Thermodynamic processes that occur without exchanging heat between the system and its environment.
Questions tagged [adiabatic]
496 questions
30
votes
1 answer
If the ground states of interacting QFTs are so complicated, how did Nature find them?
My question was inspired by trying to understand the paper Quantum Algorithms for Quantum Field Theories, by Jordan, Lee, and Preskill. The main result of that paper is that scattering experiments in one of the simplest-possible interacting quantum…
Scott Aaronson
- 2,492
23
votes
5 answers
The notion of an adiabatic process in thermodynamics -vs- quantum mechanics
I'm confused about the terminology in the two contexts since I can't figure out if they have a similar motivation. Afaik, the definitions state that quantum processes should be very slow to be called adiabatic while adiabatic thermodynamic processes…
Siva
- 6,204
22
votes
4 answers
How slow is a reversible adiabatic expansion of an ideal gas?
A truly reversible thermodynamic process needs to be infinitesimally displaced from equilibrium at all times and therefore takes infinite time to complete. However, if I execute the process slowly, I should be able to get close to reversibility. …
Mark Eichenlaub
- 53,961
21
votes
1 answer
Principle of Caratheodory and The Second Law of Thermodynamics
Background
Constantin Carathéodory formulated thermodynamics on a purely mathematical axiomatic foundation. His statement of the second law is known as the Principle of Carathéodory, which may be formulated as follows:
In every neighborhood of any…
noir1993
- 2,226
18
votes
2 answers
Why are sound waves adiabatic?
I want to know why we can treat sound waves as an adiabatic process. Precisely, I know that pressure and density vibrations occur so fast that molecules have no time to exchange energy (I might be wrong). But I would like a deeper explanation, not…
user109867
18
votes
3 answers
Formula for molar specific heat capacity in polytropic process
I found this formula for a polytropic process, defined by $PV^n = {\rm constant}$, in a book:
$$C = \frac R{\gamma-1} + \frac R{1-n} $$
where $C$ is molar specific heat and $\gamma$ is adiabatic exponent. I do not know how it was derived, can…
user34304
- 1,843
16
votes
8 answers
How is this process not quasi-static yet reversible?
Consider a (adiabatic) canister with a piston containing some gas kept in a vacuum. There are two weights on the canister which equalize the pressure of the gas on the piston. Assume the system is at equilibrium.
I remove one weight from the…
Gerard
- 2,838
15
votes
2 answers
Adiabatic theorem and Berry phase
As far as I can check, the adiabatic theorem in quantum mechanics can be proven exactly when there is no crossing between (pseudo-)time-evolved energy levels. To be a little bit more explicit, one describes a system using the Hamiltonian…
FraSchelle
- 11,033
13
votes
5 answers
Adiabatic piston: why is Callen's argument flawed?
This question is related to this one. I would ask you to read that question and my answer to the question itself before answering this one.
The problem is the following. In his book Thermodynamics, appendix C, Callen introduces the problem of the…
valerio
- 16,751
12
votes
1 answer
Is there a generalization of the adiabatic theorem into a degenerate Hamiltonian?
Adiabatic theorem states that if the Hamiltonian of the system $H(t)$ is slowly changed, and if the initial state is in the $n$th eigenstate of $H(0)$, then the final state will remain in the $n$th eigenstate of $H(t)$ assuming that the Hamiltonian…
narip
- 347
11
votes
4 answers
Basic Thermodynamics: Quasistatic Adiabatic Process
I'm going through the exercises in a Thermodynamics book, just to revise and build my intuition. Right now, I'm working on:
Show that for a quasistatic adiabatic process in a perfect gas, with
constant specific heats:
$$PV^\gamma =…
seb
- 1,278
11
votes
2 answers
When is the adiabatic approximation for solid state systems valid?
The adiabatic approximation for solid state systems is rather radical. I was wondering in which cases it breaks down.
As it is based on the idea of the nuclii being much heavier than the electrons I would imagine there would be problems for very…
Hagadol
- 1,458
11
votes
5 answers
Entropy change in the free expansion of a gas
Consider the adiabatic free expansion of a gas since there is no external Pressure hence Work done on the system is 0 and since the walls are insulated (hence adiabatic) the heat absorbed is 0. However since this is a irreversible process then…
Apoorv Jain
- 113
11
votes
2 answers
How to understand the indeterminate process in thermodynamics?
Consider a closed composite system with an internal movable adiabatic wall. If we release the piston, thermodynamics cannot determine the final equilibrium state (the temperature cannot be determined).
(About the previous example, you can refer to…
Tom
- 577
11
votes
4 answers
Why is adiabatic process isentropic?
I have read that adiabatic process is isentropic because there is no heat exchange in an adiabatic process and thus no change in entropy.
But my question is - Even in adiabatic process, work can be done. Let's take an example of an adiabatic vessel…
biogirl
- 549
- 4
- 16