AMA | September 2024

13248.204 - 13268.542 Sean Carroll

Indeed, in some sense, since we know that neutrinos are massive, neutrinos are a part of the dark matter, right? We think that they're a small part of the dark matter. For one thing, the neutrinos we know and love would be hot dark matter, which does not fit the data. And for another, we can count them, and it's more or less, you know, an energy density of 10 to the minus 4 or something like that.