There is no such thing as a singularity.
By Michael Bishop
The stringy resolution to the black hole information paradox suggests to me that there is no longer any need to invoke the pathological (even malicious*)concept of a singularity. I would hazard to guess that when a black hole forms, be it in an accelerator or by stellar collapse, that it always begins with a very small (possibly even Plank scale) horizon forming when the energy density 'enclosed' by by a given area exceeds a critical value. In the case of stellar collapse, I would hypothesize that one or many very small horizons form, evaporate via Hawking radiation, and sometimes coalesce at or very near the center of the massive neutron star, and in-falling matter causes the horizon to grow, eventually consuming the neutron star. At no point is there any matter 'inside' the horizon, but is all trapped on the stringy horizon. The need to invoke a singularity, which cannot be observed (according to the theory that predicted it) never arises. It is a situation reminiscent of the luminiferous ether, and Occam's razor can be put to use once again.
The dynamics occurring inside a massive neutron star as the first horizons form would no doubt be very interesting, possibly with shock waves facilitating the creation and possible evaporation of many small horizons, but with no large-scale shock wave like that which causes a supernova explosion, as nothing bounces off a horizon. In the case of very massive neutron stars, one might even have 2 or more macroscopic horizons for a brief period before they coalesce. These events would no doubt have a unique signature to a gravity wave detector, and and possibly even the spectra of quasars, gamma-ray bursters, and supernovae, and may also have a signature within the energy spectra of cosmic rays.
There are no doubt those who may think that the dynamics occurring 'inside' a horizon is a subject best left to mystics, as they are unobservable, but I, being of scientific bent, believe we should leave no stone unturned, no volume of space unexamined, and no Area of Information unread. Classically (by which I mean General Relativity + the Standard Model), the matter at a horizon would collapse into a singularity, but my premise is no singularity, so what happens, and why? Assuming that there is actually a volume enclosed by a horizon (as opposed to a manifestation of Leonard Susskind's Holographic Universe), the obvious question is 'What's holding it up?'. I would hypothesize that it may be a form of dark energy, akin to that which is causing the universal expansion to accelerate; If it can blow a universe to pieces, it may be able to hold up a few (million) stellar masses. Susskind's Holographic Universe suggests that it may be that an interior governed by Standard Model + General Relativity + Dark Energy is mathematically equivalent to a stringy 2-dimensional horizon, which may have some very interesting, even tantalizing possibilities. In an interior governed by Standard Model + General Relativity + Dark Energy, one may wonder what would things look like inside the horizon? Classically, the spacetime within a sphere is everywhere flat, so what would the horizon look like from the inside? For some reason my instincts suggest anti-deSitter space. What would it look like from the inside as the horizon approaches due to Hawking radiation shrinking the horizon? An anti-DeSitter horizon approaching one may look like an accelerating expansion. Hmmmm.
In my opinion the concept of a singularity residing at the center of a black hole has one unaesthetic quality; According to the theory that predicts the singularity, it cannot be observed, as the escape velocity from the direction of the singularity always exceeds c, and in fact the only way to observe it is to come within direct contact with it, which means the death of the observer or destruction of the measurement apparatus. In short, for a singularity, measurement = death or destruction. This seems to me to be rather unscientific, to say the least.
“Subtle is the lord, but malicious He is not.” -Albert Einstein, 1921
“Only a Boltzmann Brain could see a singularity” Michael Bishop, 2010
