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Landau and Tisza are definetly not BFF!

July 7, 2009

Dear blog, here we go again..

I should have been studying, but you know, things are ideal only in our textbooks.. But moving on, I cannot understand what my dog saw outside! Actually he is in the middle of the window for a while, and of course, once he is using the table to “discover the world out there” I cannot do any calculations, because in order to do so I reeeeeally need the table! I’ll let my dog be happy for a few more minutes and enjoy the internet! (Of course my advisor will love to know it!)

This is the ridiculous scene I am observing:
pi1

But I didn’t decided to write a new post just to tell the world what my dog is doing, no. Actually I was having fun with a Physical Review Letter to the Editor (volume 75, number 5, March 1, 1949) and I thought it could be funny to paste some parts here. It is a letter by Landau, named “On the Theory of Superfluidity”. In this letter, Linday Lohan, ops, I mean, Landau, starts a “battle” with Laslo Tisza due to some considerations the latter did about a previous work of the first. Let’s see some parts:
Blah, blah, blah.. “..Such a comparison shows excellent agreement between the theory and the experimental error. Therefore, one must consider as a mere misunderstanding Tisza’s assertion that this formula is in conflict with experiment“.

The hydrodynamics equations given by Tisza are, in my opinion, quite unsatisfactory. Is is easy to see that in their exact form they even violate the conservation laws!!!

And then Landau said again something like “my theory is better and his, that can be reduced to mine in some cases” and comes with “Unfortunately, however, he obtains the correct result by using an incorrect assumption of the proportionality between the entropy and the normal part of the density of Helium II. Tisza’s effort to give a thermodynamical foundation for this assumption is quite unconvincing and the formulas giving actually show that such a proportionality is absent“.

Well, after some point Landau used terms like “unconvincing remarks” and so on. I will not transcribe everything here, but you can find the complete “soap opera” just clicking the link above.

Of course Tisza had something to say about it: “Landau criticizes our ideas not so much because of their internal inconsistency but because they do not follow from his theory of phonons and rotons. We are frankly impressed by the audacity and power of Landau’s approach but we feel he has introduced into his theory more or less disguised assumptions which canot claim the same degree of certainty as the principles pf quantum mechanics“.

Well, nothing like Hungarian class, isn’t it? Despite this “not even an epsilon” friendly behavior of Landau (in my opinion, of course), I still think his original article on the Superfluidity of Helium II is one of the most beautiful things I have ever read in Physics. Probably it is the best thing about superfluidity at all, though I didn’t read Tisza’s articles and thus I cannot compare with these. It is full of insights and many simple argumentations that make lots of sense. The best part is that it is super clear! Really really amazing!

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