Trap a single air bubble in a flask of water, blast it with sound, and it will flash with light — reaching temperatures hotter than the surface of the Sun for a few trillionths of a second. Physicists have chased sonoluminescence for 90 years and still can't fully explain what happens inside that collapsing bubble.
A short visual primer showing the eerie pinpoint of blue light hanging in the water. Start here to see the effect before you try to understand it.
First spotted by accident in 1934, it's the emission of light from bubbles imploding in a liquid driven by sound. Nearly a century on, the mechanism is still contested.
A longer explainer that walks through the standing-wave trap and why the flash is so absurdly brief — under 40 picoseconds, faster than almost anything we can measure.
Nature reports the moment researchers measured temperatures over 15,000°C inside the bubble and detected plasma — a tiny, momentary star forming in a glass of water.
IEEE Spectrum on the controversial idea that a collapsing bubble might get hot enough to trigger nuclear fusion. If true, it would rewrite energy. The claim ignited one of physics' fiercest disputes.
Hackaday chronicles one hobbyist's five-year quest to reproduce the effect on a workbench with a signal generator, an amplifier, and a coil of magnet wire.
A hands-on build that shows just how finicky the setup is — degassing the water, tuning the resonance, and coaxing a lone bubble into glowing.