The general theory of relativity (or general relativity for short) is a major building block of modern physics. It explains gravity based on the way space can 'curve', or, to put it more accurately, it associates the force of gravity with the changing geometry of space-time.
Here I have the lecture notes on Classical Black holes which are analytical solutions of the Einstein Field Equations.
ULTRACOLD ATOMS
Ultracold gases are ensembles of atoms held at a temperature near absolute zero. Such systems enable the creation of exotic phenomena such as Bose–Einstein condensation. Ultracold gases are also useful simulating condensed-matter systems because their tunability opens the door to effects that are otherwise difficult to observe.
Here I have the lecture notes on the theoretical foundations of BEC