This paper is available on arxiv under CC 4.0 license.
Authors:
(1) Igor Yu. Potemine, Institut de Math´ematiques, Universit´e Paul Sabatier.
So, we are interested in Robinson-Trautman metrics describing expanding spacetimes with spherical gravitational waves. Multi-soliton solutions of this type, associated with matter trapping, correspond to our Gogberashvili multiverses.
If we admit that the null matter field has some internal spin / angular momentum, there are also more general (multi-)gyratonic solutions. They give rise to rotating Gogberashvili models/multiverses.
This intriguing topic, including a thorough comparison ot two models, should be studied in more details. In particular, the harmony of transcosmic spheres should acquire more complete meaning.