  Transition to turbulence is due to the instability of a laminar flow subject
to a disturbance. This complicated problem can be explained using a new
proposed energy gradient theory in our previous study. This theory is extended
to the instability of fluid material systems in this study. The instability of
fluid material systems may lead to the evolution of natural environments and
the occurrence of catastrophic events in the world. To better describe these
phenomena and to understand the physical mechanism behind them are very
important. In order to more generally describe the instability of fluid
material systems, laws of energy gradient are summarized for static and motion
systems, respectively. These laws could be applicable to various flow problems
and material systems. Examples are shown that many events in the world could be
explained using these laws.
