Peter wrote:
Question: If photons are stable, chargeless, massless elementary particles,
how do they react with anything?

"Stable" doesn't mean they are inert. Photons are
emitted and absorbed all the time while interacting
with other particles. I believe Hecht means that
photons don't decay over time all by themselves
(but there is some debate on that subject).
--
73, Cecil http://www.w5dxp.com