They exist - not only because the astrophysicists tell us the data fits the mathematics beautifully, but now because one has been seen in action.
Read, "see" and marvel:
https://www.syfy.com/syfywire/astro...ing-a-black-hole-right-at-the-edge-of-forever
Read, "see" and marvel:
https://www.syfy.com/syfywire/astro...ing-a-black-hole-right-at-the-edge-of-forever