Does there exist a real analytic vector field on $S^3$ all of whose orbits are dense? The second paragraph of page 285 Of this paper says that there is a vector field whose almost all orbits are dense:
http://perso.ens-lyon.fr/ghys/articles/constructionchamps.pdf
Is there an example of such a vector field which belongs to the Lie algebra of all left-invariant vector fields of the Lie group $S^3$?