Did the universe begin with a black hole in a higher-dimensional reality?
Depending on your level of cynicism, that question sounds like either an exciting idea or something you might hear from the stoner in your social circle. The reality: It's a bit of interesting but speculative science from physicists attempting to solve a somewhat obscure problem in cosmology. Despite media coverage in Nature (later picked up by PBS and io9), the paper describing the research is unpublished and doesn't correspond to existing observations. It's still an interesting idea—one that can help us understand the study of our universe.
Over the past century, astronomers discovered that the universe is expanding. In the distant past, matter was compressed into a hot, opaque plasma with no stars. It expanded into what we see today, with the distance between galaxies growing larger with time. These observations and their theoretical description are known as the Big Bang model, a remarkably successful explanation for a wide variety of phenomena.
However, there's a limit to our knowledge. Because the universe was opaque during its earliest times, we have only indirect information about what happened then. The more distant an object is from us, the farther back in time we're seeing it, since light takes time to travel. We eventually reach a point where everything in the observed cosmos may have been compressed into a single point—but that's not something we can see.
The infinite compression—called the Big Bang singularity—is problematic for many people, and for good reason. While infinity is fine in math, it causes some problems in physics, so a lot of researchers have tried to remove the singularity.
That's the motivation for the recent paper by Razieh Pourhasan, Niayesh Afshordi, and Robert B. Mann. Their proposal begins with the hypothesis that our universe is actually embedded in a higher-dimensional reality, much as a photograph or (more appropriately) a hologram compresses three dimensions onto a two-dimensional surface. The force of gravity extends into the dimensions we can't observe, but light and matter are confined to the four dimensions of space and time that we know.