Around ten years ago, Mathur proposed the "fuzzball theory" to describe black holes. The fuzzball theory defies the classic description of a black hole, whereby an enormous ball of matter gravitationally attracts itself so strongly that it gets smaller and smaller, until eventually all that mass encompasses a single point. In other words, a singularity.
The fuzzball theory instead is derived from string theory and suggests that black holes are actually spheres, made up of cosmic strings, with a definite volume and not a single point in space. The event horizon, or edge, of the black hole wouldn't be exactly defined. Instead, it would be "fuzzy". Like a fuzzball.
But when a group of researchers played around with this theory, it turned out that they were actually playing with fire. They created a theory responsible for black holes' destructive reputation called the "firewall theory." It suggests that anything that tries to cross the event horizon will encounter a flaming wall of high-energy obliteration. Nothing can pass through. All will be incinerated. You can see why black holes suffered a bit of a negative reputation after this theory came to light.
Fortunately for black holes everywhere, Mathur and his team have also been toying with the fuzzball theory, and their results (found on arxiv) disagree with the firewall theory. Instead of a fiery ball of destruction, they say that black holes are more like galactic copy machines. Black holes create near-perfect holograms of anything that touches their surface.
Their theory suggests that if the Earth were consumed by a black hole, you wouldn't even notice! (And, yes, you'd still have to go to school/work). For this theory to stand, it isn't just black holes that are holograms but possibly also the universe. (Take a deep breath, it's a lot to take in.)
A "near-perfect" hologram is an important disclaimer. There is a hypothesis in physics called "complementarity", which was originally proposed by Leonard Susskind in 1993. Complementarity basically concludes that a hologram on a black hole, like the one that Mathur describes, can only be possible if it is a perfect replica of the original matter. Unfortunately, mathematicians and physicists both agree that it is impossible for perfect holograms to form on the surface of a black hole.
So Mathur sidestepped this minor detail by saying that the hologram is "near-perfect". He argues this by saying “There’s no such thing as a perfect black hole, because every black hole is different.” Each black hole is made by different matter and information falling into it (therefore, each black hole is unique and that's what makes it a beautiful, sparkly snowflake). With this modification, the mathematics is possible.
So, we have two conflicting theories. One states that black holes destroy all that they touch. The other states that black holes recreate everything that touches them as a hologram. The competing theories can't both be correct.
“If the surface of a black hole is a firewall, then the idea of the universe as a hologram has to be wrong,” Mathur said. So, it's just a fight to establish the fundamental nature of the universe.
Fortunately (or unfortunately depending on your perspective), physicists won't be taking to the gladiator ring to establish the dominant theory.
"It's not that kind of disagreement," Mathur laughed. "It's a simple question, really. Do you accept the idea of imperfection, or do you not?"