  A critical review of gravitational wave theory is made. It is pointed out
that the usual linear approach to the gravitational wave theory is neither
conceptually consistent nor mathematically justified. Relying upon that
analysis it is then argued that -- analogously to a Yang-Mills propagating
field, which must be nonlinear to carry its gauge charge -- a gravitational
wave must necessarily be nonlinear to transport its own charge -- that is,
energy-momentum.
