Dimension Travelers or Space Travelers?

Are aliens travelers of outer space or extra dimensions? Dimensions seem infinitely more likely. Outer space is vast and perhaps easy to traverse with the right technology. But dimensional travel is a much more likely cause. A majority of E.T. sightings occur at points known as vortexes. These are spots that act as almost a door way to other dimensions. It is the easiest way to penetrate the dimensional fabric. Also dimensional travel would seem far less complex when you imagine the consumption of time and energy required to travel the distances of space. Where as dimensional travel actually would require no movement measured in distance, but rather just a dimensional mutation.