The German TV show *Dark* obviously has a certain name. But why was this name chosen?

Typically, the name of a series has a connection with its main plot point. Obviously, the cave that contains the passage between times is dark (duh). But that seems a little mundane, especially compared to the heavy symbolism of something like the name Winden (bind or twine, like a knot might; or like someone's destiny might). The name could simply be because the dome-shaped emanation that appears during the apocalypse is black in color, but seeing as this does not appear until rather late in the series, it seems doubtful.

So what is the significance of the title?