What are the cosmic dispirations?
When I described dispirations in a little paper long ago (Phil Mag 1970 22 949-952) I had biological and polymeric materials in my mind. They have since been found in crystalline polymers and liquid crystals. But now I see cosmic dispirations in the literature. What are they? Are they singularities formed by a relative screw displacement of the surfaces of a cut? Do they depend on any underlying symmetry? What kind of magnitude is the rotational component? Are they concepts in 4D space? Are they line singularities? Can they be described for someone like me who knows almost nothing about cosmology?