Sunday, 4 December 2016

Strange Moments in Science: The Battle for the Planck Length

Many people use Wikipedia as a go-to source of information on a topic. People know that anyone can edit Wikipedia at any time, but generally trust that it is largely accurate and trustworthy because of the large number of vigilant volunteers and the policy of requiring sources for facts. A few years ago, I noticed that the article on the Planck length had some very detailed yet weird and incorrect information that was causing a lot of confusion among physics enthusiasts, and I decided to look into it.

This image taken from the Wikipedia commons and based on an xkcd.

I have written about the Planck length and its physical meaning on PhysicsForums. Besides being a "natural" unit, I stressed that the main significance of the Planck length is that it is approximately the order of magnitude at which quantum gravity becomes relevant, but that the idea that it makes up some sort of "space pixel" is a common misconception. There may be additional significance to it, but that wouldn't be part of established physics.

The Wikipedia page on the Planck length made the claim that a photon with a Planck length wavelength would collapse into a black hole. This is physically problematic (what does it even mean for a photon to collapse into a black hole?) in part because it violates Lorentz symmetry, because you could just observe the photon in a different reference frame and it would have a longer wavelength. Would the black hole "uncollapse" if you moved away from it? Is it only a black hole in some privileged reference frame. There was a large "proof" of this purported fact based on the Schwarzschild metric and the gravitational self-energy of a photon (which doesn't really make sense either because photons don't have a rest frame...nor are they uniform spheres). If you're using general relativity to contradict special relativity, you have done something wrong.

I thought this was strange, so I wanted to look at the source, which was a paper with a Russian title that in English meant "Comprehending the Universe." I did a search for it, and all that came up was the same Wikipedia page. The author of the referenced paper suspiciously had the same name as the person who had made the majority of the recent edits to the Wikipedia page. The reference is published by Lambert Academic Publishing, which is widely known to be a scammy vanity press that will publish your manuscript and then sell you a paper copy. They have recently been emailing me asking if I want them to publish my thesis. I was suspicious and perturbed, so I made a comment on the Wikipedia talk page mentioning that the reference couldn't be found. The author then posted a link to a page where it could be purchased for $60.

So basically, the situation was that there was this incorrect information being passed off on Wikipedia as "proven" physical truth, based on an article published in Russian in a vanity press and added to Wikipedia by the author. This was Bad, and it was misleading people, and I wanted to fix it. It can be quite difficult to actually change things on Wikipedia, because of the large number of policies that have to be followed and protectively zealous editors who will revert a lot of the changes they see. I figured if I just started removing the relevant material, it would quickly be undone by this guy who wanted his stuff on Wikipedia. So, I went to a friend who I knew to be a pretty serious Wikipedian, who goes by the nickname Oreo Priest.  I explained the situation to him, and he logged in to back me up. He pointed out on the talk page the various policies that were being violated (original research, reliable source, conflict of interest, etc) and gave me carte blanche to remove the offending material.

So, I went ahead and started removing it, and when the author protested, my friend and some other Wikipedians backed me up by citing official policies. The author's final argument was that his work was presented at the "5th International Conference on Gravitation and Astrophysics of Asian-Pacific Countries" in Moscow in 2001, and was therefore legit. Then, the final smackdown was laid:

The fact that you also presented your work at a conference doesn't change any of the above points, sorry. 
After that, the pollution stopped, although I haven't checked the guy's profile lately to see what he's up to. A large chunk of the article was removed, and hasn't been added back. However, there hasn't been a lot of improvement to the article since, so the "Theoretical Significance" section is a bit disjointed and sparse. It, and some of the other Planck unit articles, could use the attention of some quantum gravity researchers. Still, it's much better than the page on topological insulators. That page is terrible.


  1. So... the system works, due to the diligence of people who actually know the subject.

    But it doesn't necessarily work at any specific moment in time, because people pushing their own agendas might have made the most recent edits.

    Which makes it only slightly less suspect than anything you see on the news, or read in a newspaper. They too 'edit' their content when what they have previously said turned out to be nonsense, but unlike WP they often don't leave any documentation of the changes they have made.

  2. So its two photons of 1/2 Planck energy coming from opposite directions. That's a small technical difference. To a physicist 0.5 and 2 are the same number as 1, especially when it comes to physics 20 orders of magnitude out of experimental reach.

  3. My degree is in religious studies. I'll go clean it up right now.

    1. This paper might be helpful:

    2. That's actually pretty interesting. Thanks! Unfortunately, the number of spelling and grammatical errors i found, just by the second page, made it hard to bear.

      On an unrelated note, as a science enthusaist, I myself will often edit wikipedia science articles because the people who write them write so obtusely that it's difficult to understand them at all, or they just don't give enough relevant information.

      Although, needs some help, and I think you may be more qualified.

      Simple English wikipedia is the best thing in the world.

    3. If you notice the date of that article's publication, you'll suspect that it's not entirely serious.

    4. Well of course not. But if it lacked the spelling and grammatical errors, it would be easier to take seriously as the joke it is trying to be.

      Mostly I just replied to show you the simple.wikipedia planck length page in the dream that you might start fixing simple.wikipedia's physics articles.

    5. Oh wow, the Simple English Planck Length article looks pretty wrong, espousing a lot of the same misconceptions. I would clear things up by citing my PhysicsForum article, but then I'd be guilty of the same sin as that other guy! I'll see if I can make some edits, and whether they'll stick.

    6. I made a bunch of changes and cited John Baez.

  4. It would appear that Alexander Klimets is Belarusian.