M
michaelmozina
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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Table I bottom row. <br /> Posted by DrRocket</DIV></p><p>I believe that term "possible" highly depends on how one defines the term. Here are a couple of quotes from Alfven that describe his feelings on this subject.</p><p>Plasma Cosmology - Page 29 </p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>113 .3. `MAGNETIC MERGING' THEORIES<br />What we have found means that we can describe plasma phenomena inside a finite volume only if no electric current crosses the surface . In the terminology of the magnetic field description, this means that we can describe plasma phenomena inside a finite volume only if the perpendicular component of the curl is zero at every point of the surface. All theories of `magnetic merging' (or `field line reconnection') which do not satisfy this criterion are misleading or erroneous, and deserve no attention . This does not mean that all papers in which `magnetic merging' is used are of no interest, because <strong>there exist some good papers (e .g., Hill, 1975) in which the term is merely a synonym for <em>"</em><u>current sheet acceleration</u></strong><u> .</u><em>"</em> </DIV></p><p>Emphasis mine. As long as that particular term was being used to describe current sheet particle acceleration and electrical reconnection as Hill was doing at the time, I think Alfven had no problem with the term "magnetic merging". The WIKI article however claims that "magnetic reconnection" can occur *without* a current sheet, which is something that Alfven specficially rerfered to as psuedoscience.</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>“Of course there can be no magnetic merging energy transfer. The most important criticism of the merging<br />mechanism is that by Heikkila [21], who, with increasing strength, has demonstrated that it is wrong. In spite of all<br />this, we have witnessed, at the same time, an enormously voluminous formalism building up based on this obviously<br />erroneous concept. I was naïve enough to believe that [magnetic recombination] would die by itself in the scientific community, and I concentrated my work on more pleasant problems. To my great surprise the opposite has occurred: ‘merging’ . . . seems to be increasingly powerful. Magnetospheric physics and solar wind physics today are no doubt in a chaotic state, and a major reason for this is that part of the published papers are science and part pseudoscience, perhaps even with a majority in the latter group.”</DIV></p><p>http://members.cox.net/dascott3/IEEE-TransPlasmaSci-Scott-Aug2007.pdf</p><p>I gather from reading his various papers and books that the meaning of the term "magnetic merging" began to change over time, and he began to get upset by it. Alfven seemed to have no problem with the idea that typical current sheet acceleration was a type of "magnetic merging" the way Hill was describing the energy release process, but once the term took on a new and different meaning, he attacked the idea, and he called it pseudoscience. Note the word "NO" in the second column of that same table. The magnetic field and particle flow lines in the plasma sheet can indeed "merge" in the sense that the particles that make up the current flow in the current streams can merge and "reconnect" and interact in a standard particle physics manner, but the idea that we can exclude the current flow entirely and achieve the same energy release was absolutely appauling to him. He rejected the WIKI version of "magnetic reconnecton" altogether. He rejected the idea of an energy release process that might occur in the absense of a current sheet. Note that the only controlled physical "tests" done thus far of the "magnetic reconnection" theory have involved the intentional creation of current sheets inside the plasma. The current sheet is the energy release point in these experiments, and the "reconnection" process that is occuring is kinetic and electrical in nature, not "magnetic". </p><p>My best guess is that at the time he wrote that first paper, the term "magnetic merging" was associated with current sheets as Hill was doing, and that type of "magnetic merging" is indeed "possible" according to Alfven. The type of "magnetic reconnection" that WIKI describes however is a horse of a completely different color, even though the name is similar. The ideas are ultimately very dissimilar since one involves a current sheet where particle and electrical "reconnection" is going on, and the other presumably requires no current sheet whatseover. That later idea is the one that Alfven criticised regularly and mercilessly in his work. He takes several shots at the idea in his book Cosmic Plasma. </p><p> </p> <div class="Discussion_UserSignature"> It seems to be a natural consequence of our points of view to assume that the whole of space is filled with electrons and flying electric ions of all kinds. - Kristian Birkeland </div>