A better description of entropy
Why Physics Stack Exchange recommends it
Physics Stack Exchange users link it as an accessible, non-mathematical description of entropy for people who only know the 'disorder' picture or lack a thermodynamics background.
Recommended by 2 people across 2 different months, 2018 to 2020.
What it is
Steve Mould uses a Stirling engine to explain entropy, arguing that the common description of entropy as 'disorder' is unhelpful. He offers a different framing in terms of how energy spreads out among possible states. It is an 11-minute explainer for a general audience.
What people said
Recommends BioPhysicist · 2018-07 · Physics Stack Exchange · on “About Entropy Definition”
You always have to be careful at understanding entropy as a "measure of disorder". For example, let's say we have a cup of coffee that is well mixed, so it looks very uniform and ordered. Then let's say we dump in some creamer. Very soon after we dump the creamer in everything looks very disordered: swirls of coffee and creamer intertwined as things mix up. But if we wait long enough (and maybe even help the process by stirring the coffee) we will see that our coffee becomes uniform again (albeit a bit lighter in color than when we started). But we know that mixing the coffee and creamer results in maximum entropy. So what happened? We went from order, to disorder, and then back to order, bu
Recommends Brian · 2019-04 · Physics Stack Exchange · on “Trying to understand entropy as a novice in thermodynamics”
As someone with only a high-school background in physics, I'm a fan of Steve Mould's Youtube Explanation [this video] . However, I feel like his explanation is more of a description of entropy (and of the consequences of entropy) than a "proper" definition. If nothing else, relating heat differentials to sterling engines to the heat death of the universe requires far less mathematical work compared to statistically modeling energy states (though both approaches give the same result, for the same reasons).
Cites Clemens Bartholdy · 2020-10 · Physics Stack Exchange · on “Why is there a special connection between entropy and heat?”
Caveat: I have not done statistical mechanics. All my knowledge of this subject is based on classical thermodynamics. However, I tried to keep my answer factual by only referencing already well-accepted ideas on the topic while providing references. What I would like to know is whether $dS=\frac{dQ_{rev}}{dT}$ is just essentially a 'backward engineered formula' which accounts for both ways entropy can change since $dQ_{rev}=dU+pdV$ , or whether it suggests there is some 'special' link between entropy and reversible heat transfer. The first expression which you have written is wrong. The true expression for entropy in a reversible process is given by $ dS = \frac{dQ_{rev}}{T}$ . I'm not quite