How is gravitational collapse related to momentum and pressure? What's the mainstream view as to the cause of gravitational collapse? Most of the hits you get from google say something like: "once a sufficiently massive star runs out of nuclear fuel, it collapses due to gravity". But how? Another oft-repeated theme is that nothing can escape such a collapsed body, even light. So all the matter in some sense is 'beyond c', if you see what I mean. I know (thankyou) that relativistic "mass" can be a misleading concept, it's easier to consider relativistic energy, or relativistic momentum. But isn't gravity a product of momentum? Or are these questions unreasonable? I mean, considering how ignorant I am, etc . . .