Talk:Jeans length

I like this article, and think that it can be strengthened if we merge the Jeans length and Jeans mass articles with the Jeans instability article. In addition, I have relinked the "collapse time" to the existing "free-fall time" article, and I suggest we keep "collapse time"/"free-fall time" distinct, as it is essentially a purely gravitational (as opposed to a combined gravitational/hydrodynamical) phenomenon.

Rtfisher 18:37, 29 May 2006 (UTC)


 * Holy Smoke! The article was pitched to a very learned audience, which is probably not the typical Wiki readership. I thought an introduction was needed to reach the ordinary Wiki reader but I've retained the previous stuff for the sake of more learned readers.


 * I don't agree that this page should be swallowed up by the Instability page since I am sure that page is for high-brows. Give us Neanderthal types a fair go! Lucretius

Did somebody miss the "r" for radius of the cloud in the first formula?

No the formula is OK. The density rho has units kg/m^3. This m^3 cancels out with the m^3 in G, leaving m^2 in the attic (which comes from Boltzmann's constant). Lucretius 07:09, 9 November 2006 (UTC)

The "m" in the formula (now changed to mu for clarity) is mass per particle, not the total cloud mass. This should especially obvious since kT is the thermal energy of one particle, so it should be set equal to the gravitational energy of a particle, not of the whole cloud. dclayh 20:43, 7 May 2007 (UTC)

I first reverted your revision then changed my mind. You could be right. I'll need to hunt up the original formula to check the definitions. In the meantime, thanks. Lucretius 08:38, 9 May 2007 (UTC)

I just checked out the formula and you are right. Thanks for correcting the error. I fixed the link you included. Lucretius 09:04, 9 May 2007 (UTC)