When you refract light, you change its speed, slowing it down. https://en.wikipedia.org/wiki/Refractive_index#:~:text=The%20refractive%20index%20can%20be,of%20

When you refract light, you change its speed, slowing it down. https://en.wikipedia.org/wiki/Refractive_index#:~:text=The%20refractive%20index%20can%20be,of%20that%20light%20in%20vacuum https://en.wikipedia.org/wiki/Refractive_index#:~:text=The%2.... https://www.zmescience.com/science/physics/how-to-slow-trap-light/ https://www.zmescience.com/science/physics/how-to-slow-trap-...