Undergrad Light Speed in Dense Medium: Explained

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Light bends when transitioning from air to glass due to its reduced speed in the denser medium. While light maintains its invariant speed of ##c## in a vacuum, it travels slower in materials like glass, leading to refraction. From an observer's perspective within the glass, light appears to travel at speed ##c##, creating the illusion that external light is moving faster than light speed. Additionally, particles can exceed the speed of light in a medium, resulting in Cerenkov radiation, although they never surpass the speed of light in a vacuum. This phenomenon illustrates the complexities of light behavior in different media.
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Does light travel at the same speed?
If light goes from air through glass, the reason the light bends is because I'm told that the light travels slower inside the glass. If I change my observer reference to inside the glass, the speed of light inside the medium it look like light is still traveling at the speed of light? if so, the light from outside then would have to look like it is traveling faster than the speed of light. How does this actually work?
 
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Light only maintains its invariant speed ##c## in vacuum. It travels slower in media. Particles are routinely observed traveling faster than light in a medium (although never faster than ##c##). They slow down by emitting Cerenkov radiation.
 
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