The Entropy of a Markov Chain

A brainy entropy explainer sparked instant “cool story, where’s the actual answer?” energy

TLDR: The article tries to explain entropy using a simple model of a cell, asking how “messiness” might work in a state-jumping system. Commenters immediately pushed back, saying the key math seemed missing and even calling out an apparent diagram mistake, turning the discussion into a mini fact-check frenzy.

A deep-dive post about entropy — basically the idea that things naturally slide from neat to messy unless energy is used to keep order — tried to connect old-school physics with a simple “life vs death” model built from a Markov chain, a math system that hops from one state to another. The writer’s big mission was to make sense of how “life feeds on order” by using a toy model of a cell and asking the sneaky question: can you define entropy for that kind of system the same way physics does for heat and engines?

But in the comments, readers were not content to just vibe with the philosophy. The instant mood was: nice essay, but where’s the calculation? One of the sharpest replies cut straight to the point with the digital equivalent of a shrug: stochastic thermodynamics already covers this. Another commenter went full forensic detective, asking whether the article actually explains how to compute entropy for the Markov chain at all — and then twisting the knife by spotting what they say is a label swap in the example diagram. Ouch.

That clash became the real spectacle: one side admired the grand attempt to connect life, disorder, and physics; the other wanted receipts, formulas, and fewer buried ledes. The vibe was part classroom, part comment-section roast. In plain English: the article aimed for cosmic meaning, and the community replied, "Sure, but can you show your work?"

Key Points

  • The article explains Clausius’s formulation of entropy and states that entropy increases in irreversible processes while remaining constant in reversible ones.
  • It links the second law of thermodynamics to the claim that entropy cannot decrease in an irreversible process without energy being applied to the system.
  • The author uses Schrödinger’s notion of negentropy to frame the question of how life maintains local order by consuming energy.
  • Dyson’s toy model of a cell is presented as a Markov chain with three equilibrium states, including life and death, as a possible setting for defining entropy.
  • The article turns to Boltzmann’s statistical formula, \(S = k_B \ln W\), to connect entropy with the number of microstates compatible with a macrostate.

Hottest takes

"Stochastic thermodynamics covers this" — niklasbuschmann
"how does one calculate the entropy of a Markov Chain?" — abetusk
"the edge labels swapped" — abetusk
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