Do We Really Need a Cosmological Constant? :: essays research papers

In 1916, Albert whizz made up his General surmise of Relativity without thinking of a cosmogenic invariable. The view of that time was that the introduction had to be static. Yet, when he tried to model such an universe, he realized he cannot do it unless either he considers a negative hug of matter (which is a totally unreasonable hypothesis) or he introduces a term (which he called cosmological constant), acting like a odious gravitational force. Some years later however, the Russian physicist Friedmann described a model of an expanding universe in which thither was no need for a cosmological constant. The theory was immediately confirmed by Hubbles discovery of galaxies red ink shift. Following from that, Hubble established the honor that bears his name, according to which every two galaxies argon receding from each other with a speed proportional to the outer space between them. That is, mathematically V=H Dwhere H was named Hubbles constant.From this office on, the idea of a cosmological constant was for a time forgotten, and Einstein himself called its introduction "his greatest blunder", mostly because it was later demonstrated that a static Universe would be in an unstable equilibrium and would pass to be anisotropic. In most cosmological models that followed, the expansion showed in the Hubbles law simply reflected the energy remained from the Big Bang, the initial explosion that is supposed to run through generated the Universe. It wasnt until relatively recently - 1960s or so, when more accurate astronomical and cosmological measurements could be made - that the constant began to reappear in theories, as a need to compensate the inconsistencies between the mathematical considerations and the experimental observations. I pass on discuss these discrepancies later. For now, Ill just say that this strange parameter, lambda- as Einstein called it, became over again an important factor of the equations trying to describe our unive rse, a repulsive force to account not against a negative matter pressure, but for excessively small an expansion rate, as measured from Hubbles law or cosmic microwave background radiation experiments. I will show, in the adjacent section, how all these cosmological parameters are linked together, and that it is sufficient to accurately peg down only one of them for the others to be assigned a precise value. Unfortunately, there are many controversies on the values of such constants as the Hubble constant - H, the age of the Universe t, its density , its curvature radius R, and our friend lambda.