Dark, invisible or non-existent?

The interest in so-called dark energy and dark matter continues, but so do the doubts. Is it merely a modification of gravity? Is it the product of a new type of particle? The verdict is still out, though the dominant theory still seems to point toward a mysterious, invisible substance of some kind. The term “invisible” matter or energy seems to me to be the more appropriate one, but the term “dark” does grab the headlines. This video from Canada’s Perimeter Institute for Theoretical Physics in Waterloo, Ontario, hints at the ambiguities.