Talk:Population inversion

message: Could someone please explain how both the Boltzmann statistics at equilibrium and the population decay rate as per spontaneous emission can both be true? one says the ratio N2/N1 is constant for all times and very small at room temperature, while the other says it goes to to zero exponentially.
:The key is in the word "equilibrium". At equilibrium, the Boltzmann statistics apply, and give a (statistically averaged) constant population ratio for all time. If some process places the system in a non-equilibrium (population inversion) state, then the excess population in the high energy state decays exponentially. The given expression does indeed tend to zero - this is an approximation that does not take into account the (rare) reverse transitions that maintain the non-zero Boltzmann equilibrium population ratio. This approximation will be very close to the true ratio until the populations  have returned close to their equilibrium ratio.FredV (talk) 01:58, 24 February 2012 (UTC)
replies: text: Wrong, it is not.  See my writings at laser and Talk:Laser. lysdexia 22:09, 20 Dec 2004 (UTC)
thread_title: Comments

message: starting with 'the concept of population inversion is of fundamental importance' and not explaining the term is a failure to explain what Population inversion means. It would be like starting the article for cotton with 'cotton is of fundamental importance in making a shirt' and omitting from the introduction a simple summary of what cotton is (a soft fibre). Please, somebody who knows what they're talking about, fix this. --81.154.236.221 16:01, 5 October 2005 (UTC)
replies: text: I've improved the intro a little. Let me know what you think. -- Bob Mellish 16:41, 5 October 2005 (UTC)
replies: text: I think I know what population inversion is now, but I'm really confused, because it doesn't seem to have anything to do with populations or inversions :/ Danielx (talk) 04:30, 24 May 2010 (UTC)

text: btw, I did not raise the original complaint. "Terrible" seems a bit harsh, even though "fundamental importance" is not very useful in explaining what population inversion is. Danielx (talk) 04:32, 24 May 2010 (UTC)
thread_title:  terrible introduction 

message: In the text it mentions that an electron goes from level 3 to level 2 and no light is emitted ie it is "radiationless". It explains this by  "with the energy being transferred to vibrational motion (heat) of the host material surrounding the atoms, without the generation of a photon."
I thought this needed some explanation.
john f188.30.24.136 (talk) 09:14, 8 August 2014 (UTC)
thread_title:  "radiationless" 

message: Amazing article. A beautiful recounting of the principles behind the operation of a laser. An interesting truth about Wikipedia: the information is there, but it might not be where you look for it. So
 Laser story shows up in pop. inversion @misfiled ow.ly/RSTYu 
89.217.0.204 (talk) 08:17, 6 February 2015 (UTC)
thread_title:  Topic inversion 

message: I just wanted to thank anyone that has contributed to this article for their contribution. Waaaaaaaaay more useful than my professor's notes.
Korrector (talk) 23:20, 4 May 2015 (UTC)
thread_title:  Great article