# Microstate (statistical mechanics) > [[PORTAL_Dynamical_system|Dynamical system]] spine. ## Microsims — three.js <div class="microsim-player"> <iframe src="https://wikitube-3d-microsims.netlify.app/Microstate_(statistical_mechanics).html" width="100%" height="520" frameborder="0" loading="lazy" sandbox="allow-scripts allow-same-origin" title="Microstate (statistical mechanics) — three.js microsim"></iframe> </div> <p class="wt-pending"><strong>Note:</strong> staged, awaiting CDN deploy.</p> In statistical mechanics, a microstate is one specific, fully detailed configuration of a system — the exact position and momentum of every particle, in the classical case. A macrostate, by contrast, is what is actually observed or measured: bulk properties like temperature, pressure, and volume, each compatible with an enormous number of different underlying microstates. ## Overview This build renders a small system's microstates directly and lets a viewer see how many distinct configurations correspond to the same macroscopic description, the combinatorial idea behind entropy: a macrostate's entropy is proportional to the logarithm of how many microstates produce it. The overwhelming asymmetry between the vast number of high-entropy microstates and the comparatively few low-entropy ones gives the second law of thermodynamics its statistical character, and the space of all possible microstates for a mechanical system is exactly the phase space whose evolution [[Hamiltonian_mechanics|Hamiltonian mechanics]] and [[Liouville's_theorem_(Hamiltonian)|Liouville's theorem]] describe. **On the spine:** [[Dynamical_system]] · [[Hamiltonian_mechanics]] · [[Liouville's_theorem_(Hamiltonian)]] · [[Phase_space]]. ## Wikipedia : Wikitube **Strict pair:** [Wikipedia](https://en.wikipedia.org/wiki/Microstate_(statistical_mechanics)) : [Wikitube](https://en.wikitube.io/wiki/Microstate_(statistical_mechanics)) --- *Repopulated 2026-08-05 · existing three.js asset renamed + wired, Wikipedia-sourced overview · 0 deletions.*