Talk:Planck units/Archive 2

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In case you haven't noticed...

Natural units no longer redirect to Planck units. i tried to get sections set out for all of the different proposed systems. I am using K.A. Tomilin: NATURAL SYSTEMS OF UNITS; To the Centenary Anniversary of the Planck System as a source as well as Michael Duff: Comment on time-variation of fundamental constants as sources in addition to including Atomic units and Geometrized units. Unlike the Duff paper, i do not want to assume at the outset that the Coulomb Force Constant is unity ${\frac {1}{4\pi \epsilon _{0}}}=1$ and i want to use symbols already in use here in WP rather than the symbols that Tomilin uses. Tomilin gave me permission, via email, to borrow liberally from his text and i plan to. i think the Stoney Units deserve their own article but i don't have the spit for it. r b-j 06:50, 30 July 2006 (UTC)

NPOV violation

Normalizing the coulomb force constant instead of, say, the elementary charge or permittivity of free space and to consequently make the relevant Planck units depend on this without majority academic support is a personal choice and thus a violation of NPOV. -- Dissident (Talk) 18:02, 3 August 2006 (UTC)

the reference cited is clearly made. historical qualification is clearly made (Planck did not define a natural unit of charge). Planck units, as they are presently used, do not normalize the elementary charge. there are plenty of other systems of natural units that normalize elementary charge. it may not be your POV, but it is the common use in the phyics community. don't believe me? take it up in sci.physics.research or check with some of the leading physicists that are wikipedians (like User:John Baez). the coulomb force constant is normalized in Planck units just as it is commonly in the cgs electrostatic units. (and probably for the same reason, which is why most hard-core academic physicists say that the fine-structure constant is $\alpha ={\frac {e^{2}}{\hbar c}}$ instead of $\alpha ={\frac {e^{2}}{\hbar c4\pi \epsilon _{0}}}$.)

personally, i wish that it was ε₀ that was normalized (as also 4πG instead of just G) so that flux and field strength was the same thing and so that Gauss's law is simplified. but that's not what they did. just because they made a sytlistic mistake in convention (in my POV) doesn't mean that i, or anyone else, gets to change the meanings of the definitions that are presently the common use. r b-j 18:32, 3 August 2006 (UTC)

Proposed change

"In fact, we have no understanding of the Big Bang before the age and size of the universe exceeded one Planck unit, and its temperature fell below one Planck unit"

Is this a better way to put that sentence? I was confused with the present tense for a while. Past tense seems better.

Alternately, "in fact, we presently have no understanding of the Big Bang before the age and size of the universe exceeded one Planck unit, and its temperature fell below one Planck unit" ... leaves the possibility open for future understanding of the Big Bang processes.

Elronxenu 11:32, 15 August 2006 (UTC)

hey, the Bogdanov brothers have already figured it out (what happened before the Big Bang, and, presumably during the Planck era). i might recommend instead: "in fact, we presently have no understanding of the Big Bang before the age and size of the universe exceeded approximately one Planck time and Planck length (respectively), and its temperature fell below approximately one Planck temperature" (the "approximately" because of the ambiguity of including some 4π or 8π factors in there or not, a possible oversight by Planck and even current physicists.) r b-j 18:52, 15 August 2006 (UTC)

Sounds good, I added the main part of that change but left out the clarification of "approximately" because I am not a cosmologist. Elronxenu 13:12, 2 September 2006 (UTC)

Dimensionless measurements

The Invariant Scaling article still bothers me. It still looks like a rough draft in which the argument is not concisely expressed. Also it still looks too partisan. For example, it defines measurement as a dimensionless ratio. I agree that measurement can have this aspect - e.g. any given length divided by a unit of length is necessarily a dimensionless ratio. However, a given length can also be interpreted as multiples of a unit length, and this is not even a ratio let alone a dimensionless ratio. The article's emphatic insistence on the former definition is a bit tendentious, I think, since it seems to justify Okun's rather extreme views (extreme even by the standards of his colleagues, if you read the cited texts). If all measurement are simply dimensionless ratios then obviously Okun is right and there are no dimensionful physical constants. Yet even Okun's colleagues argue for some dimensionful physical constants. In other words, I think the invariant scaling article doesn't need Okun and would be better off without its implicit endorsement of his views. I think this endorsement is an accidental by-product of the drafting process and that the drafting process should therefore continue. Lucretius 23:26, 27 September 2006 (UTC)

hi Ross... long time.

first, i think you meant to Michael Duff instead of Lev Okun, no? if you do mean Duff, it's not really that he's saying there are no dimensionful physical constants, it's that he's saying that the value of those constants, as we or anyone else measures them, are really an expression of the units we use to measure them and not a consequence of a meaningful physical parameter ("no operational meaning" i think are Duff's words)

second, do you agree with this line from the nondimensionalization article? :

Measuring devices are practical examples of nondimensionalization occurring in everyday life. Measuring devices are calibrated relative to some known unit. Subsequent measurements are made relative to this standard. Then, the absolute value of the measurement is recovered by scaling with respect to the standard.

(i didn't write it, so i'm not appealing to my own authority.) did you notice that John Baez was here and stated last May that "I'm pretty happy with the page as it stands. " [1] and even yesterday did an (inconsequential) edit to the very section that did not touch any of the content you are bothered by? if there was something factually wrong with the content, i think that John would have changed it. he has done content edits to Physical constant where there is a similar kind of issue going on, this time with User:Kehrli.

please take a look at the n-Category Café

then, do you disagree with this statement?: "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." that one i'll admit is mine. if we tell the aliens the size of our meter stick in terms of the Planck length and the length of our second in terms of the Planck time, then when we ask them to measure the speed of light in vacuum, could it even be possible that they could reply with a different value than 299792458 m/s? now we could communicate to them the length of our meter and second in terms of another set of natural units, such as atomic units or Stoney units, and then the answer they give will have dependence on α, but that is because α is operationally meaningful. it is conceivable that they could respond with a different numerical value for alpha.

lastly, what changes do you think should be made? r b-j 06:09, 28 September 2006 (UTC)

Hi RBJ.

Yes, there has been a mix up of names. By Okun I meant Duff. By Ross I think you mean me, Lucretius.

but i think your real name is Ross, no?

Anyhow, to the point:

Firstly, DUFF does take a radical view - in the cited text by the 3 authors, his contribution is titled 'A party political broadcast on behalf of the zero constants party'. The title is tongue-in-cheek but the content is seriously meant and he is talking about zero dimensionful constants, which is radical even by the standards of his 2 colleagues. His radical view follows naturally from a very exclusive definition of measurement as a dimensionless ratio, a view that the article endorses with such statements as 'The only quantities that we ultimately measure in physical experiments or in our perception of reality are dimensionless numbers'. This is an extreme statement and it implies that we ultimately live in a dimensionless universe of numbers. Duff's colleagues on the other hand believe there are some dimensionful constants, a view that follows naturally from a broader interpretation of measurement to include both dimensionless ratios and multiples of dimensionful units. Their view is plain common sense.

As for how I think the article should be written - I think you should aim for greater economy of expression. The introductory paragraph is long-winded and repetitive, as is the body of the text. The final paragraph is a conspicuous example of illucidity (I seem to remember that someone other than you wrote that one). I think the quote from Barrow is good but I don't think the article needs references to Duff et al, especially as there are other authors who express the case more simply and effectively. I would rewrite it myself but I have already made a firm commitment not to edit it again and I intend to stick by that.

Regarding the aliens from Zog, I wish them well. I'm sure if we could communicate with them in English or in Zoggian we could also manage to translate our units into theirs and vice versa without necessarily resorting to dimensionless ratios, assuming of course they do have units rather than just numbers at their command.

and this, my dear Lucretius is mistaken. we must have some common reference. perhaps it could be the Bohr radius, perhaps the reciprocal of the Rydberg constant (both are lengths), but in any case, those are candidates for a natural unit of length. same for time. nonetheless, if we communicate to them how long our meter stick is and how much time our second is, depending on the system of natural units we would have to use as a common reference, either they will have to measure the speed of light to be exactly 299792458 m/s as we do (that would happen if we defined the meter and second in terms of the Planck length and Planck time) or, if it came out differently, some dimensionless constant (most likely α) is different for them than for us. this is fundamental. the Zogians will measure the speed of light to be 1 Planck length per Planck time just as we do. to translate that to 299792458 m/s is just a matter of scaling. r b-j 23:05, 28 September 2006 (UTC)

Regarding Baez, I'm surprised to learn that he has been here but I am even more surprised that he should endorse the article. As far as I can recall, he aims for lucidity and simplicity in his own writing, a style that comes easily when you really know your stuff. Amateurs like you and me inevitably struggle to get our ideas across but I don't think we are struggling hard enough in the Invariant Scaling article. Maybe we don't know enough. If Baez made a small change to the article, maybe he was itching to make bigger changes.

i dunno, let's ask him. i imagine he's eventually watching this.

Anyhow, it's good to debate with you again and I'm glad you continue to patrol the Planck page. You're a bit like a trout patrolling a stream. I knew I'd get a bite if I dangled my line in it. Cheers. Lucretius 124.177.136.198 11:23, 28 September 2006 (UTC)

it depends on how much time i have at the particular moment. i might not have bitten for a few days.

anyway, i fully admit that the "paraphasing" or expansion or language of explanation in that section is mostly mine (but, being an encyclopedia, i thought elucidation is appropriate as long as non-factual stuff stays out), but the main concept, that it's only the dimensionless physical constants that are truly parameters of meaning defining the nature of the universe, is actually pretty uncontroversial in the physics community which is why Duff responded pretty harshly to the VSL claims made by Moffat, Davis, Davies, etc. it's a little like the current unverifiability of string theory, if the speed of light was different, how would an experiment measure or verify such a change? howver, we know how a difference in α would be noticed and if α changed sufficiently, we know life would be a helluva lot different. i realize that you think this is r b-j POV, but what i am really trying to do is to reflect the POV of the credentialed physics community (but with a paraphrase of mine that anyone else could have written). in a sense, it is virtually a tautology, i think it is nearly that uncontroversial. r b-j 14:00, 28 September 2006 (UTC)

Hello again, RBJ. I wish you wouldn't insert your replies into my text as this makes it difficult for me to get an overview of your argument. In fact I only discovered some of your replies by accident while reviewing one of my own arguments, and that was after I had already started my reply to your argument. Also your replies seem very hurried and that doesn't help with clarity. You should take more time to answer otherwise I won't get the benefit of your knowledge. Now for my reply to your interspersed replies:

I know you are trying to represent the POV of 'the credentialed physics community' but the particular slant that Duff has on that POV is hardly mainstream. I agree that 'only the dimensionless physical constants are truly parameters of meaning', but this POV does not require us to believe that all measurements are ultimately dimensionless ratios. The debate between Duff, Okun and Veneziano would be impossible if they all thought that measurements are ultimately dimensionless ratios - they are debating about the merits of different dimensionful constants. In fact their debate amounts to an argument about which dimensions have real physical significance and which are merely human constructs or abstractions. For example, we could argue that the dimension of force is a mere abstraction derived from the real dimensions of mass, space and time, and then we could argue that mass is an abstraction derived from energy, space and time. And so on, until we finally select the dimensions we think are physically real. That selection in turn decides our choice of dimensionful physical constants. But if all measurements are ultimately dimensionless ratios, then all our dimensions are ultimately abstractions and we live in a universe that is profoundly mysterious. There is some validity in such an argument but it has more to do with philosophy than science - Socrates and Duff might be comfortable with it but Okun and Newton would not, nor would the great majority of humankind.

If the article is to represent the POV of the scientific mainstream then it needs rewriting. In particular, you shouldn't overstate the dimensionless nature of measurements, particularly since this is not essential to the argument.

One more thing - how could the Zoggian fine structure constant be different to ours? Wouldn't that mean they live in a different universe, with atoms that function differently to ours? I think an interview with a Zoggian would go something like this:

"Greetings, Earthling!" "What the hell are you? And what do you want?" "I am from the planet Zogg and I want to learn how you measure things" "OK, this is a meter and that clock there tells the time in seconds. The speed of light is 3x10^8 meters per second." "Ah! Our unit of length is the Zogg, which is about half one of your meters. Our unit of time is the Ogg, which is a third of one of your seconds. The speed of light is 2x10^8 Zoggs per Ogg. But nowadays we include temperature in the measurement. The thermal speed of light in a vacuum is 8 500 Zoggs per Ogg Nord, or 1 Arbeejay. Arbeejays have real physical significance, but Zoggs, Oggs and Nords are mere abstractions. How do you measure temperature?" And so on. I'm not convinced that natural units like Plank units would be necessary for a meaningful exchange. In fact, how would you show a Planck length to a Zoggian unless he happened to be very tiny? Wouldn't you first have to use larger units of length such as the meter and then introduce him to the Planck length? But maybe you know more about this than I do. Lucretius 02:21, 29 September 2006 (UTC)

okay, L, this is a little humorous, but it misses the point. if the Zogs were to come here, we could show them a meter stick and have a common reference for length. but the axiom is taht the Zogs are "over there" and we are over here and all we can do is communicate qualitative notions and numerical information. so how do we communicate how long or big or massive or old something is (like a meter or a second)? if we use Planck units then we are already defining that their speed of light is meaningfully the same as ours. we cannot ask them to measure it in terms of these common units and expect an informative answer because they will, by definition, get the same value we do. so a varying c has no meaning. but this is not true about α. we could meaningfully inquire if it is the same for them as for us and if it is different, something is different for them. if α is significantly different, yes, atoms would no longer exist and neither would the Zogs. but if it is less (or slightly) different, we know that it's different and their existance is different. r b-j 03:17, 29 September 2006 (UTC)

sorry, but i'm interspersing comments. i'm pressed for time.

Thanks RBJ - your reply here is more carefully phrased than the other ones. But as far as I can tell you still haven't answered the question. Assuming you can only talk to the Zoggians by radio, how would you explain to them what values you assign to Planck units?

by use of the very expressions in the article, $l_{P}={\sqrt {\frac {\hbar G}{c^{3}}}}$, $m_{P}={\sqrt {\frac {\hbar c}{G}}}$, $t_{P}={\frac {l_{P}}{c}}={\sqrt {\frac {\hbar G}{c^{5}}}}$, $q_{P}={\sqrt {\hbar c4\pi \epsilon _{0}}}$. if they're smart enough to communicate with us, they will already be thinking about the same universal units. there are issues of$4\pi \$ that would have to be settled (i think that it should be $\epsilon _{0}\$ and $4\pi G\$ that is naturally normalized to one and i would bet the Zogs would too. but that's a different issue and, even with this difference, it puts us in the same ballpark.

Apparently you can't explain the Planck length in terms of the Bohr radius since their atoms might be different to ours.

no, you do it the other way around. that's how we ask them how life may be different for them than for us.

So what is the unit of length that would allow you to define Planck length accurately? You can't send them an equation for Planck length since it would include dimensionful quantities you haven't explained to them.

no, they have a concept of gravitation, of wave mechanics, of relativity and E&M. it's just that we cannot ask them to measure the speed of light using these common concepts and units of length, mass, time, and electric charge and expect a different answer than we have. even if, somehow conceptually $c\$ is different for them than for us, it makes no operational difference and there is no way that this could be communicated one way the other. but if $\alpha \$ is different for them than for us, that is operationally meanigful and that fact can be communicated.

It seems to me that the science of Zogg must be forever out of our reach until you can overcome this objection. Lucretius 07:05, 29 September 2006 (UTC)

i really don't know what you mean about that, but L, i am not sure you do either. r b-j 14:14, 29 September 2006 (UTC)

OK RBJ, this is disappointing. You are making some very big assumptions here. For instance, some of the equations you sent the Zoggians assume they know what you mean by the gravitational constant G. But you would first need to supply them with Planck values for them to work out the value of G. The fact is that you are inevitably caught in a circular argument. In order to communicate Planck quantities to the Zoggians, you must employ other quantities that they already understand. Atomic units would be ideal except you have already ruled those out on the grounds that their atoms might be different to ours. If their atoms are different then everything is different and we do not share any quantities that we can translate into Planck quantities.

Of course this whole aliens business is simply a recycling of an argument initiated by Planck himself. As far as I recall, he said "These are units even aliens would understand." If the aliens already understand these units, we can use them to explain our other units. But if the aliens don't yet understand Planck units, those units need to be translated via other units. In that case, what Planck should have said is this - "These are units that even aliens would understand, provided we first explained them in terms of other units that are common to them and us." Of course he didn't say this because it would make those other units seem universal.

I think your tendency to jump in with hurried replies is the problem here. In fact, I suspect you insert your replies even before you have read my whole argument. Or maybe you are reading with spectacles that are fogged up with impatient assumptions. Either way, you are not developing a coherent debate here. I'll be gracious and assume that you really are pressed for time. In that case, please reply only when you do have time. Lucretius 22:41, 29 September 2006 (UTC)

well, what you're bringing up is an entirely different issue. the premise of all of this (even from Planck's assertion that an E.T. could be expected to use the same units) is that we are able to communicate qualitative notions and facts (so we both have a comparable knowledge of nature) and numerical information. they understand gravity about the same as we do, we both know what 13 means (00001101 in binary), we can even communicate fractional numbers (as rationals or ratios of integers, if necessary).

but even if we could communicate this information and have a comparable understanding of physical theory, how could we describe to them how big/tall humans are, how big the planet Earth is, how fast it spins, how far we are from the Sun, how big the Sun is, how much radiant output the Sun has (or the solar radiant intensity at our distance)? we can't do it in terms of meters, kilograms, and seconds. they would have no point of common reference, not until we do it in terms of some chosen set of natural units. we could mutually agree on a set of natural units that use properties of some particles or simple atoms (like the hydrogen atom) as a common reference (such as atomic units), but if we do that, it would be silly to ask them how big the Bohr radius is because, by definition of our common reference, it would be the same for them as for us. but, given atomic units, we could meaningfully ask them what their speed of light is and if it is different than our speed of light, we know that α is different for them than for us and that is the salient difference.

but if we agreed to use Planck units instead, it would be meaningless to ask them what the speed of light is, but meaningful to ask what the electron mass (in terms of the Planck mass) and the Bohr radius (in terms of the Planck length) are. if m_e/m_P comes out to be the same number we have, but a₀/l_P comes out different, we will again know that their α is different. or vise-versa. if a₀/l_P comes out to be the same number we have, but m_e/m_P comes out different, we will again know that their α is different. α is the important quanity. whether we use atomic units and measure that c is different or use Planck units and measure that m_e or a₀ is different is not important. nature doesn't give a rat's ass. the salient difference is that they measure α to be different than us and for that reason, we know that life is different for them than for us. (or if α is the same number, we might think that the physical law for them is the same for us.) r b-j 23:14, 29 September 2006 (UTC)

Thanks RBJ. I don't disagree with this (I speak as an Earthling). In fact it has been our common assumption all along. You went off the rails earlier when we were talking about how to introduce Planck units to Zog and you brought up a varying fine structure constant - that condition made the whole task of communicating with Zog impossible since it deprived us of a set of units common to both Zog and Earth. However, my point all along has been that Zog might not know Planck units and yet could still be more scientifically advanced than we are. They could have developed a set of dimensions that unite all the fundamental forces without any reference to gravity or even electromagnetism. In short, it's a bit arrogant to assume that planck units are God's units. God could be a Zoggian. I would like to learn from Zogg, which is why I was really traumatized when you stuffed up the fine structure constant. It ruined my chances of finding out the truth. Now we have reached a happy ending but...a new thought has just popped into my head. What if the fine structure constant isn't embedded in the Zoggian dimensions? What then? We're stuffed in that case.

But to return to the original point of this debate - you need to rewrite the Invariant Scaling article. It's clumsily expressed, it overstates the non-dimensionality of measurements, it gives implicit support to Duff's extreme views. Measurements can be dimensionful without compromising invariance. Lucretius 05:09, 30 September 2006 (UTC)

okay, returnig to the original issue that you brought up - you believe that "[I] need to rewrite the Invariant Scaling [section]". this is an opinion that you have and have every right to have. two observations: i am not sure how many others share that belief. indeed, a credible physicist (Baez) said it looked okay to him and edited a minor part of that very section very recently. he's not complaining.

secondly, you attempted to bring up physical justifications to support your objection to it, but that hasn't succeeded either. i actually feel you were making red herring arguments. using the scenario of the Zoggians (which is not used in the article, nor should it be), of course there are problems (the speed of communication can't exceed that of light, having a common basis for communicating any concept or basic fact is problematic, i'm sure there are people a lot smarter than either of us thinking about how that might be done). but if we were able to communicate with the Zogs qualitative fact and numerical information (like if they spoke English and we could just simply talk with them and even show them things with a "PicturePhone") but they are over there and we are over here, we still need to identify some common points of reference to communicate physical quantity to them. now if, somehow, c or G or some other dimensionful physical constant was "different" for them than for us, there is no way for us to know that and communicate that to each other. but if α is different, that would count! we (and they) would know it.

this issue does not need Planck units to illustrate (and the Barrow quote does not use Planck units) and has found its way into VSL and Physical constants, but Planck units is useful for illustrating it and has been used which is one good reason Planck units is a concept to pay attention to. what is in the section you object to is an interpretation of that use of Planck units that is IMO and, i believe, other's opinion, faithful to the basic concept and is illustrative of it even if it uses an illustrative vehicle such as a hypothetical "god-like being" that somehow could sense the difference between different speeds of light. whether it's a "god-like being" or aliens on the planet Zog, the point is the same, in the final analysis humans or other non-supernatural physical things cannot measure or perceive anything but dimensionless quantities and it's only the dimensionless quantities that ultimately matter. if you think or measured that some dimesionful quantity has changed, that change can be traced back to a more fundamental dimensionless quantity changing. i know that Gabriele Veneziano agrees with Michael Duff on this one, and i think even Lev Okun (their disagreement is more esoteric). from other writings, i believe that John Baez, Frank Wilczek, and John D. Barrow do also. r b-j 19:55, 30 September 2006 (UTC)

Thanks RBJ. You've taken some care with this reply and I appreciate it. I diasgree with only a few things. You say the Zoggian stuff was a red herring. No, it was expanding the argument so as to further explore the issue of dimensions - do they have real physical significance or are they just abstractions. This is a big issue in the article - there it is a red herring because it has nothing to do with invariance. It became an issue in the article because of your reliance on an inappropriate reference - the debate between Okun, Veneziano and Duff. Worse still, the article slants the interpretation of measurements towards the Duff position. His argument that there are no dimensionful physical constants is completely supported by your argument that measurements are ultimately dimensionless. Not only is this basically irrelevant to the article topic but it is also, in my opinion, anti-science in its implications. A universe whose physical dimensions are mere abstractions is a universe better studied in a monastry than in a laboratory. Of course the article is so badly written that the world will never be influenced by it, but I still think you should be making an effort to tidy it up.

Anyhow, this has been my final attempt to get some changes made. Thanks for your willingness to debate the matter but I would rather you showed some willingness to change the article. Lucretius 23:25, 30 September 2006 (UTC)

Duff ain't saying "that there are no dimensionful physical constants", he is saying that the dimensionful physical constants ain't "fundamental", whatever that means (and Okun disagrees, i think). i think i understand what is meant. a fundamental physical constant is one that ultimately means something. the term i used in another argument is that it is a parameter of meaning in defining the nature of physics in the universe. the last count John Baez has is that there are about 26 of them and h, c, G, ε₀, or e ain't on the list (but there is a combination of 4 of those that is on the list). not only Duff and Baez say this, but John D. Barrow, Frank Wilczek and a bunch of other physicists you'll see on sci.physics.research that don't have Wikipedia articles about them also say this.

also, the article is not about whether or not time, length, mass, and charge are fundamentally different dimensions of physical stuff, it assumes they are as did Planck in deriving the Planck units. whether or not dimension of physical quantity is real or just an abstraction humans came up with to describe different quantities of stuff we come across is still not the purpose of the article, but i think it assumes that it is real. Still doesn't matter. we perceive time as a different thing than length (or spatial displacement). and we perceive mass as something else that is different than either time or length. whether it really is different or just that humans perceive it as different doesn't matter. the fact that we at least perceive this stuff as different means that we measure properties of free space, h, c, G, in terms of anthropometric units of this stuff and from these properties, define natural units of this stuff we call time, length, and mass that normalize those constants. that, in effect, defines a natural means of scaling time, length, and mass and as long as the size of stuff doesn't change relative to that scaling, nothing we know is different no matter what might have conceivably happened to h, c, or G. that's all that section is about. r b-j 05:06, 1 October 2006 (UTC)

Again thanks RBJ. Let me quote Duff, beginning at the bottom of page 22 of the relevant text:

"In the natural units favoured by the Zero Constants Party, there are no dimensions at all and hbar=c=G=1 may be imposed literally and without contradiction. With this understanding, I will still refer to constants which have dimensions in some units such as hbar,c and G as 'dimensionful constants' so as to destinguish them from constants such as a, which are dimensionless in any units."

I think maybe you were confused by Duff's references to 'dimensionful constants' - it looks superficially as if he accepts they are dimensionful - but as the quote shows he regards these as actually non-dimensional. Moreover, he says clearly there are no dimensions at all. The Invariant scaling article endorses this radical view by saying that all measurements are ultimately non-dimensional. I'm sorry RBJ but I can't put it more clearly than this and I don't want to keep repeating myself. If you still don't get the point then I must conclude that you will never get it. Invariance does not require us to accept Duff's particular point of view and the article should be phrased more moderately to take account of the opinions of all those (the majority) who believe that there are at least some dimensions and that at least some measurements are truly dimensionful.Lucretius 08:47, 1 October 2006 (UTC)

L, i am not confused. this quote is on p. 31 on my copy. try quoting the whole paragraph, and then tell me what it is that Duff is saying and contrasting to Okun. (it is literally what is done in the nondimensionalization section of the article. are you objecting to that also?)

L, i know you think you know of what you write, and before, despite the rigorous physics training an elementary school teacher gets in Australia, i thought so too, but am not so sure now. (it's not that in engineering we get this kind of deep physics, but we are taught the meaning of units, dimension of physical quantity, conversion factors, etc. i don't have time to deal with every misunderstanding you might have of what Duffs. r b-j 15:26, 1 October 2006 (UTC)

Dimensionless measurements 2

let's start a new section. i'm at home and using my system 9.1 Mac and i can't get Firefox for that version and IE (which sucks) limits my edit box to 32K. r b-j 15:30, 1 October 2006 (UTC)

We must both have rocks in our heads RBJ - you because you aren't thinking and myself because I'm still prepared to debate with you. I'll keep digging for a little longer in the hope that you are still breathing and that I can get you out from under all those rocks before you die. But I'm running out of hope.

I'll quote Okun, page 6.

"In such natural units all physical quantities and variables become dimensionless. In practice the use of these units is realized by putting c=1 hbar=1 G=1 in all formulas. However, one should not take these equalties too literally, because their left hand sides are dimensionful, while their right hand sides are dimensionless."

I hope you got past the first sentence. If you did, you'll see that Okun regards the non-dimensional equations as a mathematical fantasy that mustn't be taken literally. Duff on the other hand regards dimensions as a fantasy and he thinks the equations should be taken literally. Both Okun and Duff employ non-dimensional units but with very different interpretations. Okun's interpretation wouldn't shock anybody. Duff's interpretation is profoundly shocking (to most people, I believe). Just compare the two quotes I have given you and you should feel the load of rocks begin to lighten.

I have an image of you as a practical man and it is therefore difficult for me to believe that you would side with Duff rather than with someone like Okun. But, as I have said all along, their debate is actually irrelevant to the Invariant Scaling article, and the text shouldn't be referenced. You certainly shouldn't endorse Duff's views with statements about the non-dimensional nature of measurement. And you need to reword the article to make it clearer. Using as few words as possible is a good rule of thumb for the development of a lucid style.

Have you seen the light yet? Or is it too late?

I'll add this also, RBJ, as it might save time. Here is a quote from the Invariant Scaling article:

"the only quantities that we ultimately measure in physical experiments or in our perception of reality are dimensionless numbers. When one commonly measures a length with a ruler or tape-measure, that person is actually counting tick marks on a given standard or is measuring the length relative to that given standard, which is a dimensionless value. It is no different for physical experiments, as all physical quantities are measured relative to some other like dimensioned values".

Duff would subscribe to this passage, Okun and Veneziano would not. Duff thinks measurements are dimensionless ratios, the other two argue that measurements can be interpreted in that way but that they are ultimately dimensionful. Theirs is a subtle debate of profound significance. Your article simply bumbles into that debate like a bull trespassing on a minefield. Either you must add a disclaimer on behalf of Veneziano and Okun or, more simply, you remove any reference to their debate. Their debate isn't really relevant to the article as all three men subscribe to invariance. Lucretius 01:22, 2 October 2006 (UTC)\

you didn't quote the entire paragraph from the paper that i suggested. i was asking you to quote to whole thing (rather than just that one statement of Duffs that you don't like) and then tell us what you think it means. (i'll give you a hint: it means essentially what those five equations were that you insisted were worthless and deleted from the Planck units article.) you do that, and i'll tell you what Duff meant by saying in one sentence that "there are no dimensions at all" and in the next: "With this understanding, I will still refer to constants which have dimensions in some units such as ħ, c, and G as 'dimensionful constants' so as to distinguish them from constants such as α, which are dimensionless in any units." it's not complicated.

i have another suggestion, L: it's not just Duff. it's Baez, Barrow, Wilczek, and even Veneziano ("I also agree with Mike [Duff] that all that matters are pure numbers." - the disagreement he has with Duff is about what pure numbers are important). why don't you go to the newsgroup sci.physics.research or to the n-Catefory Cafe blog or another related thread? see what those guys tell you. there is debate about what parameters are important. there is virtually no debate that the net result of any physical measurement is dimensionless. the stuff you object to is essentially a tautology. tautologies don't say much but the trouble with disputing them is that one has to refute the entire premise. if one accepts the premise and disputes the "result" of a tautology, that person contridicts themself. that's why i have trouble understanding why any of this is controversial to anyone who actually understands the concepts.

i think i suggested that to you before. take your problem up with them. they'll set you straight. r b-j 03:48, 2 October 2006 (UTC)

This reply does not surprise me.

I deleted the 5 equations because they derived fundamental constants from Planck units. Planck units had already been derived from fundamental constants and I thought reversing the process was simply trivial. But if you want to restore those 5 equations by all means go ahead! Let them stand forever as a monument to your unique love of tautologies. There are more tautologies in the Invariant Scaling article than there are in all the psalms of The Old Testament.

Regarding the part of Duff's paragraph that I am supposed to have suppressed, I don't see the point you are getting at. It's simply a restatement of c=1.

Regarding Veneziano, I notice that he says the difference between him and the other 2 might simply be a difference in words. Words are important. Definitions are made from words and conclusions are often buried in definitions. My whole argument has been based on a scrupulous analysis of the words in your article and how they relate to the debate between Duff et al. Either you are incapable of understanding or unwilling to understand my concerns. You certainly haven't said anything to make me think that my concerns are unnecessary.

Finally, this argument clearly isn't going anywhere and we'll just have to agree to disagree. Cheers Lucretius 05:42, 2 October 2006 (UTC)

I forget to add one last thing, RBJ. Tautology is not a valid form of logical argument.

similarly to one of criticisms of the weak anthropic principle:

... which has been criticized, by its supporters as well as its critics, for being a tautology, stating something not readily obvious yet trivially true. The weak anthropic principle implies that our ability to ponder cosmology at all is contingent on all fundamental physical parameters having numerical values falling within quite a narrow range. Critics reply that this is simply tautological reasoning, an elaborate way of saying "if things were different, they would be different". If this is granted, the WAP becomes a truism saying nothing and explaining nothing, because in order for us to be here to ponder the universe, that universe has to be structured so that we can exist. Peter Schaefer denies that labelling the WAP a truism invalidates it, on the grounds that one cannot refute a statement merely by saying that it is true.

it depends on what you do with a tautology, L.

I'll show you how it caused your article to go off the rails.

yeah, right.

Quoting from your article:

"if all physical quantities (masses and other properties of particles) were expressed in terms of Planck units, those quantities would be dimensionless numbers (mass divided by the Planck mass, length divided by the Planck length, etc.)..."

So far so good. These quantities are dimensionless numbers because you have defined them as dimensionless ratios. But then, by way of tautology, you make these invalid transitions:

"and the only quantities that we ultimately measure in physical experiments or in our perception of reality are dimensionless numbers. When one commonly measures a length with a ruler or tape-measure, that person is actually counting tick marks on a given standard or is measuring the length relative to that given standard, which is a dimensionless value. It is no different for physical experiments, as all physical quantities are measured relative to some other like dimensioned values".

that was not extending the first statement into the second. i was not using the first statement (that you don't object to) as a rationale or justification for the second. they both are true on their own merits. (but i was using both to make the case that you are objecting to.)

These statements are wrong - when one "commonly' measures a length, and when scientists make scientific measurements, the measurements are in fact dimensionful.

that is a statement of ignorance. you name a single physical measuring device, even one as simple as our own biological human senses in which the net result of the measurement is dimesionful. as an engineer who has on multiple occuraces dealt with measuring devices (essentially that is what an analog-to-digital converter is), i, as well as any other engineer and physical scientist, know better.

again, would you like to take this belief of yours to Talk:Nondimensionalization? where the article says:

Measuring devices are practical examples of nondimensionalization occurring in everyday life. Measuring devices are calibrated relative to some known unit. Subsequent measurements are made relative to this standard. Then, the absolute value of the measurement is recovered by scaling with respect to the standard.

i didn't write that. would you like to take this on at that article?

But you seem to think these statements follow logically from the initial statement. That's where tautology gets you. Tautology is a rhetorical device, suitable for poetry but bad news for rational argument.

labeling something as true doesn't invalidate it, L.

I know this subtlety won't register with you but I figured it needed to be said. And that really is my final shot across the bow. Cheers. Lucretius 08:30, 2 October 2006 (UTC)

you need to ask yourself: why is it that the physicists haven't come over to Planck units and change that section? why is it that primary school teachers (or at least one primary school teacher with a commendable philosophical interest is this stuff) object, but the physicists seem to leave that section alone (a few mods, but they didn't delete it nor object to it here at the talk page)? why haven't you taken the physical insight that is the basis of your objection to either of those blogs or to the moderated newsgroup sci.physics.research? why haven't you done what i asked and quoted the entire paragraph of that Duff quote and tell us what that quote and its context mean? r b-j 16:10, 2 October 2006 (UTC)

Dimensionless measurements 3

Hi RBJ. I regret my bad manners in the previous section. Good manners are the clothes of good arguments and my arguments deserved better than that.

don't sweat it. -- r b-j

Adressing some of the issues you raised at the end, I've gone to a lot of trouble to quote the whole paragraph by Duff, just as you asked. In return, I would ask you not to keep inserting your replies into my text, a habit of yours that looks like an attempt to demolish an argument physically. If you can demolish my arguments through the force of your own arguments, well and good.

oooops. it's just that you make so many different points, each that deserves a response in it's own right. -- r b-j

Before I quote Duff, I'll answer another point you raised. You said that my objection to Invariant Scaling is based on a 'physical insight', as if it is my personal POV I am putting forward. My argument all along has been that the article does not represent the POV of the scientific establishment. Your article insists that all measurements are ultimately dimensionless and I say this is not the POV of the scientific establishment. It is instead Duff's POV in his debate with Veneziano and Okun. Your article references their debate and then endorses Duff's POV. The article is supposed to be about Invariant Scaling, which in fact does not require us to believe that all measurements are ultimately dimensionless. The reference to their debate is inappropriate and either you should remove it or you should at least include a broader definition of measurement to take account of the establishment POV, which is that measurements ultimately have a dimensional significance that cannot be ignored even when we argue mathematically c=1 or G=1 etc. Different people in the scientific establishment have different ideas about which dimensions are really significant, but almost nobody agrees with Duff that there are no dimensions at all.

Here is the paragraph from Duff:

"Incidentally Lev [Okun] objects that equations such as c=1 cannot be taken literally because c has dimensions. In my view this apparent contradiction arises from trying to use two different sets of measurement at the same time, and really goes to the heart of my disagreement with Lev about what is real physics and what is mere convention. In the units favoured by the members of the Three Constants Party [Okun] length and time have dimensions and you cannot therefore put c=1 (just as you cannot put k=1 if you want to follow the conventions of the Seven Constants Party [ SI ]). If you want to put c=1, you must trade in your membership card for that of (or at least adopt the habits of) the Two Constants Party [Veneziano], whose favourite units do not distinguish length from time. In these units, c is dimensionless and you may quite literally set c equal to 1.In the natural units favoured by the Zero Constants Party [Duff], there are no dimensions at all and ħ=c=G=...=1 may be imposed literally and without contradiction. With this understanding, I will still refer to constants which have dimensions in some units such as ħ,c ,G,k... as 'dimensionful constants' so as to destinguish them from constants such as α, which are dimensionless in any units."

As you see, there are a lot of different parties within the scientific establishment and they do not all argue that measurements are ultimately dimensionless. Thus length for instance can be understood as multiples of the Planck length and it retains dimensional significance for some theorists. For others, length is a ratio of some given length to Planck length and it is in fact dimensionless. The argument between Duff et al is really an argument about which dimensions are real in a universe measured in natural units, and which are not. For Duff, there are no dimensions at all and for him all measurements are ultimately dimensionless. Your article adopts this idiosyncratic POV as if it were the POV of the scientific mainstream. Lucretius 01:33, 4 October 2006 (UTC)

well, the argument, as i read the paper, is not about which dimensions of physical stuff are real and which are not, but more about which physical constants are fundamental and which are not. i certainly do not believe from reading it, that Veneziano disagrees with Duff about the fundamentally dimensionless nature of measurement (or perception) of physical quantity:

"I also agree with Mike [Duff] that all that matters are pure numbers."

by "pure numbers", i am quite certain that Veneziano means dimensionless physical quantity. i do not know if Okun agrees with that statement verbatim. he might not. assuming he does not, then Okun is saying that dimensionful physical constants like c and G are fundamental physical constants in the sense that they are parameters of meaning and physical theory, particularly, a theory of everything can hope to someday explain why those constant physical quantities are equal to the value that they are. if that is the case, it is not the POV of the physics mainstream in modern times.

the POV of the physics mainstream is that there are about 26 known dimensionless physical constants (most are about the Standard model) that are parameters of meaning whose values make a difference in how the universe and physical reality exist. not only do Michael Duff (and Gabriele Veneziano) take that position, but so does John D. Barrow, Frank Wilczek, John Baez (who have made public statements in print and/or online about it) and virtually every physicist who has commented about it on sci.physics.research and various blogs (two very recent blogs i have cited). whenever a cosmologist (Moffat, Davies, Davis, Magueijo) makes a VSL claim, the New York Times likes to feature them with an article, but the mainstream physics community either yawns or dismisses it, or people like Duff go after these guys with the persistant question: "How are you measuring this? How does it make any difference or have operational meaning?" i don't think you are representing the mainstream physics community accurately.

now, when i read that paragraph, where Duff says in one sentence that "In the natural units favoured by the Zero Constants Party [Duff], there are no dimensions at all and ħ=c=G=...=1 may be imposed literally and without contradiction" and in the next sentence "With this understanding, I will still refer to constants which have dimensions in some units such as ħ,c ,G,k... as 'dimensionful constants' so as to destinguish them from constants such as α, which are dimensionless in any units", i don't think i would come to the same conclusion of meaning as you apparently have. i'm pretty sure that Duff considers c as measured in units that are convenient to humans as a dimensionful physical quantity. indeed he says he does. what Duff is saying is essentially this:

now you, Lucretius, removed (and i didn't bother to fight it) 5 equations that you said were "pointless". the point they had was, for example:

$F={\frac {1}{4\pi \epsilon _{0}}}{\frac {q_{1}q_{2}}{r^{2}}}$

with the "pointless" $\epsilon _{0}={\frac {q_{P}^{2}t_{P}^{2}}{4\pi m_{P}l_{P}^{3}}}$

means that

$F={\frac {m_{P}l_{P}^{3}}{q_{P}^{2}t_{P}^{2}}}{\frac {q_{1}q_{2}}{r^{2}}}$

$F={\frac {F_{P}l_{P}^{2}}{q_{P}^{2}}}{\frac {q_{1}q_{2}}{r^{2}}}$

and eventually $F/F_{P}={\frac {(q_{1}/q_{P})(q_{2}/q_{P})}{(r/l_{P})^{2}}}$

now this last equation is equivalently true, in any unit system, as the first one. but, of course, every fractional quantity shown is dimensionless, it is a ratio of a physical quantity expressed in whatever units to the Planck unit of the same dimension espressed in the same unit system. but the ratio is most certainly dimensionless. in that equation, we are expressing force, in terms of the Planck force, as a function of electric charge, in terms of the Planck charge and distance, in terms of the Planck length. that's what those ratios are. but F is still force in SI or cgs or whatever consistent units you care to dream up. same with q₁, q₂, and r. they are exactly the same F, q₁, q₂, and r as in the first equation.

but, in mathematics, we have this ability to do symbol substitution, and in this case, doing this is precisely what nondimensionalization is. we have every right to substitute: $F\leftarrow F/F_{P}\$, $\ q_{1}\leftarrow q_{1}/q_{P}\$, $\ q_{2}\leftarrow q_{2}/q_{P}\$, and $r\leftarrow r/l_{P}\$. no one can tell us we can't do that, and indeed physical reality doesn't give a rat's ass (Duff would substitute "fig" for "rat's ass").

so now we have: $F={\frac {q_{1}q_{2}}{r^{2}}}$

but this expression of physical reality is every bit as valid as the original equation up top. and this expression of physical reality has absolutely no reference to any human convention and it has no reference to what some would call a "fundamental" physical constant called the permittivity of free space. there is no permittivity of free space, it's not there. if God had a knob labelled $\epsilon _{0}\$ and twisted it, the statement of physical reality would not change. you can do the same song-and-dance with $G\$, $c\$, and $\hbar \$, but you can't do that to $\alpha \$. even when you nondimensionalize, $\alpha \$ remains in the equations of physical law and if God twists the knob labelled $\alpha \$, things would be different. if you wanted to, you could leave out one of those, say $\hbar \$, and substitute the elementary charge $e\$ and say the same thing. so whether it's $c\$ or $\hbar \$ or $e\$ or $\epsilon _{0}\$ that is left out of the list (and then appears to be changing when $\alpha \$ is changed), it doesn't matter it doesn't make any difference to how physical reality would be different. whether it's $c\$ or $\hbar \$ or $e\$ or $\epsilon _{0}\$ that is changing when $\alpha \$ changes is only a matter of how you chose your units to measure things and, as Duff would say, nature doesn't give a fig what units you choose. the salient parameter that changed is $\alpha \$ or something directly proportional to it.

now, if you say that this is Duff's spin on things, i might agree with you. but if you say that it isn't the mainstream position of the physics community, then you are mistaken. not only is it the mainstream position of physicists, it is a tautology. you have to dispute the very premise:

$F={\frac {1}{4\pi \epsilon _{0}}}{\frac {q_{1}q_{2}}{r^{2}}}$

or the very definitions of $l_{P}\$, $m_{P}\$, $t_{P}\$, or $q_{P}\$ (or the "derived units") in terms of $c\$, $G\$, $\hbar \$, and $\epsilon _{0}\$. if you accept the premise (the physical law expressed with dimensional constants) and the definitions of the Planck units in terms of those physical constants, and yet dispute that invariance, you contradict yourself. tautologies don't say much, they are a "vacuous truth" but a truth nonetheless (like the weak anthropic principle), but to dispute such a tautology (while accepting the premise of it) is logically fatal.

that is my spin on what Duff (and other physicists) are saying and i am not alone (despite the fact that no one has jumped into this on either of our sides). you're asserting that this is not mainstream. that's wrong. it's the contrary (VSL, etc.) that is not mainstream. you say that the mainstream scientific community believes that the net result of physical measurements is dimensionful; that's wrong (at least regarding the mainstream physical science community, i dunno what the psychologists and social scientists would say). we physical scientists (and i, as an electrical engineer, count myself as a physical scientist) who know the nature of physical instruments and metrology, also knwo that the net "raw" result of any physical measurement is a dimensionless quantity that represents the ratio of the measured quantity to a like-dimensioned standard that is a function of how the instrument was constructed. that standard might not be a single unit of that quantity, but, by virtue of its design, is a known multiple of such a unit and that known multiple is simply reflected in the scaling of the "tick marks" of the "meter" (or the equivalent in a digital readout). then when we attach the dimensionless "reading" of the instrument to the unit we are interpreting that readout with a dimensional concept. we say "that distance is 4.8 centimeters", but we counted 4.8 on the centimeter scale.

L, i don't think you're gonna win this. either on the merits of the physics or on the acceptance of whatever mainstream scientific community either of us can dredge up.r b-j 04:46, 4 October 2006 (UTC)

Hi RBJ. This is your most careful reply so far and I thank you for it.

Regarding "Oops" - I thought so: you appear to be inserting your replies before reading my whole argument.

Regarding the 5 equations, your account here was not featured with those equations. As I recall, one of those equations set the speed of light equal to the Planck length divided by the Planck time, and the others were just as trivial. As I said then, we could equally well divide my Compton length by my Compton time and the result would still be c. Am I therefore to form the basis of a natural set of units? Anyhow, the Planck units had already been derived from physical constants and therefore the equations, as they stood, were a waste of time.

Regarding the Okun position and dimensionful Planck units - the Planck length (as 1 unit of length), when divided by the Planck time (as 1 unit of time), is equal to a dimensionful speed of 1. This dimensionful speed is not somehow disconnected from dimensionless Planck units or from any dimensionless numbers that are parameters of meaning. Any change in the speed of light would still be a change in all the other quantities, all these changes would still offset each other and consequently we could still not measure any change in the speed of light - such a change is still 'operationally meaningless'. As I understand it, most establishment scientists accept invariance on terms such as these. They believe that at least some dimensions have real significance. Therefore some measurements are ultimately dimensionful. Duff doubtless accepts that measurements appear dimensionful in scientific experiments using conventional units that we have inherited, but I think he believes that the universe is ultimately measured in natural units, and these he believes are dimensionless. Measurements for him are therefore ultimately dimensionless. That also is the argument in your article -measurements are ultimately dimensionless. That is where your article is too exclusive in its interpretation of measurements because it shuts out Okun and others, for whom some measurements ultimately are dimensionful and who still subscribe to invariance.

That is how I see the situation.Lucretius 08:15, 4 October 2006 (UTC)

well, it's gonna be round the maypole again. don't have time. i gave it my best, L. i'm off to a San Francisco to an audio engineering convention. unless i have time, i doubt i'll be back here for a week.

ta-ta. r b-j 10:18, 4 October 2006 (UTC)

The bell went? OK. Round 3 has ended. There are still 12 rounds to go.Lucretius 21:11, 4 October 2006 (UTC)

Dimensionless measurements 4

Hi, RBJ. Here is a compromise. Please read it carefully before replying. And please do not insert your replies into my text. I make two suggestions:

1) Move the Duff et al reference to the Planck non-dimensionalization article, where it really belongs. You could even quote the Duff paragraph we've debated about - it points out that for some physicists (such as Okun) non-dimensionalization is a mathematical convenience that shouldn't be taken too literally, while for some like Duff it can be taken literally. That is where the reference to their debate rightfully belongs.

2) The Invariant scaling article includes a lengthy (I think too lengthy) explanation of invariance in dimensionful or physical terms (eg how the atom would change if a physical constant changed and how these net physical changes all cancel out). This physical explanation of invariance is not really consistent with the other argument you make that all measurements are ultimately dimensionless. If measurements are ultimately dimensionless, then ultimately there are no dimensions at all and who then gives a 'rat's ass' for physical explanations of invariance? Thus your definition of measurements (as being ultimately dimensionless) could also go into the non-dimensionalization article, though even there I think it needs careful qualification.

The problem with saying that all measurements are ultimately dimensionless is this - such a definition means we could equate 12 inches with 12 months. Even if measurements can be interpreted as dimensionless ratios they still refer to specific dimensions, and without that reference the measurements are nonsensical. Thus measurements in conventional units are ultimately dimensionful. When measurements are translated into a natural set of units, then we might validly enquire which measurements are really dimensionful and which are not, because some measurements are not always convincingly translated into natural units (eg Planck charge is defined in such a way as to allign it with the elementary charge and for me this is simply a mathematical expression without real dimensional significance). In the case of natural units therefore, you can choose to argue that some measurements are ultimately non-dimensional. Possibly you could even argue like Duff that measurements in natural units are all dimensionless i.e. 12 Planck lengths = 12 Planck times. But to argue, as you do, that the measurements we 'commonly' make, and those that are made in scientific experiments, are ultimately dimensionless - this is blatantly absurd. Lucretius 08:12, 6 October 2006 (UTC)

Ave atque vale, RBJ. I enjoyed our little debate. It occupied a few spare hours I had up my sleeve. Now I've rolled up my sleeves and gone back to work and like you I don't have much time for this any more. However I will try to answer any objections you might care to make to above argument. Hope you enjoyed San Francisco and all the people there with flowers in their hair (I expect there are more grey hairs than flowers in their hair these days). Cheers. Lucretius 06:58, 10 October 2006 (UTC)

Planck area?

I've just created a redirect to this article from Planck area. There's not actually any mention of a Planck area in this article, but that may be because there's nothing interesting to say about it once you've noted that it's the Planck distance, squared. At least, I assume that's what it is. If there's a better use for that redirect, or anything that needs to be said about Planck area... maybe someone will take care of that. -GTBacchus^(talk) 00:23, 2 March 2007 (UTC)

i (or anyone else) can add it as a derived unit. i think there is some more significance to the Planck area than that it is simply the square of the Plank length (just as there are some things behind the Planck mass and Planck force than the fundamental definitions). there is only one non-trivial reference to Planck area in WP. in the Bekenstein bound article, but i know i have run across the term somewhere. if you or someone else wants to write a short Planck area article, that would be nice. r b-j 00:46, 2 March 2007 (UTC)

A question

Could someone please explain to me why "In fact, 1 Planck unit often represents the largest or smallest value of a physical quantity that makes sense given the current understanding of physical theory."

I for example, have no problem thinking about time intervals shorter than the Planck time. For example, a time interval of zero seconds seems perfectly fine with me.

And for that matter, what is so non-sensical about talking about length scales shorter than the Planck length? As far as I know, we assume space to be continuous, no? Or, why is the Planck temperature the highest conceivable temperature? Sure, all the forces might be unified at that temperature, but that doesn't prevent me from imagining hotter things. --141.154.224.145 17:01, 30 March 2007 (UTC)

The handwaving explanation is that anything with enough energy to have a wavelength shorter than the Planck length has an event horizon bigger than the Planck length, so it's impossible to make something smaller than that size. If you have nothing smaller than that size, then you have no way to measure distances smaller than that size. You also get interesting uncertainty principle effects coming into play, giving you much the same result, if I understand correctly. You get the Planck time by considering the frequency of a particle with a wavelength of the Planck length (as trying to measure time intervals shorter than that ends up not giving meaningful results), and the Planck energy (and temperature) by considering the energy of a particle with the Planck wavelength (giving particles more than this amount of energy ends up not being meaningful). While you can _specify_ a length or energy larger or smaller than the limiting Planck value, things go badly wrong when you try to plug one of these values into the equations defining the way things in this universe behave.

I hope this answer is useful to you. For a more detailed answer, you'll have to ask one of the lurking physics-types. --Christopher Thomas 17:18, 30 March 2007 (UTC)

The question shows that you haven't quite understood the significance of natural units. In natural units, there is an intimate association between all kinds of dimensional quantities. The smaller is any natural length (wavelelength) the smaller is the associated time, but the greater is the associated energy and pressure. Thus times and lengths approaching zero are associated with energies and pressures approaching infinity. We can imagine infinite energy and pressure in some kind of abstract way but let's get real - you can't put an infinite amount of air into a tyre. Nature sets a practical limit to things. Planck units seem to be nature's limit to many physical quantities, as evidenced for example by the event horizon argument above. Lucretius 07:22, 31 March 2007 (UTC)

ET and Planck units

while i agree with User:Henning Makholm that any ET would likely not be using Planck units for anything practical, if there were to be any communication with ET (i think only one-directional communication would ever be possible, we might hear a message or we might send a message something like the Arecibo message), then the only reasonable system of units would be one of the Natural units of some form, possibly with some of these units adjusted by ${\sqrt {4\pi }}$ or the reciprocal or some similar factor. we cannot expect to communicate any information to ET about how tall we are or how massive, or the radius or mass of our planet or the same for our star or the distance we are away from our star or our periods of rotation or orbit using any anthropocentric set of units. otherwise, we have nothing in common to base any common notion of scale. it is that sense of the word use that was meant in the article. and this has been in the article for a long time, well before i came upon it. r b-j 21:51, 5 April 2007 (UTC)

I don't think we disagree about the substance. The intention of my edit was to clarify the point made by the article (which I thought was phrased ambiguously), rather than to disagree with it. I have attempted a further improvement of the sentence in question now. –Henning Makholm 23:12, 5 April 2007 (UTC)

2006 CODATA values out now (at NIST site)

we might want to update the Planck unit values (in terms of SI) and some of the text. now the uncertainty for G is 1 out of 10,000 instead of 1/7000. i'm sure there are several other articles (like Physical constant) that should be updated. r b-j 17:27, 17 April 2007 (UTC)

Matrices

One the benefits of the matrix is that it emphasizes that the most elegant set of constants is c,G,hbar. With those three constants, you have only one zero in the matrix. Everyone can appreciate starting with c. Adding G adds the concept of mass. At that point you have three dimensional qualities and then adding hbar forms a non-degenerate 3x3 matrix with only one zero in it. And the QM guys are happy because hbar is involved. When you add epsilon and k, you add the concepts of static electric charge and thermal heat, but if you presented a 5x5 matrix, it would have a lot more zeros in it. It's like I mention in the text, you can take other fundamental constants and add them too and extend the tables slightly, but the "physical significance" of the new derived values start to become more and more contrived. This is best expressed, I think, by how contrived the Planck charge and Plank temperature are. I am not going to include Planck units (uselessness of). in this article, but I did include it in the Planck charge article.--Truthnlove (talk) 13:27, 5 March 2008 (UTC)

I think the linear equations are interesting but I think they require a separate section in the article. If you had a separate section for them you could then consider the difficulties involved with charge and temperature. I'd put that section near the bottom of the article for the reason that serious math is a turn off for many readers, whereas the math nut will hunt it out wherever you put it. Lucretius (talk) 01:26, 6 March 2008 (UTC)

linear equations

Hi Truthnlove. I've created a separate section for linear equations for 2 reasons. First, the math should appear lower in the page after general concepts have been established. Second, I'd like to see what you can do with temperature and charge, in which case you really do need a separate section. It would be a new development in the article since as yet there is no consideration given to the validity of deriving a Planck temperature and Planck charge. If you're not interested in following this up, that's OK. Lucretius (talk) 23:14, 6 March 2008 (UTC)

Ugh

When I looked at this article a few months ago, it was a reasonably good article. Now it's loaded with far too many tables, including a table before the TOC (WTF?), too little explanatory text, and too unreadable. It has no flow whatsoever. Why?

Andrew Rodland (talk) 23:36, 24 March 2008 (UTC)

The reason why is that Wikipedia has a policy that good articles are supposed to decline with time and that non-experts have as much or more authority than experts to determine article content. An anonymous IP |71.161.200.209 tried to restore some of the earlier version (note the TOC in the fix) and was reverted by User:Lucretius. It started out with User:Truthnlove doing wholesale changes (including his incomplete theory on how to solve for the values of Planck units using a system of linear equations, but never tells people that they need to log the field equations first and never explained anything). Anyway, the reformers who try to keep a lid on articles collecting cruft have finite energy and give up. The entropy comes into the picture and articles decline until they've reached the state of fully crappy. Feel free to revert, but better get some more people (that, hopefully, are real physicists) to come here and support you because Wikipedia's policy of egalitarianism means that Lucretius is as authoritive as John Baez and any reform will need to be supported by numbers of editors, not their authority or expertise in the subject. 207.190.198.130 (talk) 18:05, 25 March 2008 (UTC)

Hi rb-j (alias 207.190.198.130). Isn't it time you let go and allow others a chance? There have been a number of contributors here since your departure. Some have improved things and some have spoiled things. The process will sort itself out and inevitably your imprint will fade. So will mine. That's the nature of things here. Personally I think the article is better than it was when you left it. There are still issues in it I think are wrong - the invariant scaling of nature section is still wrong but I decided long ago not to edit it again after somebody continually wiped my edits. If you can get Baez to do some work here - that would be amazing - but he probably understands that everything here is, to quote Keats about his own life, 'written in water'.If you want to write the gospel of science according to rb-j, go find a block of marble.

Incidentally, I reverted the edit by 71.161.200.209 because I was pretty sure it was you yet again under another alius. The edits were typically rb-j.

Andrew, I looked at your last edit and, as far as I can tell, there are still the same number of tables. Text has been moved around by cut and paste methods, not always sensitively, but basically the meaning isn't much changed from the edit you made. I agree it could be more sweetly expressed and better set out but who has that kind of control in an encyclopaedia anyone can edit? A contributor can always try to get full control and for a while anyone can manage it with some ruthless edits but sooner or later it becomes a free-for-all again. That's the way it is. Feel free to make the changes you want. Lucretius (talk) 02:47, 26 March 2008 (UTC)

Boy is this article getting crapped up. Not only are new edits having factual errors, but sentences like A Planck velocity of 1 equals the speed of light in a vacuum, the maximum possible velocity given special relativity are ridiculously poorly written. But since the ethos here is that everybody gets to take their turn at the article, with little regard to the need or efficacy of the modifications, even at the cost of the article's decline, I guess there's nothing else to do about it. But it's really clear that the edits of the past couple weeks (since Truthnlove showed up) have reduced the readability and, even, clarity or accuracy of the article.

Lucretious, you also said that Truthnlove was rb-j, didn't you? Looks like you have an excellent record of identifying anonymous (or anonymously named) editors. Why are you so confident that you do not repeat the same mistake? (Oh, I forgot, accuracy or authority is less important than being able to express oneself.) 207.190.198.130 (talk) 03:50, 27 March 2008 (UTC)

Hi rb-j [:}]. I think there is a good chance the article will get 'crapped up'. There is a good chance if I take my car out onto a public road that it will get spattered with bugs and tar specks, it will get scratched and might even get dented. But it gets cleaned and repainted eventually and later I'll buy another car. The same with this article. It was your 'baby'. You set it up. You got it going. But it's in the public domain and it's going to get crapped up sometimes. Others will come along and clean it up again. Such is life. You really should let go as I'm sure you have better things to do with your life than haunt this place. But that's up to you.Lucretius (talk) 11:29, 27 March 2008 (UTC)

free space?

I deleted this edit:

These constants do not invoke the properties (mass, size, radius, or charge) of any elementary particle or physical object, because the selection of such a particle or object would be necessarily arbitrary. This invariance to the properties of matter, and focus on the properties of free space, distinguishes Planck units from the other systems of natural units.

I deleted it because: 1) As far as I know, the Planck scale is only associated with free space as a theoretical cut-off. There is no necessary reason in theory why there should be any cut-off at all, nor does it have to be the Planck scale. In other words, there is a circular argument here and there is no valid derivation of the Planck scale from free space. 2) I don't understand how the Planck scale is uniquely invariant to the properties of matter - what about the Stoney scale? It's a very strange kind of argument that requires us to imagine fundamental physical constants independent of matter and I don't think its valid. 3) There is no argument that the Planck units are derived from the given constants and that is the proper way to define them. Any other definition has theoretical assumptions that are going to be controversial. Those definitions should be considered in the Discussion section. Lucretius (talk) 23:47, 30 March 2008 (UTC)

Recent edit by 132.181.160.42

A lot of changes were made today (31 March 2008) by the anonymous contributor listed here. No attempt has been made to explain those changes. The deletion I made and referred to above in the section 'free space?' has been reverted without explanation. Could that contributor please justify the recent changes here. A lot of irrelevant stuff has been inserted, many claims are controversial and the general presentation is difficult to follow. Lucretius (talk) 06:24, 31 March 2008 (UTC)

The changes continue, this time by Palnot, who seems to be the same contributor as 132.181.160.42.. These changes appear to be very time consuming and they represent a very conscientious effort. However, it's arrogant to be making such large changes without consultation or explanation. Many of the changes are quite irrelevant. There is now a lengthy paragraph defining Planck charge, when the table already includes a concise definition. There is now a table expressing the properties of the universe in Planck units - why? There is now a consideration of the universe's mass in terms of leptons etc - why? And so on and on and on.

These changes are now looking like a gigantic cobweb and somebody is going to come along and knock them all down, in spite of all the hard work that has gone into them. I'll avoid the temptation of doing it myself because I know others will do it anyway sooner or later. On the other hand, it's very, very tempting and I might not be able to resist it. (:\) Lucretius (talk) 12:27, 1 April 2008 (UTC)

Well, L, maybe the chickens come home to roost. The changes that you made recently (or maybe they were made by someone else) changed the article from a stable version that was basically factual to one that was not. And it deleted important factual points made in the earlier stable version. Are you prepared to finish what you have started?

BTW, I don't know who you think I am, but I haven't been to this page or editing Wikipedia at all except for recently. Maybe the last 3 weeks, and only this article. But that might change. 72.92.150.45 (talk) 18:03, 1 April 2008 (UTC) (a.k.a. 71.161.200.209)

Someone has spent many hours working on the recent edits and he/she should be given a chance to come to the conference table before the work is deleted. There is no such thing as 'a stable version' unless you are seriously misguided about the role of Wikipedia. This is an encyclopaedia where the process is more important than the product and therefore the product is never stable. The fact that you seem to think otherwise leads me to conclude that you are indeed that master of disguise formerly known as rb-j. The false moustache almost had me fooled. Lucretius (talk) 00:10, 2 April 2008 (UTC)

Lucretius (can't remember you're real name since I deleted the email, evidently long ago, but I remember sorta where you are), I don't check WP daily (maybe I do weekly) and I'm not saying explicitly who I am, but you earlier identified Truthnlove as rb-j. I don't think the admin (with access to checkuser) thought the same. Do you think your track record in this kind of guessing is very good? Do you even think your track record at the physics is very good (good enough to consider yourself qualified to do this editing)? The quantity of your earlier edits is not the qualification, but the quality of your edits, or proposed edits is, as would be any related credentials (which you don't really have). You demonstrated above clearly what it is that you simply don't know in the "free space?" thread. If you want, I'll go through it item-by-item. The fact is that you simply do not understand all of the concepts nor even the salient ones. You don't get it. You don't get what these physicists, "orthodox" and conventional physicists say about Planck units and the entire meaning therein. The fact is John Baez edited this very article and left it in a state that is far different than what you and these other recent editors (except for 71... or 72...) have been moving the article. That's why I am saying that the article is getting crapped up and is nearly getting to a laughable state for persons in the physical sciences and who know the math and are comfortable with it.

Other people have noticed. The article took a dive and it simply isn't true that "the process is more important than the product." They are both equally important and simply because of the egalitarian nature of WP is no excuse for sacrificing article quality to it. You should want the article quality to be good. And you should want it more than the warm fuzzy feeling you get from "contributing" to it. Otherwize, your priorities are more for your own agenda and not for the project's aims. 207.190.198.130 (talk) 01:03, 3 April 2008 (UTC)

Hi 207. I'm glad if other people have noticed any deterioration in the article and I'm sure they'll get around to fixing it. I have an amateur's interest in this stuff, same as almost everyone who contributes here. If you can convince me that the Planck scale can be derived from free space, that would be wonderful - you would have rescued me from an error. However, as I've already said, as far as I know free space is conventionally defined in terms of the Planck scale and therefore it would be a circular argument to derive the Planck scale from free space. Nobody actually knows for certain the scale of the energy vacuum or how spacetime is quantized or even if it is quantized. As for all my edits here, originally I just wanted to remove the 'free space' derivation, but then I found myself in the middle of an edit war between 2 banned contributors. One of those has since departed the scene and one continues here in disguise (doesn't bother me so long as he gives others a chance, which seems to be the case for the moment). Now another contributor has arrived who is making enormous quantities of hay while the sun shines. Something about this article attracts fanatics who want to keep piling up unnecessary info and launching into speculative hobbies. My own preference is a minimalist version, avoiding all theoretical assumptions as far as possible. According to a minimalist version, Planck units are defined in terms of the given constants, and there is no room for any tendentious claim to a knowledge about free space. If anyone knows better, I hope he/she will demonstrate their knowledge here. Lucretius (talk) 08:11, 3 April 2008 (UTC)

Enough

I reverted from work by a banned contributor on Linear equations. I reverted to the work done by Palnot on 25 March. Palnot has made a lot of edits since then but without collaboration with anyone. It's time for collaboration. I have no objection to Palnot reintroducing some of his/her previous work but only after discussion. Lucretius (talk) 01:46, 13 April 2008 (UTC)

Palnot revert

I reverted from your latest edit, Palnot, because you did not make this edit with anyone's collaboration. This article is not your private toy to play around with indefinitely. It's time to work collaboratively. I do not accept that the Planck scale has some kind of unique 'focus' on free space (what does that mean?). Lucretius (talk) 04:17, 14 April 2008 (UTC)

I've just had another look at the history page and I am sure that you are in fact the banned contributor Truthnlove. Your unco-operative style should have made that obvious to me sooner. Lucretius (talk) 04:30, 14 April 2008 (UTC)

The latest edits indicate that Palnot might actually be reading comments here on the Talk page. There is now no derivation from free space and there are no linear equations. That is a big improvement from my own perspective but I still have some major concerns - for example, the section about measuring the universe in Planck units actually seems to be about large number coincidences and it strays into irrelevant arguments about the material nature of the universe. I am puzzled about Palnot's sudden responsiveness to criticism. Palnot might clear up some of these issues by addressing them here on the Talk page. Lucretius (talk) 01:46, 15 April 2008 (UTC)

Changes by 'Lucretius

Today (15/4/8) I made the changes I thought were necessary to restore the intelligibility of the article. I removed Table 1 from the Introduction because that is no place for a table and it was originally placed there only as a temporary measure. Table 1 has now been located in the section on Base units, with Table 2. I added a key to help the reader interpret symbols in the table and I also added some brief but clear explanations about the significance of the tables. I have re-arranged the various sections to restore a logical order to them. I have removed a lot of clumsy phrasing that resulted from numerous poorly co-ordinated efforts by others. These changes had to be made to improve presentation. There has been no major change to the meanings I 'inherited' and yet there are some other changes I would have liked to make - eg I would like to remove the section about measuring the universe in Planck units, as explained above, and I have always thought the invariant scaling article was poorly conceived and contains radical ideas (such as the idea that all measurements are really non-dimensional, as if indeed 12 inches is equal to 12 months! - the fact that physicists simplify their calculations by using non-dimensionalized quantities does not mean that measurements are actually non-dimensional). However, I avoided changes in meaning because I think those changes require consensus. Lucretius (talk) 05:33, 15 April 2008 (UTC)

I have now edited out the section about measuring the universe in Planck units by incorporating it into the Discussion. This is a much neater fit and it allowed me to keep useful info from the deleted section (I deleted irrelevant info about material composition of universe and also large number coincidences)

Suggested Revisions

The Section 'Alternative Normalizations' has got a lot of great info in it, but it needs to be restructured/rephrased a bit to avoid repetition and to give it a better sense of direction.

The Section 'Invariant Scaling of Nature' is long-winded and could be expressed a lot more neatly. Also, the argument needs to be aligned with more moderate views about the nature of measurement (invariant scaling does not require us to believe that measurements are actually non-dimensional or that science is the study of numbers - there is more to science than theoretical physics, and even theoretical physicists disagree among themselves about which quantities retain dimensional significance).

I'm hoping others will get involved in these edits. A consensus view is necessary if we are to arrive at a reasonably stable article. Lucretius (talk) 00:50, 17 April 2008 (UTC)

I edited out the following paragraph (italics) because the links are able to satisfy the reader's curiosity without the need to duplicate content, also because 'e' in that paragraph is clearly in the cgs rather than SI regime, whereas the Stoney units link is SI:

The constants now named after Planck and Boltzmann were then unknown. Replacing $\hbar$ in the expression defining a Planck unit with e²/c yields the corresponding Stoney unit. Since $\alpha =e^{2}/c\hbar$ with α dimensionless, and Planck units are a function of ${\sqrt {\hbar }},$, the SI numerical equivalents of a Stoney unit and its Planck analog differ by one order of magnitude, the factor $\alpha ^{-1/2}\approx {\sqrt {137}}.$.

I have placed a 'citation needed' tag on the following paragraph (italics) because it reads like fringe physics to me. I suspect this could be an invalid extension of Gravitomagnetism. But maybe the concept is well established. Anyone know about this? :

**Characteristic impedance of gravitational radiation in free space, Z₀ = 4πG/c. The c in the denominator stems from the general relativity result that gravitational radiation propagates at the same velocity as electromagnetic radiation; Lucretius (talk) 23:02, 18 April 2008 (UTC)

Invariant Scaling

A lot of text was added on the topic of doubly special relativity, which is basically about the invariant scaling of the Planck length. We already have a section on invariant scaling and I think Double SR can be added to that section but with much less text. Trouble with Double SR is that it is quite a new idea, there appears not to be a whole lot of consensus in the scientific community about it and it could be characterized as 'fringe science'. Still, it's a fascinating concept relevant to Planck units and it deserves at least a link. I'll try to supply that link with a couple of sentences. Hope this is OK. Lucretius (talk) 23:00, 23 April 2008 (UTC) I've now added a brief note about doubly special relativity to the section on invariant scaling. I've also added another link to it in the 'See Also' section. Lucretius (talk) 23:13, 23 April 2008 (UTC)

Archive?

This page is getting very long. I think we should archive most of it. Anyone second this proposal?

I've archived up to 2007. For later reference, you don't need to ask permission to archive old discussions. Just be WP:BOLD and do it, keeping sections that have seen activity in the last few months. –Henning Makholm 15:56, 24 April 2008 (UTC)

Historical OR

"Planck's choices of what to normalize were also a consequence of the state of physical theory in 1899. When he introduced the units now named after him, the understanding of electromagnetism was not what is today, so that Coulomb's law was seen as more fundamental than Maxwell's equations."

Is there any cited reference to support that? If that were the case, why is it that the electrostatic cgs system also defines the unit charge, statcoulomb, to be whatever it has to be to normalize 1/4πε₀? It's a convention and it need not have an historical explanation (especially one that is made up) other than that is what some human beings, who were in the position to define the convention, liked it better. (And they knew about Gauss' Law and the 4π issue back in Planck's day. They could have decided to do it the other way, just as the definers of cgs could have.)

The article has really taken a tumble for the worse since February. 207.190.198.130 (talk) 15:15, 13 May 2008 (UTC)

I disagree with your general assessment of the article but I share your doubts about the quoted passage. When in doubt, leave it out. Its removal won't harm anything. Lucretius (talk) 06:42, 14 May 2008 (UTC)

Do we need all these derived units?

Is that extensive listing of umpteen derived Planck units useful? Some of the articles linked are redirects back to here, and others don't have more information than their row in the table here, other than the explainations of the symbols used. Few of them, when searched for with Google like http://www.google.it/search?q=%22Planck+voltage%22+-Wikipedia or similar, give more than 1000 hits. I've added a tag to that section. --Army1987 (talk) 21:55, 16 May 2008 (UTC)

Hi Army. First of all, I think you've done some nice work on this article, particularly tidying up the presentation. Regarding the comment above, there are no international agreements that govern the Planck system of units (unlike SI), so it's pretty much up to individiual taste how comprehensive we want the system to be. There are web sites that have even more Planck units than shown in this Wiki article (e.g. [2]). The Wiki tables are designed to give the reader an idea of how a system like SI could be translated into the Planck system. The tables are not exhaustive yet you say even this sample of units is too many. Which units do you suggest we keep and which would you like to get rid of? That's an awkward question and I wouldn't want it on my plate. Lucretius (talk) 23:05, 16 May 2008 (UTC)

I've discovered that you are Italian and I've just looked at the Planck units page at Italian Wiki. There the table of derived units features 9 units, here at English Wiki the number is 11. Is that so big a difference? Your English is very good.Lucretius (talk) 06:38, 17 May 2008 (UTC)

Hi again Army1987. I've added some text to the section under your tag. I hope this answers your concerns. If it doesn't, you'll have to say plainly which units you want to keep and which units you want to get rid of. Here is a copy of the added text:

Table 3 offers a random sample of physical units that can be derived from the base units. Unlike conventional systems of measurement, such as SI, the Planck system has never been established or regulated by national or international agreements. Indeed some Planck units are in fact too large or too small for empirical or practical use and there are uncertainties in their values (see the Discussion section below). Consequently, the relevance of some derived Planck units can be considered questionable. Lucretius (talk) 02:53, 18 May 2008 (UTC)

It isn't that some of these units should not be there because they are less relevant than the others, since in principle by multiplying the right powers of the base units you could get a unit for (almost) any quantity. That paragraph gets the point, I'm trying to make the wording less "polemic". Army1987 (talk) 09:56, 18 May 2008 (UTC)

I have rephrased your edit of my edit - your English was a bit awry. I should add that my original edit wasn't intended to be 'polemic' and I'm sorry if it appeared that way. In my mind, one of the most significant aspects of the Planck scale is the fact that it has never been established or regulated by national or international agreement. Consequently there are a lot of 'grey areas' in any presentation of the Planck scale and there is no vested authority we can appeal to. That makes this system of units highly unusual and unique. Yet there is no mention of this in the article. Lucretius (talk) 00:05, 19 May 2008 (UTC)

Fat Page

Somebody has added an extra column 'other equivalents' to Table 2 Base Units and as a result the page is wider than my screen. Do we need this extra column? It only provides 2 extra bits of info and the result is very unhelpful since it unbalances the whole page. Lucretius (talk) 23:33, 24 May 2008 (UTC)

The article is not printable.

The tables are scrambled, when printed. I am wondering if this is just me. Boris. —Preceding unsigned comment added by 161.209.206.1 (talk) 18:17, 1 October 2008 (UTC)

Confusing

If expressed in Planck units G and c have the value 1. So how do I set them to unity later? It should be noted that you set the SI versions to unity and that results in the Planck units to become unity too. It should be more clear and easier to understand. 84.56.248.141 (talk) 09:09, 23 October 2008 (UTC)

Planck charge

Would it make more sense to consider the fundamental charge unit to be ¹/₃ of an electron charge, since quark charges are multiples of 1⁄3 e?  | Loadmaster (talk) 19:33, 11 December 2008 (UTC)

Well, because of color confinement you can't get free quarks, any free particle has integer charge. But anyway, what matters is what is usually done, not what would make more sense. -- Army1987 – Deeds, not words. 16:37, 12 December 2008 (UTC)

Alternate terms

I've seen in a few places the use of the term Planck second to refer to the fundamental Planck time unit. Is this worth mentioning in the article as an alternate to Planck time? Are there similar terms for the other constants, e.g., Planck gram, Planck meter, etc.? | Loadmaster (talk) 17:32, 11 January 2009 (UTC)

I haven't ever heard any of those. Where did you see this use? Are they reliable sources? (I once saw a definition of "natural minute" meaning 10⁴⁵ Planck times, but that was Urban Dictionary or some other unreliable source like that, and I've never seen that unit used (as opposed to mentioned) anywhere.) -- Army1987 – Deeds, not words. 17:59, 11 January 2009 (UTC)

Need to revise 'Planck units and invariant scaling of nature'

The section Planck units and invariant scaling of nature has always needed revision - it overstates the non-dimensional nature of measurement and it identifies too closely with the minority view of Michael Duff. Today I added the following quote to an earlier section, just under table 2:

Non-dimensional units such as these require careful use. As observed by Paul Wesson, in reference to G=c=1:

"Mathematically it is an acceptable trick which saves labour. Physically it represents a loss of information and can lead to confusion."

This mainstream view is not compatible with the section on invariant scaling as presently phrased. Any disputes about the need to revise that section? Lucretius (talk) 23:33, 24 January 2009 (UTC)

You can always list the Wesson reference as a dissent to the Duff position even though it precedes the Duff papers by 2 decades. The reference is nearly 3 decades old and the reference regarding Duff is much more current. We could get older references (all the way back to the 17^th century) about Newtonian mechanics that assume an absolute frame of reference and that everybody's clock ticks the same. Would you use that to trump the single-century old reference from Einstein that says there is no absolute frame of reference and our clocks are observed to tick differently in different frames of reference?

Clearly the "Trialogue" reference regarding Duff, Veneziano, and Okun, make it clear that the opinion that the dimensional constants are only consequences of the system of units is not an unanimous opinion. Okun dissents, but Veneziano agrees, and further more, so does Barrow in the quote given in the article. Finding an isolated reference (that is 3 decades old) is not the "mainstream view". Perhaps the physicists who post to the sci.physics.research newsgroups have an opinion. (What better source for a mainstream view would you suggest?) Try posting there and get a polling about what these guys think. Maybe inquire to how they would revise the section. But let the physicists define what is "mainstream" physics. 76.19.170.108 (talk) 02:46, 25 January 2009 (UTC)

My personal opinion is that it depends on what you are doing: if you are writing a relativistic quantum equation and you plan to get the classical limit by sending c to infinity and ħ to zero, it makes sense to include those conversion factors all along, but if you're just studying spin putting ħ everywhere is utterly pointless. But, regardless of what I or you think, the article should avoid original research and just state what the different opinions on the issue are, without giving undue weight to any. After all, this problem is more philosophical than physical (as you probably guessed when reading my very pragmatic view on this). -- Army1987 – Deeds, not words. 02:55, 25 January 2009 (UTC)

This is the paragraph that is inconsistent with mainstream physics (italics mine):

When measuring a length with a ruler or tape measure, one is actually counting tick marks on a given standard, i.e., measuring the length relative to that given standard; the result is a dimensionless value. It is no different for physical experiments, as all physical quantities are measured relative to some other like-dimensioned values. If all physical quantities (masses and other properties of particles) were expressed in terms of Planck units, those quantities would be dimensionless numbers (mass divided by the Planck mass, length divided by the Planck length, etc.) and the only quantities we would measure when observing nature or conducting experiments would be dimensionless numbers. See Duff (2004) and section III.5 (by Duff alone) of Duff, Okun, and Veneziano (2002).

Measurements are not dimensionless values. When I measure a length with a ruler, I am measuring a length not a time. The listed reference singles out Duff because he is the only one in the Trialogue who believes that there are no dimensionful constants.

I'd also challenge this assertion:

But then the size of atoms (approximately the Bohr radius) are related to the Planck length by an unchanging dimensionless constant.

The author is referring to the fine structure constant and there are in fact people in the science community who believe that this constant could be changing. The whole section in fact is poorly expressed. Tautologies abound. Lucretius (talk) 03:25, 25 January 2009 (UTC)

Regarding your notion that Wesson's quoted comment is somehow out of date, Rbj, he is saying the same as Okun here, page 6 of the Trialogue: [3] Wesson puts it in a more quotable manner - that's why I used it. Lucretius (talk) 05:43, 25 January 2009 (UTC)

The thing I materially measure when measuring a length with a rule is a number of ticks; it becomes a length because before writing it down I mentally divide it by a factor "one tick per millimetre" before writing down. But that factor is not itself a measurement, it's just an (implicit) statement by the maker of the ruler, which I have to trust. Some books on introductory experimental physics point this out. But I do agree that saying that for this reason only dimensionless numbers can be "fundamental" is a little too far-fetched (altough I do agree with the conclusion, to some extent).

As for the Bohr radius, that "unchanging dimensionless constant" is the product of some power of the fine structure constant, some power of the mass of the electron in Planck masses, and some power of that of the proton. My impression is that the view that some of these can be changing is WP:FRINGE.

As for what I think, the speed of light is just a conversion factor due to the fact that we measure time and space with different units. Once upon a time, they used to measure heat in calories and work in joules, so they had to introduce a constant "mechanical equivalent of heat" equal to about 4185.80 J/kcal; now we understand it to be just a conversion factor. Ditto with Boltzmann's constant (which all three authors in the trialogue agree to consider a conversion factor) and with the reduced Planck constant. With masses and electric charges the issue is muddier, as it's not obvious whether we should normalize G, 4πG, 8πG, m
_e⁻
or what else, and e or ε₀ or or 4πε₀ or what (and I personally believe that the CGS system does the wrong thing).

Anyway, I'm asking WP:PHYS whether they know which opinion is more widespread between theoretical physicists as of now. Besides the trialogue, I've only read the opinion of Baez (which essentially agrees with Duff's) and that of Feynman (which essentially agrees with mine). Anyway, I believe that this issue is more philosophical than physical, and it depends on what one means by fundamental, which way it is most convenient to write equations, etc. -- Army1987 – Deeds, not words. 13:00, 25 January 2009 (UTC)

Thanks for this. As I said at the start, the non-dimensional nature of measurement is over-stated in the article. We can interpret measurement as non-dimensional (e.g. counting ticks on a ruler) or as dimensional (counting lengths between ticks). The article only expresses the non-dimensional aspect. For all practical purposes, a non-dimensional value is total nonsense. Try telling a carpenter he isn't really measuring a length of wood and he'll show you the door. Try telling a race official that he isn't really timing the event and he'll throw his stopwatch at you. Tell a theoretical physicist that his calculations are mathematical abstractions and he might say "Does it matter?" but you can be sure he'll run for the bus if his watch tells him he is running out of time. There is more to science than theoretical physics. Regarding changes in the fine structure constant - the whole point of the section is that real changes in physical parameters only show up in dimensionless ratios. That's the correct view yet the article says the FSC is unchanging. Lucretius (talk) 22:06, 25 January 2009 (UTC)

Extraordinary claims require extraordinary evidence. And there is no such evidence that α is changing. Except for one 1999 experiment for which "systematic uncertainties are difficult to quantify", according to the "Fine-structure constant" article, all other experimental data are consistent with constant α. —Preceding unsigned comment added by 80.104.235.66 (talk) 12:01, 29 January 2009 (UTC)

Also see http://math.ucr.edu/home/baez/physics/ParticleAndNuclear/constants.html —Preceding unsigned comment added by 80.104.235.66 (talk) 12:05, 29 January 2009 (UTC)

Thanks but you've missed the point. IF there were a change in fundamental, physical structures, it would show up as a change in non-dimensional ratios like the FSC. But the section on invariant scaling tells us that the FSC is an unchanging constant, which is not only an unproven assumption, it even contradicts the article itself. There is nothing in the Planck scale that requires the FSC to be the inverse of 137.036. If there was a change in the relative strengths of the electromagnetic and gravitational forces, if there was a change in the structure/size of electomagnetic masses, the FSC could be 127.45 or 347.007 or whatever - none of this changes the Planck scale. That's why the Planck scale can be said to be 'invariant'. Its invariance does not require us to believe that measurements are non-dimensional and it does not require us to believe that ratios like the FSC are unchanging. But I'm obviously fighting a losing battle just trying to get people to consider the issue carefully. Lucretius (talk) 03:57, 30 January 2009 (UTC)

It does not say what you have represented. It says that the only constants the fundamentally matter are the dimensionless ones. It says that if the FSC changes, we would notice. A change in only c or G or h by itself can not be meaningful in and of itself. If all of the dimensionless parameters (such as the FSC) stayed constant, there is no way that a change in only c could be detected. That's mainstream. 96.237.148.44 (talk) 15:25, 30 January 2009 (UTC)

It does say what I have represented and you haven't read my arguments or the article carefully. The article calls the FSC an unchanging dimensionless constant. Yes it considers a hypothetical change in the FSC (look for the word if) but that hypothetical case is clearly ruled out by the subsequent assertion that it is unchanging. Who really knows if it is changing or not? Nobody. The article also says things like - When measuring a length with a ruler or tape measure, one is actually counting tick marks on a given standard, i.e., measuring the length relative to that given standard; the result is a dimensionless value. That measurement is NOT dimensionless. Nobody can build anything in this world with dimensionless units. In theoretical physics, units can be treated as dimensionless a lot of the time - but Wesson points out that there are times even in theory when dimensionless units result in confusion. I am not saying anything radical here. I am pointing out that the article is badly expressed and it OVERSTATES the non-dimensional nature of measurements. And what is really stupid about all this is that the non-dimensional nature of measurements is not necessary for an invariant scale. A unit of 1 Planck length is still 1 unit even when it's dimensionful and there are changes in the physical structure of the universe. There is a lack of language skills and a lack of critical thinking skills in that section. If you and the others think it's OK, fine we'll leave it as is. Lucretius (talk) 01:07, 31 January 2009 (UTC)

No, L, I did read both quite carefully. Unlike your suspicion (your record at guessing anonymous IPs isn't so good), that 76.19.170.108 is me was, again, misplaced. But I am whom you suspected before. Now, before some zealous admin removes this, I'll put it out for you to read. Then we'll see how long it lasts. The article says this:

We can notice a difference if some dimensionless physical quantity such as α or the proton/electron mass ratio changes; either change would alter atomic structures. But if all dimensionless physical quantities remained constant (this includes all possible ratios of identically dimensioned physical quantities), we could not tell if a dimensionful quantity, such as the speed of light, c, had changed. And, indeed, the Tompkins concept becomes meaningless in our existence if a dimensional quantity such as c has changed, even drastically.

That means, semantically, the unchanging dimensionless constant referred to, not just α, but also to the m_P/m_e, is the consequence of a conditional (that "all dimensionless physical quantities remained constant [including] all possible ratios of identically dimensioned physical quantities"). The key word in the sentence is "if". It does not insist that the FSC cannot conceivably vary in general, in fact, it says that if it does vary sufficiently, we mortals would notice. The point it makes is that given the condition that α nor any other dimensionless measurement is measured to have changed, there is no tangible meaning to the concept of c (or any other sole dimensionful constant such as G) changing. Because we do not nor can not detect such a change except with respect to another like-dimensioned standard quantity, such as $e^{2}/(4\pi \epsilon _{0}\hbar )$ which is also, dimensionally, a speed quantity which happens to be "the velocity of the electron in the first circular orbit of the relativistic Bohr atom". We can detect a change in c relative to $e^{2}/(4\pi \epsilon _{0}\hbar )$, but unless you are using units that tie down the other dimensionful factors in the latter, you do not know it was c that changed. But someone else, using a different set of unit definition might say that it's the elementary charge or Planck's constant that changed and caused that ratio to change. And since the reality of Nature does not depend on your choice of units, then all you can say fundamentally is that the dimensionless ratio ${\frac {c}{e^{2}/(4\pi \epsilon _{0}\hbar )}}$, which is the reciprocal of the FSC (the 137.035999.. number) has changed.

Now, I would suggest that you ponder both what both Army and 76.19.170.108 said. Counting tick marks on a ruler is dimensionless. It is the ratio of length over length. What you're saying might not sound radical to the layman, but, referring to what 76 said, neither does the Newtonian world view (where all of our clocks are ticking the same same no matter how they might be moving relative to each) sound radical. But these commonsense understandings of Nature are, alas, mistaken. You say it's a length, not a time. That same ratio represents the time taken for light to travel the distance you measured divided by the time it takes light to travel the distance between tick marks. It could be a ratio of time also. Does that mean you are going to interpret the measurement as a dimensionful measure of time?

One last comment, it may be true that 80.104.235.66 missed the point. Not so much the point you're making, L, but the point of this section of the article (and that of Fundamental physical constant). As Duff puts it, the concept of a varying FSC is a legitimate area of inquiry; did it change? how might we be able to detect it with Oklo or astronomical measurements? The accuracy of the section you dispute is not based on the notion that most physicists likely doubt that α has changed. Maybe it has, probably not. The point of the section is that if it hasn't been detected to have changed (nor any other dimensionless ratio of physical quantity) there is no point in considering a variation of a sole dimensionful quantity like c. If α is detected to have changed, that means something tangible. We would notice if the change was sufficient. The concept of c changing, all by itself, is "operationally meaningless" (Duff) or "observationally indistiguishable" (Barrow). It wouldn't make any difference. Now I'll disappear for a couple of weeks. 96.237.148.44 (talk) 02:57, 31 January 2009 (UTC)

Hi again Rbj. You of course are the author of the section on invariant scaling and you have previously reverted my edits to it, which is why I can't be bothered editing it again without support from others, because I know you'll keep reverting to your own edit. You trot out the same arguments as always. I have no problems with invariant scaling. I have no problems with the argument that measurements can be regarded as non-dimensional for some purposes. I have no problems with the idea that changes to physical parameters are revealed only in non-dimensional ratios. But none of these ideas requires me to believe that measurements are really non-dimensional. It's absurd to say they are really non-dimensional. I don't live in a Pythagorean world of numbers. I am extended in space and time and I measure my world in units of space and time. Anyhow, Rbj, Go in peace and find happiness somewhere else. Lucretius (talk) 04:54, 31 January 2009 (UTC)

Think about this: when you measure something with a ruler, you count a (dimensionless) number of ticks and multiply it by a factor of "1 millimetre per tick". Only the former is a measurement, the latter is an (implicit) assertion of the ruler maker. If, unknown to you, the ticks were actually 1.05 millimetres apart, you could do as accurate a measurement as possible with your ruler, but it would be 5% smaller than it should. Now suppose you only know the distance between ticks is somewhere between 0.95 mm and 1.05 mm; the relative error on your dimensionful "measurement" will be the relative error of the tick count (the only thing you actually find empirically, whose error depends on the way the measurement is done), plus a ±5% relative error in the distance between ticks (which you don't measure, you just trust the person who gave you the ruler). So, while you "don't live in a Pythagorean world of numbers" and distances do have a dimension, you can't directly measure them. You can only measure dimensionless numbers, and trust the maker of the measurement instrument about the way to convert them to dimensionful. --80.104.234.159 (talk) (same person as 80.104.235.66, who also edited this page with a user name, but not rbj) 12:29, 31 January 2009 (UTC)

new edit for invariant scaling

I have now made a new edit of the disputed section. It is an objective edit that considers all sides. It's a whole lot better than the previous edit in my opinion and I'd like to hear the views of different contributors. Thanks. Lucretius (talk) 14:08, 31 January 2009 (UTC)

"However, as shown in Table 2, Planck units are derived from ratios of physical constants. Planck units therefore cannot be used to measure changes in those constants since the units themselves would change" is false. Do you know what a "transfer standard" is, L? There's a sorta-kinda definition of it at Kilogram. (That's literally how Planck units can be used to measure physical quantities, but it wouldn't be the most accurate measurement because we think we can count clocks of Cs-133 radiation much more accurately than we can measure G with a Cavendish-like machine.) Using your argument, you can't use a ruler with inches to measure anything either because constants of nature determine the sizes of atoms that make up the ruler. 96.237.148.44 (talk) 16:50, 31 January 2009 (UTC)

I've now removed part of my edit as it was unnecessary. That part was my explanation of the equation and I think it's better left to Barrow to explain it. I have also slightly rephrased the equation so that it includes c, h and e and so the FSC stands on its own. This dovetails the equation to suit Barrow's comment. Lucretius (talk) 05:33, 1 February 2009 (UTC)

random sample

I don't understand the objection to 'random sample' as a description of the derived units - they are a random sample of the kind of units that can be derived from the base units i.e. we could add more derived units or we could remove some. The matter was discussed above in the talk section titled Do we need all these derived units? Lucretius (talk) 06:44, 28 February 2009 (UTC)

My objection to it is that it sounds like the article is arguing against itself. We should strive to write articles that sound coherent, not ones where one paragraph instructs the reader that the next one is silly. It may well be that fewer examples should be given, but in no case should an article claim that it itself is badly edited (except as meta-text in appropriate cleanup templates). The cure for a sprawling random list is not to have the article say "the following list is random and sprawling", but to make the list less so. Be bold! –Henning Makholm (talk) 23:31, 28 February 2009 (UTC)

Hi Henning. Sorry but I don't follow your logic - 'random' is not a pejorative term and it doesn't invite the reader to think that the article is silly. The reader is entitled to know why the article presents that particular list of derived units and the simple fact is that it was generated randomly by a variety of editors. Otherwise you will need to edit the list according to a selection process and that could well put some noses out of joint. So what are your criteria for a selection of derived units? I'm almost certain that your criteria will be randomly chosen along the lines 'these are the ones I like or that I think are important or that I have seen elsewhere'. Is that better than a list that is randomly selected by a variety of editors? Also - according to what criterion is the present list a 'sprawling' list? According to a criterion like this perhaps: 'I think it's too big'. Lucretius (talk) 01:37, 1 March 2009 (UTC)

In this context, I perceive "random" as clearly pejorative. The only other possible meaning "random" could have in this context is "stochastic", and I'm not prepared to believe that any editor ever sat down and rolled dice to decide whether to include this or that example.

I do not have any criteria for a selection of derived units. I do not have any opinion about which units should be included in the first place.

Explicitly calling the list "random" is either a pejorative judgment, or an untrue assertion that it has been selected by a stochastic process. Neither of these provides the reader with useful information; neither belong in an encyclopedia article. We could say "selected according to no particular principles", which would sound less self-deprecating, but still not leave the reader any wiser. Just calling it a "sample" is at least honest; that neither claims that the list is something it is not, nor makes the article judge itself. –Henning Makholm (talk) 03:17, 1 March 2009 (UTC)

My concise Oxford Dictionary actually uses the phrase 'random sample' to demonstrate the meaning of random. The list of derived units is a random sample since different editors compiled it without reference to any criteria - the units might as well have been pulled from a hat (in fact that's not a bad selection process where samples are concerned). But random is willing to go if that is all you want. Lucretius (talk) 21:38, 1 March 2009 (UTC)

i found this article to be very informative and just wanted to say thanks

not sure if there is a better place/way to do this, but i wanted to thank the authors for this page. at my level (physics buff of some years) it was just right. in general, i understand the Planck units concept much better now and i also have more details to draw on.

btw, do i understand correctly Planck units having nothing (or little) to do with Planck's constant? if so, could be useful to briefly explain that here.

Ronewolf (talk) 00:23, 12 September 2009 (UTC)

Hi Rbj

I see that you have been reinstating your edits again even though you are banned (you make a nice appearance in the rogue's gallery of banned users here: Wikipedia:List_of_banned_users). Apparently your latest edits were motivated by Ronewolf's nice comment above - hence your post on his talk page here: [[4]]. However, I am not going to revert your edits. I decided some months ago not to edit Wikipedia articles anymore - editing can be as addictive as eating salted peanuts, as you yourself have discovered, and I don't want to get back into the habit. You are an example to us all! User:Lucretius

— Preceding unsigned comment added by 124.185.48.98 (talk) 04:18, 20 September 2009 (UTC)