Austin said,
"Jeez - even with the rather high velocity of the
photons (about light speed, maybe...?) they have
no mass, so they can't provide thrust!"

I have this cute "Radiometer" which has a four
blade vertical axis paddle wheel suspended on a
needle bearing inside a clear decorative glass
envelope, not unlike a light bulb.  When exposed
to the sun, it spins like crazy.  Light gives No
thrust you say?  Or maybe the equal but opposite
force rule doesn't apply to light?

"Aiming them *forward*, however, will strip all
atomic elements caught in the light
tractor beam down to elemental particles making
the nasty air pressure that
is in front of you disappear - & form a VACUUM to
suck the Vanagon forward!!!"
That sounds appealing too, but the way it's worked
out is that the intense rearward facing light
striking minute air borne particles causes them to
vaporize and create fog which further absorbs the
light, converting it to more heat.  On balance,
Bob's van is not only pushed forward by the
backward facing light, but pushed forward by the
heat induced localized high pressure area behind
it.
So much for Friday...