A question of scale

A basic gear of a future nanomachine © Numerical Aerospace Simulation Systems Division (NAS) of the NASA Ames Research Center.

The prefix "nano" comes from the Greek nannos, meaning "dwarf". It divides the number it precedes by one billion. For example, a nanosecond (1 ns) is a billion times shorter than a second. A nanometre (1 nm) is 30,000 times smaller than the diameter of a hair. An atom of hydrogen measures about 0.1 nm. There is the same size difference between an atom and a tennis ball as there is between the tennis ball and the Earth. This change in scale means we can compare the exploration of the "infinitely small" with that of the "infinitely large".