Sterile neutrinos are one of the last loose ends in understanding the universe.

Neutrinos once again claim their share of prominence. And they do it for a good reason. Just two weeks ago we told you that CERN scientists have launched a project that seeks to find a very peculiar class of these particles: sterile neutrinos. Their importance lies in the fact that they may be very useful in explaining the matter-antimatter asymmetry of the universe and the nature of dark matter.

However, before moving forward we are interested in briefly reviewing what makes these particles so special. Neutrinos were first described from a theoretical point of view in the 1930s by Wolfgang Pauli, one of the fathers of quantum physics (we owe him, among other contributions, the exclusion principle). However, its experimental discovery occurred two and a half decades later, in the mid-1950s.

The problem is that they are extraordinarily difficult to identify for a reason: they barely interact with ordinary matter. Furthermore, their mass is very small, their electric charge is neutral and they are not influenced by the strong nuclear interaction or the electromagnetic force, although they are influenced by gravity and the weak nuclear interaction. There is no doubt that they are irresistible particles, and many scientists are determined to hunt them down.

Physicists who are developing their research activity in the field of neutrinos have managed to set up observatories specifically designed to capture them. The most imposing of all of them is the Japanese Super-Kamiokande, a mass housed in Hida, a city located in the central area of Honshu, the largest island in the Japanese archipelago. It is built in a mine, 1 km deep, and measures 40 meters high and another 40 meters wide, which gives it a volume similar to that of a fifteen-story building.

Neutrinos give rise to a structure with the properties of a fluid whose expansion can be described by relativistic hydrodynamics.

Fortunately, from now on researchers will have another tool at their disposal with the ability to provide them with new knowledge about neutrinos. And a group of physicists from the University of Ohio, in the United States, has published a very interesting study in which they argue that supernovae can reveal crucial information about the mechanisms used by neutrinos to interact with each other.

Supernovae are extraordinarily energetic explosions that occur when a star exhausts its fuel reserve and loses the hydrostatic balance that has kept it in equilibrium until that moment (we explain this process in some detail in the article we have dedicated to the life of the stars). What is surprising is that the authors of this study defend that the neutrinos emitted during a supernova interact with each other, giving rise to a structure that has the properties of a fluid whose expansion can be described by relativistic hydrodynamics.

A simple way to understand what we are talking about is simply to observe this idea as the possibility of obtaining new knowledge about the properties of neutrinos by studying the way in which they interact as a whole with the solid bodies that they encounter when They travel through the false cosmic vacuum.