Abstract: | Human history is rich in models of the universe, though only a few passed the verification tests for limited times. Starting with the geocentric, then the heliocentric and finally, the widely accepted ΛCDM. While the latter is a mathematically and physically sophisticated model, it relies mainly on inflation, dark matter and dark energy. These, however, are still serving as mathematical terms, with no evidence for their existence in nature. And as if it were not enough, recent observations confront the model, emphasizing the necessity to look for alternatives. Recently, the UNIcentric Model of the Observable UNiverse (UNIMOUN) was proposed, which relies on numerical solving the GR field-equations in combination with HD and using a new time-dependent metric to follow the time-evolution of the spacetime's topology during the big bang and thereafter. Based thereon, UNIMOUN predicts that: • The observable universe was born in a flat spacetime environment and will ultimately diffuse out into the large and flat parent universe. • The progenitor of our Big Bang was of a measurable size, and its explosion took off in our neighbourhood. • The energy density of matter in the universe is upper and lower-bounded. • Big bangs are neither singular events nor invoked by unknown external forces, but they are common self-sustaining events of the parent universe. • The progenitors of the BBs are formed through the merger of cosmically dead neutron stars that turned into invisible Bose-Einstein condensates, made of purely incompressible entropy-free gluon-quark superfluids and embedded by flat spacetimes |