On 19 Mar, 17:57, wrote:

Of course if you think about the analogy the energy for the whole
operation comes from the electric motors that drive the steps and
carry everyone's sorry butts to the next floor up. In soaring the
power is provided by the sun heating the air that rises (or forms
pressure systems that creates wind that flows over mountains). Gravity
and aerodynamics are just the way we turn that energy into a combined
forward and downward motion.

Give the man a coconut!

Ian