What are vacuum samples, exactly?

I never really thought about until now.  I hate to do strings, it complicates.

The vacuum may change into three different shapes, but still maintain the absolute density of space, quite a feat. I would think a zero phase sample has symmetric shape.  A positive phase has the opposite shape of the negative phase, but still, all three have to overlap to each other the same, and maintain the density of space. The difference by which the positive shape and the negative shape is the space curvature assumed. The problem is further complicated because there is no orientation. We need a topologist, and that is not me.  But a exchange of phase is simply two samples exchanging shapes.The negative phase is more like a doughnut, zero a sphere, and positive a barbell, would work. The centers of each remain equidistant in space.