What physical principle necessitates that the intrinsic luminosity (L) of an outshining supernova must be monumentally large?

Answer

The inverse square law (F {L}/d^2) applied over vast cosmic distances

Detectability of these extremely bright events across billions of light-years confirms their immense intrinsic luminosity, as the observed flux is heavily diminished by the inverse square law over distance.

What physical principle necessitates that the intrinsic luminosity (L) of an outshining supernova must be monumentally large?
galaxyastronomystarssupernovabrightness