Black holes could be like a hologram, where all the information is amassed in a two-dimensional surface able to reproduce a three-dimensional image. In this way, these cosmic bodies, as affirmed by quantum theories, could be incredibly complex and concentrate an enormous amount of information inside themselves, as the largest hard disk that exists in nature, in two dimensions.
For scientists, black holes are a big question mark for many reasons. According to the first theory, they would be simple bodies without information. According to the other they would be "the most complex existing systems" because they would be characterised by an enormous "entropy", which measures the complexity of a system, and consequently would have a lot of information inside them.
To study black holes, the two authors of the research, Francesco Benini (SISSA Professor, ICTP scientific consultant and INFN researcher) and Paolo Milan (SISSA and INFN researcher), used an idea almost 30 years old, but still surprising, called the "holographic principle". The researchers say: "This revolutionary and somewhat counterintuitive principle proposes that the behavior of gravity in a given region of space can alternatively be described in terms of a different system, which lives only along the edge of that region and therefore in a one less dimension. And, more importantly, in this alternative description (called holographic) gravity does not appear explicitly. In other words, the holographic principle allows us to describe gravity using a language that does not contain gravity, thus avoiding friction with quantum mechanics".
What Benini and Milan have done "is apply the theory of the holographic principle to black holes. In this way, their mysterious thermodynamic properties have become more understandable: focusing on predicting that these bodies have a great entropy and observing them in terms of quantum mechanics, you can describe them just like a hologram: they have two dimensions, in which gravity disappears, but they reproduce an object in three dimensions".
"This study," explain the two scientists, "is only the first step towards a deeper understanding of these cosmic bodies and of the properties that characterise them when quantum mechanics crosses with general relativity. Everything is more important now at a time when observations in astrophysics are experiencing an incredible development. Just think of the observation of gravitational waves from the fusion of black holes result of the collaboration between LIGO and Virgo or, indeed, that of the black hole made by the Event Horizon Telescope that produced this extraordinary image. In the near future, we may be able to test our theoretical predictions regarding quantum gravity, such as those made in this study, by observation. And this, from a scientific point of view, would be something absolutely exceptional".
In one strict sense, it mean little. The same laws of physics you've been living with for your entire life would seem to remain exactly the same. Your house, dog, car, and body would keep appearing as three-dimensional objects, just like they always have.
But in a deeper sense, this discovery would revolutionize our existence on a profound level.
It doesn't matter much for your day-to-day life that the universe was formed 13.8 billion years in a sudden, violent expansion from a single point of matter. But the discovery of the Big Bang is instrumental for our current understanding of the history of the universe and our place within the cosmos.
Likewise, the bizarre principles of quantum mechanics — like entanglement, in which two distant particles somehow affect each other — don't really change your daily life either. You can't see atoms and don't notice them doing this. But these principles are another basic truth that tells us something utterly unexpected about the fundamental nature of the universe.
Proving the holographic principle would be much the same. Living our normal lives, we probably won't think much about the peculiar, counterintuitive fact that we live in a hologram. But the discovery would serve as an important step toward fully understanding the laws of physics — which dictate every action you've ever taken.
