2 later in this article. Current limits on and the age and density of the universe. Broad limits on are illustrated at 0.1 and 1.0. The past three decades have witnessed remarkable achievements in our ability to detect and accurately measure elemental isotopes that arise in part from radioactive decay. A great deal of effort has been spent in converting the data gathered from laboratory measurements of extraterrestrial materials to knowledge about the age of the elements, and thus, by assumption, the age of the galaxy.
Different workers approach the problem in different ways.
Others argue that neucleosynthesis alone cannot give us a firm value for the age of the galaxy. Space does not permit a full review of this important area of research, so I will only give the basic results from the published literature. Interested readers can refer to the review by Cowan et al. The trick is to obtain a value for the parameter , the time between the formation of the galaxy and the formation of the solar system. One can obtain a simple lower limit for from the following argument.