Presence Is Not the Same as Visibility

Visibility is not a complete test of presence.

The aurora makes this easy to see.

Auroral activity can occur while a particular observer cannot see it because the observer is at the wrong latitude, the sky is too bright, clouds intervene, light pollution interferes, or geomagnetic conditions place the visible display elsewhere.

The phenomenon and the conditions of observation both matter.

That distinction is useful beyond astronomy.

Something may be available in a situation without being visible from our current position.

A pattern can be present before we have language for it.

A possibility can exist before anyone in the room notices it.

A person's effort can be real without being visible to the person judging the outcome.

This should not be turned into a mystical proof that whatever we imagine is secretly present.

Absence of evidence can sometimes be evidence of absence.

The point is narrower.

Observation is conditional.

What we can see depends partly on where we stand, when we look, and what makes seeing possible.

Presence and visibility are related.

They are not identical.