Weighing neutrinos by galaxies

2002/04/11 Orobengoa, Olatz - Elhuyar Zientziaren Komunikazioa

• Astronomia

Neutrinos are tiny subatomic particles, lack of electric charge and so far the presence of masses has been questioned. In space they move at the same speed as light and can cross the planets without causing or suffering any change.

According to the scientific group, the neutrino weighs only one million of the mass of the hydrogen atom. With this weight it would not have as much gravitational force as to influence the evolution of the visible part of the universe, that is, to form galaxies. But only 5% of the universe is spectacular. Everything else is what scientists have called dark matter, and neutrinos would be one of its components. Thus, scientists conclude that 20% of the mass of the universe is constituted by neutrinos.

To achieve all these conclusions, the scientific team has drawn up a three-dimensional map of a part of the universe. In it have been measured the ‘grains’ that appear, that is, galaxies and groups of galaxies. It seems that neutrinos travel to redistribute the mass through the universe, thus softening the universe. Consequently, the heavier the neutrinos are, the softer the universe is.

The theoretical physicist Stephen King of the University of Southampton has affirmed that these values are similar to those obtained in other investigations. However, they still do not know exactly what a neutrino weighs, and the question seems to remain unanswered for a long time.