Anything that specifically goes counter to physics takes an incredible level of power, but yes it is possible. If you construct the spell to work with physics instead of against it somehow (wormholes, gravity, etc...) it costs far less power, but instead messing with laws on that level is far more complicated. Basically magic works like this: Anything you don't understand when casting gets filled in with raw power, so the better you understand what you're trying to do, the easier it is to cast.