A quick back-of-the envelope estimate, in the style of Fermi:

For a neutrino mass of m ~ 1 eV, and a Planck mass M ~ $10^{27}$ eV, and supplanting the newtonian potential $(m/M)^2/r$ for the Coulomb potential $e^2/r$, yields a Bohr radius for such neutrinuum atoms of $$ r \sim M^2/m^3 \sim 10^{54}/\hbox{eV} \sim 10^{47} ~~\hbox{m}. $$
Compare this to the present diameter of the entire universe...

A quick back-of-the envelope estimate, in the style of Fermi:

For a neutrino mass of m ~ 1 eV, and a Planck mass M ~ $10^{27}$ eV, and supplanting the newtonian potential $(m/M)^2/r$ for the Coulomb potential $e^2/r$, yields a Bohr radius for such neutrinuum atoms of $$ r \sim M^2/m^3 \sim 10^{54}/\hbox{eV} \sim 10^{47} ~~\hbox{m}. $$
Compare this to the present diameter, $10^{27}$ m, of the entire universe...

A quick back-of-the envelope estimate, in the style of Fermi:

For a neutrino mass of m~ 1eV, and a Planck mass M ~ $10^{27}$eV, and supplanting the newtonian potential $(m/M)^2/r$ for the Coulomb potential $e^2/r$, yields a Bohr radius for such neutrino atoms of $$ r \sim M^2/m^3 \sim 10^{54}/eV \sim 10^{47} m. $$
Compare this to the present diameter of the entire universe...

A quick back-of-the envelope estimate, in the style of Fermi:

For a neutrino mass of m ~ 1 eV, and a Planck mass M ~ $10^{27}$ eV, and supplanting the newtonian potential $(m/M)^2/r$ for the Coulomb potential $e^2/r$, yields a Bohr radius for such neutrinuum atoms of $$ r \sim M^2/m^3 \sim 10^{54}/\hbox{eV} \sim 10^{47} ~~\hbox{m}. $$
Compare this to the present diameter of the entire universe...