Is it possible to take statistical mechanics without quantum mechanics?

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Discussion Overview

The discussion centers around the feasibility of taking a statistical mechanics course without having completed a quantum mechanics course first. Participants explore the prerequisites and the extent to which quantum mechanics is necessary for understanding statistical mechanics, considering various educational contexts and personal experiences.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Homework-related

Main Points Raised

  • One participant expresses concern about being behind in their physics major and questions whether taking statistical mechanics concurrently with quantum mechanics would suffice.
  • Another participant suggests that only basic concepts like the Pauli exclusion principle and the infinite potential well are necessary for statistical mechanics.
  • A different participant advises caution in bypassing prerequisites and recommends consulting the professor for guidance, noting that course approaches may vary by institution.
  • One participant shares their experience of learning thermodynamics and statistical mechanics before quantum mechanics, indicating that while it can be frustrating, it is not necessarily detrimental.
  • A participant currently taking both courses simultaneously asserts that only a limited amount of quantum mechanics knowledge is needed, suggesting that self-study could fill any gaps.
  • Another participant outlines several important quantum concepts that may arise in statistical mechanics, such as the Heisenberg uncertainty principle, discretization of energy levels, and the statistical mechanics of bosons and fermions, emphasizing that while one could manage without prior knowledge, it may lead to conceptual difficulties.

Areas of Agreement / Disagreement

Participants express differing views on the necessity of quantum mechanics for statistical mechanics, with some suggesting minimal knowledge is sufficient while others caution against proceeding without a solid foundation. There is no consensus on whether it is advisable to take statistical mechanics without prior quantum mechanics.

Contextual Notes

Participants mention varying educational structures and personal experiences, indicating that the necessity of quantum mechanics may depend on specific course content and teaching methods at different institutions.

xbomber88
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So I didn't start my physics major until my sophomore year which means I'm a year behind. Because of this I won't be able to take quantum mechanics until the first semester of my senior year which is also when statistical mechanics is offered. I'd really like to take statistical mechanics but quantum is listed as a prerequisite. How much quantum would I really need to take stat mech? Would it be enough to be taking quantum at the same time even if I hadn't had it previously? I don't really know enough about stat mech to know if it uses a lot of quantum mechanics or just uses some very basic stuff. What do you guys think about taking stat mech without quantum? I do plan on asking the professor who teaches the course eventually but I think I'll probably wait until the spring when it comes close to time to register for my senior year classes.
 
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You just need to know a bit about the Pauli exclusion principle and maybe the infinite potential well. Of course knowing more never hurts but you don't need to.
 
In general, I'd be wary of bypassing prerequisite courses unless you've studied the material extensively yourself. Talk to the professor who's going to teach stat mech and see what he thinks. It may be like Klockan3 says and you won't actually need to know much QM, but I wouldn't gamble blindly about it. Different schools often take different approaches in what look like the same courses.
 
The way my school has it set up, we learn thermo and stat mech before quantum because of the scheduling of professors that teach it. It's not especially detrimental, but it's somewhat infuriating to work with equations that you haven't derived yet and seem to pop up like magic.
 
I'm taking quantum mechanics and statistical mechanics at the same time right now. It's fine - you don't need to know THAT much quantum mechanics. Just a handful of ideas that you could learn on your own.
 
There are some important concepts from Quantum Mechanics that will come up in Stat Mech. You won't be sunk if you don't know them beforehand, but it may just seem like you're moving symbols around on a page with little understand why if you don't. Those concepts are:

-The Heisenberg uncertainty principle, \Delta x \Delta p \geq \hbar/2. This will come up when discussing writing down the partition function for an ideal gas or counting available states in a classical system, for example. One typically needs to coarse-grain the phase space into bins, and this provides the natual size of the bins.

-Discretization of energy levels: when writing down the partition function or counting states it's easier to work with discrete possibilities rather than continuous ones, so one typically deals with the discrete energy levels found in quantum mechanical systems, as there you don't need to worry about coarse-graining your phase space into discrete cells because it's already built in.

-Simple Harmonic Oscillator: You might calculate the partition function for the SHO both classically and quantum-mechanically.

-Bosons and Fermions and the Pauli Exclusion Principle: the statistical mechanics of bosons and fermions will naturally take into account some quantum mechanics and the exclusion principle.

You could probably take these concurrently and not be totally lost, and maybe even take stat mech without quantum at all, but it may be more conceptually difficult. You should probably ask your department for advice on the matter.
 

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