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Some Cosmologists have speculated that the Universe formed from the debris ejected when a four-dimensional star collapsed into a black hole a scenario that would help to explain why the cosmos seems to be so uniform in all directions.

It is also difficult to explain how a violent Big Bang would have left behind a Universe that has an almost completely uniform temperature, because there does not seem to have been enough time since the birth of the cosmos for it to have reached temperature equilibrium.

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 Cosmologists modeled 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.

The 3D Universe we live in might be just such a brane — and that we detect the brane’s growth as cosmic expansion. “Astronomers measured that expansion and extrapolated back that the Universe must have begun with a Big Bang.

The models also naturally explains our Universe’s uniformity. Because the 4D bulk universe could have existed for an infinitely long time in the past, there would have been ample opportunity for different parts of the 4D bulk to reach an equilibrium, which our 3D Universe would have inherited.

Has this theory been tested?

Source: http://www.nature.com/news/did-a-hyper-black-hole-spawn-the-universe-1.13743

Noah
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Being a layman, probably better answers are also possible. Here is what I know/think.

The problem is, that there is no evidence. The LHC is actively on the search to find extra dimensions, without any result (until now).

The branes are beyond SM things, i.e. there are a lot of papers about them, but no experimental data proving or disproving them.

A theory is only acceptable, if it can predict things, and if it is falsifiable. Thus, no evidence exist against it, but it predicts experimentally verifiable things. Until that, it is only a hyphothesis. This hyperblackhole thing falls in this category, too.

There is a (not very strong) argument against it: recently the WMAP data and other experiments were used to measure the curvature of the Universe. The surprising result was that it is flat - below the measurement precision. It is a (not very strong) argument for that the Universe is infinite in size, and it is not on a 4D sphere. But every measurement has a finite precision.

A similar situation already happened in the history of the physics. If you look around (i.e. make an experiment), you can see that the Earth is flat with zero curvature. But actually its curveture is not zero, but very small and your free eye experiment is not enough accurate. To find its exact curvature and to know that it is sphere, you need more accurate experimental data. In the case of the Universe, we don't have this. The few results we have show that the Universe is flat, or if it has a spherical geometry, its radius is at least 300 billion light years (reference).

The WMAP experiment and others are a stronger argument as the free eye experiment was for the flatness of the Earth: actually there were 3 independent, significantly different experiments with corresponding results:

  1. the WMAP
  2. 1a supernovas
  3. sorry I've forgot, if somebody knows and edits here, thank you very much

If the Universe is flat, it probably disproves that brane model you've read.

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peterh
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