Friction is one of the oldest phenomena in the history of mankind. It appears in every technical
application, wherever parts are in motion. About nine percent of the gross national product of the
US is lost due to friction.
Wherever we face friction consciously, it is assumed unwanted. However, friction is a
highly important phenomenon for our daily life. Without friction we could not walk, no violin would sing,
no moving body would come to rest.
Friction has been studied since the Renaissance but anyway it is only poorly understood and
therefore it counts as Dirty Physics. The invention of the friction force microscope and the
nanoscopic laws of adhesion and friction have disproved old ideas and led to a new understanding
of this highly interesting phenomenon.