As engineers figure out how to cram more chip power into smaller spaces, they also have to tackle the problem of excess heat. Built-in cooling fans and heat sinks (like the thermally conductive aluminum case of the Macbook Air) take off some of the heat. The next step may be tiny plumbing systems that allow water to flow through and whisk away heat.

IBM has designed such a system of hermetically sealed, double-layered pipes of silicon and silicon oxide just .002 inches in diameter, illustrated here, which it hopes to make commercially available in a few years. IBM says short-circuiting won't be a problem.