We Don't Need No Stinkin' Black Holes I.

Black holes again. Some of you may recall that I am something of a fan of the allegedly crackpot theories that black holes don't really form because they evaporate first.

There are a few recent relevant papers up on the ArXiv.

My first candidate is Sean A. Hayward's Formation and evaporation of regular black holes (gr-qc/0506126). A regular black hole, as I learned, is a black hole without a singularity at the center. From the abstract:
Regular (non-singular) space-times are given which describe the formation of a black hole from an initial vacuum region, its quiescence as a static region, and its subsequent evaporation to a vacuum region. The static region is Bardeen-like, supported by finite density and pressures, vanishing rapidly at large radius and behaving as a cosmological constant at small radius. The dynamic regions are Vaidya-like, with ingoing radiation of positive energy flux during collapse and negative energy flux during evaporation, the latter balanced by outgoing radiation of positive energy flux.
In Hayward's model, an hypothesized equation of state for matter at extreme densities provides an effective cosmological constant which, in his words:
...which seems to act as a charm against singularities.
His conclusion mentions a further virtue:
Most discussions of black-hole evaporation mention a certain I-word, as a paradox, problem or puzzle. The above space-times, regular and with the causal structure of flat space-time, show that this word need not be mentioned.

To paraphrase an old gravitational adage: what goes in, must come out.

It's important to note that in this model there are things that, from the outside, look just like black holes, and can last arbitrarily long, which is handy, since objects of that sort seem common in our Universe. Of course this model only works if the equation of state at extreme densities has the desired form.


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