Acceleration of the expansion of the universe

The acceleration of the expansion of the universe is the name given to the phenomenon which sees the speed of recession of the Galaxie S compared to the Milky Way increasing during time. This phenomenon has for the first time explicitly highlighted in 1998 by two international teams, the Supernova Cosmology Project, carry out by Saul Perlmutter, and the High-Z supernovas search TEAM, carried out by Adam Riess.

This discovery was made by measuring what one calls the Distance of luminosity of star whose absolute Magnitude is supposed to be known, of the Supernova E of the Ia type. The relation between distance from luminosity and Décalage towards the red of these objects makes it possible to reconstitute the history of the expansion of the universe on several billion years, and thus to check if the Expansion of the universe accelerates or decelerates with time. By acceleration or deceleration of the expansion, one understands here the evolution of the relative distance between two remote galaxies.

The simplest interpretation of discovered acceleration of the expansion of the universe that there exists in the universe a form of energy, traditionally is called black energy (or dark energy, translation in a case as in the other of the English term dark energy ) with the atypical properties, since its Pression must be negative. The true nature of this black energy is not known to date, but several possible candidates exist. Simplest of them cosmological Constante is the , but there is the different one like the quintessence. However, no direct detection of this energy seems possible, alone at present its gravitational influence with very large scales being measurable.

This result indicates that according to any probability, the Destin of the universe will be probably a universe eternally expanding, increasingly cold and more and more vacuum. The phase of current expansion will not thus stop probably to leave room to a phase of recontraction followed by a Big Crunch. However, among the possible candidates with black energy, one of them, called phantom energy could lead to a scenario extremely atypical cosmology, or the acceleration of the expansion of the universe would be accompanied, a surprising way, an increase in its density which in a finished time would reach an infinite value, signing at this time there the end of the universe. This scenario is commonly called Big RIP.

See too

• Expansion of the universe

• black Energy
• Constant cosmological
• Quintessence (cosmology)
• Destiny of the universe
• Big RIP