Kenneth Chang in the New York Times:
When the force of sound waves implode tiny bubbles within a liquid at room temperature, the surface of the bubble can reach temperatures at least 25,000 degrees Fahrenheit, more than twice as hot as the surface of the sun, scientists reported this month.
The center of such a bubble may be even more astonishingly hot…
Their finding supports the intriguing notion that it may be possible to compress these bubbles so violently that vapor molecules in them are heated to multimillion-degree temperatures.
The phenomenon of imploding bubbles, called sonoluminescence because it emits a flash of light as the bubble collapses, has been increasingly studied since it was discovered 15 years ago.