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Schematic view of the Cherenkov effect
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The Cherenkov Effect

The theory of relativity states that no particle can travel at the speed of light in a vacuum. However, light travels at lower speeds in dense media, like water. A particle traveling in water must have a speed less than the speed of light in a vacuum, but it is possible for it to move faster than the speed of light in water. If the particle is charged, it will emit radiation (light). This process is similar to the sonic boom heard when an airplane exceeds the speed of sound. Neutrino interactions with water can produce such particles. Sensitive light detectors measure this Cherenkov radiation in Neutrino experiments.

This material is considered too complex to be written about at an intermediate or beginner level, so all levels appear in the advanced form.

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA