Misplaced Pages

Revision as of 03:52, 6 February 2005

I would like to see some information on the nuclear resonnance properties of type II superconductors. If electromagnetic radiation is applied to the superconductor at its main resonnance frequency will the radiation be deflected or absorbed? --cacapitol

Somewhere we need to mention the specific temperatures for some superconductors - and note that high temperature is not high in normal life. Probably need to use Celsius, not Kelvin scale for general readers. --rmhermen

I have re-written the article so that the distinction between conventional superconductors and unconventional superconductors is made clear. This is important, because although the field of unconventional superconductivity (including high-temperature superconductors) is very ebullient, conventional superconductivity on the other hand is a very well-established subfield of solid-tate physics (and particularly BCS theory is a fully-working theory, if you apply it to conventional superconductors). But the article seemed to have more about unconventional superconductors than conventional ones, which is odd. I have not deleted that material, but moved it to new articles (unconventional superconductors, high-temperature superconductors, technological applications of superconductivity). Hope this is all right.

By the way, I think keeping the Kelvin is all right, since it is the natural unit in superconductivity. It is important to have links to its definition, though. --quintanilla

I'm a bit in doubt about the first line. I'm not sure superconductivity is a "state of matter", but a characteristic of certain elements and substances in given conditions.

--

We know that superconductivity is not a property of metals, but a thermodynamic state of matter different from the metallic state, because of the Meissner effect. The argument is quite standard: a perfect metal (i.e. one with zero resistivity) would support resistanceless flow of an electric current and expel magnetic fields from its interior, just like a superconductor, but if at high temperatures, when the resistivity is finite, a magnetic field is applied, and then the temperature is lowered, the perfect metal does not expel the field, while the superconductor does. In contrast superconductivity is really a thermodynamic state which is characterised by zero field inside the sample however you got there (applying field first, cooling down afterwards, or the other way around). I know this is very sketchy. When I have time I will write it more carefully in the articler about the Meissner effect. Or if you have more time than me maybe you can look it up in "Superconductivity", J.B. Ketterson and S.N. Song, Cambridge University Press 1999, Section 1 - Introduction (pages 1 and 2) or in any other textbook on Superconductivity (e.g. the one by Tinkham, or the one by Schrieffer). Since this argument usually appears in the introduction of such textbooks, it is usually written in a way that is relatively easy to understand. Ciao, jqt

Why change "External links" to "Web resources"? The former is more common in wikipedia? Tiles 08:06, 29 Jul 2003 (UTC)

I'm very curious what energies have been achieved in superconductors, as a novice. I have heard rumours that superconductors have potential applications as energy storage devices. --dikaiopolis

Currently it says Superconductivity was discovered in 1911 by Onnes. This is somewhat disputed and it is more diplomatic to write Onnes was awarded the Nobel Prize for discovering superconductivity in 1911. I have not rewritten it yet, awaiting more comments before doing so.

Any references? -- CYD

This is known within the superconductivity research community, which is where I picked it up. As with much dirty linen it is not washed in public, thus the rewrite proposal that Onnes got the Nobel prize for it in 1913 (which is undisputed) for the discovery made in 1911 (which is where the controversy lies). A number of Nobel Prize laureates have turned out to be under some controversy. Very, very little of this can be found on the net, one example is the omission of Bell for discovering pulsars. You could make a Misplaced Pages entry for this alone, that is if you wanted the mother of all edit wars; there is a lot of prestige at stake. Thus I propose Onnes was awarded the Nobel Prize in 1913 for the discovery of superconductivity in 1911.

I deleted reference to Tesla. The patent mentions the well known fact that resistance increases with temperature. The patent talks about reducing the resistance by cooling, but no mention of zero resistance. He discusses metallic conductors and liquid air cooling. Even today, there is no metallic conductor which is superconducting in liquid air. pstudier 23:05, 2005 Jan 24 (UTC)

The patent mentioned is:

• Tesla, Nikola, 685,012, "Means for Increasing the Intensity of Electrical Oscillations". 1900 March 21. USPTO.

pstudier 23:13, 2005 Jan 24 (UTC)

Is this true? Additionally, melanin is an organic, polymeric superconductor currently in use in bio-tech research as a possible replacement for gallium arsenide and silicon in high-tech devices -- most notably in nanotechnology and plastic electronics applications. What is its critical temperature? 69.225.131.186 00:53, 6 Feb 2005 (UTC)

You're right. The three edits by Deeceevoice were vandalism. I have reverted them. Thank you for catching that. RJFJR 01:48, Feb 6, 2005 (UTC)

(The prior statement that the edits were vandalism may have been unnecessarily strong; however, the contention that melanin is a superconductor is not supported by mainstream science and does not belong in this article. RJFJR 02:11, Feb 6, 2005 (UTC) )

I do not engage in vandalism. I have reinserted the passage. Please don't speak/write on matters about which you know nothing. Use your computer's search engine and discover the truth. I believe the winners of the 2000(?) Nobel Prize in science were engaged in this kind of research. There are numerous biotech companies currently engaged in melanin research. What is with you folks, anyway? If melanin were any other organic substance and not associated with black folks, would you have been so quick to assume "vandalism"? Ya better check yourselves.deeceevoice 03:43, 6 Feb 2005 (UTC)