General relativity describes how matter and gravity interact. However,
unlike in Newtonian gravity, at an instant of time, the universe cannot
look however it wants. There are equations that initial data must obey.
Thus, an interesting question is, What can the universe look like?
What freedom do we have? In this talk, I'll introduce relativity, and
discuss recent progress using the conformal method, the most common
method of trying to answer this question.