Afther listenign almost all the confrences of strings 2008 that I mentioned in the earlier post I had to make a break into blogging because of a few diferent reasons (computer virus, preparing people for september exams and so on). In the while I have ahd time to read a few papers and a few books, the books not mainly about quantum gravity related things.
In all this time the most interesting source of news has, umdoubtly, been the LHC. Oo one side because of all those people worring about the end of the world black hole. On the other the bets about what will be discovered when the machine at last would collide protons.
About the first subject I have readed a few arxiv articles about evaluationof the possible danger of black holes. The subject depends (once Hawking radiation is discarded as a way to destroy the black hole, a very unprobable thing) on classical general relativity and rates of acrretion and things like that. I must say that I had no previous knowwledge on the subject and I have found it interesting althought certainly a bit far from the usual target of cutting edge theoretical physics. As a side effect I have had to reconsider the precise meaing of the grouth of a black hole. It could seen obvious, but in fact it isn´t. The classical scenary is to calculate the rate of accretion (using Bondi theory or whatever) and later relay on the classical laws of black holes stated by Hawkings, specially the one relating the icrement of area to the increment of mass. But the reality is more complex and to get a precise mathematical tratement one must go to the theory of dynamical and isolated horizonts. I´ll write a post about the details in the other blog as soon as possible.
But the LHC is important not because of the black hole and similar catastrofic secenaries (all of them very unlikely, to say the less, people worried about real problems have a lot of better places to wath for). The real interst is if it will find the higgs bososn, supersymmetry or whatever. In fact it seems that it has benn an increasing amount of papers diving into the data of the tevatron with the aim of profiling the best chances for the LHC finding new physyc. In one of hat scenaries there was a good chance tht in the first five days, or so, of activity (that is, colliding activity) of the LCH the supersymmetry could be found. That was supposed to be as soon as the next week (althought probably the actual annalisis of data would require most time). I was, partially, waiting that notice. It would be certainly a relly good notice for a post (afther all it would be the best new in particle physics in around 30 years). But unfortunatelly it seems that ther has been a somewhat serious problem in the LHC, rupture in a part of the collider has resulted in the lost of liquid hellium. It is still ot known how seriously the problem is but some people say it could mean that the LHC propgram would be dealyed untill the winter shutdown so we would need to wait a litle bit more to get relevant experimental data. If this is confirmed stil there are possibilties of getting new physic from astrophysic/cosmology. In fact this week has been seen what looks like a bridge of dark matter aaround which galaxied penetrate into regios that, untill now, where considered as giant vacua in the universe. And the GLAST satelite is working propoerly for more than a mounth so it is possible that it could find signals of WIMPS (weakly interacting massive particles) a favourite candidate of same people for dark matter constituent, or, maybe a final answer (possitive or negative) for the LQG prediction about dispersion of light speed in vacuum. In fact I had readed in a newspaper that a great gamma ray burst had been detected a week ago and I have been waitng since them to read that the GLAST had looked at it so the question could be really, reaaly, next to be answered, but, unfourtunately, It seems that the GLAST losed it, aand we must wait a litle bit more.
Anyway, as unfourtunately it seens that great news are delaying I decided to blog agin about more conventional things.