What function do neutrinos perform in the great scheme of things? They are massless, travel at the speed of light and barely interact with anything, yet are produced in great quantities by stars. Why? What are they for?
Stuart Vasepuru from Edinburgh (Age 45-54)
Filed under: age 45-54, Answered Big Questions, Inst. of Particle Physics Phenomenology's Big Answers, Particle Physics Big Questions
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Neutrinos are a key ingredient in our model of the fundamental particles. Without them our theory wouldn’t make sense. They are the partner of the electron in nuclear decay type reactions that allow neutons and protons to turn into each other. It is these processes that occur in fusion (in stars) and fission (in nuclear reactors). Without the neutrino, these processes couldn’t occur because the ‘quantum numbers’ of process wouldn’t add up properly.
Neutrinos are also an essential ingredient in constucting models of the evolution of the universe, from the big bang to what we say today. Without them the models wouldn’t work properly.
In the last 10 years it has been established that the neutrino has a very small mass. This is very interesting because it means that the three different types of neutrino can interchange with each other. The mechanism for giving the neutrino a mass may give clues to a more fundamental theory of nature than we have at present.