The shot of the ground shaking under Clark didn't suggest levitation or anti-gravity to me at all.
If Clark can time travel by flying fast enough in a certain way, without mechanical aid, it's an innate power. It's not a "side effect of speed," because he can (could) fly FTL without time traveling. That would be the same as calling his super-breath (a pretty ridiculous power, granted) a "side effect of respiration."
If Clark can time travel by flying fast enough in a certain way, without mechanical aid, it's an innate power. It's not a "side effect of speed," because he can (could) fly FTL without time traveling. That would be the same as calling his super-breath (a pretty ridiculous power, granted) a "side effect of respiration."