Today, a new post in this fascinating Cosmology thread… The Big Bang Nucleosynthesis in a nutshell When the Universe was young, about , the following events happen 1st. Some particles remained in thermodynamical equilibrium with the primordial plasma (photons, positrons … Continue reading

# Category Archives: General Relativity

The current Universe has evolved since its early phase of thermal equilibrium until the present state. The departure from thermal equilibrium in the early Universe made a fossil record we can observe at current time! There are some easy rules … Continue reading

Evolution of the Universe: the scale factor The Universe expands, and its expansion rate is given by the Hubble parameter (not constant in general!) Remark (I): The Hubble “parameter” is “constant” at the present value (or a given time/cosmological age), … Continue reading

The next thread is devoted to Cosmology. I will intend to be clear and simple about equations and principles of current Cosmology with a General Relativity background. First of all…I will review the basic concepts of natural units I am … Continue reading

In 1905, one of Einstein’s achievements was to establish the theory of Special Relativity from 2 single postulates and correctly deduce their physical consequences (some of them time later). The essence of Special Relativity, as we have seen, is that … Continue reading