Is there evidence for or against the interior of black holes being similar to distinct separate universes? Is that a popular idea at all, in physicists' circles?

How much (and _what_) would I need to read and understand to get a feeling of the nature of black holes?

I'm a total layman when it comes to physics and it would put some distant worries of me to rest.

I'd rather measure a lot of Hawking radiation while throwing bottles in flasks into a black hole. However, I'm currently preoccupied with figuring out why my mouth keeps talking when I'm not thinking of anything.