• Question: please explain sonoluminescence..

    Asked by shobhit to Chris, Dave, David, Fiona, Jack on 21 Jun 2013.
    • Photo: Chris Mansell

      Chris Mansell answered on 21 Jun 2013:

      Sonoluminescence occurs when sound waves are directed at a bubble in a liquid and it collapses so strongly that energy related to the collapse leads to light being emitted.

      The light that is emitted is usually ultraviolet light. People have found that changing the type of gas inside the bubble can significantly change the amount of light that is emitted.

      Scientists think that the process works like this. The gas in the bubble gets hotter as it collapses. The heat ionises some of the gas. In other words, the heat causes some parts of the gas to become charged. When a charged particle changes its velocity, it emits light.

      (I have taken most of this information from Rev. Mod. Phys. 74, 425–484 (2002) “Single-bubble sonoluminescence” by Michael P. Brenner, Sascha Hilgenfeldt and Detlef Lohse.)

    • Photo: David Freeborn

      David Freeborn answered on 21 Jun 2013:

      That was a great answer, Chris, I don’t have much more to add.

      There’s still some of controversy about what causes sonoluminescence. Some scientists produced some very bizarre theories, which you can read about here:
      http://en.wikipedia.org/wiki/Sonoluminescence#Other_proposals

      I definitely think Chris’ explanation is the most likely though, and I think that’s pretty much the mechanism scientists have agreed on now!

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