i have a better question. if helen keller falls in the woods does it make a sound?
A wormhole is technically theoretical, but definitely not impossible. In theory the universe or portions of it aren´t entirely linear. Meaning that there are portions that are folded over on top of each other. It´s actually quite hard to explain without a diagram. So here´s one...
But keep in mind that the diagram is only really an analogy. Based on the diagram, ¨time travel¨is possible, because matter and time itself traveling through the wormhole travel a shorter distance than time and matter traveling around the other portion of the universe. The universe is really so complex, that only a select few bright minds can even make postulates about its properties.
This also gets into the messy business of parallel universe theory. Which would explain the results of time travel like a ¨branching river¨ or ¨pulling apart a piece of thread¨. For example... if you theoretically went back into time and killed your own grandfather, the result would be 2 parallel universes. One with the consquence of killing your own grandfather (for example you and your father not being born), and one which already contains your existance.
Seriously though... astrophysics and spacetime is a little much for NS discussion...