The universe is said to be currently well approximated by de Sitter space.

In theories of electro weak vacuum decay, de Sitter space and Anti de Sitter space differ by one dimension and the energy densities.

Other researchers using measurements of Higgs boson and the Top quark have produced estimates of possible eventual propagation of Anti de Sitter bubble, crossing the universe in billions of years.

Frame dragging can be represented as a difference in stress energy density.

Can Frame Dragging In The Extreme Create A Bubble Of Anti de Sitter Space?