After four years of running a virtual world, Linden Lab is finally committing to a long overdue upgrade to its physics engine. Havok 4 should, in theory, make Second Life a little less clunky by reducing crashes, minimizing lag, and improving collision detection (physical interaction between objects) and the world's actual physics. Of course, this engine is already a year old , Havok announced the newest iteration last month. [Worlds In Motion ]