Searle argues that this is impossible, since consciousness is a physical property, like digestion or fire. No matter how good a simulation of digestion you build on the computer, it will not digest anything; no matter how well you simulate fire, nothing will get burnt. By contrast, informational processes are "observer-relative": observers pick out certain patterns in the world and consider them information processes, but information processes are not things-in-the-world themselves. Since they do not exist at a physical level, Searle argues, they cannot have "causal efficacy" and thus cannot cause consciousness. There is no physical law, Searle insists, that can see the equivalence between a personal computer, a series of ping-pong balls and beer cans, and a pipe-and-water system all implementing the same program.