So I was reading a couple threads today, one current and one long dead, and rather than resurrect or hijack, I’m starting a new one.
Given that photons and other massless particles have effective “mass” of m=e/c[sup]2[/sup] (since e=mc[sup]2[/sup]), and “momentum” p=e/c (since p=mv, and by substitution ec/c[sup]2[/sup]=e/c)…
My question is this:
Assuming that a photon sail is an achievable concept, would it be preferable to make it reflective, thus bouncing the photons back away from the intended direction of travel, or light-absorbent, thus fully absorbing the momentum and energy of the photons?
Maybe an absorbent back with a reflective surface facing it from the front, so that radiated heat is directed to the rear for extra thrust? Or would that be the same effect as reflection, and lose efficiency from the extra mass of the reflective layer?