Black holes play a central role in the investigation of the Universe. We are fortunate to live in an era when this has become a widely appreciated truism, both in the observational front ---with the recent historic breakthroughs from the LIGO-Virgo collaboration, and the images from the Event Horizon Telescope--- and in the theoretical front, where the study of black holes provides a unique entry into the problem of uniting the physics of the very small ---quantum physics--- and the physics of the very large ---gravitational physics. Black holes naturally excite the imagination of scientists and laypeople alike. Their mystery and fascination makes them the perfect vehicle to convey why fundamental research on the Universe, even in its apparently remotest confines, is an intensely human endeavour which, even if not of immediate practical applicability, is of paramount interest to the society at large.
Unraveling the dynamics of black holes is an extremely intricate problem, due to the complexity of solving Einstein's equations of General Relativity in the fully non-linear regime where black holes become most interesting. Big efforts have been made to tackle this problem with the help of supercomputers ---certainly an invaluable tool, but also one that has serious shortcomings: the big expense required, in time and resources, and perhaps more importantly, the 'black box' opaqueness of its outcomes, which often yield relatively little physical insight. Novel, fresh approaches to gravitational dynamics can have a substantial impact, both in terms of practical improvement and as conceptual clarification.
At the core of this proposal lies a radically new idea that has already shown its potential for simplifying several of the thorniest problems in black hole physics, while still retaining their most interesting aspects. We use the number of spacetime dimensions, D, as an adjustable parameter in the theory. Then, by considering the limit in which D goes to infinity, we find that, in many instances, the equations of the problem simplify to the extent that they can often be solved in a closed, exact form. Subsequently, corrections in powers of 1/D can be computed, which improve the quantitative accuracy of the results.
This approach not only has practical use as an efficient calculational tool. It also sheds new light on dynamical features of black holes. For instance, it has revealed that the fluctuations of the black hole horizon can naturally be separated into two classes, one of which retains the peculiar features of a black hole, while the other class is common and universal to most types of black holes. This discovery has led to the development of simple, effective theories of black hole fluctuations that have been efficiently applied to a variety of problems, including applications to the 'holographic AdS/CFT' correspondence. We expect that further new insights can be obtained in other pressing problems in gravitational physics, in particular on the appearance and significance of 'naked' spacetime singularities, and on the quantum theory of black holes.
Given the current high level of public interest in all aspects of black holes, our team has engaged in a serious effort to reach out to wide audiences, enhancing the visibility of scientists as citizens in the midst of modern society, eager to share and return to the community the fruits of their research.
