Whether you need a new villain or an old Spider-Man, your sci-fi movie will sound more scientifically respectable if you use the word "multiverse." The Marvel multiverse puts different versions of our universe "out there," somewhere. In these films, with the right blend of technology, magic, and imagination, travel between these universes is possible.

For example (spoilers!), in "Spider-Man: No Way Home," we discover there are other universes and other Earths, some of which have their own local Spider-Man. In the universe of the movie, magic is possible.

This magic, thanks to a misfiring spell from superhero Dr. Strange, causes some of the other Spider-Men to be transported into our universe, along with a few supervillains.

In "Doctor Strange in the Multiverse of Madness" (in cinemas this week), the universe-on-universe buffoonery threatens a "desecration of reality."

So, which of these ideas has Marvel borrowed from science, and which ones are pure fiction?

To read more, click here.