Why light fades over distance?

[smuga]

According to our observation light fades over distance.
Please explain to me why light fades over distance in space (type 1a supernovas are observed fainter when they occur farther). Why is that since every individual photon’s energy is constant through its movement through space? Am I right?

 

[Doc Al]

While each individual photon's energy is constant, the number of photons per unit area diminish with distance according to an inverse square law. See: http://hyperphysics.phy-astr.gsu.edu/HBASE/vision/isql.html"