Which solution dictates *where* we can look versus *how bright* sources appear?

Finite age dictates *where* we can look (horizon); expansion dictates *how bright* things look

The two primary resolutions to Olbers’ Paradox work in distinct yet complementary ways to ensure the sky remains dark. The finite age of the universe establishes a spatial limit based on time, defining the observable horizon; it fundamentally determines which sources of light are even included in our observation set—the *where*. In contrast, the ongoing expansion of space affects the nature of the light that does reach us from within that horizon. The expansion causes cosmological redshift, diminishing the energy and thus the perceived brightness of the light received from those visible but distant galaxies—the *how bright*.