Such large ranges can remain intact, the scientists suggest in the May 22 issue of Physical Review Letters, since neutrinos pass right through most of the universe's matter.
An open question is whether gravity—say, the pull from an entire galaxy—can force a meganeutrino to collapse down to a single location.
"Quantum mechanics was intended to describe the universe on the smallest of scales, and now here we're talking about how it works on the largest scales in the universe," Kishimoto said.
"We're talking about physics that hasn't been explored before."
According to physicist Adrian Lee at the University of California, Berkeley, who was not part of the study team, "gravity is a real frontier these days that we don't really understand.
"These neutrinos could be a path to something deeper in our understanding with gravity."
Follow the Gravity?
But answers to such questions depend on eventually detecting these predicted meganeutrinos.
Although they should be extraordinarily common in the universe, the relic neutrinos now have only about one ten-billionth of the energy of neutrinos generated by the sun.
"This makes relic neutrinos near impossible to detect directly, at least with anything one could build on Earth," study co-author Fuller said.
Still, the fact that there are so many relic neutrinos means that together they likely exert a significant gravitational pull—"enough to be important for how the universe as a whole behaves," Fuller added.
Dark matter, for example, has never been directly observed. But astrophysicists have found proof that dark matter exists based on its effect on colliding galaxies.
"So by looking at the growth of structures in the universe," Fuller said, "you might be able to detect relic neutrinos indirectly by their gravity."
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