Einstein Didn't Say Thermodynamics Needs a Box

Why It Matters

Understanding that thermodynamics presumes a closed system challenges its universal application, especially in cosmology and non‑equilibrium engineering, potentially driving revised models for open‑system physics.

Key Takeaways

• Einstein praised thermodynamics as universally unassailable, yet omitted its limits.
• Thermodynamics originated from steam engine efficiency studies requiring a closed container.
• Clausius’s entropy definition hinges on a slowly changing, bounded system.
• Kinetic theory assumes particles confined within elastic walls of a box.
• Speaker questions thermodynamics’ applicability when the essential “box” condition disappears.

Summary

The video revisits an oft‑quoted Einstein remark that thermodynamics is the only universal physical theory unlikely to be overturned, pointing out that he never specified the theory’s domain of applicability. The speaker argues that the missing piece is the implicit “box” – a closed, bounded system – that underpins the entire framework, a point he expands upon in his Janus‑point thesis.

Thermodynamics emerged from Sadi Carnot’s 1824 analysis of steam‑engine efficiency, which required steam to remain confined within a cylinder. Clausius later formalised entropy as the change in heat for a system whose volume is altered slowly, explicitly assuming a container. Subsequent atomistic derivations by Maxwell, Boltzmann and Gibbs all model molecules bouncing elastically off rigid walls, reinforcing the necessity of a bounded volume.

Key quotations include Einstein’s confidence in the theory’s permanence, Clausius’s definition of entropy, and the observation that a steam engine ceases to work when steam escapes. The speaker highlights that no serious inquiry has been made into how thermodynamic laws behave when the “box” is absent, a gap he believes the Janus‑point concept exposes.

If thermodynamics fundamentally relies on closed‑system conditions, its extrapolation to open or cosmological contexts—such as the expanding universe, black‑hole thermodynamics, or far‑from‑equilibrium processes—may be conceptually flawed. Recognising this limitation could prompt new theoretical frameworks that accommodate unbounded or dynamically evolving systems.

Original Description

Einstein praised thermodynamics as unassailable, but overlooked a crucial detail: its applicability framework. The core of thermodynamics relies on systems 'in a box,' a condition often ignored. What happens when that box is removed? This is the central question of the Janus Point. #Thermodynamics #Physics #Einstein #ScienceFacts #JanusPoint Full podcast with Julian Barbour: https://youtu.be/bprxrGaf0Os