Maybe there are "inherent physical limits" - but the ones you mention aren't.
http://tezcat.com/~eliezer/workarounds.html
-- sentience@pobox.com Eliezer S. Yudkowsky http://tezcat.com/~eliezer/singularity.html http://tezcat.com/~eliezer/algernon.html Disclaimer: Unless otherwise specified, I'm not telling you everything I think I know.