the haptic void is the term used by haela hunt-hendrix in the transcendental black metal manifesto to describe the limit (in the mathematically analogous sense) of intensity of experience, the teleological extension of intensity into a vision of god as as a perfect scream, which is the unattainable notional goal towards which black metal orients itself.
the haptic void is unattainable not just because it is infinitely far removed. it isn't a point in experience-space that happens to be unreachable, it's a topological feature of that underlying experience-space. the question of reaching it isn't just as absurd as asking how far you have to sail to fall off the edge of the earth, it's like asking how far you have to sail to fall off the edge of the map.
there is a sense in which the area that's the closest you can draw to the haptic void ("closest" although there isn't really a distance anything is from it except infinity) is the penumbra, within which it is possible to move so as to return to a different place, like a caterpillar passing through the point of liquefaction / total freedom to return to a new kind of life. this is the boundary set of the empty set or the mirror's surface.