What is the universe? Is it infinite, or finite?

The problem of how to make a theory of a whole universe is thus the problem of how to construct a theory without making any reference to anything that exists … outside of the system we are describing.

No matter how smart she is, no matter how modern her methods and how tricky her reasoning, a detective cannot be a good detective unless in the end the bad guys are found out. It is the same with science.

At present … the question of what happens inside of a black hole when quantum effects are taken into account remains unresolved.

It is mathematics, more than anything else, that is responsible for the obscurity that surrounds the creative processes of theoretical physics.

[A] theory of a whole universe, if it is to be consistent with what we know of quantum theory and relativity, must be a theory of a complex, self-organized universe.

[N]o one has been able to construct a theory which is completely satisfactory as a unification of quantum mechanics and relativity. It is still not even clear whether this can be accomplished without a radical change in the basic principles of either, or both, theories.

[W]e now have in our possession laws that can describe correctly every experiment we have been able to invent.

According to general relativity every bit of the collapsed star and every particle that falls afterwards into the black hole will end up at a last moment of time, at which the density of matter and strength of the gravitational field become infinite.