Why can we see darkness?

[C C]

Backtracking to the second part of the OP just briefly...

[...] And yet I see darkness quite clearly. If I drive up to a store and the lights are out, I know it is closed because I see it is dark inside. If I look into a deep hole in the ground, I can see the darkness inside. Even when I enter a completely dark space, I can see the blackness in front of me. It is a distinctive color telling me it is dark. I can see shadows and silhouettes and the clear night sky and even black holes. [...]  We can see the non-physical absence of light just as clearly and unmistakeably as we can see its physical presence because of the relational property of contrast between the two.

Yah, our representation or private manifestation of an external tunnel would indeed be black or dark. But there are other regions of the EM spectrum passing through what seems to be a "dark space" to us, that the eyes can't detect. We can see things in the visible-light brand of darkness when wearing infrared googles. So the blackness or the darkness isn't a physical absence of all waves, it's just a mental depiction for us resulting from our photoreceptors lacking the capacity to be stimulated by radio waves, ultraviolet, etc. 

So to me this suggests a fundamental error about what it means to see. Seeing is not just light entering the eye. It is the phenomenal visibility of any datum change whatsoever.

Yah, the sensory information has to go beyond the eye and reach the brain to be transformed into illumination and a "showing" and alteration of whatever. The mindless or non-conscious way that things exist outside of neural processes really isn't even darkness and silence, since black is usually extended (a featureless image). One could probably zero in on a phenomenal black pixel and it would acquire dimension. Absence of everything (what pertains to the usual non-consciousness of matter) actually wouldn't even entail a manifestation of blankness. That's still "something" for a brain, that it uses to represent with, and wouldn't apply to the general, mindless be-ing of a physical universe. The latter would lack an extended presentation of itself even as darkness (and silence).

[Magical Realist]

The mindless or non-conscious way that things exist outside of neural processes really isn't even darkness and silence, since black is usually extended (a featureless image). One could probably zero in on a phenomenal black pixel and it would acquire dimension

That we experience darkness as spatially-extended and pervasive struck me as interesting last night. Even though it may be completely and continuously opaque thruout itself, it is yet conceived as present all around us and not in our own eyes like when we close our eyes. That suggests that like the luminosphere or light bubble I have elsewhere mentioned it carries spatiality inside of itself via our bodily motion within it. We can as easily move around in it as when there is light.

The other kind of invisibility or non-luminescence we experience---as the transparence between the 3-D images inside the light bubble--is also spatialized as physically-objective space itself. An absolute emptiness or "absence" that nevertheless somehow also contains all physical things even though physics assures it is really a teeming plenum of quantum energies. It is the stubborn Newtonian assumption on which the mechanistic model of transiting photons and waves is founded. This notion of absolute space. Light defined as a transmission across the gaps of an invariant and self-identical space instead of as an omnipresent and self-interrelating information field.

I believe all these abstract and reified properties we describe the world with have their origin in the phenomenal qualities of the mind--from the psychic "dreamstuff" out of which the world beyond is both imagined and sensed. They form the intuitively-felt yet unconscious template that instantiates a structured and presentational physical reality around us. It is thru these qualities that the world is mediated for us and made manifest as if already "there" and in-itself. But the world is never just "there" and given to us. It is always being made anew around us, never a static thing in itself but a shapeshifting amalgam of unmediated albeit projected phenomenal qualia. And the whole thing, the common thread that knits this whole panoramic movie together, is Time.