Wikenigma is a fascinating encyclopedia of the holes in human knowledge

Wikenigma describes itself as "a wiki-based resource specifically dedicated to documenting fundamental gaps in human knowledge" that lists "scientific and academic questions to which no-one, anywhere, has yet been able to provide a definitive answer."

More than 1,100 of these "known unknowns" are documented on the site.

Here are some that the Wikenigma di…