  We study the collisions of two scalar wave packets in the asymptotically flat
spacetime and asymptotically anti-de Sitter spacetime in spherical symmetry. An
energy transfer formula is obtained, $y=Cm_{i}m_{o}/r$, where $y$ is the
transferred energy in the collisions of the two wave packets, $m_i$ and $m_o$
are the Misner-Sharp energies for the ingoing and outgoing wave packets,
respectively, $r$ is the areal radius and collision place, and $C=1.873$ and
$C=1.875$ for the asymptotically flat spacetime and asymptotically anti-de
Sitter spacetime circumstances, respectively. The formula is universal,
independent of the initial profiles of the scalar fields.
