Neutrinos passing through black holes

Question

What would happen to a neutrino that, traveling parallel to the black hole, crossed it's event horizon? Would it come through the other side unaffected? Or, A neutrino and a black hole just happen to be traveling in the same direction but the neutrino get close enough to cross the event horizon. Is it now trapped inside the event horizon even though technically it only interacted with the black hole on a gravitational level?

Answer 1

In general, don't think of black holes as material objects like stars or planets. We can ascribe properties like mass, charge and angular momentum to them, but if you're near a black hole and reach out to touch its event horizon, you won't feel anything (assuming you're still alive). Your hand will simply pass through empty space, and then into the black hole. Think of black holes instead as regions of spacetime, with the curious property that if you enter one, you can never exit.

I'm guessing your question is motivated by the fact that neutrinos interact extremely weakly with normal matter. They have very little mass and no electric charge, and mainly influence other particles through the weak nuclear force - which is, of course, weak, although not as weak as gravity. The problem with taking this assumption further and concluding that a neutrino might pass through a black hole unharmed is that black holes aren't "normal matter". They're sections of spacetime, and while they may contain matter, that matter is not at all important when interacting with other particles. The only thing here that is important is that they are sections of space which have only one-way openings. Once inside, nothing can leave.