Nature: Speed of light

Suppose that we shoot the two of them [a photon, and an electron] into a huge tank of water.

If we did that, the electron would continue to travel at 99.99% the speed of light in the vacuum, while the light beam would instantly slow down to 75% its normal speed.

In this situation, the electron would be travelling faster than light.

Boom! Mind blown! :)

– Don Lincoln, about Cerenkov radiation, https://www.youtube.com/watch?v=Yjx0BSXa0Ks