Talk:Planck units

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[edit] Planck charge?

What is Planck charge? I think it has no real meaning because it's dimensionless. And why it's definition contains 4πε0 while others contain only G \hbar c (and optionally k)?--Semenov Roman (talk) 18:37, 20 February 2008 (UTC)

It has the same dimension of physical quantity that the elementary charge has. Why it contains 4πε0 is because that how the math works out. Two Planck charges spaced apart by one Planck length, will exert a force of one Planck force on each other. Also who says that the Planck charge has any G in it? If that's the gravitational G, it does not belong in any expression of the Planck charge. The article is pretty clear about what the Planck charge is and what it isn't (it wasn't defined by Planck originally). 207.190.198.130 (talk) 02:41, 22 February 2008 (UTC)
As with the Boltzman constant, the permittivity was added after the fact and extends the tables only slightly. Both are expendable, but I am tolerant of leaving them in. I added a helpful new section in that article: Planck charge#Physical significance.--Truthnlove (talk) 10:41, 5 March 2008 (UTC)

[edit] Recent changes

Recent changes include some arguments that seem dubious to me, such as:

Originally proposed by Max Planck, these units are also known as natural units because the origin of their definition comes only from properties of nature and not from any human construct. Planck units are only one system of natural units among other systems, but might be considered unique in that these units are not based on properties of any prototype, object, or particle (that could be thought of as arbitrarily chosen) but are based only on properties of free space.

Any distinction between a 'property of nature' and a 'human construct' is difficult to maintain since it includes philosophical assumptions that are questionable. Also the distiction is by no means self-evident. A Planck length, for example, could be considered as both a human construct and a property of nature, or even as a human construct without any real physical significance (how do we know length is a natural dimension - it could be how humans interpret things). The distinction is also at odds with the fact that the universe looks well suited to human existence, a fact that some physicists try to explain in terms of the 'Anthropic' argument, while others explain it in terms of 'Intelligent Design'.

Also I don't know how Planck units can be defined as uniquely based on properties of free space. I don't know what is meant by an 'arbitrarily chosen particle' and I don't know what is meant by a 'prototype' etc. I'm sorry but it all looks like gobblygook to me. Does anyone agree with me that the quoted paragraph should be removed? Lucretius (talk) 23:15, 4 March 2008 (UTC)

A prototype is a human-made object that is used as the standard of measurement of some physical quantity to base all measurement of that physical quantity against. Sometimes this standard object is called an artifact.
"Arbitrarily chosen particle" ... So if you are going to define the mass of the electron as your unit mass, why choose the electron? Why not the proton, or neutron, or some quark or boson?
"Property of nature" vs. "human construct". The precise size of our planet is an accident of history. It could have been smaller or bigger by a percent or two and little would have been significantly different, except the metre would have been smaller or bigger by a percent or two. Also why divide the polar circumference of the Earth by 40,000,000? Why not some other number? Who chose that number? Nature or humans?
Finally, I don't know what the anthropic principle or intelligent design has to do with this at all. 207.190.198.130 (talk) 23:38, 4 March 2008 (UTC)

Hi 207 - I get the feeling that you are probably the contributor 'Truthnlove' and that you are defending your own contribution. With all respects, I don't think you have answered my objections. The dictionary meanings of 'prototype' and 'arbitrarily chosen particle' are not in question. I am questioning the validity of their use in the definition of Planck units and I am saying they don't make sense in that context. The paragraph says that Planck units are not the property of a prototype, object or arbitrarily chosen particle - this is to assume that there are no such objects as Planck particles, that the Planck mass is not the prototype of masses, and that it is not an object. How do you know all this? Again, how do you know that Planck units are properties of free space? This is to define free space in terms of the Planck scale. If by 'free space' you mean the energy vacuum, then you have some support for that idea, since many theorists define the vacuum in terms of the Planck scale, but that's still only a theory. The paragraph makes a distinction between natural and human and I am saying this distinction is vague and almost meaningless, particularly in a universe that appears geared to human needs - theorists try to understand this human-centred universe in terms of the anthropic principle and intelligent design, and in this universe the distinction between human and natural is not self-evident. In short, the paragraph is somebody's personal interpretation of Planck units yet it is being presented as orthodox thinking. It is not appropriate. Lucretius (talk) 00:12, 5 March 2008 (UTC)

No, no, no! I ain't Truthnlove (I just undid nearly every change he/she made). I can't tell you who I am, but you know me from before. The issue for Planck units or natural units is that they are defined without measuring the distance from tip of nose to the end of thumb of some monarch that physical reality does not give a rat's ass about. It is not controversial that Planck units normalize quantitative properties of free space because these constants that are normalized exist fundamentally in field equations of free space that make no reference to any particular particle or object.
But if you were to compare to other sets of natural units, you would find that some property (like mass or charge) of some particular particle was chosen (by a human being) as the unit definition (and some other human being might arbitrarily choose something else). Now these other definitions of natural units (like atomic units) might be just as "good" or just as "natural" as Planck units, but they picked a particle and defined the set in terms of that particle. It's no better or no worse than Planck units, but only Planck units (or some variation of it with factors of 4π slipped in) do not require one to pick a "special" particle, object, or "thing" to base it on. Lucretius, this is not controversial stuff, and excluding the [German page], this article has been adopted and translated nearly verbatim by several other Wikipedias. I don't think that would have happened if it was not appropriate. 207.190.198.130 (talk) 01:09, 5 March 2008 (UTC)

I do not care about any of my intermediate changes except ensuring that the order of the dimentions are listed as L M T and that the emphasis on the derivation of the exquations in the second table is clear.--Truthnlove (talk) 01:37, 5 March 2008 (UTC)

Hi 207. Yes I know who you are and I forgive you your sins. But I disagree with your observations. What term in the field equations has any necessary association with Planck units? Do you mean c^4/G ? That is often called 'Planck force' but it is in fact the force associated with any mass self gravitating around its Schwarzscilde radius - in other words, it's typical of any black hole, whatever the mass or scale of the hole. Einstein was not thinking of Planck units when he devised his equations. The association between those units and equations is coincidental and cannot be considered fundamental until science proves that free space is structured according to the Planck scale. Science is a long way from understanding that much!

If the paragraph has been translated into Bulgarian or French or whatever, that merely proves that the translators are not thinking critically about the content - they are probably students of English rather than students of science. Lucretius (talk) 01:52, 5 March 2008 (UTC)

The system of linear equations does not need to be "developed". We do not need to waste space explaining how to solve a 3x3 system of linear equation in the prose because it is handled adequately over in the other article. We do need to show the reader where those formula come from. True, the select group of those who are graduate students "already know that", but it is not obvious to the bright high school student or the below-average college student.--Truthnlove (talk) 02:43, 5 March 2008 (UTC)

I think the current revision looks better. However, I would still delete this bit:

Planck units are only one system of natural units among other systems, but might be considered unique in that these units are not based on properties of any prototype, object, or particle (that could be thought of as arbitrarily chosen) but are based only on properties of free space, as measured by anthropometric units, such as SI. Note that, to have meaning, the Boltzmann constant and the concept of temperature require more than just free space; they require matter.

I think Stoney units could just as well be derived from 'free space', simply by substiting charge for h-bar, and that takes away the Planck uniqueness asserted in the paragraph. Also the inclusion of Boltzmann's Constant indicates that free space is not really a significant context for Planck units. Anyhow, has science actually decided that there is a specific set of constants that define free space? Free space is more a vague ideal than a clearly defined physical reality, as far as I know. The only adequate definition of Planck units is within the traditional context of the equivalence of quantum and gravitational effects. Either that or it should simply be defined in terms of the given constants. But not free space. Lucretius (talk) 04:03, 5 March 2008 (UTC)

I've made a few changes to the article to overcome the objections I raised above. I notice that Table 3 has dimensions listed MLT, yet Truthnlove has changed the order to LMT as in Table 1. Truthnlove might know some good reason for the order he has given (convention in dimensional analysis?) but on the other hand MLT is more like the order for listing SI quantities such as momentum Kg.m./s etc. I don't know enough to decide which order is best and I'll leave it to others. However, I have to agree with 207 that the tour into 'linear equations' seems unnecessary and seems merely to interrupt the flow of things. Surely the idea can be more simply explained as an arrangement of given constants so as to cancel out unwanted dimensions, and then maybe we could add a separate section for derivation from linear equations. I've retained the linear equation explanation in my revision but only out of courtesy to Truthnlove, because Truth and Love are beautiful concepts and I don't want to offend him. Lucretius (talk) 06:07, 5 March 2008 (UTC)

Hi Truthnlove. I'd like to revise this paragraph that you recently included:

Each constant in Table 1 is the primary constant for an important aspect of our universe. c is an aspect of space and time, G is about gravitation of matter, h is about the quantum nature of energy. Epsilon is about the electromagnetic force of static charge. k is the primary physico-chemical constant which describes the conversion of other forms of energy into thermal energy in matter, which is measured as temperature. This latter process will likely lead at some later time to the heat death of the universe. There are other physical constants that could be used to slightly expand this table.

I don't think the heat death of the universe is relevant. I think the constants might best be associated with scientific theories rather than with 'aspects' of the universe. Hence this revision looks right to me:

Each constant in Table 1 is a constant of proportionality associated with one or more scientific theories of fundamental significance for our understanding of the universe. Thus for example c can be associated with Special Relativity, G with General relativity, h with quantum physics, ε0 with classical electromagnetism and k with Thermodynamics.

Anyhow, that's what I'll revise your edit to unless you have some objection or some better idea Lucretius (talk) 08:29, 5 March 2008 (UTC)

The heat death of the Universe is "an important aspect" of our Universe and is *why* the Boltzman constant gets to be included. It is the "big picture" issue of the nature of heat and temperature and entropy. Entropy is confusing to the layman and death is not confusing. As far as I am concerned, the Boltzman constant is expendable because only two entries to the latter tables: the Planck temperature and that "degrees of freedom" item, but I realize that we are gonna keep it because amateurs love to talk about the temperature of the Universe after the Big Bang, so we might as well explain what it *really* means.--Truthnlove (talk) 10:18, 5 March 2008 (UTC)

Hi Truthnlove. I don't agree that the heat death of the universe is important for this article. This article is about Planck units and their nature and significance and these are not conceptually dependent on the future of the universe. Is the future of the universe significant for SI or cgs or the old British imperial system or any other system of units? Boltzmann's constant is not included simply to introduce heat death into the article. It is a very fundamental quantity with innumerable applications. It's inclusion is awkward, I agree, but it's about as fundamental as a constant can get and we just have to put up with it. I'll go ahead with the revision I mentioned above. I notice that in some of your revisions you take care to point out that the permittivity of free space is 'electrostatic' rather than 'electromagnetic'. It is of course both electrostatic and electromagnetic, depending on context; 'electromagnetic' is more inclusive and I'll retain that in my revision. Also, until we get paid for our contributions, we are all amateurs. I'm not intending any major changes to the article, though I think it could do with some polishing. I only got involved this time because I'm certain that Planck units cannot be derived from free space (unless of course we first define free space in terms of the Planck scale).Lucretius (talk) 23:27, 5 March 2008 (UTC)

[edit] 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)


[edit] 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)

[edit] 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)


[edit] 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)


[edit] 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)


[edit] 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)


[edit] 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)


[edit] 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}..[1]

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)


[edit] 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)


[edit] 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)

[edit] 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)

[edit] 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. [1]). 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)

[edit] 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)