A Blow for Gravastars

[Steel]

I though this may interest the more Physics & Astronomy inclined among you.

I read a phys.org article that I found interesting today, so I dug around a little. Believe it or not, the classical black hole is far from the only suggested object that satisfies the Schwartzchild solutions of general relativity, so while black holes are perhaps the most known (and perhaps having the most observational evidence supporting them) there are a host of other suggestions, including the Gravastar (Wikipedia link here if you want a quick overview).

A quick Gravastar summary: From the bits I've read today, gravastars are an attempt to re-write a lot of black hole theory using elements of quantum mechanics, including the idea of smallest possible lengths, times e.t.c (for instance, respecting the Planck length as the smallest possible quantum of length, not something that is traditionally stuck to when talking about black holes). The result of this is that - in the Gravastar Hypothesis - when a star collapses, rather than collapsing to a singularity the matter in it instead undergoes a "phase transition" into an as yet unseen form of matter whose gravitational energy behaves similar to certain properties that we have observed here on Earth in Bose-Einstein condensates. This appears as an interior of vaccum surrounded a hard matter shell where the event horizon would be in a classical black hole (imagine a bubble). Outwardly, these have all the same properties as required (i.e. they look the same as a black hole would) but the inner workings are very different.

The long and the short of it is that this formulation solves a lot of the traditional issues with black holes, i.e the conceptual difficulty with event horizons, the information paradox, the issue with a collapse to a singularity creating almost infinite entropy e.t.c.

However, the recent detections by LIGO of gravitational waves has thrown a spanner in the works. Both gravastars and classical black holes would produce waves in a collision, however models have suggested that gravastars have a very slightly different characteristic tail-off of these waves (or ringdown from the phys.org article) than a classical black hole. The analysis of the LIGO results did not find that this difference to the expected outcome, meaning the Gravastar Hypothesis takes a big hit.

[KSK]

Interesting - thanks for posting.