Mid Term Exam

MID-TERM EXAM

Read carefully the texts and answer the questions in good Spanish.
-------------------------------------------------
A black hole is a region of spacetime from which nothing, noteven light, can escape. The theory of general relativity predicts that a sufficiently compact mass will deform spacetime to form a black hole. Around a black hole there is a mathematically definedsurface called an event horizon that marks the point of no return. It is called "black" because it absorbs all the light that hits the horizon, reflecting nothing, just like a perfect blackbody in thermodynamics.  Quantum mechanics predicts that black holes emit radiation like a black body with a finite temperature. This temperature is inversely proportional to the mass of the black hole, making itdifficult to observe this radiation for black holes of stellar mass or greater.
-------------------------------------------------
Objects whose gravity field is too strong for light to escape werefirst considered in the 18th century by John Michell and Pierre-Simon Laplace. The first modern solution of general relativity that would characterize a black hole was found by Karl Schwarzschild in 1916,although its interpretation as a region of space from which nothing can escape was not fully appreciated for another four decades. Long considered a mathematical curiosity, it was during the 1960sthat theoretical work showed black holes were a generic prediction of general relativity. The discovery of neutron stars sparked interest in gravitationally collapsed compact objects as a possibleastrophysical reality.
-------------------------------------------------
Black holes of stellar mass are expected to form when very massive stars collapse at the end of their life cycle. After a blackhole has formed it can continue to grow by absorbing mass from its surroundings. By absorbing other stars and merging with other black holes, supermassive black holes of millions of solar masses may...