Are black holes now considered to be 'proven' real objects in the universe?

I think the circumstantial evidence for the existence of black holes is now so strong that it would be hard not to consider them to be real objects in the universe. The strongest evidence we have is for the stellar-mass and supermassive black holes. General relativity, however, predicts that if the conditions are right, black holes can have any mass. Once you open the floodgates by accepting the existence of one kind of black hole, you have opened the question of whether other less massive ones may also exist, and under what conditions such holes could be spawned. The favored spawning ground for sub-stellar black holes is during the first few minutes after the Big Bang when matter was rattling around with enormous collisional energies.

I have watched the evidence mount during the last three decades with astonishing speed, culminated by the fantastic observations by the Hubble Space Telescope. It is hard to imagine that some other mechanism can be the host for the phenomena we see in the cores of quasars and active galaxies. And it is not that theoreticians have not been actively pursuing other non-black hole possibilities. But one by one, I have seen these other ideas succumb to new observations, while the simplest explanation predicted, and even demanded by general relativity grows in strength.

There have been many episodes in scientific advancement when a new idea was initially met with some discomfort, but after a few decades and the accumulating weight of evidence, the community began to grow comfortable with the new idea. Not too long ago, many physicists did not 'believe' in the existence of atoms, or in quarks. They are now hallowed members of the modern repertoire of things in nature. The above HST photo shows the core of a galaxy which has a vast disk of gas swirling around a massive black hole near the bright point of light at its center. This black hole has over 100 million times the mass of the sun.

Years ago, a young girl wrote to a newspaper asking whether Santa Claus existed, the answer was " Yes, Virginia, there is a Santa Claus". So far as I am concerned, "Yes, dear reader, there are in fact black holes!"