Researchers suggest a new origin for our universe: it is a three-dimensional "wrapping" around a four-dimensional black hole's event horizon.
13.7 billion years ago, the Big Bang led to the creation of our universe. It's a solid theory - solid enough for it to be the prevailing model that scientists base themselves on, because it explains a number of phenomena we observe in the universe.
But what caused the Big Bang? What came before it?
"Cosmology's greatest challenge is understanding the Big Bang itself," write Perimeter Institute Associate Faculty member Niayesh Afshordi, Affiliate Faculty member and University of Waterloo professor Robert Mann, and PhD student Razieh Pourhasan. But they've developed a new idea that may hold the answer.
The current Big Bang model has this cosmic eruption originate from a singularity - the center of a black hole, a place of infinite density and temperature. The three researchers took issue with this model, asking how something as structured and ordered as our universe could originate from something that defies our understanding of physics.
The researchers suggest that perhaps our universe is the three-dimensional mirage of a phenomenon in a four-dimensional universe. Consider a black hole; in our universe, a black hole has a two-dimensional event horizon (the "point of no return," where gravity becomes too powerful to possibly escape). But a theoretical four-dimensional black hole would then have a three-dimensional event horizon. In their model, the researchers believe that our universe may be the three-dimensional "wrapping" around a four-dimensional black hole's event horizon.
Did I lose you? It can be difficult to conceptualize, but mathematically, it works out. And science is filled with examples of concepts that seem absurd but are mathematically possible. In the researchers' scenario, the universe came into being outside the event horizon of a singularity created by the death of a star in a four-dimensional universe.
Now, before you say, "We already live in a 4D universe - the fourth dimension is time," let's clarify that these researchers mean four spatial dimensions. And because we have no way of conceptualizing what four-dimensional space would look like, that is why we have an incomplete picture - and consequently understanding - of the cosmos.
Of course, this simply passes the buck on the issues of the origin of the universe. Even if we know where our 3D universe came from, then where did its parent 4D universe come from? Let's hear your wildest theories.