I agree we need to invent some things, but I don't think that it will necessarily defy our laws of physics, since we haven't reached an ultimate conclusion on what the laws of physics are, we have theories that express the laws. And some theories, such as Superstring theory, supports 10 dimensions that would allow for dimensional space and time travel if accessible through our technology. Seeing that quantom cumputers have already been invented, I would hope that humans survive long enough to explore our neighborhood of the milky way using non-propulsion systems versus our current rocket propulsion.

I, however, don't think humans will live long enough to create multiple dimensional travel. And even if we did have that, as said before, what are the chances of finding intelligent life during our spec of an existence.