Talk:Natural units

message: Seriously, by removing 4\pi in the denominator we neglect the connection between inverse square laws and how the surface area of a sphere relates to its radius.--195.194.89.243 (talk) 12:52, 25 February 2015 (UTC)
replies: text: Totally agree.  Take a look at the Planck units article.  The problem, 195, is historical and some understandable inertia in the discipline.  Whether it's G or 4\pi G that is normalized to 1 (by the judicious choice of units) or if it's 4 \pi \epsilon_0 or \epsilon_0 that is normalized, the Planck scale is still about the same order of magnitude.  So a lot of physicists think "why bother" regarding changing the meaning of something, even if the change is more optimal and more natural.  65.183.156.110 (talk) 04:46, 26 February 2015 (UTC)
thread_title:  Normalizing <math>G</math> and not <math>4\pi G</math> 

message: revert (Several issues. k_e is not as well known as epsilon_0. In this article, Planck units do not necessarily normalize k_e.) seems a little POV, so I summarily re-reverted it.  Look a little closer:
; k_e is not as well known as epsilon_0: This seems to be a difficult claim to justify.  Looking at the Google Ngram viewer, it is known pretty well.
; In this article, Planck units do not necessarily normalize k_e: Whyever not? One could argue that ε0 could be normalized in Planck units, I guess, but the choice of normalization would have to be stated. Consistency with the article Planck units would require normalization of the Coulomb constant, and no justification is given in this article for any other normalization. The text explicitly says: "Planck units are a system of natural units that is not defined in terms of properties of any prototype, physical object, or even elementary particle. They only refer to the basic structure of the laws of physics ...", so to introduce a rather arbitrary choice of the elementary charge and the fine structure constant (and then to normalize a complicated expression of these) goes directly against that.
Technically speaking, Planck did not introduce an electromagnetic unit at all.  Perhaps we should simply omit the Planck charge from this entry (as well as in Plank units)? A system of units should not be artificially extended by Wikipedia. —Quondum 06:27, 2 March 2015 (UTC)
replies: text: There apparently are sources for the unit Planck charge.  Whether it was created by Planck or named for him later, it seems appropriate to include here. Bcharles (talk) 21:47, 21 March 2015 (UTC)
replies: text: Gravitation (Misner, Thorne, Wheeler), for example, mentions Planck units for time, length and mass, but makes no mention of charge or temperature. I managed to find an explicit naming in a "reputable" reference (Roger Penrose, The Road to reality), but even here it is rather unsatisfactory, as he gives the normalization choices leading to Planck units, but these choices (G = c = ℏ = kB = 1) do not determine a Planck charge, yet he then concludes what the value of the Planck charge is (about 11.7 proton charges).  Several sources say something like "one could define a Planck charge as...".  I have no in-principle objection to the idea that charge and temperature could have been considered to be part of the system post-dating Planck, as long as we get this from a reputable source. At least all the sources that do give a value that I looked at were consistent in their choice, not giving the alternate CGS-Gaussian version of Planck units that I reverted.  Whatever the origin, Planck charge and temperature seem to have some momentum. —Quondum 03:41, 22 March 2015 (UTC)
thread_title:  Silliness about Planck units 

message: I am deleting this bullet point under "advantages and disadvantages".  There is no reason to presume that mP and lP would be omitted when stating values in Planck units. Bcharles (talk) 22:41, 21 March 2015 (UTC)
replies: text: This does not really hold: it is reasonable that when using Planck units, many people would omit their explicit mention, and examples are not difficult to find. For example, Penrose says "... in terms of Planck units, gram = ", where he omits mP. Nevertheless, the point was made rather fuzzily in the article, and I'm not going to argue that it should be retained. —Quondum 04:08, 22 March 2015 (UTC)
thread_title:  Greater ambiguity? 

message: In natural units space and time have the same dimension due to c=1. This statement deserves further details.--5.2.200.163 (talk) 13:52, 1 February 2016 (UTC)
thread_title:  Same dimension of space and time 

message: The bulk of the NIST CODATA tables can be explained in terms of Bohr's atom, since this provides the units for further calculations, and this is what the CODATA values do.  Since the bohr atom throws up a dimensionless constant (fine-structure constant), setting the base to this allows many more units to become simple values.  Everything relating to the electron are simple values of π or the reciprocals of 137/π.  
One then uses K=137.036 etc, as an exponent-marker like E=10, so as E5 = 10^5 then K^5 means 137.036^5.  The tables are set so that the speed of light, the electron mass and the electron charge are set to K-units (eg K4 'm/s').  The unnamed K-units occupy the same space as the given SI unit.
There is a thread on  Dozensonline->Applications->New Systems of Measure->Other measurement systems->Ku And Ko
KU follows much of modern metric theory, CGS lightly rationalised to SI.  If the same light rationalisation is applied to give a HLU theory, then the charge is reduced by a factor of \sqrt{4\pi}.  We see that the electron mass is K-2 (so the unit is about the size of a boron atom, and N_a is a number bigger than 1), and the speed of light is K3.  The unit of charge is K-1.
KO shows the results of calculating Bohr's atom in HLU theory, from first principles.  We still have the electron charge at K0, and the electron mass at K-2, but the speed of light is set to K4.  One will notice that lengths and times are increased by a factor of 4π, which represents a change from radius to circumference or surface of a sphere, and from radian-times (\lambdaba and \hbar) to cycle-times (\lambda and h).  The value of h changes from 2pi to 1/2.
The tables represent the 'exact values' of the CODATA variables, since the errors have been moved into conversion from this system.  
--Wendy.krieger (talk) 11:13, 1 April 2016 (UTC)
thread_title:  Bohr atom in Heaviside Lorentz Units 

message: under the flag of "natural units" often dimensionless length units are in use like M~rG=rs/2. These are usually built using Planckunits, or G c° kB ke and h°, I denominate them with a sub-"r":
*m_r=lP*m/mP
*Q_r=lP*Q/QP
*L_r=lP*L/h°
*T_r=lP*T/TP
I think these should be mentioned in the article too. Ra-raisch (talk) 19:26, 8 December 2016 (UTC)
thread_title:  length units 

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thread_title:  External links modified (February 2018) 

message: There is a contradiction between the lead section, which limits "natural units" to physical constants. And the Introduction, where it is written:  "Natural units are "natural" because the origin of their definition comes only from properties of nature and not from any human construct"  (For example, the mass of a cm3 of water, could be a "natural unit" -- but this does not seem to fit with the way the lead section writes about the "natural units".  Perhaps the lead section could add an indication that a "narrow" definition is being used.  Or maybe it could be expanded to indicated different meanings? Sdc870 (talk) 15:27, 16 April 2018 (UTC)
thread_title: Clarification of lead section

message: Some few articles in Wikipedia refer to "absolute units" such as watt, ohm, International System of Electrical and Magnetic Units, Centimetre–gram–second system of units, History of the metric system, History of the metre.  There are about 30 articles altogether right now -- where some of these pages are referring to units in webpage design. It seems appropriate/useful to have such a page (so I can read more about it!) Sdc870 (talk) 15:27, 16 April 2018 (UTC)
thread_title: Why no article on "absolute units"?

message: After modifying the section "System of natural units" to make the proper symbol U+210F ℏ PLANCK CONSTANT OVER TWO PI appear wherever I saw a plain italic h, I called up page history and noticed that it already was some kind of barred h with italics, probably U+0127 LATIN SMALL LETTER H WITH STROKE + italics. All I can say is that for some reason the original character looked like a plain italic h (with no stroke) in the CologneBlue skin I'm using. I suppose that in this case U+210F is the proper character to use anyway. — Tonymec (talk) 08:55, 17 April 2020 (UTC)
replies: text: I think that on different systems (browser default font selection, installed fonts, etc.) either if these may occasionally present a problem.  U+210F often renders as though it is not from a matching font and is generally pre-italicized, making it non-ideal.  I had assumed that the Latin Extended-A character set, having been present from a very early version of Unicode, would have wider support than the Letterlike Symbols set, but this could have been wrong, and your experience might suggest otherwise.  Some Unicode characters are present for legacy reasons and are essentially deprecated (an example being U+00B5 micro sign).  My guess is that either way will present problems in some systems – the question probably being which works best on most.  —Quondum 12:33, 17 April 2020 (UTC)
thread_title:  How to represent the reduced Planck constant? 

message: The NIST website lists several "natural unit of ..." units ().  These are clearly based on ,  and  and together form a mechanical system (no dimension of electric charge).  There are several historical unit systems mentioned by Tomilin ("NATURAL SYSTEMS OF UNITS. To the Centenary Anniversary of the Planck System") that fit this, except that these all include an electrical dimension.  This is not reflected in any of the systems listed in this article.  Does anyone know or have a reference that might illuminate what NIST is basing this on?  —Quondum 00:20, 15 May 2020 (UTC)
replies: text: I see that the 8th SI Brochure defines natural units of speed, action, mass and time based on these constants, and describes them as "used only in their own special fields of particle and atomic physics".  It seems very probable that this is the basis of NIST's natural units that I described above.  I suspect that these fields also so routinely take ε0 and μ0 as being dimensionless 1 that it is rarely mentioned (as I can show, for example, that Wilczek does).  It seems that this would be a separate system of natural units, possibly worth adding, since it can readily be sourced.  —Quondum 01:35, 31 May 2020 (UTC)
thread_title:  "natural units" on NIST 

message: {2~\pi~\hbar \over c~Q_e} is the boltzman constant in whatever unit system you are in though those units c, \hbar, q_e might be different values in different systems want multiple people to confirm this math is correct before I push the edit up
===Summary table===
Quantity / Symbol                             	Planck                 	Stoney             	Hartree                         	Rydberg
Defining constants                            	c, G, \hbar, k_\text{B}	c, G, e, k_\text{e}	e, m_\text{e}, \hbar, k_\text{e}	e^2/2, 2m_\text{e}, \hbar, k_\text{e}
Speed of light  c                             	1                      	1                  	\frac{1}{\alpha}                	\frac{2}{\alpha}
Reduced Planck constant  \hbar=\frac{h}{2 \pi}	1                      	\frac{1}{\alpha}   	1                               	1
Elementary charge  e                          	-                      	1                  	1                               	\sqrt{2}
Gravitational constant  G                     	1                      	1                  	G                               	G
Boltzmann constant  k_\text{B}                	1                      	-                  	-                               	-
Electron rest mass  m_\text{e}                	m_\text{e}             	m_\text{e}         	1                               	\frac{1}{2}
where:
* is the fine-structure constant,  ≈ 0.007297,
*A dash (–) indicates where the system is not sufficient to express the quantity.
* is the electron charge
:The newest Current Stoney Hartree Rydberg values are {2~\pi \over \alpha}, {2~\pi~\alpha}, and {\pi~\alpha \over \sqrt{2}} respectively. Provided my math is correct waiting for a few people to get the same answers
:
:also may need to include something about avogadro constants in each system for instance avogadro for the planck mass is:
P_A = 1.310679E19 mol^{-1}={N_A \over m_p}={6.02214076\times10^{26}\over 2.176434\times10^{-8}}
:Glas(talk)Nice User skin 18:37, 26 January 2022 (UTC)
thread_title:  Boltzman Constant 

message: Quantity / Symbol                             	Planck                 	Stoney             	Hartree                         	Rydberg
Defining constants                            	c, G, \hbar, k_\text{B}	c, G, e, k_\text{e}	e, m_\text{e}, \hbar, k_\text{e}	e^2/2, 2m_\text{e}, \hbar, k_\text{e}
Speed of light  c                             	1                      	1                  	\frac{1}{\alpha}                	\frac{2}{\alpha}
Reduced Planck constant  \hbar=\frac{h}{2 \pi}	1                      	\frac{1}{\alpha}   	1                               	1
Elementary charge  e                          	-                      	1                  	1                               	\sqrt{2}
Gravitational constant  G                     	1                      	1                  	G                               	G
Boltzmann constant  k_\text{B}                	1                      	-                  	-                               	-
Electron rest mass  m_\text{e}                	m_\text{e}             	m_\text{e}         	1                               	\frac{1}{2}
where:
* is the fine-structure constant,  ≈ 0.007297,
*A dash (–) indicates where the system is not sufficient to express the quantity.
* is the electron charge
:The newest Current Stoney Hartree Rydberg values are {2~\pi \over \alpha}, {2~\pi~\alpha}, and {\pi~\alpha \over \sqrt{2}} respectively. Provided my math is correct waiting for a few people to get the same answers
:
:also may need to include something about avogadro constants in each system for instance avogadro for the planck mass is:
P_A = 1.310679E19 mol^{-1}={N_A \over m_p}={6.02214076\times10^{26}\over 2.176434\times10^{-8}}
:Glas(talk)Nice User skin 18:37, 26 January 2022 (UTC)
thread_title: Summary table