Fighting Fire with Sound
“I throw more power into my voice, and now the flame is extinguished,” wrote Irish scientist John Tyndall in 1857, upon realising that soundwaves could be used to put out fires. Over a century later, scientists are still trying to determine why this is so. A research team from the University of West Georgia have experimented on sound and fire in a zero-g environment for possible applications on spacecrafts, as water is not an efficient extinguisher without gravity. The researchers placed a lit candle in a topless chamber, then blasted Nickelback’s How You Remind Me through bass speakers—and within 10 seconds, when the song hit a low note of about 40-50 hertz, the flame extinguished. Perhaps the music was so horrible that the flame went out in disgust, but a more likely theory is that the soundwaves caused the pressure around the flame to drop, forcing it to extinguish. Sound is basically a vibration of particles in the air, travelling out in a wave—i.e., in a pattern of varying of pressure. Since temperature, pressure and volume are related, a decrease in pressure could lead to a decrease in temperature, thus extinguishing the flame. This technique could not only be used to put out fires on the International Space Station and Space Shuttle, but also in more conventional settings such as computer server rooms, where water damage from normal extinguishers would be costly.
Read the original report on the experiment by Dmitriy Plaks