Visualizing stick–slip: experimental

observations of processes governing the

nucleation of frictional sliding

S M Rubinstein, G Cohen and J Fineberg

The Racah Institute of Physics, The Hebrew University of Jerusalem, Givat Ram, Jerusalem, Israel


Received 8 January 2009, in final form 13 April 2009

Published 22 October 2009

Online at


Understanding the dynamics of frictional motion is essential to fields ranging from

nano-machines to the study of earthquakes. Frictional motion involves a huge range of time

and length scales, coupling the elastic fields of two blocks under stress to the dynamics of the

myriad interlocking microscopic contacts that form the interface at their plane of separation.

In spite of the immense practical and fundamental importance of friction, many aspects of the

basic physics of the problem are still not well understood. One such aspect is the nucleation of

frictional motion commonly referred to as the transition from static to dynamic friction. Here

we review experimental studies of dynamical aspects of frictional sliding. We focus mainly on

recent advances in real-time visualization of the real area of contact along large spatially

extended interfaces and the importance of rapid fracture-like processes that appear at the onset

of frictional instability.

(Some figures in this article