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Dr. Pierre-Marie Robitaille: On the Validity of Kirchhoff's Law

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this might enlighten you rationalwiki.org/wiki/Pierre-Marie_Robitaille . There was a discussion here on his cosmic background radiation ideas, which really are bizarre. – anna v Sep 1 '15 at 2:44

You are being too kind--indeed inaccurate--by calling it "highly controversial". He's completely wrong and everyone knows it. There's no "controversy" here at all. – Steve B Sep 4 '15 at 13:36*

Looks like you're right, Steve. I saw the rationalwiki link anna v posted above, he's not just making a strange misunderstanding of a physics law, but rather there is some weird motivation about disproving the standard explanation of the cosmic microwave background. – Nanite Sep 8 '15 at 7:07*

Do the above remarks answer the physics question on the page cited above, or are they just irrelevant comments? If the latter why was the following 'comment' deleted by the administrators?

Nanite - You are mistaken. Professor Robitaille has NOT claimed that epsilon/alpha is dependent upon angle. What he has argued is that unless a cavity contains a black material, such as soot, at thermal equilibrium, the radiation within the cavity is NOT black, and so the radiation always depends upon the nature of the cavity walls, contrary to Kirchhoff who asserted, without any experimental evidence, that the radiation is independent of the nature and form of the cavity walls. Also, thermal equilibrium CAN and IS reached by arbitrary materials, but unless the material is black, the radiation is not black. At thermal equilibrium Stewart's Law applies, i.e. emission = absorption. It does not follow that the emission and absorption are total (i.e. black). Arbitrary materials have reflection as well (unless the material is black when reflection = 0). Reflection cannot build up a black field on its own without violating the First Law of Thermodynamics, and so it does not. Reflection can build up a black field only if it can be driven by input of energy via the walls and a black material, such as a piece of carbon in contact with the walls. In the case of arbitrary cavity walls, infusion of heat into the walls will not produce enough photons from the walls to build black radiation inside the cavity because the temperature of the cavity walls will rise, and thereby drop out of thermal equilibrium.

  • $\begingroup$ By the way Physics.SE is not a forum. It is a Question and Answer site. $\endgroup$
    – Gonenc
    Feb 7, 2016 at 14:38
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    $\begingroup$ As a comment of mine is used as an illustration, I want to stress that comments are comments and answers are answers, on this site. A comment expresses opinion and is not an answer which must be based on peer reviewed physics *( preferably with links) or standard textbook physics. . $\endgroup$
    – anna v
    Feb 7, 2016 at 14:55
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    $\begingroup$ Your answer was deleted because it didn't answer the question asked, it was a comment to someone else. $\endgroup$
    – Kyle Kanos
    Feb 7, 2016 at 15:54
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    $\begingroup$ Since this particular section is titled ‘add a comment’, I comment. Anna-v has objected to my use of her/his comment as an example of an irrelevant comment that did not answer the question. But it was not removed for being an irrelevant comment and thereby not an answer to the question. $\endgroup$ Feb 8, 2016 at 4:32
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    $\begingroup$ Kyle Kanos, one of two who removed my remarks, asserts here that my remarks were removed because they were comments on another person and not an answer to the question. However, my remarks to Nanite were a correction to the wrong answer given by Nanite. My correction to Nanite is reproduced above in relation to my question above. $\endgroup$ Feb 8, 2016 at 4:32
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    $\begingroup$ dmckee (?) now says “You tried to put a comment into an answer, but that comment did not answer the question. So it was deleted as "not an answer" because it was not an answer.” But my ‘comment’ was a correction, using science, to Nanite’s wrong answer to the question. In the end the science remains, as given clearly in my ‘comment’ on Nanite’s wrong answer to the question. $\endgroup$ Feb 8, 2016 at 4:33
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    $\begingroup$ However, my remarks to Nanite were a correction to the wrong answer given by Nanite. Yes, this is precisely what I said and meant. Physics Stack Exchange is not a “discussion forum,” it is a question and answer site. As such, we expect posts to be either questions or answers; yours was neither. $\endgroup$
    – Kyle Kanos
    Feb 9, 2016 at 18:33
  • $\begingroup$ Also, to respond to someone in a comment directly, you can append the at symbol (@) to their username. This will flag the user that someone is replying to them. $\endgroup$
    – Kyle Kanos
    Feb 9, 2016 at 18:38
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    $\begingroup$ @Kyle Kanos - My correction of an answer is an answer, since it corrected the wrong answer given by Nanite. Surely the person who asked the question is entitled to a correct answer. $\endgroup$ Feb 10, 2016 at 13:58
  • $\begingroup$ You did not answer the question asked in that post, you made a comment to someone else. What you can do is write an answer that actually answers the post and addresses what you think is incorrect about the other post. No one will stop you from doing that (in fact, we encourage that). $\endgroup$
    – Kyle Kanos
    Feb 10, 2016 at 14:01

1 Answer 1


Hmmm. I just noticed that your rep does not currently allow access to the comment system. That makes many of the remarks below inapplicable to you.

I think the best thing for the site would be to have a question on the issue at hand so that you can answer it. Which would solve the rep issue as well.

What Kyle said in a comment. You tried to put a comment into an answer, but that comment did not answer the question. So it was deleted as "not an answer" because it was not an answer. Nor is "what I wanted to say took more than 600 characters" a defense.

It's very easy to lose track of the main mission of this site (which is accumulating good answers to good questions) because a lot of interesting stuff happens in the comments, but for all that comments are strictly side-show stuff and if you find yourself trying to defend a position in the comments you're doing it wrong.

Things you can do if you feel the need to debate in the comments and it won't fit:

  • Write an answer to the question that addresses the point in play.
  • Write a question about the point in play and write an answer to it.
  • Invite the other party to chat if they are willing.
  • Live with the disagreement.

You'll occasionally see some people string comments together but I would like to discourage that. From my point of view if you can't condense it into a single comment it is too extensive a issue to be treated in the comments.

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    $\begingroup$ I think most of these remarks are applicable regardless of the poster's reputation. The only thing that changes with reputation should be one's available options if one wants to post something that doesn't answer the question. Also, while I certainly agree that chaining multiple comments together shouldn't be a habit, I don't think it's so bad if done on occasion. $\endgroup$
    – David Z
    Feb 8, 2016 at 1:31

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