Talk:Alfvén wave

$\mu _{0}$ [edit]

Can someone confirm whether $\mu _{0}$ is supposed to be the permeability (as opposed to permeativity) of free space? Or can someone provide a definition for permeability of a plasma? That is correct.

Answer: There's no such thing as "permeativity". There is permittivity, usually given the symbol ε₀. Permeability is correct in this context. 11/12/2007 —Preceding unsigned comment added by 81.108.237.248 (talk) 17:15, 11 December 2007 (UTC)[reply]

speed[edit]

Since the constant coefficient in the second expression is approximately seven times the speed of light, many readers will surely wonder how this propagation speed avoids violating Einstein's speed limit. Would someone who knows this field be so kind as to insert a brief mention? Peter (talk) 16:11, 23 January 2008 (UTC)[reply]

That's not the propagation speed, because you have yet to multiply it by all the factors to the right -- mass ratio, number density, and field. In particular, the factor of one over the square root of number density will decrease that value by many orders of magnitude. Anarchic Fox (talk) 17:01, 8 December 2009 (UTC)[reply]

There seem to be a problem with the velocity v : according to the third formula when va = c, v = c / sqrt(2) and not c. This is not what is written in the following paragraph... — Preceding unsigned comment added by 87.88.186.12 (talk) 09:35, 12 December 2011 (UTC)[reply]

Alfvén velocity[edit]

Alfvén velocity is $v_{A}\approx (2.18\times 10^{11}\,{\mbox{cm/s}})\,(m_{i}/m_{p})^{-1/2}\,(n_{i}/{\rm {cm}}^{-3})^{-1/2}\,(B/{\rm {gauss}})\approx (2.18\times 10^{6}\,{\mbox{km/s}})$ , faster than speed of light? Newone (talk) 09:58, 10 May 2010 (UTC)[reply]

No, that formula is valid in the non-relativistic limit. The relativistic formula is in the "Relativistic case" section. ― ___A._di_M. (formerly Army1987) 19:52, 11 May 2010 (UTC)[reply]

This article may be too technical for most readers to understand.[edit]

The section on the heating of the corona appears to have information that is more understandable than the technical information contained in the definition and math sections. Unfortunately, I do not have enough understanding of the physics topic of this article to be able to properly condense it into a more easily digestible format.

If someone with an understanding of Alfvén waves could take the basic info on the waves from the third paragraph of the corona section and combine it with a less technical definition then I think that would make for a better intro to the article.

Epolk (talk) 03:53, 25 October 2012 (UTC)[reply]

I think that an initial figure that corresponds to the basic theory would be most helpful. FIG 4.5 of Alvfén "Cosmical Electrodynamics" is simple and appropriate, though if there is a public domain animated gif of a simple shear alfven wave that would be ideal. — Preceding unsigned comment added by MichaelLstevens (talk • contribs) 16:47, 12 February 2018 (UTC)[reply]

currently in the science news[edit]

https://phys.org/news/2018-03-scientists-year-old-mystery-magnetic-sun.html

--Kmhkmh (talk) 14:31, 9 March 2018 (UTC)[reply]

A Commons file used on this page has been nominated for deletion[edit]

The following Wikimedia Commons file used on this page has been nominated for deletion:

Alfvén waves.jpg

Participate in the deletion discussion at the nomination page. —Community Tech bot (talk) 20:21, 22 October 2018 (UTC)[reply]

Historical timeline[edit]

Is the Alfvén wave#Historical timeline appropriate here? I think prose would be better for this info (see MOS:TIMELINE), but would like to see what others think before converting it. CoronalMassAffection (talk) 15:30, 16 September 2022 (UTC)[reply]

μ 0 {\displaystyle \mu _{0}} [edit]