This thread is about a Bill Unruh article ("Where are the particles created...?") and an article on the same theme by Unruh and Ralf Schützhold ( http://arxiv.org/abs/0804.1686 "Origin of particles in BH evaporation") and Schützhold's participation in the LQG-BH workshop taking place this month at the University of Valencia. This page has photos and brief CVs for both Unruh and Schützhold: http://royalsociety.org/page.asp?id=7185 The Unruh article is here: http://pos.sissa.it//archive/conferences/043/039/QG-Ph_039.pdf He didn't post it on arXiv, but it is free for download at PoS (proceedings of science). It's interesting. I guess most people know about Unruh discovering the Unruh temperature and Unruh radiation about the same time (1970s) that Hawking came out with the Hawking temperature and Hawking radiation. Unruh has remained active and creative. The PoS article is based on a talk he gave at a QG conference in the summer of 2007. It cites his work with Schützhold. In this paper Unruh uses a hydrodynamic toy model of a black hole to develop intuition and useful concepts---he thinks in a concrete physical way about BH radiation through this fluid flow model. The speed of sound in the fluid plays the role of the speed of light. What called my attention to this is the fact that just a day or two ago the organizers of the March 2009 University of Valencia workshop on Black Holes and Loop Quantum Gravity added Schützhold to their speakers list. http://www.uv.es/bhlqg/ http://www.uv.es/bhlqg/speakers.htm Abhay Ashtekar Martin Bojowald Alejandro Corichi Bianca Dittrich Jonathan Engle Amit Ghosh Viqar Husain Jerzy Lewandowski * Alejandro Perez Jorge Pullin Hanno Sahlmann Ralf Schuetzhold Madhavan Varadarajan In the past two years there have been a number of new LQG BH results---Corichi, Engle, Ghosh, Sahlmann have been principals in that. Bianca Dittrich has co-authored with Loll about BH in CDT---I can't say but it's possible she could report on some Triangulations BH research. In any case knowing the recent work of some of the speakers one can make a rough guess about what new stuff will be covered in the workshop. BTW Schützhold is fairly young---PhD Dresden 2001, postdoc at British Columbia where Unruh is, professor 2008 at Duisberg-Essen. Schützhold's name was unfamiliar and caught my attention. So this goes back to what William Unruh was saying in 2007. Let's look at that paper.