QUO VADIMUS - MUCH HARD WORK IS STILL NEEDED

Physical aspects of computation that just a few years ago appeared ten tative and tenuous, such as energy recycling in computation and quantu m computation, have now grown into full-fledged scientific businesses. Conversely, concepts born within physics, such as entropy and phase t ransitions, are now fully at home in computational contexts quite unre lated to physics. Countless symposia cannot exhaust the wealth of rese arch that is turning up in these areas. The ''Physics of Computation'' workshops cannot and should not try to be an exhaustive forum for the se more mature areas. I think it would be to everyone's advantage if t he workshops tried to play a more specialized and more critical role; namely, to venture into uncharted territories and to do so with a sens e of purpose and of direction. Here I briefly suggest a few possibilit ies; among these, the need to construct a general, model-independent c oncept of ''amount of computation'', much as we already have one for ' 'amount of information''. I suspect that, much as the inspiration and prototype for the latter was found in physical entropy, so the inspira tion and prototype for the former will be found in physical action. (C ) 1998 Elsevier Science B.V. All rights reserved.