Spaghettification - Singularity is just energy? So... as matter falls into a black hole the tidal forces tend toward infinity as you get closer to the singularity.
These tidal forces overcome the bonds between atoms, then the bonds between nucleons etc. etc.
Has there been any research to indicate whether or not it is possible that these tidal forces get so strong that they break the fundamental building blocks of matter (be that string or otherwise). Then you would have a signularity that is purely composed of energy, which gets over the whole compressing mass into such a small volume thing.
I thought about this the other night and I couldn't immediately think of any fundamental reason to dismiss it. However, it seems slightly too obvious for it to have never been looked into.
 A: Thinking about the singularity as a lot of mass in a tiny volume is a popular science simplification. When you do the math of the Schwarzschild metric right, you can find that while the singularity corresponds to $r=0$ in the usual coordinate system, the actual geometry makes it more like a surface than a point. This is also a spacelike surface, something more akin to a certain time rather than a place. As it is approached tidal forces go to infinity, but regardless of whether particles are disrupted or not, the remnants end up at the singularity.
Models of the quark-gluon plasma give some evidence of how it heats up as the singularity is approached. There have been proposals that strings unwind to form "fuzzballs" but these are still black holes with singularities (and remain rather speculative).
In the end, the singularity is not composed of matter or energy. The singularity is not even a proper place, but a limiting state reached by infalling stuff. It is not made of anything.
A: If fundamental entities (strings, point-like particles, or whatever structure) could be torn apart then they aren't fundamental anymore. So if particles get torn apart inside a black hole then that means there are more fundamental structures.
These structures will just stay what they are inside the black hole. As these structures have a mass, they have energy. So there is only mass (or energy) inside the black hole. Maybe all mass is converted into photons (due to a mutual annihilation of elementary particles), which seems to me the closest to viewing the content of the black hole as pure energy (when you consider photons as pure energy)
