Talk:Planck units

Changing constants of nature

In the section "Planck units and the invariant scaling of nature" is referred to George Gamov's book where the speed of light in vacuum is decreased. This has an effect on our perception. However, an editor wrote that this "is challenged" by Barrow (2002). This does is not follow. If $c$ is changed, and $e$ and $h$ are fixed, the world is empirically distinguishable from the original. The fixation of $e$ and $h$ are implicitly assumed in the story about Mr Tompkins. This is not challenged by Barrow's text. It is only if $\alpha$ is fixed (consistent with certain combined change of $c$, $e$ and $h$), the world is empirically indistinguishable.

I propose to remove the part with "challenge". Furthermore, we should either remove Gomov's text or put it in a different context.

Note that below the citation (Barrow, 2002) is an explanation on the type of constants (the ones that do and the ones that don't give a distinguishable world). This may need some extra citations and more clarity. Hulten (talk) 12:18, 19 July 2013 (UTC)

No, the Barrow text says that it "would be a mistake...to think that a world in which the speed of light was slower would be a different world." Barrow disputes that "this has an effect on our perception." Directly.

True, he says this. However, if c is changed while e and h are kept constant, the fine structure constant α would change. Most of the discussion I've seen, including Duff's comments, argues that a change in α does result in an empirically distinguishable world.

Absolutely. Virtually everyone agree that a change in a dimensionless "constant" is salient. Most physicists understand that all measurements of physical quantity (including the first, very crude measurements which are anthropometric) are done against a like-dimensioned physical standard, which means those measurements are dimensionless. The issue that this section speaks to is whether the change in this dimensionless physical constant can be attributed to a change in c and not h or e. The point is that it's meaningless to ascribe the change in the dimensionless constant to any of the constituent dimensional constants since the meaningful and salient constant is whatever dimensionless change in quantity that was measured in the first place.

And the Duff stuff are additional citations. 12.226.82.60 (talk) 06:49, 21 July 2013 (UTC)

I've read Duff (2002), the Comment on time-variation of fundamental constants. My impression from the discussion between Duff, the referees and Davies, is that Duff's point of view is not scientific consensus.

I have doubts whether the whole section Planck units and the invariant scaling of nature should be here in the first place, because of several reasons. Firstly, there does not seem consensus on this issue (yes, it is in Discussion making this less of an issue). Secondly, it is not specifically on Plank units but a more general discussion. Maybe part of the discussion should be moved to another page. Or even removed altogether.Hulten (talk) 11:54, 21 July 2013 (UTC)

The issue also is discussed at the Dimensionless physical constant page which was renamed from Fundamental physical constant and the latter redirects to the former. However, both Duff references make specific references to Natural units systems specifically Planck units to make their points. 12.226.82.60 (talk) 16:48, 22 July 2013 (UTC)

Planck Volume (citation not specified)

This edit → [1], [2]
Provide the source for the Planck Volume value. >> Kron7 (talk) 13:36, 25 June 2014 (UTC)

The volume given is simply the cube of the Planck length. No citation is necessary. (See my comment in the next section below.) — Loadmaster (talk) 22:54, 28 October 2014 (UTC)

Planck Area (citation not specified)

This edit → [3], [4]

Wolfram contains incorrect (inaccurate) value.

For example, the Wolfram says that the Planck length is:

1.6161×10⁻³⁵ m

Now let's see the correct value on the NIST:

1.616199(97)×10⁻³⁵ m

Rounded to the 4th digit after the point (as on the Wolfram):

1.6162×10⁻³⁵ m

Thus, the values ​​of the Wolfram and the NIST are different. Consequently Wolfram contains not quite correct values​​.

Provide the source for the Planck Area value. >> Kron7 (talk) 14:42, 25 June 2014 (UTC)

Can someone please explain what the fuss regarding the Planck Area and Planck Volume citations are about? The difference between the Wolfram and WP values for Planck area are inconsequential. NIST doesn't seem to show either Planck area nor volume. Of course the Planck area is the square of the Planck length and the Planck volume is the cube. Why is there such a fuss about this when there are no citations required for any of the other derived units like the Planck momentum or Planck energy or Planck pressure or Planck voltage? Or even the Planck charge (which is a base unit)?

Please, let's stop being silly about this. 70.109.186.241 (talk) 17:23, 27 October 2014 (UTC)

This article has a long, slow-burning problem with IP editors (a suspiciously high fraction of whom are registered to a single ISP) aggressively reverting other editors, particularly those who try to alter the language in the lede. The "fuss" here is not due to the editors who are asking for a citation, it's due to the editors who seem to forget that they don't own the article. Zueignung (talk) 05:07, 28 October 2014 (UTC)

The Planck volume is simply the cube of the Planck length. That's how I calculated them when I added it to the table back in Dec 2008 (here). Someone else had already added the Planck area, which is just as obviously the square of the length. No citations are necessary. — Loadmaster (talk) 22:54, 28 October 2014 (UTC)

Why not begin with basic values ?!

Having studied the subject for quite some time, it occured to me that the complete "Planck world", i.e. all Planck values (and their derivatives) are necessarily wrong, since they all rely on the reduced Planck constant ("h-bar") instead of the true value. Wherever h-bar is used, typically in a square root, the result of the calculation is off by a factor of roughly 2,5 (or roughly 6 when h-bar itself is used). There is no problem introducing reduced constants or some normalisation, mentioning their further application, once the unchanged constant(s) of nature have been used. My suggestion is obviously to begin the corresponding articles with the basic calculations, using especially the Planck constant in the original form. It would not surprise me when it should turn out that a few problems raised in the article just vanish due to this issue. Regards, K. Cormann 80.136.3.251 (talk) 13:10, 24 December 2014 (UTC)

ħ is in no sense less (or more) fundamental or basic than h. If you normalise h to 1 you will lose a few factors of 2π in some places, and gain some in others. It's an arbitrary choice, but if you choose something different to ħ = 1 you need to give it a different name. Djr32 (talk) 18:53, 24 December 2014 (UTC)

This objection to ħ is nonsensical. If the results of your calculations are "off", it means you made a mistake somewhere. Zueignung (talk) 02:11, 25 December 2014 (UTC)

First, ħ is not fundamental, as it is derived from the true fundamental, which is h, the original Planck constant. I don't mind normalisations which may - or may not - become necessary for further use, say, in quantum mechanics. But when calculating basic elements such as the ones in tables 2 and 3 (and considerations as in table 5), the result is simply and evidently off by the factors I've mentioned. So, I don't "choose" anything different to ħ, but return to the unchanged h itself. Second, what really is nonsensical is the use of an arbitrarily changed constant for basic calculations, no matter how it "simplfies" the use in other domains than cGh physics. Before assuming that my calculations are off, just try any of the data in tables 2 and 3 (or re-calculate any in table 5), using h instead of ħ. Given that the results are provided with amazing accuracy, this accuracy even suggests a precision which blurs the issue of a changed basic value, affecting much more than the last decimal places. Just to make sure: I don't mind the normalisation to ħ, when it is required as described in the article. But basic calculations such as the ones in the tables mentioned above need to be done with the basic values to be physically correct. K.Cormann 80.136.18.243 (talk) 08:09, 25 December 2014 (UTC)

ħ is no more or less fundamental than h. If you choose ħ = 1, you get the values given in the tables in the article. If you choose h = 1, you get a different set of values which most physicists would probably not identify as "Planck units". Zueignung (talk) 18:33, 25 December 2014 (UTC)

Neither h nor ħ = 1, the correct interpretation is presented right here in Wikipedia (article on Planck's constant). ħ gets relevant when angular momentum comes into play. The importance of h is not only explained in some detail in the corresponding article, it has been measured by Planck itself to a noteworthy accuracy (esp. for his time). Calculating the physically correct Planck data for esp. time, length and mass is not a matter of "choosing", but of inserting the correct data, which are c, G and h. 80.136.22.25 (talk) 08:36, 26 December 2014 (UTC)

This is why ħ is more fundamental than h. It is what relates angular frequency to particle energy and angular frequency is more fundamental to calculus than is ordinary frequency. This is why you see ħ in Schrodinger's equation and not h (unless h has all that 2π crap attached to it). It is a matter of convention, but your convention, K, is not as good (as simple or fundamental) as the ħ convention. The convention for Planck units could be better, in my opinion. It would be better (more "fundamental") if Planck units normalized 4πG rather than normalizing just G. And if they normalized ε₀ rather than normalizing 4πε₀. That way, whether it's EM or GEM, the quantities of field strength and flux density are (in free space) exactly the same thing. Nature doesn't have to pull these unit-dependent scalers outa her butt to change flux density (calculated from "cause" like charge or mass density) into field strength ("effect"). But others will say it's better to normalize 8πG as more fundamental (but I think the "2" belongs in the most fundamental form of the Einstien equation).

It's convention. Might not be the best convention, but it could get worse, and frankly K, I think your convention regarding h is worse than the existing convention using ħ. 50.198.99.124 (talk) 04:38, 29 December 2014 (UTC)

Please provide a link to a published, reputable source which explains why one must use h (and not ħ) in order to obtain "physically correct" data (whatever that means). Please include page number, paragraph number, etc. as appropriate. Zueignung (talk) 03:06, 27 December 2014 (UTC)

Why should I bother? After all, you didn't care to rationalise your choice using ħ in basic equations eg. for length, time and mass, although in the article on the Planck constant, it is made explicitly clear that the key issue to use ħ would be an angular momentum (or "angular frequency"). The article is quite exhaustive on the meaning and use of h or ħ. However, here is a simple question: What is the smallest wavelength observed in nature or produced in a lab? Is it the Planck length using h or the one using ħ? (Another issue would be the entropy of a black hole - but that's pretty hard to study.) And, btw: The question above is tightly linked to physical correctness, which means that an equation describes nature. To note that there is always an easy compromise, which would be to just add a column to the tables including the results for the units using h instead of ħ. This way, all possible informations were there. 80.136.19.191 (talk) 11:19, 27 December 2014 (UTC)

It is not for the editors of this article to justify the choice of ħ or h in the definition of the Planck units, that decision was made by the people who invented Planck units, and is reflected in the values of the Planck units in SI units published e.g. by NIST. It would be highly undesirable to add an extra column to the table to give values of something that aren't the Planck units. A number of people above have tried to explain the errors in your arguments, until you have understood these issues then I think that further discussion of the topic would be a waste of time for both sides. Djr32 (talk) 00:00, 28 December 2014 (UTC)

There is a difference between justification and explanation, and the article lacks either one. As for a possible (or hopefully likely) addition to the current publication by the NIST, I've contacted them parallel to the topic here. You tried to re-enforce your point and did not care about the still open question, even contradicting, to some extent at least, the article on Planck's constant itself, which obviously has not been considered once by the "number of people above". Never mind, though. It's not the first time Wikipedia ignores inputs, maintaining a single-sided view on a topic. Of course, the value of the encyclopedia keeps decreasing with this position, as has been noted by quite a number of people around. 80.136.1.79 (talk) 06:52, 28 December 2014 (UTC) Edit (since you've asked): You might be interested that indeed there is a source for the, in our view correct, explanations for Planck length, time and mass, which is the Encyclopedia Britannica (just in case I happen not to provide the links correctly): , , . Perhaps something at least to think about. 80.136.1.79 (talk) 12:55, 28 December 2014 (UTC)

Table 3: Derived Planck units

In Table 3, the column “Approximate SI equivalent” gives the value 4.63298 × 10¹¹³ J/m³ for the Planck energy density and the value 4.63309 × 10¹¹³ Pa for the Planck pressure.

The final Expressions, however, for the two are identical, and since it can readily be shown, that Pa is equivalent to J/m³, shouldn’t the two SI equivalents be the same, even though they are merely approximate? Wouldn’t it be sensible to make them identical (choose one value or the other or a compromise value) or, alternatively, to indicate that the last three digits are uncertain? This, I think, is an edit that a physicist, expert in the subject matter, should make. --Wikifan2744 (talk) 06:14, 18 August 2015 (UTC)

"Interchangeable experimental parameters" vs. "human construct".

I have to agree with IP 76 about the description:

"... from properties of the fundamental physical theories and not from interchangeable experimental parameters..." does not really say anything. "... from properties of nature and not from any human construct..." actually says something, and I added links to say specifically what it says. 4.15.65.187 (talk) 23:25, 18 September 2015 (UTC)

From your inability to avoid gratuitous overlinking and violations of WP:EGG, it's obvious that you're the same IP editor who's been reinserting the exact same language into the lede/first section over many years, and who has been curating the nonsensical blahblah section about "Planck units and the invariant scaling of nature". Kindly stop littering this article with your trash. Zueignung (talk) 04:36, 5 October 2015 (UTC)

I am the "76" IP and I am not the IP 4.15.65.187. And it is you that is crapping up the article with your POV. You seem to have a conflict reputation here at Wikipedia to show for it. 76.118.23.40 (talk) 22:41, 5 October 2015 (UTC)