Register to reply

Statistical mechanics with a negative amount of atoms

by Catria
Tags: atoms, mechanics, negative, statistical
Share this thread:
Catria
#1
Nov10-12, 12:53 PM
P: 56
My advanced statistical mechanics prof told me that it wouldn't make any physical sense to allow N (the number of particles in a system) to be negative. But, somehow, I think that this possibility should be theoretically left open; perhaps there are some systems whose statistical behavior would be best explained if we allowed N < 0.

My question is: what would happen if we wanted to solve stat-mech problems of systems with negative quantities of particles?
Phys.Org News Partner Physics news on Phys.org
'Squid skin' metamaterials project yields vivid color display
Scientists control surface tension to manipulate liquid metals (w/ Video)
Simulation method identifies materials for better batteries
Dickfore
#2
Nov10-12, 01:18 PM
P: 3,014
Do you know why thermodynamic temperature must be a positive quantity?
Catria
#3
Nov10-12, 01:19 PM
P: 56
Quote Quote by Dickfore View Post
Do you know why thermodynamic temperature must be a positive quantity?
Is it possible to have a thermodynamic themperature > 0 with N < 0?

Vanadium 50
#4
Nov10-12, 06:53 PM
Emeritus
Sci Advisor
PF Gold
Vanadium 50's Avatar
P: 16,459
Statistical mechanics with a negative amount of atoms

Your professor is right. What does it even mean to say "I have negative four atoms in this box"? Sure, you can always plug numbers into equations, but that doesn't mean what comes out makes any sense.
Catria
#5
Nov27-12, 08:42 PM
P: 56
Come to think of it, a system whose statistical behavior is that of N < 0 would be quantum in nature, regardless of whether the system contains bosons or fermions.
Mute
#6
Nov28-12, 10:13 AM
HW Helper
P: 1,391
Quote Quote by Catria View Post
My advanced statistical mechanics prof told me that it wouldn't make any physical sense to allow N (the number of particles in a system) to be negative. But, somehow, I think that this possibility should be theoretically left open; perhaps there are some systems whose statistical behavior would be best explained if we allowed N < 0.

My question is: what would happen if we wanted to solve stat-mech problems of systems with negative quantities of particles?
Which systems' statistical behavior do you think would be best explained if we allowed N < 0? Do you have any examples in mind?

I doubt there's any physical meaning to having a negative number of particles, even in quantum statistical mechanics. Even in ensembles in which you allow particle fluctuations, they don't have fluctuations to less than zero particles in the system.


Register to reply

Related Discussions
Statistical mechanics: Particles with spin Introductory Physics Homework 1
Statistical mechanics - diatomic particles leaving and entering a box Advanced Physics Homework 1
Statistical behaviour of ideal particles in a closed box Classical Physics 5
Is it possible to take statistical mechanics without quantum mechanics? Academic Guidance 5
Particle Accelerators: How do I calculate the amount of particles per bunch? Advanced Physics Homework 3