  A spontaneous breakup of a liquid jet results in the formation of a chain of
droplets, which is a daily observed phenomenon, such as in the raining process
and under an open water-faucet. We here report inkjet printing experiments for
the formation of droplets which are inconsistent with existing theories and
thereafter propose a novel concept of surface area minimization to address the
droplet-formation condition. The novel concept is also capable of predicting
the formation of satellite and subsatellite droplets, which cannot be
comprehended by the classic Rayleigh theory for the formation of droplets. We
also present a new evolution behavior of liquid jets not yet reported before
that the jet initially transforms into droplets and then becomes a
uniform-radius jet again. The current results can be applied to a variety of
disciplines where liquid jets are present.
