Author: Roberto Denti
Horizon of events: it is a ray, that is a particular distance from the singularity that Leonard Susskind calls "The point of no return", beyond which every object and information is sucked into the black hole.
Entropy: The second principle of thermodynamics states that thermal energy it always flows from a warmer body to a warmer one and never in the opposite direction. This heat transfer ends when the two bodies they reached the same temperature. Entropy is the measure of the degree of equilibrium achieved by a system at a given time. If you do not add more energy from the outside, entropy is determined by a transfer of energy between the elements that make up the system itself and it is defined as a state of disordered balance of a system. In theory, the entire universe can also be considered a "system" and therefore in the cosmos the energy tends to distribute itself from the warmer bodies to the less hot ones and the entropy increases.
Quantum vacuum: Quantum theory of fields states that not even an ideal vacuum, with a measured zero pressure, is truly empty. There are quantum-mechanical fluctuations in the vacuum
which make it a bubbling of virtual particle pairs that are born and annihilated continuously. This quantum phenomenon could be responsible for the observed value of the cosmological constant.
File:Vacuum fluctuations revealed through spontaneous parametric down-conversion.ogv
Author: Denysbondar Date: 1 October 2012, 17:58:31