In A Computable Universe, Zenil and others take the idea of computation as an abstract process, capable of being performed on any system that can store and manipulate information, to its logical extreme. Computers might not only be made from chemicals and cells and light, they say; the universe itself could be a computer, processing the information of which our everyday experiences -- and everything else -- are composed.

This is a tricky idea -- if the universe is computed, what's the computer? [link to www.wired.com]