The distinctive pop of opening a champagne bottle is more than the cork coming free. The sudden release of high-pressure gas creates a freezing jet that’s initially supersonic. It even creates a Mach disk, like those seen in rocket exhaust. That supersonic flow can only be maintained, though, with a large enough pressure difference between the gas in the bottle and the atmosphere outside. Once the pressure drops below that critical point, the jet slows down and becomes subsonic. For more on champagne popping and its colorful plume, check out this previous post. (Image and research credit: G. Liger-Belair et al.; via Nature; submitted by Kam-Yung Soh)
Champagne’s Shock Wave
