Radiation energy causes fluctuation of the molecules in vanes of
the Crooks radiometer. Through this fluctuation, molecules of the
vanes strike the adjacent air molecules and as reaction cause recoil
of the vanes. It seems that this is also the mechanism of Nichols
radiometer. But, in the vacuum of the space, there are not practically
such molecules to be leaned by the striking molecules of the vanes
of solar sails. So, the vanes will not recoiled to be propelled. It is
shown that a comet’s tail and antitail are common tides produced by
Sun rather than any phenomena produced under influence of radiation
pressure.
(35) Actual justification of the Crookes and Nichols radiometers (pdf)