It would have to be simple.

A default.

Here. Picture this.

Waves of fluctuating equal and opposite relativity of dimension collide. Peaks and troughs. At the intersection of troughs, the change in space is negative and persistent.

A negative change in dimension, the negative of something, is nothing. Negative change in dimension is negative energy.

A wisp of smoke collides with another wisp of smoke. Where the wisps intersect, the crease in the air is more pronounced. The area in between is more pronounced, as well.