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Physics + MathPhysics & Math

Collapsing 4D Star Could Have Spawned Universe

ByAllison EckNOVA NextNOVA Next
Some astrophysicists propose that the universe was formed by a collapsing 4D star.

There could be a gaping hole in the Big Bang theory. Or rather, a giant, colossal black-hole caused by the collapse of a four-dimensional star.

One of the main problems with the Big Bang is that the temperature of the universe is nearly uniform. If a “big bang” event had created the universe, then according to some explanations, there hasn’t been enough time between then and now for it to have reached that temperature equilibrium. Here’s Zeeya Merali writing for Nature News:

To most cosmologists, the most plausible explanation for that uniformity is that, soon after the beginning of time, some unknown form of energy made the young Universe inflate at a rate that was faster than the speed of light. That way, a small patch with roughly uniform temperature would have stretched into the vast cosmos we see today.

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But the Big Bang, as it’s envisioned, was so chaotic that few people had any idea what or from where that initial homogenous patch could have come from.

So 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":

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.

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.

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:

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Illustration by NASA

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