as of now the scientist are intented about the idea of a wormhole. which has never been seen before but proven in physics so its a matter of time or our physics is wrong
but if where "theorizing" then one idea of mine is a little bit simple:
when your using a flashlight, and light is in a wall. in logic you know the light is in the wall. if you put a colored plastic for example a green plastic then the light in the wall will be colored green also. if there is a way to create a engine/portal/etc that will let us be the green plastic and be transported in the wall in the speed of light then that would be exciting.
i have that one unique engine, but too bad youll have to be in my dream to see it

