Rough Times Ahead
Clusters of conventional computers have almost replaced vector-based supercomputers among the world9s 500 biggest computing complexes, thereby tapping a computing resource with lower costs. But as
 Kirkpatrick
 explains in his Perspective, this approach brings new problems. He highlights the report by
 Korniss et al ., who demonstrate that the simulations times of the different processors can diverge very quickly, leading to temporal "roughening." As a result, it can be difficult to synchronize computations performed on many different computers. Intermittent synchronization over random distances can suppress the roughening.