When neutrinos pass through matter or they propagate in a medium (not in the vacuum), a subtle and potentially important effect occurs. This is called the MSW effect (Mikheyev-Smirnov-Wolfenstein effect). It is pretty similar to a refraction of light in … Continue reading
There are some indirect constraints/bounds on neutrino masses provided by Cosmology. The most important is the one coming from the demand that the energy density of the neutrinos should not be too high, otherwise the Universe would collapse and it … 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
In this short blog post, I am going to list some of the greatest “naturalness” problems in Physics. It has nothing to do with some delicious natural dishes I like, but there is a natural beauty and sweetness related to … Continue reading