They are no longer theoretical...................
Well, that’s the opinion of some.
1. by definition, they cannot be seen as nothing including light escapes them.
2. Hawkings Radiation-apparently does not exist as it pertains to the theory of BH existence, so it is not evidence of BHs.
3.Uncertainty Principle- states it is not possible to locate something exactly
4. The idea of BH is an attempt to explain another theory- the big bang, because mass ought to be evenly distributed throughout the universe but it is not, shooting (black) holes as it were, into that theory of origins ( besides, even my 3rd grade grand child asks where did the big bang come from, who made it go bang? ) and no, it did not occur because “it had to” like some famous dead guy declared. “It”, demands identity, an actor, not nothing doing something; irrational and illogical.
However, as in all science (body of knowledge) and research, seeking is important, but finding is not a function of consensus (ask Galileo, who actually read the Bible), the truth is always self-supporting and self-evident.
He Lives!