Basically, a four dimensional star collapses into a 4 dimensional dies, explodes as a supernova (causing outer layers to shoot out violently while the inner layers collapse into a 4 dimensional black hole.
More details below.
(source: http://www.pbs.org/wgbh/nova/next/ph...wned-universe/ )
Canadian astrophysicist Niayesh Afshordi and his colleagues have turned to an idea first proposed 13 years ago. In that model, our 3D universe is merely a membrane—also known as a brane—floating through a 4D “bulk universe:”
Afshordi’s team believes that the universe—its stars, nebulae, planets, even us—might be that very membrane, and that its inflation might be triggered by motion through a “higher-dimensional reality.” In other words, we might be living in a brane around the event horizon of a collapsed hyperdimensional star that gave birth to the universe.Ashfordi’s team realized that if the bulk universe contained its own four-dimensional (4D) stars, some of them could collapse, forming 4D black holes in the same way that massive stars in our Universe do: they explode as supernovae, violently ejecting their outer layers, while their inner layers collapse into a black hole.
In our Universe, a black hole is bounded by a spherical surface called an event horizon. Whereas in ordinary three-dimensional space it takes a two-dimensional object (a surface) to create a boundary inside a black hole, in the bulk universe the event horizon of a 4D black hole would be a 3D object — a shape called a hypersphere. When Afshordi’s team modelled the death of a 4D star, they found that the ejected material would form a 3D brane surrounding that 3D event horizon, and slowly expand.
It’s a bold claim—but one that solves a handful of problems in fundamental physics. Read Merali’s article for more details, and watch NOVA’s “Origins: Back to the Beginning” to learn more about other theories behind the creation of the universe.