A theory is the more impressive the greater the simplicity of its premises, the more different kinds of things it relates, and the more extended its area of applicability. Therefore the deep impression that classical thermodynamics made upon me. It is the only physical theory of universal content which I am convinced will never be overthrown, within the framework of applicability of its basic concepts. Albert Einstein

Thermodynamics is a funny subject. The first time you go through it, you don't understand it at all. The second time you go through it, you think you understand it, except for one or two small points. The third time you go through it, you know you don't understand it, but by that time you are so used to it, it doesn't bother you any more. Arnold Sommerfeld

This is the realm of thermodynamics!

Oxford Instruments: Dilution refrigerator insert T = 10 mK B = 15 T

From Helsinki Univ. Archive

10 16 K 1 TeV 1 GeV 1 MeV 1 KeV 1 eV 1 meV 1  eV K K 10 7 K 10 4 K 10 1 K K High Energy Physics Nuclear Physics Life and Chemistry Condensed Matter Physics

Thermodynamics ignores microscopic details Examples: Heat always flows spontaneously from a hot object to a cold object, never the other way around (cf arrow of time) The maximum possible efficiency of an engine, working over a given temperature range is independent of the working substance (steam, air, compost …). Liquids always boil more readily at lower pressure.

Convert heat into motion (work). Heat  Work

DEMO Stirling Engine

Phase transitions

Classical Mechanics Concerns the response of a solid body (or system of bodies) to forces.

Electrostatics (and dynamics) Test charge Source charges

Classical Mechanics and Electrostatics You are usually stuck dealing with the vector calculus of vector functions such as momentum, electric field, etc.. which depend on the variables x, y and z, and often t as well, e.g. Both are highly idealized, i.e. they ignore non conservative processes, or dissipation. Can be simplified by constructing potentials. Nevertheless, one still has to deal in the end with vector calculus, e.g.

Thermodynamics Deals with equilibrium systems (slightly misleading). Thus, the variables x, y, z and t are irrelevant! Microscopic (statistical) theory concerned with the average behavior of an extremely large number of microscopic entities, i.e. atoms or molecules. However, classical theory ignores the microscopic details and deals instead with a few macroscopic variables which are easily measurable, e.g. pressure, volume, temperature, etc.. It is a continuum theory. Deal only with scalar functions! However, the course does require mastery of multi-variable calculus.

Thermodynamics deals with large numbers of objects (atoms, molecules, electrons, photons ….) Discuss “mole” and Avogadro number

Thermodynamics Large number of particles ~ N A Dissipation  Ohms law breaks TRS Equilibrium systems Mathematics is different Lots of new definitions  Quite verbal, unusual for physics N A =  = mole (the quantity of matter that contains as many identical objects (e.g. atoms, molecules, formula units, ions) as the number of atoms in exactly 12 g of )

Thermodynamic limit

P, V, T Pressure, Volume, Temperature F/A L3L3 Something to do with heat