What is the spacetime of {\em physically realizable} spherical collapse?
  We argue that a particular spacetime, a spherically symmetric spacetime with hyper-surface orthogonal, radial, homothetic Killing vector, is a physically meaningful spacetime that describes the problem of spherical gravitational collapse in its full "physical" generality. 
Sanjay M. Wagh, Ravindra V. Saraykar and Keshlan S. Govinder