  The discovery of acceleration of the universe expansion in recent
astrophysics research prompts the author to propose that the Newton's
gravitation law can be generalized to accommodate the antimatter: While the
force between matters(antimatters) is attractive, the force between matter and
antimatter is a repulsive one. A paradox of negative-mass in gravity versus a
basic symmetry (m-->-m) based on quantum mechanics is discussed in sufficient
detail so that the new postulate could be established quite naturally.
Corresponding modification of the theory of general relativity is also
suggested. If we believe in the symmetry of particle and antiparticle as well
as the antigravity between them, it might be possible to consider a new
scenario of the expansion of universe which might provide some new insight into
the interpretation of cosmological phenomena including the accelerating
universe observed.

General Physics