Einstein proved wrong about blue sky!!!! In 1911 Einstein published an explanation of why the sky is blue based on analysis of Rayleigh scattering by nitrogen and oxygen molecules. His analysis was sufficiently detailed and accurate that it was used to provide an independent measurement of the Avogadro number. See Usenet Physics FAQ http://math.ucr.edu/home/baez/physics/ http://math.ucr.edu/home/baez/physics/General/BlueSky/blue_sky.html However according to recent posts on PF, revisionists have overturned Einstein, dismissed the idea that the blue is caused by scattering from N2 and O2 molecules, and demonstrated that it is caused by an alternative mechanism---fluctuations in air density. This is certainly possible but no URLs have been offered to allow verification. Can anyone say if the standard explanation of blue sky has, in fact, been credibly supplanted? Here is a quote from a recent post stating that it has, but without online corroboration: "Molecule of N2 is too small (d~0.3 nm) to give any essential contribution into blue sky color. Recall that intensity of scattered light is proportional to (d/λ)4, so it drops dramatically with size. It would take about hundred times more air to get essential contribution into scattering from individual molecules. But the distribution of molecules in air is fluctuating, and it turns out that most contribution into intensity of scattered light comes from fluctuating pockets of air of order of 10-100 nm in size. These pockets can have dramatically different number of molecules per unit volume." This SOUNDS reasonable. But the analysis flies against Einstein's calculations and the standard picture from, for instance, Usenet FAQ! This is curious and provocative---hope someone has some links about this.