In Second Life, Piet Hut of Princeton's Interdisciplinary Studies Institute for Advanced Study is known as Pema Pera. The two identities are intimately related, for Hut is one of the driving forces behind MICA, the Meta Institute for Computational Astrophysics, a group dedicated to creating simulations of comsmological phenonena in virtual worlds. Why? In the past, he explains to Tish Shute of UgoTrade,
[S]imulations were where scientists spent years and visualization was an afterthought, a few pictures in a journal, never the right tools to really mine the data, not enough time, money, tools. So we can use virtual worlds to start with visualization and then have the simulations follow.
Working with Japanese scientists and metaverse developers, MICA recently created an N Body Simulation of Newtonian mechanics in Open Sim, the open source spin-off of Second Life. Here's a video of it in action, an impressively complex simulation (even with "Final Countdown" as the background music.) [Update, 8/12: Piet writes in to credit the video's producers, Jeff Ames and Adam Johnson.]
Interested in reading more about the technical/theoretical background? UgoTrade exhaustively reports from Japan, Open Sim, and Second Life, and interviews all the players involved. MICA also holds regular "coffee time" discussions in Second Life as well-- details here.