For small Mach numbers the Rayleigh-Plesset equations (modified to inc
lude acoustic radiation damping) provide the hydrodynamic description
of a bubble's breathing motion. Measurements are presented for the bub
ble radius as a function of time. They indicate that in the presence o
f sonoluminescence the ratio of maximum to minimum bubble radius is ab
out 100. Scaling laws for the maximum bubble radius and the temperatur
e and duration of the collapse are derived in this limit. Inclusion of
mass diffusion enables one to calculate the ambient radius. For audib
le sound fields these equations yield picosecond hot spots, such as ar
e observed experimentally. However, the analysis indicates that a deta
iled description of sonoluminescence requires the use of parameters fo
r which the resulting motion reaches large Mach numbers. Therefore the
next step toward explaining sonoluminescence will require the extensi
on of bubble dynamics to include nonlinear effects such as shock waves
.