Famed turn-of-the-century Tenor Enrico Caruso could purportedly shatter Champagne glasses by belting out high notes. And Ella Fitzgerald did it herself in a 1972 Memorex commercial (although she had a little help from two speakers). So it can be done, but it’s incredibly difficult. What you’ll need is a good ear, some powerful pipes, and a lesson in Physics 101. Here’s why it works: All objects have a “resonant frequency”— in other words, everything vibrates at a certain wave frequency. If you’ve ever tried tracing a wet finger around the rim of a crystal glass, you’ll notice that it rings a specific note: That’s the glass’s resonant frequency. If a strong singer matches that pitch, her voice’s sound waves will cause the air molecules around the glass to shake. As those air molecules vibrate, the glass will vibrate too. The louder she sings on pitch, the more likely those vibrations will cause the glass to crack. That’s why opera singers are the glass-breaking champions of the world: They’re trained to sing loudly without amplification, with some voices topping 100 decibels!