Objects appear smaller as distance increases due to the decreasing number of photons reaching the observer's eye, which can render them invisible to human sight at great distances. While visibility to the human eye diminishes, theoretically, objects remain detectable if one waits long enough for photons to reach them, assuming no intervening obstacles. This detection is contingent on the conditions of the universe, particularly if it were not expanding. The discussion highlights the distinction between visibility and detectability in the context of distance and photon interaction. Understanding these concepts is crucial for exploring the limits of perception in physics.
