Published online by Cambridge University Press: 15 August 2009
The considerations on gravitational collapse so far have been with the motivation to address the physical questions such as the role of collapse in astrophysics and cosmology. Many of the cosmic processes, such as the birth of stars, the formation of galaxies, and others, are not well understood today, but it is clear that gravitational collapse will play a major role there. Hence, understanding the dynamics of the collapse is important, as has been attempted here in various cases.
The important question of the final fate of massive stars at the end of their life cycle, when they have used all their nuclear fuel, and when gravity becomes the sole and key governing force, has drawn much attention for many decades. The importance of this issue was highlighted by Chandrasekhar (1934), who pointed out that the life history of a star of small mass must be essentially different from that of a star of large mass, and that while a small mass star can pass into a white dwarf stage, a star of large mass cannot go to this state, and one is left speculating on other possibilities. The question as to what happens when a massive star, heavier than a few solar masses, collapses under its own gravity has been a fundamental key problem in astronomy and astrophysics. If the star is sufficiently massive, beyond the white dwarf or neutron star mass limits, then a continued gravitational collapse must ensue without achieving any equilibrium state, when the star has exhausted its nuclear fuel.