According to our greatest understanding of the Universe, if you voyage back in time as far as you can, about 13.8 billion years or so, you will finally reach a singularity, a super-thick, hot, and energetic point, where the laws that rule space-time collapse.

Despite our best efforts, we can't spy past that singularity to understand what caused the birth of our Universe - but we do know of only one other example in the history of our Universe where a singularity survives, and that's only inside a black hole. And the two occasions might have more in common than you have ever thought, as physicist Ethan Siegel explains at Forbes.

It might sound a little foolish, but, as Siegel says, from a mathematical viewpoint, at least, there's no reason that Big Bang couldn't have been the outcome of a star collapsing into a black hole in an alternate, four dimensional universe.

Actually, the idea was first suggested by theoretical physicists at the Perimeter Institute and University of Waterloo (PI&UW) in Canada back in 2014, and regardless of physicists' best efforts, not even a single one has been able to rule itout.

As a result let's step back for a second here. What we know about the Big Bang so far is that, instantly after the singularity, our Universe started expanding. Within a hardly any fractions of a second, it suffered a quick period of inflation, growing in size by around 1026, before decelerating again and expanding more regularly.

What we understand about black holes is that, in our three-dimensional Universe, black holes grow two-dimensional event horizons - which basically mean that they are enclosed in a two-dimensional frontier that makes the 'point of no return' for matter.

Artist's impression of what that might look like:

What the Big Bang and black holes have in common is that they are the simply two cases of a singularity that we understand of in the Universe. (A singularity mostly just means a point where the laws that hold our Universe no longer work.)

To the best of our understanding, our Universe is governed by two sets of rules: quantum mechanics for all the trivial stuff like particles; and general relativity for all the bigger stuff, like planets, stars, and you and me.

If you crunch the numbers, black holes confront these rules, because their event horizons are bigger and better than can be clarified by the performance of the particles inside it.

"The point that black holes in our Universe are much more enormous than this isn’t a difficult problem," explains Siegel.

"It purely means that the laws of physics that we know collapse at the singularity we analyze at the center. If we ever want to define it accurately, it’s going to take a union of general relativity theory with quantum. It’s going to need a quantum theory of gravity."

For now, yet, we do not have that 'theory of everything', so our knowledge of black holes stops at the singularity – similar to our understanding of the Universe.

Knowing that, three physicists from the PI&UW (Perimeter Institute and University of Waterloo) proposed two years ago that the dual singularities could be one and the same - possibly our Universe was born out of the singularity of a much bigger black hole.

Or, to put that another way, perhaps our Universe is the three-dimensional packing around another universe's event horizon.

"In this situation, our Universe eruption into being when a star in a four-dimensional universe warped into a black hole," a Perimeter Institutepress release clarified back in 2014.

Mathematically talking, this holds up.

While we can't estimate what happens with a black hole's singularity, what we can estimate is what happens on the edge of the event horizon - and it ties up pretty sound with what happened at the birth of our Universe, Siegel added.

"As the black hole first formed, from a star’s core collapsing and imploding, the event horizon first derived to be, then quickly expanded and continued to develop in area as more and more matter constantly to fall in.

If you were to put an organize grid down on this two-dimensional packaging, you would discover that it originated where the gridlines were very near together, then stretched rapidly as the black hole grew, and then expanded more and more gradually as matter fell in at a far lower rate. This matches, at least theoretically, what we detect for the expansion speed of our three-dimensional Universe."

Of course, this whole indication remains a hypothesis until we have some computable way of unification the laws of quantum mechanics and general relativity, and looking past a singularity.

But, until then, the exciting thing to consider is that, based on this idea, there's no reason that our Universe couldn't be spawning new two-dimensional universes each time black holes are born. "As wild as it sounds, the answer seems to be maybe," writes Siegel. Oof.

We can't wait to finally get that ‘theory of everything’ so we can start to test some of these big concepts out.

You can hear more about the black hole forming our Universe supposition in the video given below, and read their full paper on arXiv.org.

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