Why do we have vertigo?

The vertigo comes from the difference between movement and vision, the brain receiving conflicting information.
This may be a physical state or a phobia, the acrophobia.

This sense of rotation that come from of a difference between what one sees and what the vestibular system feels, differs from acrophobia, a state of anxiety when one faces the emptiness.

Vertigo

The vestibular system perceives a movement which is different from the information that the vision should sent to the brain. This dissonance produces a sensation of rotation and nausea.

This may be a disease of perception but happens also with virtual reality systems.

Acrophobia (virtigo of heights)

It is a form of phobia, a condition that can not be controlled although the reason say there is no risk.

Physiologically it is also a dissonance between what we see and the vestibular system, which must be consistent with the movements that we perform. When one moves, objects around us change position. When one advances, they grow and become smaller when one goes aways.

In height, vision presents a static picture, the landscape is embraced as a whole while also going to make movements. The displacement of the body, perceived by the vestibular system of the inner ear does not accord with the environment seen that is not moving.

For the brain, the risk inherent in the emptiness prevails over information on the movements. Follows an uncontrolled reaction of panic, nausea, sweating, tension ...