Register to reply

Entropy - Physical Meaning

by TimNguyen
Tags: entropy, meaning, physical
Share this thread:
TimNguyen
#1
Aug26-05, 03:24 AM
P: 81
Hello.

I know that entropy equals the Boltzmann's constant times the natural log of the multiplicity but I do not know the physical interpretation of what "entropy" really is. I understand the units of it are "Joules per Kelvin" but what does that really mean?
Phys.Org News Partner Physics news on Phys.org
Physicists unlock nature of high-temperature superconductivity
Serial time-encoded amplified microscopy for ultrafast imaging based on multi-wavelength laser
Measuring the smallest magnets: Physicists measured magnetic interactions between single electrons
Juan R.
#2
Aug26-05, 05:40 AM
P: 416
Quote Quote by TimNguyen
Hello.

I know that entropy equals the Boltzmann's constant times the natural log of the multiplicity but I do not know the physical interpretation of what "entropy" really is. I understand the units of it are "Joules per Kelvin" but what does that really mean?
The most simple and direct interpretation

[tex]U = TS[/tex]

entropy is a "measure" of the increase of internal energy with temperature or

[tex]S = \frac{U}{T}[/tex]

If two bodies have the same temperature but one has more energy, then it has more entropy.

If two bodies have the same energy but one has less temperature, then it has more entropy.
ZapperZ
#3
Aug26-05, 06:22 AM
Emeritus
Sci Advisor
PF Gold
ZapperZ's Avatar
P: 29,239
Quote Quote by TimNguyen
Hello.

I know that entropy equals the Boltzmann's constant times the natural log of the multiplicity but I do not know the physical interpretation of what "entropy" really is. I understand the units of it are "Joules per Kelvin" but what does that really mean?
Try this:

http://www.entropysite.com/

It has a good collection of basic articles, especially in dispelling the notion that entropy is nothing more than "disorder".

Zz.

Juan R.
#4
Aug26-05, 12:26 PM
P: 416
Entropy - Physical Meaning

Quote Quote by ZapperZ
Try this:

http://www.entropysite.com/

It has a good collection of basic articles, especially in dispelling the notion that entropy is nothing more than "disorder".

Zz.
Nice link!

Effectively, the old (archaic) idea of entropy like disorder is not justified and would be abandoned of literature.

Moreover, the standard formula [tex]S = k \ ln W[/tex] often invoked in that old interpretation is valid only in the very special case of an isolated system at equilibrium.

That is reason that one would reasoning what is entropy from above formulas.
vipul_rop88
#5
May19-09, 02:30 AM
P: 1
Quote Quote by TimNguyen View Post
Hello.

I know that entropy equals the Boltzmann's constant times the natural log of the multiplicity but I do not know the physical interpretation of what "entropy" really is. I understand the units of it are "Joules per Kelvin" but what does that really mean?
ans:
it realy means how quickly the energy is spreding in medium.


Register to reply

Related Discussions
Physical Meaning Quantum Physics 4
Help on physical meaning General Math 6
Physical meaning for wavefunction Quantum Physics 4
What is the physical meaning for time? General Physics 6
What is the physical meaning of this eqn Advanced Physics Homework 2