Your browser does not fully support modern features. Please upgrade for a smoother experience.
Submitted Successfully!
Thank you for your contribution! You can also upload a video entry or images related to this topic. For video creation, please contact our Academic Video Service.
Version Summary Created by Modification Content Size Created at Operation
1 handwiki Vivi Li -- 2896 2022-11-07 01:36:45

Video Upload Options

We provide professional Academic Video Service to translate complex research into visually appealing presentations. Would you like to try it?
Cite
If you have any further questions, please contact Encyclopedia Editorial Office.
HandWiki. Statistical Ensemble (Mathematical Physics). Encyclopedia. Available online: https://encyclopedia.pub/entry/33244 (accessed on 23 September 2026).
HandWiki. Statistical Ensemble (Mathematical Physics). Encyclopedia. Available at: https://encyclopedia.pub/entry/33244. Accessed September 23, 2026.
HandWiki. "Statistical Ensemble (Mathematical Physics)" Encyclopedia, https://encyclopedia.pub/entry/33244 (accessed September 23, 2026).
HandWiki. (2022, November 07). Statistical Ensemble (Mathematical Physics). In Encyclopedia. https://encyclopedia.pub/entry/33244
HandWiki. "Statistical Ensemble (Mathematical Physics)." Encyclopedia. Web. 07 November, 2022.
Statistical Ensemble (Mathematical Physics)
Edit

In physics, specifically statistical mechanics, an ensemble (also statistical ensemble) is an idealization consisting of a large number of virtual copies (sometimes infinitely many) of a system, considered all at once, each of which represents a possible state that the real system might be in. In other words, a statistical ensemble is a probability distribution for the state of the system. The concept of an ensemble was introduced by J. Willard Gibbs in 1902. A thermodynamic ensemble is a specific variety of statistical ensemble that, among other properties, is in statistical equilibrium (defined below), and is used to derive the properties of thermodynamic systems from the laws of classical or quantum mechanics.

statistical equilibrium idealization probability distribution

References

  1. Gibbs, Josiah Willard (1902). Elementary Principles in Statistical Mechanics. New York: Charles Scribner's Sons. 
  2. Simulation of chemical reaction equilibria by the reaction ensemble Monte Carlo method: a review https://doi.org/10.1080/08927020801986564
  3. This equal-volume partitioning is a consequence of Liouville's theorem, i. e., the principle of conservation of extension in canonical phase space for Hamiltonian mechanics. This can also be demonstrated starting with the conception of an ensemble as a multitude of systems. See Gibbs' Elementary Principles, Chapter I.
  4. (Historical note) Gibbs' original ensemble effectively set h = 1 [energy unit]×[time unit], leading to unit-dependence in the values of some thermodynamic quantities like entropy and chemical potential. Since the advent of quantum mechanics, h is often taken to be equal to Planck's constant in order to obtain a semiclassical correspondence with quantum mechanics.
  5. In some cases the overcounting error is benign. An example is the choice of coordinate system used for representing orientations of three-dimensional objects. A simple encoding is the 3-sphere (e. g., unit quaternions) which is a double cover—each physical orientation can be encoded in two ways. If this encoding is used without correcting the overcounting, then the entropy will be higher by k log 2 per rotatable object and the chemical potential lower by kT log 2. This does not actually lead to any observable error since it only causes unobservable offsets.
  6. Technically, there are some phases where the permutation of particles does not even yield a distinct specific phase: for example, two similar particles can share the exact same trajectory, internal state, etc.. However, in classical mechanics these phases only make up an infinitesimal fraction of the phase space (they have measure zero) and so they do not contribute to any volume integral in phase space.
More
Upload a video for this entry
Information
Contributor MDPI registered users' name will be linked to their SciProfiles pages. To register with us, please refer to https://encyclopedia.pub/register :
View Times: 1.5K
Entry Collection: HandWiki
Revision: 1 time (View History)
Update Date: 07 Nov 2022
Notice
You are not a member of the advisory board for this topic. If you want to update advisory board member profile, please contact office@encyclopedia.pub.
OK
Confirm
Only members of the Encyclopedia advisory board for this topic are allowed to note entries. Would you like to become an advisory board member of the Encyclopedia?
Yes
No
${ textCharacter }/${ maxCharacter }
Submit
Cancel
There is no comment~
${ textCharacter }/${ maxCharacter }
Submit
Cancel
${ selectedItem.replyTextCharacter }/${ selectedItem.replyMaxCharacter }
Submit
Cancel
Confirm
Are you sure to Delete?
Yes No
Academic Video Service