  Metal whiskers often grow across leads of electric equipment and electronic
package causing current leakage or short circuits and raising significant
reliability issues. The nature of metal whiskers remains a mystery after
several decades of research. In addition, metal whiskers exhibit a rather
unusual dynamic property of relatively high amplitude movements under gentle
air flow or, according to some testimonies, without obvious stimuli.
Understanding the physics behind that motion would give additional insights
into the nature of metal whiskers. Here, we quantitatively analyze several
possible mechanisms potentially responsible for the observed movements: (1)
minute air currents, (2) Brownian motion due to random bombardments with the
air molecules, (3) mechanically caused movements, such as (a) externally
transmitted vibrations of the sample, and (b) torque exerted due to material
propagation along curved whiskers responsible for the whisker growth (similar
to the known garden hose oscillations), (4) time dependent electric fields due
to diffusion of ions across the metal surface, and (5) nonequilibrium electric
field configurations making it possible for {\it some} whiskers to move. For
all these scenarios we provide numerical estimates. Our conclusion is that the
observed movements are likely due to the minor air currents, intentional or
ill-controlled, and that external mechanical vibrations could force such
movements in a rather harsh environment or/and for whiskers with severe
constrictions. We argue that under non-steady state conditions, such as caused
by changes in the external light intensity, some whiskers can exercise
spontaneous oscillations.
