Talk:Physical constant/Archive 2

Archive 1

Archive 2

Archive 3

Suggestion by Picomp314

It seems that the constant .08206 L*atm/(mol*Kelvin) also known as the gas constant needs to be added somewhere on this table. Picomp314 15:54, 12 April 2006 (UTC)Picomp314

Physical vs Universal

It was my understanding that a physical constant is a universal constant, but a universal constant is not nessisarily a physical constant. Kevin Breitenstein has redirected universal constant to physical constant, and I was wondering if they are in fact the same thing, as I don't really know for sure.

These are matters of definition. For example pi is a universal constant. But when the state legislature of Tennessee decreed that that pi shall be three that also would have made made one and the other counting numbers into transcendental numbers. (Pretty hard to build a civilization with computers on that basis.) Fortunately reason has prevailed on this count. --Ancheta Wis 10:06, 8 July 2006 (UTC)

Thus a physical constant is not the same as a universal constant. But this is a matter for definition, and the Wikipedia community will decide. For what it's worth, the Pioneer plaque used graphic depictions of some physical relationships in hopes that universal constants might be used for communication with other civilizations. In this sense, a 'universal constant' could be considered to be 'a constant which would be understood across the universe'.

Thats decently close to what I had thought, thanks for the clarification.

Removed paragraph

I removed the following paragraph because I think it is wrong:

Unless the system of natural units is used, the numerical values of dimensionful physical constants are artifacts of the unit system used, such as SI or cgs; that is, they are essentially conversion factors of human construct.

The point is that constant quantities do not depend on the units used. To give an example: the height of the Eiffel tower is a physical constant. The height of the tower, however, is always the same independent on the units in use. The sentence confuses the physical quantity Q with its numerical factor {Q} which depends on the units.

I also removed/changed the following paragraph:

The fine-structure constant α is probably the most well-known dimensionless fundamental physical constant. The dimensionless ratios of masses (or other like-dimensioned properties) of fundamental particles are also fundamental physical constants, as are the measure of these properties in terms of natural units.

I do not think that dimensionless constants are more fundamental than other constants. This is a misunderstanding coming from the believe that quantities depend on systems of units. However, all quantities do not depend on the system of unit, independent wether they have dimensions or not. The ratio of the Eiffel tower to the empire state building is always the same and does not depend on units, as is the height of the Eiffel tower. --Kehrli 01:44, 12 August 2006 (UTC)

you are fully mistaken in thinking that dimensionless physical constants (like α) are not more fundamental than the dimensionful physical constants. the former are numbers that are properties of the universe (and the aliens on the planet Zog will come up with the same number) and the latter are human constructs. you should read and understand How Many Fundamental Constants Are There? from John Baez before injecting this truly mistaken POV into a science article. also you should buy or check out the John D. Barrow book The Constants of Nature to get a decent understanding about what the salient nature of these constants. also, take a look at the Natural units, Planck units, Dimensional analysis, and Nondimensionalization articles. you can learn something from them. r b-j 04:10, 1 September 2006 (UTC)

Rbj, I did read the pages of John Baez, Natural units, Planck units, Dimensional analysis and I did think a long time before I made my changes. I am aware Beaz is probably ten times more intelligent than I am, but here he is wrong.

besides Baez, you have some authorative insight into this that exceeds that of Michael Duff or John D. Barrow or Frank Wilczek or Gabriele Veneziano? somehow your understanding of this trumps theirs? Kehrli, you overestimate your understanding and consequently your "authority" to negate what these physicists have been saying for decades with your own flawed understanding (or shall i say "misconceptions"). that over-esteem of one's self knowledge/understanding is what is getting you into these POV wars. you don't really understand it, you change the world to make it agree with your understanding, and when it pushes back

Look, Rbj, I know that you think you are right and you know that I think I am right. If we want to find out who is really right we need to engage in a discussion, not in a flaming war with accusing the oder side. If I tell you that you have a flawed understanding this won't convince you - because it is not a useful argument. The other way round it is the same. So let's discuss like grown-ups. ok? --Kehrli 09:27, 12 September 2006 (UTC)

Let us go through the details once again:

1) a constant physical quantity Q is the product of a numerical value n and a unit U: Q = n*U

unless if comes from a system of natural units, the unit U is a human construct and nature doesn't give a rat's ass about it.

2) it is true that the value n is an "artifact" of the choosen unit, but Q is not. You are mixing up Q and n. Q is the physical constant, not n.

if it's not a dimensionless quantity (perhaps a ratio of like dimensioned quantities like m_p/m_e or the mass of a particle divided by the Planck mass), it is of no consequence to nature. nature doesn't give a rat's ass what units humans decide to use.

3) in the case of α the quantity consists only of a numerical value n, no units: Q = n. Therefore the constant Q implies that n also is constant. This, however, is rather trivial and does not justify that α is considered more fundamental as let's say c. --Kehrli 06:13, 11 September 2006 (UTC)

this is evidence of your misconception, Kerhli. and it is a fundamental misconception. you take your ideas to the sci.physics.research USENET newsgroup and bounce it off of those guys and see how well it sticks. (but i have to warn you, Baez hangs out there a lot, but none of the other physicists would support you on this anyway.) r b-j 04:17, 12 September 2006 (UTC)

Rbj, I completely agree with your bigger picture: Nature will not change the speed of light just because we decide to use a different unit. This is why constant physical quantities do not depend on units. Thanks for proving my point. --Kehrli 09:35, 12 September 2006 (UTC)

What the hell is happening? The values of dimensionful constants do depend on the choice of units. They are only a conversion factor between different units. We're used to measure the three space dimensions in metres and the time dimension in seconds, 299 752 458 m/s is just a conversion factor between them. Sailors are used to measure two space dimensions in nautical miles and the other space dimension in fathoms, and nobody would call the conversion factor 1 012.6859... nautical miles per fathom a fundamental constant. People using the same unit for all three space dimension don't need it, just like astronomers, who measure everything in (light-)years, don't need c. (I've never heard or read the phrase "one light year per year", which gives as few as 70 Google hits.) Boltzmann's constant is just the conversion factor betveen joules and kelvins. Avogadro's number just expresses how many times 1.2% of a certain piece of platinum and iridium in Sevres is heavier than an atom of carbon-12. One can get rid of all of these by choosing the right units (e.g. Planck units), but one can't get rid of the fine-structure constant or of the masses of particles expressed in Planck masses -- these are fundamental constants which are parameters of the Universe. --Army1987 09:00, 13 August 2006 (UTC)

Army, the speed of light c is a constant quantity. Einstein made his theory of relativity based on this assumption. If it would be possible to change c by simply choosing different units, his theory would collapse. You are mixing up the numerical value n and the quantity Q.

Q = n * U

c = 300'000 * km/s

c = 300'000'000 * m/s

The numerical value n changed, the unit changed, c is constant. Do you really think changing the speed of light is as simple as choosing another unit? All you change is the numerical factor, which is very trivial since it is only an artefact of the unit. The product of the numerical factor and the unit is what matters, and that is constant for dimensionless quantities as well as for quantities with dimensions. --Kehrli 09:33, 11 September 2006 (UTC)

This is because you are used to consider time and space as different entities, and need a conversion factor between units of time and units of space. People considering work and heat as different entities need a 'constant' called 'mechanical equivalent of heat' or something like that, equal to 4186.8 J/kcal. Yes, you can change the number and the unit with their product staying constant, e.g 778.17 ft lbf/BTU. But once you realize that work and heat are the same quantity (namely, energy), you can use the same unit for both work and heat, and you no longer need any conversion factor. Likewise, if you measure space and time with the same units, you don't need any factor of conversion such as 'speed of light'.

For example, imagine we didn't define the unit force as simplily the force which would give an unit acceleration to an unit mass. In Newton's second law we'd see a 'constant' such as 23.8 pond seconds per pound knot. --Army1987 12:32, 11 September 2006 (UTC)

I completely agree with what you say, but what is the point? Even if you get rid of units that does not make constant quantities depending on units. If you know it uses 1 cal to heat 1 cm^2 of water for one K, you can get rid of cal and switch to J, but it will still need the same amount of energy to do the process. The (constant) amount of energy needed does not depend on the units you use. And: I cannot change the length of the Eiffel tower by merely using different units. This is very trivial. And when I decide to measure the Eiffel tower with a time quantity it still does not change its height. (The only reason why the height of the Eiffel tower is not a fundamental constant is that the aliens on planet Zog do not know the Eiffel tower or have their own version which most probably does not have the same height. It is not because "height" it is a dimensioned quantity.) --Kehrli 18:25, 11 September 2006 (UTC)

They have defined the metre to be the space travelled by light in 1/299792458 s. If they had defined it to be 1/299792459 s, the light would travel at 299792459 m/s, the Eiffel tower (and anything else in the universe) would be longer by about 3 part per billion. You could not change the value of the fine-structure constant by changing units, instead.

The kilogram is defined as the mass of a piece of metal in Sévres. If I somehow managed to steal that artifact, use half of it to make a checkers piece set, and put the other half back where it was, my mass would immediately change from 86 kg to 172 kg. Newton's constant would change from 6.67×10⁻¹¹ N m²/kg² to 3.34×10⁻¹¹ N m²/kg², Planck's constant would change from 6.626×10⁻³⁴ J s to 3.313×10⁻³⁴ J s, and the elementary charge (given the way the ampere is defined) would change from 1.602×10⁻¹⁹ C to 1.133×10⁻¹⁹ C. But the fine-structure constant would stay 1/137.036, the mass ratios between elementary particles would stay the same, and any experiment would have the same outcome as before, except that any quantity involving mass (or electric charge, given the way ampere is defined) would change its numerical value.

no reading of any present instrument would change if you were to somehow fudge the International Prototype Kilogram. but when the various national prototypes get recalibrated, there would be a big problem (and if this radical discrepency between the Paris prototype and the national prototypes were simply accepted and the national prototypes changed to match it and, given enough time, weighing instruments including bathroom scales were recalibrated or redesigned to the new prototypes, then, if you bought a new scale, your new scale would say your weight is 172 kg.

In conclusion, the only meaningful answer to the question "what if light travelled at 50 mph?" is "I would be 13,9 micrometres139 nanometres tall, Earth would be 476 millimetres in radius, but we would notice nothing strange". --Army1987 20:18, 11 September 2006 (UTC)

Army, of course I am discussing under the presumption that the units are not changed. But even if they were changed: the constant physiscal quantities would stay the same. Nature does not care what units we use. Nature will not change the speed of light just because we decide to change the meter. --Kehrli 09:32, 12 September 2006 (UTC)

i dunno if you got your calculation correct, Army. 13.9e-6 m × (299792458/(50*0.44704)) is 186 meters. i don't think you're that tall. nonetheless, you would still measure your height to be the same length as you did before because your meter stick also shrinks by the same about (from the POV of some "god-like" observer who is somehow not affected by the hypothesized reduction of c from 299792458 m/s to 22.352 m/s or 50 mph). r b-j 04:17, 12 September 2006 (UTC)

Yeah, I must have put the decimal point in the wrong place somewhere. I meant 139 nm. The fact that my meter stick would shrink, too, is included in "we would notice nothing strange". What I meant is that, as long as α, m_p/m_e etc. stay constant, the values of dimensionful constant is irrelevant. --Army1987 09:44, 12 September 2006 (UTC)

i reverted Kehrli's content edits (only discovered them yesterday) but i thought the new subsection headers he/she put in were a good idea (except it's called the "Anthropic principle" not "Anthroposiphic" which is not a word but is very close to Anthroposophic in spelling, which is completely non sequitur to the subject here). r b-j 04:10, 1 September 2006 (UTC)

Rbj, please revert your changes (not my spelling errors, of course). In my opinion they are wrong. Please read the IUPAC green book to get a better idea about quantities. Thanks. --Kehrli 09:33, 11 September 2006 (UTC)

Kerhli, you got conceptual issues to straighten out before making these substantive changes. take this up with the experts (like sci.physics.research). also i suggest that you submit your content editing a bit more to the folks at Wikipedia:WikiProject_Physics or write and publish your own book. besides not entirely knowing or understanding the facts, i am a little concerned for your fact-checking effort as reflected by the use of "Anthroposiphic" which is not really a mispelling of "Anthropic" but more like a misspelling of something completely non sequitur. Kehrli, edits like yours are one reason Wikipedia is getting such a bad rap. the real experts come here and look at an article and blanch. r b-j 04:17, 12 September 2006 (UTC)

What is wrong, exactly? They state that the numerical value of dimensionful constant depends on the choice of units. This is true. The numerical value of c is 299792458 in SI and 29979245800 in cgs. The numerical value of k_C is 1 in esu and 8,987,551,787.3681764 in SI. Army1987 20:30, 11 September 2006 (UTC)

So you agree with "the value of a physical constant does not depend on the units used"? --Kehrli 08:42, 12 September 2006 (UTC)

one last remark. there is a semantic issue about the use of the word "fundamental" to differentiate between physical constants that have dimension and those which do not (which are more fundamental in defining the nature of the universe). but sites like NIST as well as other places that list dimensionful physical constants call them "fundamental". but this is semantic. physicists everywhere (except for Kerhli) recognize that it's only the dimensionless physical constants that are parameters of meaning that define the nature of the universe. dimensionful physical constants are not on that list. and there's a reason for it. anyway, if this topic changes to that of renaming Fundamental physical constants to Dimensionless physical constants, that is a different issue and is only semantic. r b-j 04:28, 12 September 2006 (UTC)

Rbj, thanks for this constructive remark. I would very much wellcome this change of name for the very reasons you listed: it would be in line with NIST and no longer be POV. Additionally I think dimensionfull constant quantities are not per se less fundamental than dimensionless constant quantities. Here is where we disagree and we can go on with a fruitfull and exciting discussion if you like. --Kehrli 09:20, 12 September 2006 (UTC)

Good ol' disambiguations... I've created fundamental physical constant (disambiguation) article. --Army1987 10:19, 12 September 2006 (UTC)

is α an artifact too ?

Some people seem to think that α is a more fundamental constant than, let's say, c. The reason being that α has always the same numerical value independent on the units used. Is this really true? α is defined as:

$\alpha ={\frac {e^{2}}{\hbar c\ 4\pi \epsilon _{0}}}={\frac {1}{137.03599911(46)}}$

I agree that if you use a "reasonable" system of units, the units of α cancel and the numerical factor is always the same. However, if you use a "unreasonable" system of units where you use, for example, SI units for the quantities in the denominator and atomic units of charge for the nominator, the units do no longer cancel and the numerical factor changes too. Not that I want to promote the use of such "unreasonable" systems of units. My point is just that the "lack of units" of α is also somewhat arbitrary and can be removed by choosing an "inconvenient" system of units. Or, in other words, dimensionless is not quite equivalent to unitless. --Kehrli 09:53, 11 September 2006 (UTC)

the above has little meaning without a clearer definition of a "reasonable" system of units and "unreasonable" system of units. i have no idea what is meant by the difference. r b-j 05:30, 12 September 2006 (UTC)

with a "unreasonable" system of units I mean a system where different units are used for quantities that may have the same dimension. See the example of Army who understood what I meant: you can use cal for thermodynamic energies and J for mechanical energies, as it was common to do for a long time. Now we use J for both and thereby get a "reasonable system". --Kehrli 08:36, 12 September 2006 (UTC)

No. You mean 2.843×10⁻³⁵ au²/C²? That's still the same real number, since the quantity au²/C² is a pure number and equals 2.367×10^-38. Multiplied by 2.843×10⁻³⁵ you get 0.0073, i.e. 1/137. --Army1987 12:54, 11 September 2006 (UTC)

yes, exactly:

2.843×10⁻³⁵ au²/C². and

1/137

are the same constant quantity exatly as

300'000 km/s and

300'000'000 m/s

are the same. For α it is exactly the same story as for c. You can express the speed of light c in different units but you can always transform back to SI system and you will always get the 300'000 km/s. The only difference is that km/s is not a pure number but 10^-3 m/s. The numerical value n is not constant, it is the product of the numerical value and the unit which is constant. Therefore there is no big difference between dimensionless units and units with dimensions. --Kehrli 17:04, 11 September 2006 (UTC)

Kerhli, this quote of yours immediately above is the smoking gun. i think it is pretty definitive of your misconception of the subject. just as there is a big conceptual difference between dimensionless quantities and dimensionful quantities (which you don't appear to understand), the same is true of dimensionful units and dimensionless units (that latter is about units applied to dimensionless quantities, osensibly to make the measurement more anthropocentric). degrees of angle is a unit on a dimensionless quantity. measuring angles in radians is both dimensionless and unitless. r b-j 05:30, 12 September 2006 (UTC)

Rbj, I know that there is a difference between dimensonfull and dimensionless quantities.

but you fail to appreciate the difference.

All I am saying is that the difference is not large enough to justify calling all dimensionfull quantites "not funtamental". That's all.

even if "that's all", you're still wrong about it. the dimensionless physical constants are fundamental and the dimensionful physical constants are really just human constructs unless they are expressed in terms of some set of natural units. but, once you pick your set of natural units, then about 4 or 5 of those "fundamental" dimensionful constants simply disappear (become one).

we define the SI unit of force, the Newton to be whatever force it takes to accelerate 1 kg at 1 m/s^2 (assume constant mass). but we can define the unit force to be whatever we want it to be as long as we're willing to put some conversion factor, K in F = ma and live with F = K ma is the conversion factor: 1 (Nt s^2)/(kg m) a "fundamental" physical quantity? does nature or the laws of the physical universe give a rat's ass about it? does nature care whether we use a conversion factor in Newton's 2^nd law or not?

now, take for example the Boltzmann constant. temperature is not a unique dimension of physical quantity; it just an expression of how much energy on average each molecule (and degree of freedom) is getting. the Boltzmann constant can be whatever we want it to be by just defining the unit temperature judiciously to make k be what we want it to be. does that make it a "fundamental" physical constant? it's just an artifact of where we put the tick marks on our thermometers!

the permittivity of free space or Coulomb constant is another such "fundamental" physical constant. we can define it to be whatever we want by choosing the unit of charge judiciously and that is precisely what they do in the cgs system of units. it's no more fundamental than our choice of where to put tick marks on the electroscope we use.

now, for the "fundamental" physical constants, c, h, and G, it's just a little bit trickier because, instead of only needing to judiciously adjust one particular unit that fully controls some corresponding dimensionful "fundamental" constant, here we have three constraints and three unknowns. but we can still solve that set of three equations and we can make c, h, and G be whatever we want them to be. we can set them to 1 and get rid of them from all of our equations of physical law. does nature give a rat's ass whether or not we put those conversion factors into equations such as the Schrodinger Eq., or Einstein Eq., or Maxwell's Eqs? r b-j 03:25, 13 September 2006 (UTC)

And NIST seems to agree with me since they list all those quantities like c, G ... as fundamental quantities. The notion that only dimensionless quantities are fundamental is only backed by a non-reviewed web articel of Baez. Therefore I think it is POV. --Kehrli 08:58, 12 September 2006 (UTC)

If the matter is the meaning of the word fundamental, now there shouldn't be any POV problem anymore as I included the NIST usage too. But please don't claim that c is fundamental (in Baez's meaning of the word). —Preceding unsigned comment added by [[User:{{{1}}}|{{{1}}}]] ([[User talk:{{{1}}}|talk]] • [[Special:Contributions/{{{1}}}|contribs]])

it is not just Baez. it's Michael Duff, John D. Barrow, Gabriele Veneziano, Frank Wilczek, User:Chris Hillman and, essentially, the consensus of the physics community. Baez's, Duff's, Barrow's, Veneziano's, Wilczek's POV weighs more heavily than yours, Kehrli. this is why you need to learn something about this rather than propogate the misconception onto others. r b-j 03:25, 13 September 2006 (UTC)

Yeah, formula would get much simpler, if besides c and $\hbar$ we also set α and 2π to 1. Setting -1 to 1 would in addition eliminate all those pesky sign errors. --Pjacobi 08:40, 12 September 2006 (UTC)

Important friendly notice

I feel obligated to stop by and inform those involved in this discussion about the history of this discussion. I hope no one (especially Kehrli) feels that I am trying to discredit or bias anyone against Kehrli. There is currently an arbitation case to be found at Wikipedia:Requests_for_arbitration/Kehrli that is relevant to this discussion. There are also volumes of similar discussions to this one at Talk:Mass-to-charge_ratio regarding the officially dimensionless measurement m/z. This area is not my area and I do not have a lot to contibute here but I would suggest that anyone involved in this discussion inform themselves before engaging too deeply in it. My advice is to look up whatever the dispute is about in a modern college level textbook and be done with it. If the vast majority of scientists in the field are somehow mistaken let the mistake be corrected in the scientific literature before it is corrected here. Engage in discussions about truth at your own risk. Just a friendly note. --Nick Y. 20:58, 11 September 2006 (UTC)

i didn't want to jump into either the MS thing or the arbitration thing, but i may have to now, at least the latter. these kind-of non-experts correction of the well established state of accepted science (or history or whatever subject) is what gives Wikipedia a bad rep. r b-j 04:32, 12 September 2006 (UTC)

Rjb, did you ever consider that you could be the one that is too self-assured? Did you ever consider that you could be wrong? Did you ever consider that you could be the kind of persons that harms the quality of Wikipedia? Please calm down and get engaged in a real discussion. --Kehrli 09:14, 12 September 2006 (UTC)

Kehrli, i am reverberating what current heavyweights in physics such as John Baez or Michael Duff or John D. Barrow or Gabriele Veneziano or Frank Wilczek are saying about it. below, i will juxtapose what i think or believe or interpret what they mean. but i recognize that as my POV or OR. if i were to try to slip that POV into this or any other article, just because i "think" it's correct, you or other editors would be right to remove it. the problem with your POV edits are not that they contradict what I want to believe, it's that they contradict what the consensus of the physics community is saying. take your dispute up with them. r b-j 03:25, 13 September 2006 (UTC)

Let's come to the point

There has been a lot of distractive discussion going on. Many things have been stated by Army that I perfectly agree with, but which are not to the point. What is the point? Here it is:

The values of dimensionful constants do depend on the choice of units. (from Army)

I think this sencence is wrong. It is only the numerical value n that depends on the units, but this is very trivial since Q = n*U. Can we agree on the following sentence:

The value of a dimensionful physical quantity (and hence also a constant physical quantiy) does not depend on the units used.

Army, what do you think? --Kehrli 09:11, 12 September 2006 (UTC)

Sometimes it doesn't, simplily because, in natural units, it is the dimensionless 1, or 4π for constants involving spheres, or some power of α for constant involving the fact that electric charge is discrete, etc. The value of the speed of light does not depend on units because if you realize that space and time are the same thing, it is 1. From this perspective, 299,792,458 m/s is the same thing as 4186.8 J/kcal, or even 0.3048 m/ft. And stating in this article that 1 is a constant is a bit useless.

Anyway, sometimes they do depend on the units chosen because different systems work differently. For example, the magnetic permeability of free space in cgs is 1 because there the electric field and the magnetic field have the same units, but in the Lorenz force equation there is a constant equal to 1/c which is not there in SI because there the electric field has the units of magnetic field times speed. --Army1987 09:43, 12 September 2006 (UTC)

Army, I think that stating in the article that the value of dimensionful physical quantities do not depend on the units in use is very useful because there are many people out there that mix up "quantity" with "numerical value of a quantity" and therefore are not aware of this fact. (Also, we cannot assume that all people that visit Wikipedia know that space and time are "the same thing"). Of course there may be some rare cases where constant quantities have slightly different definitions in different system of units and, unfortunately, still have the same names. However, in this case the problem is rather that the same name is used for two different quantities (for example do not even have the same dimensions, as in the case you mentioned above).

Could you please now read the article that Rbj reverted (the one with my edits) and give your fair opinion if this article is really not better than the one that is currently active (of course without the spelling errors and the stupid "antroposophic")? Thanks, --Kehrli 18:23, 12 September 2006 (UTC)

an interpretation for why virtually all physicists understand dimensionless physical constants as more fundamental than the dimensionful physical constants

This is an interpretation of mine. I am not saying that this is how John Baez or Michael Duff or John D. Barrow or Gabriele Veneziano or Frank Wilczek would put it. But all of those guys would say and have said in the past that constants like α are fundamental and constants like c, h, and G are not and that the reason is that the former is dimensionless and the latter is dimensionful. Some of this is a rehash of a long debate I had with the creator of the VSL article. But it's still my interpretation, which is why it is here on the talk page and not in any article.

So, to avoid misunderstanding, I'm gonna try to pick this apart, so we know precisely where we don't agree. A physical constant or parameter of the universe is more "fundamental" than another if its quantity is more meaningful than the other. Its quantity is more meaningful if changing it has a measureable or, at the very least, perceptible consequence. The word "meaningful" is used by me if changing it is or could be perceptible. If something or some change is not perceptible, it is not meaningful in my semantic. In this semantic, only the physical constants or parameters that, when changed, cause a measurable or perceptual change in our world view is truly "fundamental".

The distance from Vermont (where I live) to the Himalayas is meaningfully large to me but might not be if I were as big as a planet or perhaps if I lived for 10,000 years. The mass of a mountain is meaningfully large to me but might not be if, again, I were as big as a planet. The speed of propagation (light, E&M, gravity, any other ostensibly "instantaneous" action) seems fast to me given the scale that I sense distance and time. How I sense meaning in distance and time and mass has to do with how the matter and tissues and organs of me are constructed. It has to do with the fact that there are maybe about 10¹⁴ cells in my body, that each cell is about 10⁵ times bigger (in one length dimension) than the atoms that they are made of and that these atoms are about 10²⁵ larger than the Planck length. It is a matter of science (that we don't completely understand yet) that our particular beings are about 10³⁵ bigger than the natural unit of length and we perceive scale in that same order of magnitude. If some God somewhere twists a control knob of the universe and changes any of those dimensionless ratios significantly, life would be meaningfully different. For whatever reason, atoms need to be 10²⁵ bigger than the natural unit of length and living cells and the molecules therein need a minimum number of atoms so that they can function the way they do, and beings like us need a minimum number of cells to do what we do. A protozoa will not perceive reality like we do and a protozoa cannot exist at the scale of an atom and an atom cannot exist at the scale of $l_{P}={\sqrt {\frac {\hbar G}{c^{3}}}}$. You can go through a similar song and dance regarding how we perceive time relative to $t_{P}={\sqrt {\frac {\hbar G}{c^{5}}}}$. I imagine a housefly will perceive the same length of time a lot more slowly than we do (which might explain why it's so damn hard to kill the bastards), but for us, a very short "instant" of time seems to be about 10⁴³ Planck times.

The same is true regarding instruments we make to extend our range and accuracy of measurement of length and time and mass. The ratio of the wavelength of cesium radiation in an atomic clock to $l_{P}\$ is some dimensionless number. And the ratio of the period of one cycle of this radiation to $t_{P}\$ is the same dimensionless number. It is only because of how we perceive length and time that we perceive the speed of propagation of E&M to be about 10⁸ m/s. Every measurement of that dimensionful quantity we call c has built into it an "accident of history".

Now if somehow, conceptually, $l_{P}\$ increased, if all of these dimensionless ratios remained the same, we and our meter sticks (and the wavelength of that cesium radiation) would get larger by the same factor. A similar argument could be made regarding $t_{P}\$ and our measurement of time. The meter and the second remain the same dimensionless multiples of $l_{P}\$ and $t_{P}\$ or some dimensionless quantities have changed, which is not the premise. Light (or other EM or gravity) will always travel one $l_{P}\$ during the time elapsed by one $t_{P}\$ and it's simply a matter of applying (invariant) scaling to say that this light will continue to travel 299792458 meters in the time elapsed by one second. If not, then some dimensionless quantity, which we can measure has changed.

It's sorta like the natural units define the tick marks on a sorta membrane (not to be confused with branes in string theory) of which all of reality exists. Stretch it in the time dimension and all times, including $t_{P}\$ change by the same factor but not relative to each other. Stretch it in the length dimension and all lengths, including $l_{P}\$ change by the same factor but not relative to each other. Same for mass and $m_{P}\$. If not and some dimensionless quantity has changed and that change is measureable, perceptible, and meaningful. The quantities $G,\hbar ,c\$ are simply diagonal slopes on this membrane and a change in any of these, such as c, would simply be a stretch in one direction over another. Still, nothing meaningfully changed unless there is a change in times relative to $t_{P}\$ or lengths relative to $l_{P}\$, etc. All $G,\hbar ,c\$ tell us is where these tick marks are relative to the units we have created to measure $G,\hbar ,c\$ with.

Now perhaps the result of Oklo is that $\alpha ={\frac {e^{2}}{\hbar c4\pi \epsilon _{0}}}\$ may have changed in the last couple of billion years. That, if true, is a meaningful change. It could be interpreted as a measurement of the speed of light, where $c\$ is measured against another like-dimensioned quantity: ${\frac {e^{2}}{\hbar \epsilon _{0}}}\$. So the standard of measurement against which $c\$ is measured is ${\frac {e^{2}}{\hbar \epsilon _{0}}}\$ and $c\$ apparently has changed relative to that standard according to Oklo. Why interpret that as $c\$ changing? Why not something in the standard that $c\$ is measured against? Since, in my world of natural units (I can choose my units to be whatever I want and I choose them to normalize $G,\hbar ,c\$ and $4\pi \epsilon _{0}\$). Then that result of Oklo would be the result of the elementary charge, measured in natural units of charge, being different long ago than it is now. It's just as plausible (more so for my money) than a change in c which is just stretching that membrane.

If, in any of our measurements, we think we have measured a change in c or h or G or e, what we have truly perceived to have changed is a dimensionless quantity (such as α) involving such dimensionful quantities and it is this dimensionless quantity that is the salient parameter. You can say that "we measured the speed of light to change" and I would respond "no, it was the fine-stucture constant you measured to change" and the latter is what is salient.

r b-j 03:25, 13 September 2006 (UTC)

Now you get me confused. I would think that the less likely it is that a constant changes, the more fundamental it is. Now you are not only saying that a change in c cannot be distinguished from a change in α (which would make both equally fundamental) you even claim that you would "prefer" the interpretation of a change in α which would make c more fundamental than α?

--Kehrli 18:14, 13 September 2006 (UTC)

Kerhli, just as if there are holocaust deniers at the WWII page or aetherists at the General relativity page, i am not here to argue the merits of different physics ideas with you (not anymore, anyway). go to sci.physics.research to do that. publish a peer reviewed paper to do that. perhaps write and post something for arXiv. at least read the damn Barrow book or Duff's paper (the latter is available on the internet) that spells this out. but don't expect your "confusion" or non-conventional POV to replace the current and accepted state of knowledge regarding the nature of dimensionless vs. dimensionful physical quantities in WP.

what we debate here is what is the present state of accepted physics theory (and practice, since the topic is very closely related to the issue of measurement) by the physics community and the known authorities in that community (which is not you). if you don't get it, there is little more that i can do about it. this is an encyclopedia. we put accepted convention and body of knowledge here. we don't remove it and call it a "common misconception". first you have to prove to the physics community (to some level of acceptance) that it's a common misconception, and then it goes here. but, as it stands, the misconception about this lies with you.

you can take this "interpretation" and do with it whatever you want. i was not offering it for article content. it was just an attempt to explain something that is commonly accepted in the physics community to you and anyone else who is listening. r b-j 19:33, 13 September 2006 (UTC)

Rbj, I did read Duffs paper [1] and he is actualy arguing along my line and against yours.

yeah, right. Duff:"The possible time variation of dimensionless fundamental constants of nature, such as the fine-structure constant, is a legitimate subject of physical enquiry. By contrast, the time variation of dimensional constants, such as h, c, G, e, k..., which are merely human constructs whose number and values differ from one choice of units to the next, has no operational meaning."

i s'pose that up is down and down is up, black is really white, etc. ...

He claims that α is less changing than dimesonful constants:

An obvious example is again provided by units in which time is measured in years and distance in light-years. Here c = 1 and Δc/c=0, whatever your theory. Similar remarks apply to ΔG/G. As discussed in Appendix A, it is guaranteed to vanish in Planck units (3), for example, but might vary in Dirac units (13). By contrast, Δα/α is unit-independent.

And anyway: when I read those articles I do not get the impression that there is a "commonly accepted" opinion on this issue. It is rather the opposite.

So let's come back to the real issue: di you still think that the value of constants depend on the units in use? If so, please show me some references.

--Kehrli 22:49, 14 September 2006 (UTC)

what you have in that particular article is a point-by-point refutation of different claims made by some cosmologists of a meaningfully decreasing c, with the persistent questions, "how are you going to measure it? and if it can't be measured (of if the measurement depends on the capricious human choice of units), how is it operationally meaningful?"

Kehrli, having a disagreement with a bunch of other mass spectrometrists about convention (when they say "mass-to-charge ratio" do they mean m/q or (m/q)/(u/e) ?) is one thing, but with this you're being a crank. you're taking a position that is widely not accepted (but this changing dimensionful constant thing does perenially pop up since it is not commonly understood in the widespread media that if c appears to change, it would be changing relative to something else and you cannot tell whether it was the parameter or the standard it's measured against that changes). then you somehow try to contort what one well respected author is saying into something diametrically opposite. in USENET, we have a term for this: "troll". the fact is, that you apparently do not understand or appreciate the difference between a dimensionless parameter (that may or may not be considered constant) and a dimensionful parameter. perhaps you don't understand that in any physical measurement, a physical quantity is being compared to some like-dimensioned standard which means the net result is always dimensionless. it's the dimensionless quantities that matter. a dimensionful quantity is an interpretation of what is measured or perceived. just because you don't understand it doesn't mean that this lack of understanding becomes canonized in Wikipedia. start your own website for crank material. r b-j 23:34, 14 September 2006 (UTC)

Rbj, look, I don't want to be a crank and I don't want to be a troll. It was you that diverted a discussion about a relatively simple questions (do quantities depend on units used) into a highly theoretical discussion about what would happen if the fundamental constants would change. I tried several times to get back to the initial points and you never answerd to those. You should understand that to me you also look like a troll, even though I know you don't do this on purpose. So let's go back to the basic points:

- I know that measuring a physical quantity Q means comparing it to a like-dimensioned standard (which is called unit U, btw).

- I know that the result of this comparison is dimensionless (it is called the numerical value n of the quantity Q).

- However, I also know that the result of the measurement process is Q = n*U. The product n*U does not depend on the units used. This product (the quantity Q) is the same whatever unit you use.

- You seem not to understand the difference between the quantity Q and its numerical factor n. n alone (e.g. whithout knowledge of the unit U) is absolutely useless. The value of n is, in your words, an interpretation of what is measured or percieved. Q is what matters.

Q is independent of the units ! Once you understand this we can change the article accordingly. Before you understand the difference between Q and n it does not make sense to discuss whether dimensionless quantites Q = n are more important than dimensionful quantities Q = n*U. --Kehrli 07:35, 16 September 2006 (UTC)

Just a question. Today the charge of an electron is equal to the charge of a proton, except for the sign. If tomorrow you found that the charge of an electron has become −1.01 times the charge of a proton, would you say that the absolute value of the electron charge has increased, or that of the proton has decreased? And why? Well, unless you define some unit of charge, you have nothing with which to compare charges, to say which of the two happened. The only thing you can say is that their ratio changed.

And if you have defined a different unit of charge than mine, we might disagree. For example, if you had defined e to be equal to the charge of a proton, and I had defined e to be the charge of an electron times −1, tomorrow you would find that the abs. value of the electron charge is slightly more than e, and I'd find that the proton charge is slightly less than e. --Army1987 15:49, 16 September 2006 (UTC)

Army, let me just start by saying that we probably would not survive this change. All neutral matter would suddenly have a net charge and the coulomb explosion would just blast us appart. Then let me mention that if you choose a quantity to become a unit you should make sure it is constant. In your scenario the choice of the electron charge (or proton charge) as a unit was simply a bad choice. But luckily the definition of the coulomb is not based on the electron charge, but based on a current. Maybe the definition of current is unaltered by the electron's change of charge, then there is not a problem. Just don't use natural units any more and use SI units. Then, I would take a mass spectrometer and measure the m/q of electrons and protons and I would compare them with the values from the day before. This way I could say which one changed (assuming there was no change in mass) and I could start using natural units again where the constant charge carrier, whichever it is, can serve as the reference. --Kehrli 20:36, 16 September 2006 (UTC)

I know that the example I made was impossible, it was just a thought experiment. Anyway, what you do in the answer is requiring that the magetic permeability of free space should remain 4π×10⁻⁷ H/m. This is due to the way the ampere is defined. Therefore it is due to the system of units choosen. --Army1987 11:10, 17 September 2006 (UTC)

time to start a new section.

okay, i am going to try to boil this back down to what the dispute is about. it is about content of this article. both content that has been removed (and restored) and content that was added (and removed). perhaps there are other editors, but my dispute is with Kerhli's additions and removals, as far as i can see i don't have a dispute with Army or any other recent editor about content. my dispute with Kehrli is that his additions are not consistent with the current thought of actual physicists that write about this in the lit (both books and papers) and those who talk about it on various blogs and USENET newsgroups (specifically sci.physics.research). it is also about my own understanding of the topic but that goes no further in momentum than Kerhli's understanding of the topic. he thinks he's correct every bit as much as i do. but when he made these changes he relied primarily on "because [he] think[s] it is wrong".

these two statements that Kerli added are false. they are not the widely held consensus of the physicists who have published and commented about this kind of stuff (that usually crops up when some cosmologist gets a lot of new press because he claims to have discovered a meaningful change in c):

"Contrary to wide belief, physiscal constants do not depend on systems of units."

"Fundamental physical constants, are basic properties of nature, not depending on our culture. Another civilisation in another Galaxy would find the same values for those constants. All examples above are considered fundamental physical constants, "

the latter is almost a difference of semantic. but it is not true that both the first two and also the last sentence are true for either given semantic. if physical constants such as c, G, h or e are counted among the fundamental physical constants (which is claimed by the last sentence), then it false that they are independent of culture. assuming we could communicate with the aliens on Zog qualitative fact and numerical information, there is no way that we could ask them to compare their measurement of c or G or h to what we measure to see if they are consistent. no way to do that at all. but it is possible to ask them to measure α and tell us if they get the same number that we get. likewise with m_p/m_e or any other ratio of like-dimensioned universal quantities. this is common knowledge in the physics community, they are often correcting the neophyte who doesn't yet understand it. if i look in Google Groups hard enough, i can go back and find where they corrected me about it on sci.physics.research.

Kerhli removed:

Unless the system of natural units is used, the numerical values of dimensionful physical constants are artifacts of the unit system used, such as SI or cgs; that is, they are essentially conversion factors of human construct.

" because [he thought] it is wrong"

and

The fine-structure constant α is probably the most well-known dimensionless fundamental physical constant. The dimensionless ratios of masses (or other like-dimensioned properties) of fundamental particles are also fundamental physical constants, as are the measure of these properties in terms of natural units.

because he does "not think that dimensionless constants are more fundamental than other constants."

both paragraphs removed (and later restored) are correct and Kerhli's justification for their removal is inadequate. (he can think whatever he chooses to, but that thinking, in and of itself, does not trump the position and understanding of the physics community, particularly the peer published statements of multiple and esteemed authors to the contrary.) his belief that "dimensionless constants are [not] more fundamental than other constants" or that it's a "misunderstanding coming from the believe that quantities depend on systems of units is wrong" is itself wrong. the misunderstanding lies with Kehrli.

lastly, even though i said i wouldn't rehash this again, i will try once more to repeat the main point for why Kehrli's conception is the misconception. i don't expect he will accept it (which is why crank might be appropriate) but maybe someone else will. again, i qualify this with "my interpretation":

The reason that human beings measure c to be 299792458 m/s is because (before they redefined the meter to fix c to 299792458 m/s) the distance between the two little scratch marks of the platinum-iridium International Prototype Metre was, to the same precision, very nearly 6.18718916×10³⁴ Planck lengths and the number of Planck times in one cycle of radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium-133 atom is, to the same precision, very nearly 2.01778195×10³³ and that humans have anthropometrically decided that 9192631770 of those cycles make up one second (and that c is always 1 Planck length per Planck time). that is a human construct. and that is solely why c = 299792458 m/s.

we could more historical about it when we find out that the meter was chosen so that there would be exactly 10 million of them on an arc of the earth from the north pole to the equator going through Paris (making the meridional circumference 40 million meters - they got that wrong by 0.02%, but not bad for the 18^th century). and given that the mean solar day was originally 86400 seconds (before the atomic clock), the human POV of the measure of c is that light is fast enough to make 647551.7 revolutions around our planet at the mean surface radius and over the poles in the period of time between consecutive instances that the sun is directly above the same given meridan. that is what c = 299792458 m/s means to humans, and that is purely anthropometric. the aliens on the planet Zog could give a rat's ass about it.

r b-j 23:03, 16 September 2006 (UTC)

Rbj, lets pick your examples: instead of communicating the dimensionless ratio m_p/m_e with the Zorgs you could as well tell them the (dimensionfull) proton mass in a unit that you think they understand, e.g. the electron mass:

m_p = 1836 m_e

This examle illustrates perfectly that there seems to be no big difference between dimensionless and dimensionful constant quantities that would justify to call either non-fundamental. Maybe there is a good reason, but I still have not heard it from you. --Kehrli 11:11, 17 September 2006 (UTC)

that's because you're a crank and you proved it by your either cluelessness or obstinance again and again. i said, that there is no way to communicate to the Zogs a dimensionful quantity without referencing that against another like-dimensioned quantity (call it a standard, if you choose). but how do we communicate the magnitude of the standard to them? we could use something like Planck units as a standard to communicate the size of anything to them, but as soon as we say "we measured the speed of light to be 299792458 m/s" to them, that means, from our definitions of the meter and second, precisely the same as "we measured the speed of light to be 1 l_P/t_P." in other words, it says nothing (new) at all.

there are so many misconceptions you have Kehrli that it's difficult to begin because i see no end to it. one example, you said "...luckily the definition of the coulomb is not based on the electron charge, but based on a current." guess what, there is a serious proposal oto redefine the kilogram in such a way that the consequence would be to exactly define the coulomb as exactly 6 241 509 479 607 717 888 elementary charges. what's gonna happen to us if they do that? are we gonna turn into radishes?? (personally i am cheering for the proposal to redefine the kg from this lump of metal in Paris to fix Planck's constant in the same way that the meter was redefined to fix c. most all of your points i have left unanswered simply because they do nothing to refute this well established physical principle. of course, when we represent a dimensionful quantity we do so with a dimensionless number and a unit. big, fat, hairy, deeeal! it says nothing to support your two false statements you tried to slip into the article or to support your anemic argument ("because i think it's wrong") for deleting two salient statements which are key to differentiating dimensionful physical constants (which are human constructs) from dimensionless physical constants which are fundamental parmaters of meaning for how the universe exists.

i'm through with this. you don't get it. i have no hope that you will. a little bit of knowledge is a dangerous thing, but please turn your crank somewhere else. r b-j 13:48, 17 September 2006 (UTC)

Rbj, you don't need to communicate the magnitude of the kg to the Zorgs because you can use a unit that they understand, like the Plank mass, the electron mass, the proton mass. According to the current consensus these quantities are the same for the Zorgs as they are for us, just because they are fundamental constants. You can even have the Zorgs doubble check by sending your quantity in three different units. The Zorgs can then see if it makes sense for them. If not, you would have found that at least one supposedly fundamental quantity is not fundamental. --Kehrli 18:47, 17 September 2006 (UTC)

Rbj, here is to my edits:

Unless the system of natural units is used, the numerical values of dimensionful physical constants are artifacts of the unit system used, such as SI or cgs; that is, they are essentially conversion factors of human construct.

I removed this sentence not because it is wrong but because it is irrelevant. Nobody cares about the numerical value of constants exactly because they are only artifacts. What really matters are the values of the dimensionful physical constants and those are not depending on units. I was afraid that your sentence could mislead readers of wikipedia because they may not realize the difference between "value of a quantity" and "numerical value of a quantity" (which, by the way, would better be called value of the numerical factor of a quantity).

The fine-structure constant α is probably the most well-known dimensionless fundamental physical constant. The dimensionless ratios of masses (or other like-dimensioned properties) of fundamental particles are also fundamental physical constants, as are the measure of these properties in terms of natural units.

I also agree with this one. Here is where I do not agree:

Constants that are independent of systems of units are dimensionless numbers ...

This is wrong because all constants do not depend on units, regardles wether they are dimensionles or dimensionful.

Constants that are independent of systems of units are dimensionless numbers known as fundamental physical constants, ...

not all dimensionless constants are fundamental physical constants, as this suggests. For example the ratio of the height of the Eiffel tower and the standard meter in Paris is a dimensionless quantity but most people would agree it is not a fundamental quantity.

... and are truly meaningful parameters of nature, not merely human constructs.

The proton mass is also a truly meaningful parameters of nature, not merely human construct, even though it is dimensionful. And its value does not depend on the units in use. Then to the sentences I inserted:

"Contrary to wide belief, physiscal constants do not depend on systems of units."

This is true and does not apply only to constants but to any physical quantity. I hope Army and Ed will confirm this. It basically means that you cannot change the height of the Eiffel tower merely by switching from in feet to meters. It is very trivial and I can't believe we are arguing about it.

"Fundamental physical constants, are basic properties of nature, not depending on our culture. Another civilisation in another Galaxy would find the same values for those constants. All examples above are considered fundamental physical constants, "

As far as I remeber I did not write this from scratch but only changed it to include dimensionful fundamental constants. These constants are called fundamental because it is the current consensus that they are basic properties of nature, not depending on our culture. If you would find out that the Zorgs get different values they would no longer be called fundamental. Hence, again we seem to have a different definition of the term fundamental. Your definition is "it can easily be communicated" and my definition is "it is an universal constant". Now frankly I do not know which is the "correct" definition. But I can tell you why your definition does not make a lot of sense to me. Let's assume that you communicate with the Zorgs and you find out their m_p/m_e is different from ours. What now? According to your definition, m_p/m_e would still be a fundamental constant even though you just proved that it is not universal. Even your height-to-waist ratio would qualify as a fundamental physical constant just because you can easily communicate it to the Zorgs. --Kehrli 18:37, 17 September 2006 (UTC)

God could choose to change the ratio m_p/m_e, but which of the two would change depends on how our measurement units work. For example, since the kilogram is defined as the mass of an artifact, to whose mass protons contribute much more than electrons, if m_p/m_e increased, that would mean that the mass of the proton in kilograms increases by a very small fraction, and the mass of the electron decrease by a larger fraction. If the kilogram were defined in terms of the mass of an electron, the electron mass would stay constant and the mass of a proton would increase, whereas if it were defined in terms of the mass of a proton, the proton mass would stay constant and the mass of an electron would decrease. Only if we measured masses in terms of the Planck mass, would the new values of the masses be meaningful to the aliens on the planet Zog.

α is defined as e²/(ħc4πε₀). Some say that α changed. Does that mean that e increased, or that any of the constant in the denominator decreased? Well, c has a fixed value (299792458 m/s); so does 4πε₀ (10⁷/299792458² F/m). Now, if they decided to define the kilogram in terms of Planck's constant, then we could say that it was e that increased. If they defined it in terms of the elementary charge, we could say it was ħ which decreased. If they defined it in terms of the electron mass, or of the mass of an atom of C¹², we would need to know wheter the ratio between an electron mass (or the mass of a carbon-12 atom) and a Planck mass changed, and assuming it didn't, we could say it was e which increased. (Too bad that until they redefine the kg, this question is meaningless, since when the Oklo reactor was in function and when light left from those quasars, there was no piece of platinum-iridium in Sevres, and no city of Sevres indeed...) --Army1987 12:31, 17 September 2006 (UTC)

sorry for butting in before your answer, Army. i felt compelled to. r b-j 13:48, 17 September 2006 (UTC)

Army, I completely agree with you. I foregot that the Plank mass would be an even better unit for the Zorgs. So we have two possibilities to comminucate a dimensionful proton mass with the Zorgs: in units of electon masses and in Plank units. This definitely shows that the claim of Rbj, that only dimesionless quantities can be used to comunicate with the Zorgs, is not true. --Kehrli 18:37, 17 September 2006 (UTC)

Do you agree that, assuming that the fine structure constant did change, the constant which changed can be either e or h (or even c or ε₀, or several of them) depending on the way the system of measurement works?

Anyway, the height of the Tour Eiffel is not constant, it varies with the weather due to thermal expansion. Also, the Tour Eiffel wasn't always there, and won't be always there; and God/nature/the software of the Matrix/call it what you want doesn't give a damn about it. If the Tour Eiffel is bombed and the height of the remains is half the original heigth of the tower, no physical law changes. --Army1987 21:11, 17 September 2006 (UTC)

Army, most constants are not really constant. They are temporary relatively stable. The solar constant for example changed in the lifecycle of the sun. The proton mass is only a constant since protons exist. I always thought that fundamental constants are "real" constants, but now you are telling me that even α may be changing. So strictly speaking there are no constants at all, at best there are "supposed constants". In daily life, however, we treat even our size as a constant. This is why it is in the passport along with the eye color. This only makes sense because both are relatively constant over time. The waist, on the other hand, is changing too much and therefore is not in the passport and maybe not a constant. I think it is a fuzzy concept. The Eiffel tower certainly is not a fundamental constant, and if you look closely it moves constantly. However, if the height would not be considered a constant you would not find it indicated on wikipedia. --Kehrli 21:41, 17 September 2006 (UTC)

The fact is that the height of the Eiffel tower does not show up in physical laws. Also, it is artificial: we could change it, whereas we couldn't change the mass of a proton. Anyway, you haven't answered my question about varying α.

You say: the measurement of a quantity Q measured in the unit u is Q = n u, and the product n u does not depend on u. This is true because conversion factors between different units are either defined (e.g. 1 yard = 0.9144 m), or rely on a constant (e.g. 1 amu = 1.660 538 73×10⁻²⁷ ± 13×10⁻³⁵ kg, relies on the ratio of the mass of an atom of carbon-12 and that of Le Grand Kilo). What if there were no such constant? Let's say something today costs 1.01 $ or 0.80 €, another day it will cost 1.00 $ or 0.81 €. Will it be cheaper or more expensive? You can't say without choosing in which currency one measures prices. What if the "constants" on which some conversion factors are based weren't really constant? [2] --Army1987 21:53, 17 September 2006 (UTC)

Army, I now realyze that we both give a different meaning to the term "physical constant". For you this is a constant that plays some role in physics. For me it is just a shorter version for "a constant physical quantity". Therefore, for me any physical quantity that is constant becomes a physical constant, also the height of the Eiffel tower or the mass of a stone in the middle of some ocean. For you this is not the case because it does not play a role in physics. So maybe we need to write two articles. --Kehrli 17:34, 18 September 2006 (UTC)

Army, in my opinion the use of units makes only sense if you find a reference (the unit) which is sufficiently constant for your measuring task. Frankly I did not think too much about what would happen if such a constant reference is missing. In my opinion this is a very interesting and challenging problem but it should not dominate the article about physical constants on wikipedia since it is a highly hypothetical issue. I very much like the section questioning the constancy of the fundamental constants. It shows to the reader that things may be more complicated than what is the current consensus. But otherwise I think the article should stress more what is the current consensus (in ISO 31 for example) than what are the unsolved problems in science. Wikipedia is made for people that want to look up something. Some of those are looking for a simple answer and will only get confused. Others would like to get inspired by the unresolved questions of science. So we need to write an article that serves both these groups. But coming back to your question: as I said before, the concept of "constant" is somewhat fuzzy. For many measurements it is good enough to have a relatively constant unit. If you buy some cheese it probably doesen't matter if the mass unit would only be constant to 1/1000. For other measurements this is not acceptable. This is why many people work on finding better standards. And this would be my answer to your question: find better standards. And, to address the hidden agenda of your question, it probably does not matter wether you use dimensionful or dimensionless quantities. As I said before: you can indicate the mass of the proton as a dimensionless quantity:

m_p/m_e = 1836

or a dimensionfull quantity:

m_p = 1836 m_e

and there is obviously almost no difference. At least I don't see any. But now that I understand your interpretation of "physical constant" I can understand if you don't like my fuzzy answers. --Kehrli 17:34, 18 September 2006 (UTC)

Obviously any quantity which does not change can be called a constant, but usually when one talks about constants one refers to meaningful ones. For example, the concept of mathematical constant. The number (86764364846846.1189648311)^443986743368/arccosh(6867+log_131354345844863438486485481)−₅₇∫⁹⁹ cos x sen ln x Γ (x) dx is constant, of course, but nobody would expect to see it in an encyclopedia. The same goes with physical constant. The height of a piece of bronze (a door hinge) I once found on a desk in my school, when kept at exactly 297 K and 96.5 kPa, is constant, but somebody talking about a physical constant is very, very unlikely to be referring to it. Usually, physical constants are quantities which are equal all over the Universe, not properties of a specifical object. One can find the value of G with an experiment in any arbitrary place of the Universe, but you can find the height of the hinge I was talking about only having it at your disposal.

If you say m_p = 1836 m_e what you are doing is comparing two quantity of the same dimension, and any measurement is about that. What you get is a number multiplied by a name, and the name symbolizes a quantity which may be arbitrary (though I must admit in this case it is much less arbitrary than a piece of metal in Sévres). Suppose we tell an alien that c = 299792458 m/s. What will the alien learn? The relationship between the metre and the second. If he hasn't the faintest idea of what a metre is and what a second is, he will gain no knowledge about how fast light is. If we tell him m_e=9.109 3826×10⁻³¹ what he learn is how heavy a kilogram is (supposing he knows how heavy an electron is). He won't learn how heavy an electron is if he can't have any idea about how heavy a kilogram is. --Army1987 19:29, 18 September 2006 (UTC)

Army, for the first time your replies puzzle me:

1) I am not saying that any constant should be mentioned in wikipedia. I was just addressing the question: "what is a physical constant?". Is it a constant relevant in physics or is it any constant physical quantity? I have no answer. I assumed the latter, but I may be wrong.

2) If I say m_p = 1836 m_e I am using m_e as a unit. Thats all. Thereby I am communicating a dimensionful quantity (the proton mass) in a way that is as useful as if I would communicate the dimensionless quantity m_p/m_e. Therefore I do not see why the later constant sshould be more fundamental then the first quantity, as the current article suggests.

3) I would not tell an alien c = 299792458 m/s, I would only use c as a unit, assuming they know c (in their own SI system).

4) I would never tell the aliens m_e=9.109 3826×10⁻³¹ since every dimensionful quantity needs a unit. If anything I would tell them m_e=9.109 3826×10⁻³¹ kg. From this they could figure out the kg and I could use kg in my next messages. --Kehrli 08:37, 19 September 2006 (UTC)

Sorry, I meant m_e=9.109 3826×10⁻³¹ kg. I forgot to type the symbol of the unit. My mistake. Anyway, the article says: Unless a system of natural units is used, the numerical values [...] The dimensionless ratios of masses [...] are also fundamental physical constants, as are the measures of these properties in terms of some set of natural units. So I don't understand where you claim the article says that m_p = 1836 m_e is not fundamental.

As for physical constant, the article starts talking about "a physical quantity whose value does not change", but then only mentions quantities which can be measured all over the Universe. Reading above in this talk page, I found out that this article used to contain constants such as the electron mass, but they were deleted on the ground that This page is about physical constants not particle properties. Particle properties are unique to the particle they describe, and are not universal constants. I disagree with this because all electrons in the universe have the same rest mass, and in any place of the universe, even if there is currently no electron, a virtual electron-positron pair could pop out and its components would have the same mass. But anyway, nobody when talking about a physical constant would refer about the mass of his favourite guitar pick. --Army1987 10:02, 19 September 2006 (UTC)

which is why natural units not based on the physical properties of any prototype, artifact or thing (that is Planck units which are defined on the basis of properties of free space) are a better definition of natural units than one based on the properties (mass, size, charge, etc.) of such a thing that must be chosen (possibly arbitrarily) by some one. r b-j 00:36, 22 September 2006 (UTC)

Discussion at The n-Category Café

Someone sent User:Kehrli to talk to me. Since User:Kehrli made some points I hadn't thought of before, I started a discussion of dimensional analysis over at the n-Category Café. You may enjoy watching or even joining in, though I don't want your whole arguing party to switch to that venue - you're having plenty of fun right here!

I think the true meaning of terms like "fundamental constant", "physical constant" and "dimensions" is a serious philosophical problem on which there's no consensus. I hear that Wikipedia articles should not be based on "original research", but that's just what you all are engaged in now. A serious bunch of people writing an article on quantum gravity might similarly feel the need to figure out the correct theory of quantum gravity first - but it's not clear that's the right approach. It's very worthwhile to figure these things out, but I suspect that a Wikipedia article should primarily report the standard consensus view among physicists, perhaps downplaying or at least not endorsing the aspects that seem naive, controversial or downright wrong.

Luckily, to most readers, what will be most important is not the definitions of "physical constant", "fundamental constant", etc., but a nicely presented list of constants - which must certainly include dimensionful ones to be of practical use! In my constants webpage I focused on dimensionless fundamental constants with a certain notion of when two such units were "independent", in order to achieve a finite list and focus attention on certain interesting problems. But there's no need to do that here: it's better to envision what a typical reader might want to know. I think a reader turning to a page on "physical constants" is much more likely to want to know Avogadro's number or the speed of light than the constants I consider on my webpage (e.g. the entries of the Maki-Nakagawa-Sakata matrix).

So, while the argument you're having is very interesting, its outcome shouldn't affect the actual article much. If it does, I think you're probably doing something wrong. John Baez 07:43, 22 September 2006 (UTC)

We were not discussing on which constants to list in the article, but on how the intro should read. [3]. --Army1987 08:13, 22 September 2006 (UTC)

and John, it is a little bit of a categorization issue. specifically, IMO, the debate discussion is whether these two statements (since removed):

"Contrary to wide belief, physiscal constants do not depend on systems of units."

"Fundamental physical constants, are basic properties of nature, not depending on our culture. Another civilisation in another Galaxy would find the same values for those constants. All examples above [c, G, h, ε₀, e] are considered fundamental physical constants, "

are "correct" or represent the position or consensus of the credentialed physics community, particularly the "leaders" or "experts" or primary authors that have written about this. it is also about whether these two paragraphs (since restored) should have been removed:

Unless the system of natural units is used, the numerical values of dimensionful physical constants are artifacts of the unit system used, such as SI or cgs; that is, they are essentially conversion factors of human construct.

The fine-structure constant α is probably the most well-known dimensionless fundamental physical constant. The dimensionless ratios of masses (or other like-dimensioned properties) of fundamental particles are also fundamental physical constants, as are the measure of these properties in terms of natural units.

if a bunch of real physicists like you were editing the article, how would you come down on this? if you think the article is okay as is, fine, but if you think it needs to have some falsehood or fallacy fixed, can you please do that? my intention was to represent the consensus of the established and credentialed physics community as well as i could determine what that is from arXiv papers, sci.physics.research, blogs, books (like Barrow) and such, not the r b-j POV.

i think from Kehrli's statements, the issue is really if there is any good reason for a separate article on 'Fundamental physical constants or Dimensionless physical constants, because i don't think, from how i read his/her comments here, that Kehrli thinks there is any qualitative difference between the two groups of physical constants. if there really is no substantive difference, that the extent that α is different from c is the same as the extent that c is different from G (that all it is that they are physical constants with different dimensions) then Fundamental physical constants should not exist as a separate article and that paragraph in the intro of this article should not exist. i do not believe that is at all the consensus of the credentialed physics community, but i would be happy for you to correct that impression if it needs to be. perhaps we should put an {{expert}} tag on this? r b-j 15:32, 22 September 2006 (UTC)

A couple more comments. Army1987 writes:

We were not discussing on which constants to list in the article, but on how the intro should read.

I know. I suggest that the intro to a page on "physical constants" is not the place to take a stand on the slippery problem of which physical constants are "fundamental". It's not necessary to get involved in that issue here. The readers are more likely to seek information on specific physical constants, regardless of whether they are "fundamental".

In my webpage I gave a specific definition of "fundamental physical constant" which was precise enough to let me count the number of such constants in the Standard Model, general relativity and other theories. This was a fun exercise, and I think my viewpoint formalized some very widespread attitudes among 20th-century theoretical physicists, namely that fundamental physical constants should be

1) definable without reference to arbitrary human artifacts such as meter rods, and therefore

2) dimensionless, but

3) not merely dimensionless but also uncomputable, in the sense that we cannot (currently) write a computer program that can crank out digits of these numbers, as we can for pi.

Note that criterion 3) but not criterion 2) rules out the dimensionless constant 299,792,458. The fact that this is precisely the speed of light in meters per second means that it's computable; this implies it's not a "fundamental physical constant" in my sense.

On the other hand, I wasn't attempting to "lay down the law" on what count as fundamental physical constants. In particular, experimental physicists and engineers are much more likely to regard dimensionful quantities like Newton's gravitational constant as "fundamental" - perhaps because these are the people who actually struggle to measure such quantities, or build devices whose functioning depends on accurate knowledge of their value. This difference often leads to friction between theoretical physicists and their more applied colleagues.

Furthermore, User:Kehrli did make some points that seemed obviously wrong when I first heard them, but obviously right after I took some time to think. Most importantly:

1) dimensionful quantities do not always depend on our choice of units - e.g. the speed of light c is a dimensionful quantity does not depend on our choice of units;

2) dimensionless quantities may depend on our choice of units in a certain sense - e.g. the dimensionless quantity c/(m/s) = 299,792,458 depends on our definition of the meter m, and would double if we halved the meter.

This touches on a slippery point in the now deleted sentence:

Unless the system of natural units is used, the numerical values of dimensionful physical constants are artifacts of the unit system used, such as SI or cgs; that is, they are essentially conversion factors of human construct.

The "numerical values of dimensionful physical constants" are themselves dimensionless. I don't see that this fact makes the sentence incorrect - just a bit slippery. I don't know if it matters.

I have other problems with this sentence, but I'm too tired to explain them. If it were up to me, I might replace this:

Unless the system of natural units is used, the numerical values of dimensionful physical constants are artifacts of the unit system used, such as SI or cgs; that is, they are essentially conversion factors of human construct.

The fine-structure constant α is probably the most well-known dimensionless fundamental physical constant. The dimensionless ratios of masses (or other like-dimensioned properties) of fundamental particles are also fundamental physical constants, as are the measure of these properties in terms of natural units.

with something more like this:

The numerical values of dimensionful physical constants depend on the unit system used, such as SI or cgs. As such, numbers like the speed of light in meters per second (299,792,458) are not things that a theory of physics can be expected to predict.

Dimensionless ratios of physical constants do not depend on unit systems in this way, so they are numbers whose values a future theory of physics could hope someday to predict. Thus, theoretical physicists tend to regard these quantities as more "fundamental". The most famous example here is the fine-structure constant α. Nobody knows why it is almost 1/137.036. Many attempts have been made to derive this value from theory, but so far none of have succeeded. The same holds for the dimensionless ratios of masses of fundamental particles. But, with the development of quantum chemistry in the 20th century, a vast number of previously inexplicable dimensionless physical constants were successfully computed from theory. So, theoretical physicists still hope to make progress on these issues someday.

r b-j writes:

if a bunch of real physicists like you were editing the article, how would you come down on this?

For one thing, I would try to make the introduction uncontroversial by not trying to lay down the law about what makes a physical constant "fundamental". I would certainly delete the sentence "Anyway this meaning of the adjective fundamental is the only one in use." Starting a paragraph with "Anyway" is unprofessional: it sounds like the encyclopedia author is arguing with something the reader just muttered under her breath. Besides, it's not true: people use "fundamental" to mean all sorts of things. (Maybe the word "not" got deleted? In any event, get rid of that "Anyway".)

r b-j writes:

i think from Kehrli's statements, the issue is really if there is any good reason for a separate article on 'Fundamental physical constants or Dimensionless physical constants, because don't think, from how i read his/her comments here, that Kehrli thinks there is any qualitative difference between the two groups of physical constants.

I don't know if there needs to be a separate article, but dimensionless physical constants are indeed qualitatively different - they're dimensionless! Furthermore, they're of special interest to theoretical physicists, and for very good reasons, which I tried to sketch above. So, they deserve some special section or article somewhere, and maybe the stuff I wrote above belongs there. I'm a bit biased, because just yesterday I spent an hour trying to improve the article on Dimensionless physical constants. But it's not just me - lots of theoretical physicists are fascinated by dimensionless constants. —Preceding unsigned comment added by John Baez (talk • contribs)

John, thanks for stopping by. This is a big help to me and, more importantly, this article. I have increasingly come under pressure on wikipedia. Rbj called me names on this talk page and I have been banned from editing the mass-to-charge ratio article just because I insisted that the symbols for mass-to-charge ratio be m/Q as is the wider consensus of the scientific community in described in the IUPAC green book and the IUPAP red book instead of m/z which is used by some in the small mass spectrometry community. Thanks again. --Kehrli 09:27, 23 September 2006 (UTC)

Kehrli: you've made some excellent points that really took me by surprise. At first I thought you were full of baloney, because you were saying strange things I'd never heard before. But when I tried to explain why you were full of baloney, I eventually realized you weren't. So, I hope Rbj and others cool it and try to listen carefully to what you're saying.

On the other hand, for this very reason, you should not simply drop sentences in the Wikipedia like "Contrary to wide belief, physical constants do not depend on systems of units." It's a bit like an astronomer who discovers a planet between Mercury and Venus and announces it simply by sticking a line in the Wikipedia entry on planets saying "Contrary to wide belief, there's a planet between Mercury and Venus". Everyone would just think he's nuts! This is one reason Wikipedia has a ban on original research. I hope you read that ban.

We don't want the Wikipedia to convey misinformation, but neither should it contain shocking new information without references or explanation - even if it's true, people can't tell. I've suggested some compromises that try to solve this dilemma. Another thing you might do is write and publish a little paper making the points you're making here. Not so you can cite it on the Wikipedia - just because it would be interesting to people! But, you'd need to explain things very carefully to keep the referees from rejecting the paper before they get the pont.

As for m/Q versus m/z, I know nothing about that. But if the mass-to-charge ratio article is about mass spectrometry, it should probably use the notation mass spectrometers use, even if other people think it's weird. Of course it should explain this notation.

A similar example that always bugs me: every physicist I know calls $\hbar$ "Planck's constant". But, Planck's constant was originally $h$; it was Dirac who invented $\hbar =h/2\pi$. So, in the Wikipedia $\hbar$ is called "the reduced Planck constant" or "Dirac's constant". From certain viewpoints this is correct - but if I talked like that to any physicist, they wouldn't know what the heck I meant! —Preceding unsigned comment added by John Baez (talk • contribs)

John, in retrospect you may be right, I should have introduced the "new" concept more carefully. However, here are some points to consider:

1) It is not really a "new" concept but only what complies to the IUPAC green book and the IUPAP red book. Therefore I considered (and still do consider) this "new" concept the "standard" concept and definitely not as OR.

2) I had no idea that the theoretical physics community has its own terminology not in line with the official IUPAC green book, the IUPAP red book and the ISO 31 conventions. So I thought I would just correct an erronous entry.

3) I did not simply delete the sentence and insert a new one. I also made an extensive comment in parallel on this talk page Talk:Physical_constant#Removed_paragraph on which I tried to explain why I made the deletion.

In short: I had no idea that my edit would stirr up a controversy. --Kehrli 11:03, 24 September 2006 (UTC)

John, here is to the m/z issue:

it is my very point that the mass-to-charge ratio is used by many different scientific communities, among them lithography, electron microscopy, cathode ray tube technology, accelerator physics (particle physics), nuclear physics, Auger spectroscopy, cosmology and mass spectrometry. All scientific fields that use charged particles in electic or magnetic fields will use the mass-to-charge ratio since it directly follows from:

$\mathbf {F} =Q(\mathbf {E} +\mathbf {v} \times \mathbf {B} )=m\mathbf {a}$

From all these communities only mass spectrometrists use m/z. Therefore I argued that m/Q should be on this page instead of m/z.

Then, there are also some more subtile issues: m/z is defined (since recently) as a dimensionless quantity. Before it was defined as a mass/charge dimensioned quantity. At that time, some famous mass spectrometrists suggested a new unit thomson (1 Th == 1 Da/e) for the mass-to-charge ratio. Today, since m/z is now dimensionless, the unit Th and m/z are no longer compatible. Now I have been banned from editing the article unit thomson because I insisted on this point. --Kehrli 17:57, 24 September 2006 (UTC)

John, i tried to write to the blog but was not able to. i would appreciate if you could elaborate about the "some excellent points [of Kehrli's] that really took [you] by surprise". frankly, i don't get it (and i remember when you set me straight about it on sci.physics.research perhaps 4 years ago). Kehrli keeps repeating that a physical constant (like a general physical quantity) is a (dimensionless) numerical value attached to a possibly dimensionful unit. while no one disputes that, it still begs the question; it does nothing to support her claims that were removed. she also continues to refer to the "IUPAC green book, the IUPAP red book and the ISO 31 conventions", the first i looked at and does nothing to support her, and frankly these conventions are non sequitur. i just want the article to say something substantive and to reflect what physicists like you had been repeating to thick skulls like me for years. if that is POV, it is the correct POV. the POV should be that of the consensus (or, at least, the wide majority) of the credentialed and practicing physics community. particularly the "leaders" or widely respected authors.

BTW, can you get me onto that blog? i sent my entries to the email (yours) directed, but i would like to post to it directly if that would be okay with you. r b-j 23:47, 26 September 2006 (UTC)

RBJ, I don't think John still hangs out here. But I can explain you what this is all about:

A physical quantity Q is the product of a numerical factor n and an unit U.

Q = n*U

If the quantity Q is constant, the product n*U must be constant. So, if U changes it immediately follows that n has to change accordingly. This means: n depends on the units U whereas Q does not depend on the units U. So far everyone agrees, I suppose. Where there seems not to be an agreement is the following: theoretical physicist seem to think that n is the value of a quantity whereas the IUPAC green book explicitly states that n*U is the value of the quantiy Q.

If you have further questions don't hesitate to ask.

I agree with you that the current article leaves out the substantial point, namely that the value of a physical constant (and thereby I mean the IUPAC version n*U) does not depend on units. You may change the article accordingly. I won't do it 'cause I am kind of tired of wasting time for editing articles just to have the edits reverted by people who overestimate their knowledge. --Kehrli 19:34, 27 September 2006 (UTC)

Important Question Regarding Kehrli Ban

I should clarify Kehrli's statement above. He has been banned from all articles relating to m/z and as a you can see from this discussion there is a clear relationship to this article if one would like to make it. In addition he is currently blocked from all of wikipedia for 24 hours for violation of this ruling. This has occured primarily because of his behavior in discussions on talk pages quite similar to this one where he presents interesting original research. Essentially he was banned for advocating the same points he makes here. I would remind the editors here that this discussion is not consistent with wikipedia policy. Wikipedia is not a place for "proposing theories and solutions, original ideas, defining terms, coining new words, etc." nor is it a place for "discussion forums. Please try to stay on the task of creating an encyclopedia." I would suggest that discussions about orginal research be held in a different forum. It would be responsible of me to bring this to the attention of administrators however it would be considerate of me to let all of you make your own decision if you would like this discussion to continue. What would you like?--Nick Y. 00:44, 26 September 2006 (UTC)

Nick, we're just trying to (now with the help of John Baez, hopefully other credentialed physicists will get involved) discuss/debate what is the orthodox position of the physics community). the bulk of the discussion here in the talk page was about that and then some elaboration why. there was also a semantic issue regarding the word "Fundamental" regarding a category of physical constant, but i think that remains semantic. the questionable edits that Kehrli made to this article no longer are there but the discussion remains and John has opened it up to a wider group outside of WP (i can see why he did, but do not see his newfound affinity for, what continues to appear to me to be the cranky positions of Kehrli). also i think Kehrli is a she and her first name is Vera (that's what John says, anyway).

we're doing okay here, Kehrli is not asserting changes without checks and balances. if it gets bad, i'll go crying to someone or 'nother. i am a little confused about John's response, though. i am pursuing that directly. r b-j 00:57, 26 September 2006 (UTC)

Okay, that is what I thought might be the case. It seems there are sufficient checks and balances (A quorum of editors) to keep her agressiveness in changing scientific concensus via wikipedia at bay. I still believe that the discussions here are not appropriate but as long as no one objects neither will I. Kehrli's ideas are interesting, well thought out and very original (as in not appropriate for an encyclopedia). She is sometimes right and sometimes wrong but always original. I actually personally agree with most but not all of her position on the m/z stuff. Wikipedia is about accuracy, verifiability and proportionality based on general acceptance not truth and equal space for all positions. Kehrli needs to have an outlet for her pursuit of truth. I did hear that there is some wiki out there that is specifically about truth in that it is mostly a debate forum for original ideas. I am available whenever someone objects to the course of this discussion or inappropriate editing.--Nick Y. 17:52, 26 September 2006 (UTC)

Frankly, I wish my ideas were original. Unfortunately they are not. I just reiterate what is in the IUPAC green book, writen down by people who are experts in the field for people like you and me. --Kehrli 19:40, 27 September 2006 (UTC)

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