Thermal physics, and sciences that involve codes
UM-StL Physics & Astronomy, Copyright (1999) by P. Fraundorf

Introduction: Fluctuations accompany phase changes. As physics content and pedagogy vary to meet the challenge of relevance to a changing world, one area that deserves attention is thermal physics. Discoveries in mid-20th century physics connected the foundations of thermal physics to gambling theory or statistical inference: the science of making decisions with only partial information. These discoveries have already resulted in deep reorganization of senior undergraduate and graduate statistical physics texts, although introductory physics shows little sign of change. The relevance of this information-based thermal physics has broadened in subsequent decades, with discoveries in biology and information theory about the role of partially random codes in the way lifeforms share both molecules and ideas. These connections are deeply relevant to research outside of physics, particularly in the information and life sciences. We outline briefly some of these connections, and discuss the role that introductory physics can play in providing crucial physical insight to workers in emerging professions of the 21st century.

I. Thermal physics in the information age, or ``Gambling with Heat''

• Uncertainty & the 0th law (draft essay pdf in testing for Saunders): S in [nats], coldness 1/T=dS/dE.
• Heat capacity dE/dT, in bits of uncertainty per two-fold increase in absolute temperature.
• Thermodynamic possibility puzzlers: 90% losses thermalizing flames; energy-free ovens (Jaynes' pdf).

II. The Engines of Life

• Plants as steady-state heat engines, and life’s 10^15 watt power stream.
• Correlation or mutual information I, and it's IkT price in available work.
• Steady-state information engines dear to us: molecular and macroscopic.
• Information storage strategy: one-of-a-kind structures or replicable code?

III. Excitations and codes

• Our role as "disposable vehicles" for evolving codes (both genes and ideas).
• Tracking "not just genetic" code inheritance, through organisms & computers.

Conclusion: Some widely useful and fundamental augmentations of the traditional thermal physics curriculum, in the direction of what one might in a larger sense call information physics, are discussed here. Those with an "in-discipline" focus have already changed the face of senior undergraduate and graduate statistical physics texts. Those with an "extra-discipline" focus could offer much-needed physical insight, via introductory physics, for 21^st century workers in the information and life sciences. Challenges to implement remain. The first step may involve diversifying the curriculum (as in math with the teaching of digital and formal calculus as separate but complementary courses). Modeling workshop, and Tom Moore's "Six Ideas that Shaped Physics", are steps in this direction. Thus fluctuations may again prove to be both a bell-weather of, and prerequisite to, meaningful change.