Examples of such a tensors are the Ricci tensors R ab , g ab R, as well as g ab . The constant is called the cosmological constant . Later still, he changed his mind again, and expressed regret that he had ever come up with it in the first place. The cosmological constant remains a problem child to this day . We shall set it equal to zero in what follows.
Question Explain why the non-zeros terms have the above form.
This gives the pressure gradient required to keep the plasma static in a star. Thus, the pressure gradient is larger in relativistic theory than in classical theory. You can go directly to Lecture 15 on stellar collapse to find out more. In the exercise set, you will see how this leads to Newton's Law of Gravity. Exercise Set 13 1.