My researches had always been focused on gravitation theories, general relativity in practice. Its inventor was Albert Einstein, which you can see in the picture looking perplexed at mercury, while revolving round the sun.

Untill the last few years, these was intended mainly to understand further aspects of quantum field theory in a curved background. Then black holes went to capture me (and many others), with the classical theory till to arrive at issues involving the quantum theory, in some of its very fundamental aspects. The link below will bring you to my lectures on black holes, as a (hopefully) useful introduction to the subject.
The black holes ask physicists a lot of questions:

Lectures  on  Black Holes

• "Why you (physicists) think we (black holes) have to exist ?"
• "Why should we radiate away the stuff that made us ?"
• "Can we reach a quiescent state ? (we don't like to explode!)"
• "Are you sure we like to eat that information meal ?"
• "We don't care about unitarity! (no question)"
• "Why you think we are disordered ? (with apology)"

S=¼A

where A is the area of the surface known as the event horizon, as measured in units of Planck's area (each around 10^66 cm^2, the square of the Planck's length). So, a solar mass black hole roughly has (100000000000000000000000000000000000000)^2 degrees of freedom per square centimeter of the horizon, much larger than that of the matter that collapsed to form the black hole. This is why we think there must be a large contribution of gravitational entropy, even if we dont know exactly what this means.
Of course, even such large numbers can be obtained in QFT. What is hard to obtain in precise form, is the area law, that entropy scales with area rather than spatial volume. Moreover, the entropy formula for large masses typically is a quadratic function of the mass, so the density of states increases as fast as EXP(cM*M). This is by far faster than the density of states of any known matter configuration. For example, the greatest entropy in a given volume and for a given temperature, is that of black body radiation, which increases with the power ¾ of the energy.
The known class of theories which may have such a large densidy of states are 2D conformal field theories, of which the string is a well known realization. So the idea is that the collective coordinates of the horizon are quantum fields, to be governed by a 2D conformal field theory.
This is what i'm working out. Let me explain some line of thought in this direction.