Correlation Functions for Black Holes and White Holes in Bose-Einstein Condensates

Résumé

General Relativity has changed completely our concepts of space and time. The way an object attracts gravitationally is by curving the spacetime geometry. The prediction of the existence of black holes is the most striking one: gravitational effects can have such a radical effect on the spacetime metric that they produce a region where nothing -not even light- can escape. Astrophysical black holes are the result of the gravitational collapse of objects of mass bigger than 3M_{\odot}, being M_{\odot} the solar mass. In that extreme case repulsive forces (pressure) inside the star cannot counterbalance the gravitational force and a black hole forms. Another type of extreme situation allowed by Einstein's equations is that of a white hole. White holes are a sort of time reversal solutions of black holes. These objects are not realizable in astrophysical scenarios, since they require the presence of an initial singularity. This is the main reason why much less attention has been devoted to white holes compared to black holes.