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

In 1916, Albert mental capacity made up his oecumenic Theory of Relativity without thinking of a cosmological constant. The view of that measure was that the Universe had to be static. Yet, when he tried to model such an universe, he realized he cannot do it unless either he considers a prejudicious pressure of matter (which is a totally unreasonable hypothesis) or he introduces a term (which he called cosmological constant), acting like a salacious gravitational force. Some years later however, the Russian physicist Friedmann describe a model of an expanding universe in which there was no unavoidableness for a cosmological constant. The theory was immediately confirmed by Hubbles uncovering of galaxies red shift. Following from that, Hubble established the law that bears his name, according to which every both galaxies are receding from each other with a speed proportional to the distance between them. That is, mathematically V=H Dwhere H was named Hubbles constant.From thi s point on, the idea of a cosmological constant was for a measure forgotten, and Einstein himself called its introduction "his greatest blunder", mostly because it was later show that a static Universe would be in an unstable proportion and would tend 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 vatical to have generated the Universe. It wasnt until relatively recently - 1960s or so, when more accurate astronomic 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 will discuss these discrepancies later. For now, Ill just say that this strange parameter, lambda- as Einstein called it, became again an important factor of the equations trying to describe our universe, a re pulsive force to account not against a negative matter pressure, scarcely for too small an expansion rate, as measured from Hubbles law or cosmic microwave background radiation experiments. I will show, in the next section, how all these cosmological parameters are linked together, and that it is sufficient to accurately determine only one of them for the others to be assigned a critical 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 whiz lambda.