Computing with a difference (SSPL/Getty)

NOT only did Charles Babbage lay the foundations for the computer revolution, his designs for mechanical computers also provide a blueprint for energy efficiency. So say Raj Mohanty of Boston University and his colleagues, who have created a nanoscale mechanical logic gate that could form the basis of tiny mechanical computers.

The mechanical logic gate is slower than its traditional equivalent, but loses far less energy

The gate consists of a strip of silicon 300 nanometres wide sitting between two chunks of silicon. Applying a voltage between one chunk and the strip causes the strip …