Editing Boltzmann constant

The '''Boltzmann constant''' (<math>k</math> or <math>k_B</math>) is the physical constant relating [[temperature]] to energy.
It is named after the Austrian physicist [[Ludwig Eduard Boltzmann]].
Its experimentally determined value (in SI units, 2010 [http://physics.nist.gov/cgi-bin/cuu/Value?k#mid  CODATA] value) is:

:<math>k_B =1.3806488 \times 10^{-23} </math> <math>\left. JK^{-1}\right.</math>



In units with molecular significance it is close to 1, for example see: [[DL_POLY | DL_POLY units]].
==History of Boltzmann's constant==
:''"This constant is often referred to as Boltzmann's constant, although, to my knowledge, Boltzmann himself never introduced it - a peculiar state of affairs, which can be explained by the fact that Boltzmann, as appears from his occasional utterances, never gave thought to the possibility of carrying out an exact measurement of the constant."''
Max Planck, [http://nobelprize.org/nobel_prizes/physics/laureates/1918/planck-lecture.html Nobel Lecture, June 2, 1920]
==Experimental determination of Boltzmann's constant==
Boltzmann's constant can be obtained from the ratio of the [[molar gas constant]] to the [[Avogadro constant]]. 
The molar gas constant can be obtained via acoustic gas thermometry, and Avogadros constant from either the ''Silicon sphere'', or via the watt balance. 
Recently laser spectroscopy has been used to determine the constant (Refs. 3 and 4). Other techniques include Coulomb blockade thermometry (Refs. 5 and 6).
#[http://dx.doi.org/10.1088/0026-1394/22/3/023 L. Storm "Precision Measurements of the Boltzmann Constant",Metrologia '''22''' pp. 229-234 (1986)] 
#[http://dx.doi.org/10.1088/0957-0233/17/10/R01  B Fellmuth, Ch Gaiser and J Fischer "Determination of the Boltzmann constant—status and prospects", Measurement Science and Technology  '''17''' pp. R145-R159 (2006)]
#[http://dx.doi.org/10.1103/PhysRevLett.98.250801 C. Daussy, M. Guinet, A. Amy-Klein, K. Djerroud, Y. Hermier, S. Briaudeau, Ch. J. Bordé, and C. Chardonnet "Direct Determination of the Boltzmann Constant by an Optical Method", Physical Review Letters '''98''' 250801 (2007)]
#[http://dx.doi.org/10.1103/PhysRevLett.100.200801  G. Casa, A. Castrillo, G. Galzerano, R. Wehr, A. Merlone, D. Di Serafino, P. Laporta, and L. Gianfrani "Primary Gas Thermometry by Means of Laser-Absorption Spectroscopy: Determination of the Boltzmann Constant", Physical Review Letters '''100''' 200801 (2008)]
#[http://dx.doi.org/10.1103/PhysRevLett.73.2903 J. P. Pekola, K. P. Hirvi, J. P. Kauppinen, and M. A. Paalanen "Thermometry by Arrays of Tunnel Junctions", Physical Review Letters '''73''' pp. 2903-2906 (1994)]
#[http://dx.doi.org/10.1103/PhysRevLett.101.206801  Jukka P. Pekola, Tommy Holmqvist, and Matthias Meschke "Primary Tunnel Junction Thermometry", Physical Review Letters '''101''' 206801 (2008)]

==References==
[[Category: Physical constants]]