The idea sprang from calculations showing that the density of dark energy is comparable to the value of neutrino mass, said lead researcher Jitesh Bhatt, with the Physical Research Laboratory in Ahmedabad, India.But what does "comparable" mean? Same order of magnitude? And how many neutrinos are there really? It's only been within the past decade or so that we solved our solar neutrino problem (in which the sun seemingly only produced 1/3 the number of neutrinos that theory predicted - turns out that neutrinos change their type as they travel, and we were only looking for one type at the time). Up until this time, one could have been forgiven to presume neutrinos massless. Yet here we are today saying the amount of dark energy is comparable to neutrino mass. Both are notoriously difficult to measure and, again, comparable may mean neutrino mass is half of the dark energy equivalent.
"It will take much more work before we can pin down the nature of dark energy," Bhatt said. "Without knowing the nature of the dark energy, our knowledge of theoretical physics would remain incomplete."Indeed.