[Zeneta]

I have an honest question.

Can or is the Speed of Light slowed down while traveling through different medium?

[Boogieman]

The speed of light in a vacuum is what is universally invariant. The speed of light in a medium does indeed vary depending on the medium. This leads to a peculiar phenomenon, where some particles can exceed the local speed of light when it is traveling through a medium. When that happens, the particles begin emitting "cherenkov radiation", which is kind of an electromagnetic equivalent of a "sonic boom".