Why light fades over distance?

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Light fades over distance due to the inverse square law, which states that the intensity of light decreases as the distance from the source increases. Although each individual photon retains its energy, the number of photons reaching a given area diminishes with distance. This phenomenon explains why distant objects, like type 1a supernovas, appear fainter. The reduction in photon density results in a lower observed brightness. Understanding this principle is crucial for interpreting astronomical observations.
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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?
 
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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"
 
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