The following is a Letter to the Editor of the IEE journal
'Electronics and Power' published in the July, 1966 issue at p. 236.
Dear Sir - I read with interest P.
Knight's letter on the radiation-pressure discrepancy.
The fallacy in the
discrepancy may lie in the assumption used in deriving the Poynting vector
itself. This is that the field energy in an electromagnetic wave actually moves
with the wave. The quantum theory and experiment have shown that an energy
quantum can be received at a region remote from a wave source long before enough
energy to sustain the quantum has, using the Poynting vector, been intercepted
by that region. The Poynting vector may really have no significance in
electromagnetic energy transfer. An electromagnetic wave is a disturbance of the
medium which propagates it, and may well be sustained by energy deployed from
that medium. The process of electromagnetic energy transfer may be a lot more
complicated than we presently believe.
Furthermore, the normal source of
electromagnetic radiation, the accelerated electron, does not really radiate
electromagnetic wave energy - though it can be calculated that it does if we
ignore the presence of the electric field which causes the acceleration. This
was pointed out in a discussion  of Prof. Hammond's paper  about the
Poynting vector. It may also be shown  that the familiar formula
E=Mc2 is an essential requirement for non-radiation of energy by the
accelerated electron, and it is not surprising that, as Mr. Knight has found,
the formula and the Poynting vector lead to a discrepancy if used
IBM United Kingdom
Hursley Park, Winchester, Hants.,
1 ASPDEN, H.: Discussion contribution, Proc. IEE,
1958, 1O5C, p. 359 [See [1958a]
HAMMOND, P.: 'Electromagnetic energy transfer', ibid., 1958, 105C, p. 352
ASPDEN, H.: 'The theory of gravitation' (Sabberton Publications, Southampton,
1966). See [1966a]