Dark matter is not residual energy from a dead black hole because it does not interact with ordinary matter in the way that evaporated particles from a black hole would.

“the particles that evaporate out of it we interact with those particles those are like it's regular matter that comes out so no so you can't you can't appeal to black holes for that”

Sean Carroll believes we will eventually discover what dark matter is, even though it will not provide us with any immediate practical technology.

“and when we do discover which one which I'm very optimistic that we're going to do we'll be able to do essentially nothing with it to answer the question”