Is Our Universe a 3 Dimensional Wrapper Around a 4 Dimensional Black Hole?
A new theory points to a possible alternative explanation to the Big Bang. Our universe may have arisen from the collapse of a hyper-dimensional star in a 5 dimensional universe.
It was often reported 100 years ago that when astronomer Fred Hoyle coined the term Big Bang he was being derisive. Though he denied this it’s not hard to see why that was easy to believe. That the universe popped into existence in an explosion of space and time from a singularity, a point of infinite density and temperature seemed absurd. Over the years though, the theory had the annoying propensity of explaining a host of observed phenomena like the Cosmic Microwave Background (CMB) radiation (the after-glow of the bang), the structure of the universe at it’s largest scales, the amount of light elements like hydrogen and helium…the list goes on and on.
Some observations though required some physics gymnastics to deal with them.
- The Horizon problem in which the CMB is so uniform in temperature that a faster than light connection between spatially separated sections of the universe are required to explain this thermal equilibrium.
- The Flatness problem which arises due to the exquisite lack of curvature of the universe. To stay this flat after almost 14 billion years requires an energy density soon after its birth that is fine-tuned to 1 part in 100 trillion.
- The Magnetic Monopole hub-bub. These north or south pole-only particles should exist in profusion but none have ever been detected.
These observational problems were all dealt with well by tacking on a bizarre event to the early universe called Cosmic Inflation in which the early universe’s expansion goes into hyper-drive briefly and exponentially.
A problem that has never been satisfactorily dealt with is the singularity that preceded the big bang itself. Imagine the entire universe squished into a ball smaller than the head of a pin. Temperature and densities are so high that all laws of physics say “screw this” making predictions nigh impossible. How could the well ordered and predictable universe be birthed from something as chaotic and bizarre as this singularity? Determining what could have triggered the big bang is therefore a veil we can never pierce which kinda blows because who wouldn’t wanna know what happened before everything happened?
Scientists from the Perimeter Institute for Theoretical Physics have taken a look at this problem and claim to have neatly sidestepped this singularity problem. They think our universe may have been created on the outside of a 5 dimensional singularity in another universe. Our universe has 4 dimensions, three of which are spatial and one temporal. This theorized universe was similar (in some ways at least) but it has one extra spatial dimension.
WARNING: Don’t even try to imagine this. Thinking about moving in a direction that is at right angles to reality should only be attempted under adult artificial intelligence supervision.
Sounds deliciously wacky right? It’s not a complete flight of fancy though, at least in it’s broad strokes. It is grounded in the mathematics that is used to describe space-time in our universe. Included in this is a suite of holographic tools that can successfully translate events that occur in one cluster of dimensions into another (from 4D to 3D for example). In fact, dealing with higher dimensions is fairly trivial to do mathematically. The question is, can and do these dimensions really exist.
Here’s the best way to describe it that I’ve come across. Imagine a 4 dimensional star collapsing to form a black hole (I know, but do your best). The debris ejected from that process becomes incorporated somehow into a 3D brane around the event horizon of the singularity. This is our universe. This is analogous to a 3D black hole in our universe forming a 2D spherical surface (event horizon) around itself. This brane is expanding and…13.7 billion years later, we’re talking about it. This would make our universe essentially a 3D wrapper around the the event horizon of a 4D black hole.
The authors claim their solution does away with the problem with singularities since our universe would not ever have been inside one. It also does not require Cosmic Inflation to handle the horizon problems and others since the technicalities of a 4 dimensional birth apparently explains them away.
As fun as this theory is to contemplate there are some big red flags that should dampen your (and my) enthusiasm. This paper was published on the Arxiv server over a year ago. In that time no one has cited it, not even the authors. Such apathy is not a good sign at all. I’m not even sure why it’s in the news now. This doesn’t mean it’s total garbage but it does put it into perspective. Furthermore, this work isn’t even very original. It is merely a minor follow-up to a truly popular paper (over 200 citations) that describes what’s called the DGP model. This model says nothing about doing away with the big bang, it describes 4D gravity on a 3D-Brane in 5D space.
Image Credit: Perimeter Institute for Theoretical Physics
*Thanks to Physicist Brian Wecht for putting this theory into perspective for me