Does Cerenkov radiation travel faster than light? (Intermediate)

I have always heard that nothing travels faster then the speed of light, but I recently read an article on Cerenkov Radiation, which states that it does travel faster then light.

Nothing can travel faster than the speed at which light travels *in a vacuum*. But, as explained here, it's possible to slow light down in a medium other than vacuum. In such a medium, it's possible to have a source of light that travels faster than light does *in that medium*. When this happens, you get the equivalent of a sonic boom for light: Cerenkov Radiation. You can read more about it here.

About the Author

Christopher Springob

Christopher Springob

Chris studies the large scale structure of the universe using the peculiar velocities of galaxies.  He got his PhD from Cornell in 2005, and is now a Research Assistant Professor at the University of Western Australia.

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