant | 6.62607015×10−34 J⋅s | 0 | [2] |
[math]\displaystyle{ \hbar = h/2\pi }[/math] | reduced Planck constant | 1.054571817...×10−34 J⋅s | 0 | [3] |
[math]\displaystyle{ \mu_0 }[/math] | vacuum magnetic permeability | 1.25663706212(19)×10−6 N⋅A−2 | 1.5×10−10 | [4] |
[math]\displaystyle{ Z_0 = \mu_0 c }[/math] | characteristic impedance of vacuum | 376.730313667(57) Ω | 1.5×10−10 | [5] |
[math]\displaystyle{ \varepsilon_0 = 1/\mu_0 c^2 }[/math] | vacuum electric permittivity | 8.8541878128(13)×10−12 F⋅m−1 | 1.5×10−10 | [6] |
[math]\displaystyle{ k, k_{\text{B}} }[/math] | Boltzmann constant | 1.380649×10−23 J⋅K−1 | 0 | [7] |
[math]\displaystyle{ G }[/math] | Newtonian constant of gravitation | 6.67430(15)×10−11 m3⋅kg−1⋅s−2 | 2.2×10−5 | [8] |
[math]\displaystyle{ k_{\text{e}} = 1/4\pi\varepsilon_0 }[/math] | Coulomb constant | 8.9875517923(14)×109 N⋅m2⋅C−2 | 1.5×10−10 | [9] |
[math]\displaystyle{ \Lambda }[/math] | cosmological constant | 1.089(29)×10−52 m−2 | 0.027 | [10] |
[math]\displaystyle{ \sigma = \pi^2 k_{\text{B}}^4 / 60 \hbar^3 c^2 }[/math] | Stefan–Boltzmann constant | 5.670374419...×10−8 W⋅m−2⋅K−4 | 0 | [11] |
[math]\displaystyle{ c_1 = 2 \pi h c^2 }[/math] | first radiation constant | 3.741771852...×10−16 W⋅m2 | 0 | [12] |
[math]\displaystyle{ c_{\text{1L}} = 2 h c^2 / \mathrm{sr} }[/math] | first radiation constant for spectral radiance | 1.191042972...×10−16 W⋅m2⋅sr−1 | 0 | [13] |
[math]\displaystyle{ c_2 = h c / k_{\text{B}} }[/math] | second radiation constant | 1.438776877...×10−2 m⋅K | 0 | [14] |
[math]\displaystyle{ b }[/math] [lower-alpha 3] | Wien wavelength displacement law constant | 2.897771955...×10−3 m⋅K | 0 | [15] |
[math]\displaystyle{ b' }[/math] [lower-alpha 4] | Wien frequency displacement law constant | 5.878925757...×1010 Hz⋅K−1 | 0 | [16] |
[math]\displaystyle{ b_\text{entropy} }[/math] | Wien entropy displacement law constant | 3.002916077...×10−3 m⋅K | 0 | [17] |
[math]\displaystyle{ e }[/math] | elementary charge | 1.602176634×10−19 C | 0 | [18] |
[math]\displaystyle{ G_0 = 2 e^2 / h }[/math] | conductance quantum | 7.748091729...×10−5 S | 0 | [19] |
[math]\displaystyle{ G_0^{-1} = h / 2 e^2 }[/math] | inverse conductance quantum | 12906.40372... Ω | 0 | [20] |
[math]\displaystyle{ R_{\text{K}} = h / e^2 }[/math] | von Klitzing constant | 25812.80745... Ω | 0 | [21] |
[math]\displaystyle{ K_{\text{J}} = 2 e / h }[/math] | Josephson constant | 483597.8484...×109 Hz⋅V−1 | 0 | [22] |
[math]\displaystyle{ \Phi_0 = h / 2 e }[/math] | magnetic flux quantum | 2.067833848...×10−15 Wb | 0 | [23] |
[math]\displaystyle{ \alpha = e^2 / 4 \pi \varepsilon_0 \hbar c }[/math] | fine-structure constant | 7.2973525693(11)×10−3 | 1.5×10−10 | [24] |
[math]\displaystyle{ \alpha^{-1} }[/math] | inverse fine-structure constant | 137.035999084(21) | 1.5×10−10 | [25] |
[math]\displaystyle{ m_{\text{e}} }[/math] | electron mass | 9.1093837015(28)×10−31 kg | 3.0×10−10 | [26] |
[math]\displaystyle{ m_{\text{p}} }[/math] | proton mass | 1.67262192369(51)×10−27 kg | 3.1×10−10 | [27] |
[math]\displaystyle{ m_{\text{n}} }[/math] | neutron mass | 1.67492749804(95)×10−27 kg | 5.7×10−10 | [28] |
[math]\displaystyle{ m_\mu }[/math] | muon mass | 1.883531627(42)×10−28 kg | 2.2×10−8 | [29] |
[math]\displaystyle{ m_\tau }[/math] | tau mass | 3.16754(21)×10−27 kg | 6.8×10−5 | [30] |
[math]\displaystyle{ m_{\text{t}} }[/math] | top quark mass | 3.0784(53)×10−25 kg | 1.7×10−3 | [31] |
[math]\displaystyle{ m_{\text{p}}/m_\text{e} }[/math] | proton-to-electron mass ratio | |||
[math]\displaystyle{ m_{\text{W}} / m_{\text{Z}} }[/math] | W-to-Z mass ratio | |||
[math]\displaystyle{ \sin^2 \theta_{\text{W}} = 1 - (m_{\text{W}} / m_{\text{Z}})^2 }[/math] | weak mixing angle | 0.22290(30) | 1.3×10−3 | [32] |
[math]\displaystyle{ g_{\text{e}} }[/math] | electron g-factor | −2.00231930436256(35) | 1.7×10−13 | [33] |
[math]\displaystyle{ g_{\mu} }[/math] | muon g-factor | −2.0023318418(13) | 6.3×10−10 | [34] |
[math]\displaystyle{ g_{\text{p}} }[/math] | proton g-factor | 5.5856946893(16) | 2.9×10−10 | [35] |
[math]\displaystyle{ h / 2 m_{\text{e}} }[/math] | quantum of circulation | 3.6369475516(11)×10−4 m2⋅s−1 | 3.0×10−10 | [36] |
[math]\displaystyle{ \mu_{\text{B}} = e \hbar / 2 m_{\text{e}} }[/math] | Bohr magneton | 9.2740100783(28)×10−24 J⋅T−1 | 3.0×10−10 | [37] |
[math]\displaystyle{ \mu_{\text{N}} = e \hbar / 2 m_\text{p} }[/math] | nuclear magneton | 5.0507837461(15)×10−27 J⋅T−1 | 3.1×10−10 | [38] |
[math]\displaystyle{ r_{\text{e}} = e^2 k_{\text{e}}/ m_{\text{e}} c^2 }[/math] | classical electron radius | 2.8179403262(13)×10−15 m | 4.5×10−10 | [39] |
[math]\displaystyle{ \sigma_{\text{e}} = (8 \pi / 3)r_{\text{e}}^2 }[/math] | Thomson cross section | 6.6524587321(60)×10−29 m2 | 9.1×10−10 | [40] |
[math]\displaystyle{ a_0 = \hbar^2 / k_{\text{e}} m_\text{e} e^2 = r_{\text{e}} / \alpha^2 }[/math] | Bohr radius | 5.29177210903(80)×10−11 m | 1.5×10−10 | [41] |
[math]\displaystyle{ E_{\text{h}} = \alpha^2 c^2 m_{\text{e}} }[/math] | Hartree energy | 4.3597447222071(85)×10−18 J | 1.9×10−12 | [42] |
[math]\displaystyle{ \mathrm{Ry} = hcR_{\infin} = E_{\text{h}}/2 }[/math] | Rydberg unit of energy | |||
[math]\displaystyle{ R_{\infin} = \alpha^2 m_{\text{e}} c / 2 h }[/math] | Rydberg constant | 10973731.568160(21) m−1 | 1.9×10−12 | [43] |
[math]\displaystyle{ G_{\text{F}} / (\hbar c)^3 }[/math] | Fermi coupling constant | 1.1663787(6)×10−5 GeV−2 | 5.1×10−7 | [44] |
[math]\displaystyle{ N_{\text{A}}, L }[/math] | Avogadro constant | 6.02214076×1023 mol−1 | 0 | [45] |
[math]\displaystyle{ R = N_{\text{A}} k_{\text{B}} }[/math] | molar gas constant | 8.31446261815324 J⋅mol−1⋅K−1 | 0 | [46] |
[math]\displaystyle{ F = N_{\text{A}} e }[/math] | Faraday constant | 96485.3321233100184 C⋅mol−1 | 0 | [47] |
[math]\displaystyle{ N_{\text{A}} h }[/math] | molar Planck constant | 3.9903127128934314×10−10 J⋅s⋅mol−1 | 0 | [48] |
[math]\displaystyle{ m({}^{12}\text{C}) }[/math] | atomic mass of carbon-12 | 1.99264687992(60)×10−26 kg | 3.0×10−10 | [49] |
[math]\displaystyle{ M({}^{12}\text{C}) = N_{\text{A}} m({}^{12}\text{C}) }[/math] | molar mass of carbon-12 | 11.9999999958(36)×10−3 kg⋅mol−1 | 3.0×10−10 | [50] |
[math]\displaystyle{ m_{\text{u}} = m({}^{12}\text{C}) / 12 }[/math] | atomic mass constant | 1.66053906660(50)×10−27 kg | 3.0×10−10 | [49] |
[math]\displaystyle{ M_{\text{u}} = M({}^{12}\text{C}) / 12 }[/math] | molar mass constant | 0.99999999965(30)×10−3 kg⋅mol−1 | 3.0×10−10 | [51] |
[math]\displaystyle{ V_{\text{m}}(\text{Si}) }[/math] | molar volume of silicon | 1.205883199(60)×10−5 m3⋅mol−1 | 4.9×10−8 | [52] |
[math]\displaystyle{ \Delta\nu_{\text{Cs}} }[/math] | hyperfine transition frequency of 133Cs | 9192631770 Hz | 0 | [53] |
Uncertainties
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 [math]\displaystyle{ m_{\text{u}} }[/math] is exactly known when expressed using the dalton (its value is exactly 1 Da), but the kilogram is not exactly known when using these units, the opposite of when expressing the same quantities using the kilogram.
Technical constants
Some of these constants are of a technical nature and do not give any true physical property, but they are included for convenience. Such a constant gives the correspondence ratio of a technical dimension with its corresponding underlying physical dimension. These include the Boltzmann constant [math]\displaystyle{ k_{\text{B}} }[/math], which gives the correspondence of the dimension temperature to the dimension of energy per degree of freedom, and the Avogadro constant [math]\displaystyle{ N_{\text{A}} }[/math], which gives the correspondence of the dimension of amount of substance with the dimension of count of entities (the latter formally regarded in the SI as being dimensionless). By implication, any product of powers of such constants is also such a constant, such as the molar gas constant [math]\displaystyle{ R }[/math].
See also
Notes
- ↑ The values are given in the so-called concise form; the number in parentheses is the standard uncertainty and indicates the amount by which the least significant digits of the value are uncertain.
- ↑ In some instances an exact value has been displayed, calculated from the defining expression, rather than the incomplete decimal expansion as given by the source.
- ↑ [math]\displaystyle{ b=\frac{hc}{k\left(5+W_0\left(-5e^{-5}\right)\right)} }[/math], where [math]\displaystyle{ W_0 }[/math] is the principal branch of the Lambert W function.
- ↑ [math]\displaystyle{ b' = \left(3+W_0\left(-3e^{-3}\right)\right)\frac{k}{h} }[/math], where [math]\displaystyle{ W_0 }[/math] is the principal branch of the Lambert W function.
References
- ↑ "2018 CODATA Value: speed of light in vacuum". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?c. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: Planck constant". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?h. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: reduced Planck constant". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?hbar. Retrieved 2019-08-28.
- ↑ "2018 CODATA Value: vacuum magnetic permeability". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?mu0. Retrieved 2019-05-20.
- ↑ Derived from Z0 = μ0c – "2018 CODATA Value: magnetic constant". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?mu0. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: vacuum electric permittivity". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?ep0. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: Boltzmann constant". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?k. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: Newtonian constant of gravitation". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?bg. Retrieved 2019-05-20.
- ↑ "vacuum electric permittivity". NIST. https://physics.nist.gov/cgi-bin/cuu/Value?ep0.
- ↑ Planck Collaboration (2020). "Planck 2018 results. VI. Cosmological parameters (page 17: Λ = (2.846±0.076)×10−122 mPl2).". Astronomy & Astrophysics 641: A6. doi:10.1051/0004-6361/201833910. Bibcode: 2020A&A...641A...6P.
- ↑ "2018 CODATA Value: Stefan–Boltzmann constant". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?sigma. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: first radiation constant". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?c11strc. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: first radiation constant for spectral radiance". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?c1l. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: second radiation constant". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?c22ndrc. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: Wien wavelength displacement law constant". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?bwien. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: Wien frequency displacement law constant". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?bpwien. Retrieved 2019-05-20.
- ↑ "Entropy of radiation: the unseen side of light". Scientific Reports 7 (1): 1642. May 2017. doi:10.1038/s41598-017-01622-6. PMID 28490790. Bibcode: 2017NatSR...7.1642D.
- ↑ "2018 CODATA Value: elementary charge". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?e. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: conductance quantum". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?conqu2e2sh. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: inverse of conductance quantum". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?invconqu. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: von Klitzing constant". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?rk. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: Josephson constant". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?kjos. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: magnetic flux quantum". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?flxquhs2e. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: fine-structure constant". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?alph. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: inverse fine-structure constant". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?alphinv. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: electron mass". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?me. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: proton mass". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?mp. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: neutron mass". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?mn. Retrieved 2019-08-23.
- ↑ "2018 CODATA Value: muon mass". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?mmu. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: tau mass". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?mtau. Retrieved 2019-05-20.
- ↑ "t-quark mass". Particle Data Group. https://pdglive.lbl.gov/Particle.action?node=Q007&init=0. "t-quark mass (direct measurements): 172.69(30) GeV/c2"
- ↑ "2018 CODATA Value: weak mixing angle". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?sin2th. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: electron g factor". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?gem. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: muon g factor". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?gmum. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: proton g factor". The NIST Reference on Constants, Units, and Uncertainty. NIST. June 2015. http://physics.nist.gov/cgi-bin/cuu/Value?gp. Retrieved 2019-03-08.
- ↑ "2018 CODATA Value: quantum of circulation". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?qucirchs2me. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: Bohr magneton". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?mub. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: nuclear magneton". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?mun. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: classical electron radius". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?re. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: Thomson cross section". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?sigmae. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: Bohr radius". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?bohrrada0. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: Hartree energy". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?hr. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: Rydberg constant". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?ryd. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: Fermi coupling constant". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?gf. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: Avogadro constant". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?na. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: molar gas constant". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?r. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: Faraday constant". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?f. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: molar Planck constant". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?nah. Retrieved 2019-05-20.
- ↑ 49.0 49.1 "2018 CODATA Value: atomic mass constant". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?u. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: molar mass of carbon-12". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. https://physics.nist.gov/cgi-bin/cuu/Value?mm12c. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: molar mass constant". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?mu. Retrieved 2019-05-20.
- ↑ "2018 CODATA Value: molar volume of silicon". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?mvolsil. Retrieved 2019-06-23.
- ↑ "2018 CODATA Value: hyperfine transition frequency of Cs-133". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?nucs. Retrieved 2019-08-18.
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