In his (1926) book ''The Internal Constitution of the Stars'', Sir Arthur
Eddington not only stated that the BKG radiation of the Universe is about 3
degrees Kelvin, but also deduced the Planck distribution formula, but from a
direction opposite to that used by Einstein. Eddington presumed the principles
(1.) Thermodynamic equilibrium requires reversible exchanges, and (2.) Electromagnetic energy exchanges occur in a ''quantized'' fashion.
He then deduced Boltzman's formula and Planck's formula from ''pure quantum
theory'' (Einstein presumed Boltzman's formula to deduce the quantization
concept.). See pages 44 -53.
Eddington's argument was based upon the absorption and emission coefficients,
a12 and a21 between quantum states 1 and 2, and the spontaneous coefficient (of
decay from 2 to 1) given by the coefficient, +b21. Balancing the transitions
between states 1 and 2 (the equilibrium assumption) he formulates the famous
Einstein balance equation.
Eddington then considers the detailed balance between 3 states, and ultimately
deduces as the only possible solution, the Bose-Einstein distribution formula.
Eddington then demonstrates that at a temperature T >0 for the atom in the
higher energy state, the ''emission is stimulated by the presence of radiation
in the field. This stimulated emission is called by Einstein negative
absorption''. Quotes by Eddington.
With further characteristic insight, Eddington examined equilibrium between four
states, and obtained a slightly modified distribution law which was supposedly
useful to include the dissociation and combination of atoms which might take
place in a radiation field. All of this was done before 1926! and before the
Fermi-Dirac distribution was known.
What is remarkable is that if the coefficient +b12 is taken to be negative, then
all of Eddington's arguments are still valid, and the result for the minus sign,
-b12, yields the Fermi-Dirac distribution law!!!
By comparison, the negative coefficient, -b21, could be interpreted as
"stimulated absorption" (in the same sense as when the positive coefficient is
interpreted as stimulated emission).
Stimulated absorption of what? Could it be the stimulated absorption of
components to form topologically coherent Self-Organized complex systems? Is
Stimulated Absorption the basis of molecular self-organization into 1-100
nanometer sized aggregates from proteins to viruses?