Sunday, September 27, 2009

Measuring Planck's constant by thermodynamics

An incredibly important and useful equation is the Sackur-Tetrode equation which gives the absolute entropy of an ideal gas and shows how

-Planck's constant enters statistical mechanics in a way that is measurable
-to resolve the Gibbs paradox

I did not appreciate just how significant the equation was until I taught a statistical mechanics course.

The latest APS News has a beautiful article by Richard Williams on the equation in the This Month in Physics History column.

Did you know Tetrode as only 17 when he derived the equation from Boltzmann's equation (see below)!
By at
Labels: , ,

1 comment:

  1. StuNovember 19, 2009 at 12:43 PM

    Hi! I am curious, how DOES one measure Plank's constant with thermodynamics?

    ReplyDelete

Subscribe to: Post Comments (Atom)

Tony Leggett (1938-2026): condensed matter theorist

Tony Leggett died last week. The New York Times has a nice obituary. One measure of his influence on me is that more than 20 posts on this ...

  • Nobel Prize predictions for 2025
     This week Nobel Prizes will be announced. I have not done predictions since 2020 . This is a fun exercise. It is also good to reflect on w...
  • What is Herzberg-Teller coupling?
    Is it something to do with breakdown of the Born-Oppenheimer approximation? In molecular spectroscopy you occasionally hear this term thro...
  • NF - mysteries of a small molecule
    Nitrogen fluoride (NF) seems like a very simple molecule and you would think it would very well understood, particularly as it is small enou...