LOG#169. A two level problem.

This post is the solution of the following problem: pick an atom with two energy levels. They have a transition wavelength of 580nm. At room temperature are in the lower state. 1) How many atoms are in the upper state, … Continue reading

LOG#108. Basic Cosmology (III).

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

LOG#106. Basic Cosmology (I).

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