Interstellar travel is a staple of science fiction, but writers and filmmakers often take different approaches to it. Here's what "Project Hail Mary" does.

“The whole thing is very hypothetical at this point,” Stephen Hsu said of wormholes, a caution that still defines the subject ...

Add Yahoo as a preferred source to see more of our stories on Google. Five physical barriers may prevent civilizations from ever meeting, from light speed limits to cosmic timing gaps. (CREDIT: ...