A definite solution to the solar neutrino problem was found in 2002, when astrophysicists Ray Davis and Masatoshi Koshiba demonstrated that neutrinos have mass. The problem disappears if it is assumed that neutrinos are able to shift from one state to another, which frustrates efforts to detect them.Continue Reading
For decades, the standard model of solar energy production held that the sun converts hydrogen into helium near its core via nuclear fusion. This process generates several forms of radiation as byproducts, including electron-neutrinos. Unfortunately, the standard model predicted the generation of far more neutrinos than could actually be detected on Earth. The quantities of neutrinos detected ran from 33 to 50 percent of the expected total. This discrepancy was dubbed the solar neutrino problem.
By 2002, an international team carried out an experiment to test the hypothesis that solar neutrinos have mass and can therefore change into muon-neutrinos or tau-neutrinos. The results were positive, demonstrating that electron neutrinos, which are the type produced in the sun, travel slower than the speed of light. This means they have a slight mass, which allows them to oscillate between three states. As detectors had always been calibrated to look for just the expected electron-neutrinos, the ability to shift into two additional states explained the two-thirds shortfall in detection rates and solved the problem.Learn more about Our Sun