Sonoluminescence (SL) observed in the cavitation of water is explained by the Planck theory of SL that treats the bubbles as miniature masers converting the velocity of bubble collapse to electromagnetic (EM) waves at microwave (MW) frequencies. The Planck theory of SL is consistent with historical experimental data that shows MW's concurrent with SL are produced in cavitation. As the bubbles collapse, MW's are absorbed and the Planck energy accumulates through the rotation quantum state of the bubble wall molecules. A MW photoelectric effect for accumulated MW photons is identified as a new SL parameter. During ultrasonic cavitation, cold fusion on average between the D's on colliding D₂O bubble wall molecules does not occur as the Planck energy is limited to about 2 keV, but a limited number of cold fusion events with a Planck energy in excess of 10keV are possible. However, high power microwaves (HPM) pulsed to less than ~1 ns appear to be a far more efficient way of creating cold fusion in D₂O than by ultrasonic cavitation.