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
1016 K
1 TeV
1013 K
1 GeV
1010 K
1 MeV
High Energy Physics
Nuclear Physics
107 K
1 KeV
104 K
1 eV
Life and Chemistry
101 K
1 meV
10-2 K
1 meV
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)
Source
charges
Test charge
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.
•Can be simplified by constructing potentials. Nevertheless, one still has to
deal in the end with vector calculus, e.g.
Both are highly idealized, i.e. they
ignore non conservative processes,
or dissipation.
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 ~ NA
NA = 6.022  1023 = 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 12C )
• Dissipation
 Ohms law breaks TRS
• Equilibrium systems
• Mathematics is different
Lots of new definitions  Quite verbal, unusual for physics
Thermodynamic limit
Pressure, Volume, Temperature
P, V, T
F/A
L3
Something to
do with heat