SonoShine

The bubbles involved are typically on the order of 1–10 micrometers in diameter during their stable oscillation phase.

When these bubbles collapse due to the extreme pressure changes caused by ultrasonic waves (frequencies usually in the range of 20 kHz to several MHz), they compress to sizes as small as a few nanometers at the moment of collapse.

This rapid compression creates extreme temperatures and pressures inside the bubble—estimated to reach thousands of kelvins and up to 1,000 atmospheres—sufficient to produce brief flashes of light.

The precise size and behavior of the bubbles are critical, as deviations can disrupt the conditions required for sonoluminescence to occur.

These microscopic bubbles are an incredible example of how small-scale dynamics can produce such extraordinary energy concentrations.