Everything that has speed is in motion. (1) Everything that is in motion exists. (2) Darkness doesn't exist (3) Because It is the absence of light, a state of matter, not an actual thing. (4)
Therefore, Darkness doesn't have a speed.
Actually, Motion doesn't exist either. (5) Because, at any given instant of time, everything is static. (6) And since time is entirely composed of instants. (7) Motion Doesn't Exist. (8)
Therefore, Speed doesn't exist. Your 질문 is completely incoherent.