This comes from this thread https://www.physicsforums.com/showthread.php?t=647627&page=7 discussion in posts #103,#104,#107 and #108. The Oppenheimer-Snyder model was mentioned by PeterDonis as a more plausible model than the Schwarzschild spacetime, well this has an element of subjectivity, but one reason I don't share this view is because the only way to relax the highly idealized conditions required by the O-S model is to recurr to the Kruskal-Szekeres diagram for the Schwarzschild solution as is shown in MTW sec. 32.5 second paragraph. So how can one consider more plausible a model than the one it owes its plausibility to? Also I have a few things to clarify from this model. As I understand it the O-S model basically joins the exterior Schwarzschild to a contracting FRW spatially spherical solution, (a pressureless isotropic and homogeneous dust). I usually interpret the exterior Schwarzschild solution to refer to the Schwarzschild metric, outside the Schwarzschild radius, or region I in the K-S diagram and this leads me to a second dependency of the O-S model on the maximally extended Schwarzschild solution, since in order to sy that the Schwarzschild exterior includes region II and the event horizon one must obviously rely on the K-S diagram (that didn't exist in 1939) to begin with. I'm still not convinced that it is commonly understood that the region inside the Schwarzschild radius is also considered an exterior region, since then, what is the interior region?, the singularity by itself? More doubts about the model: Here is the abstract from the original paper from O-S "When all thermonuclear sources of energy are exhausted a sufficiently heavy star will collapse. Unless fission due to rotation, the radiation of mass, or the blowing off of mass by radiation, reduce the star's mass to the order of that of the sun, this contraction will continue indefinitely. In the present paper we study the solutions of the gravitational field equations which describe this process. In I, general and qualitative arguments are given on the behavior of the metrical tensor as the contraction progresses: the radius of the star approaches asymptotically its gravitational radius; light from the surface of the star is progressively reddened, and can escape over a progressively narrower range of angles. In II, an analytic solution of the field equations confirming these general arguments is obtained for the case that the pressure within the star can be neglected. The total time of collapse for an observer comoving with the stellar matter is finite, and for this idealized case and typical stellar masses, of the order of a day; an external observer sees the star asymptotically shrinking to its gravitational radius." My bold: the first sentence I bolded lists some of the conditions required for the model to hold, have they all been theoretically and empirically ruled out? If so how? And I mean by other ways other than the K-S spacetime mathematical solution, that is considered not plausible due to its implying white holes. And by gravitational radius are O-S referring to the Schwarzschild radius?