Dear Sev, first of all, a simple thing. Light in the vacuum
always moves by the speed 299,792,458 meters per second: this
fact is exactly true because of the modern definition of one
meter. The speed of light in the air is just 0.03% smaller than
the speed of light in the vacuum. Nothing ever travels faster
than light in the vacuum. Second, mirrors typically reflect less
than 100% of coming light - something like 70%. But that's not
the main problem here. Third, the energy is conserved, so you
can't produce much more "light" by putting mirrors. You can't
illuminate 100 households by having 1 light bulb and "copying"
it by mirrors. Why not? While you may increase - and almost
double - the "amount of light" that is hitting a particular
area, this fact is (more than) balanced by the fact that the
light that would be absorbed by the area occupied by the mirror
itself is not absorbed. So when it comes to the energy budget,
ideal mirrors (that reflect 100% of light, just for the sake of
simplicity) only rearrange t