Black holes were foreseen in 1783, John Michell postulated that an invisible star could be massive enough to trap light, so called Dark Stars. The idea, expressed only in a Royal Society letter, remained largely unconsidered for a decade.
In 1798, Henry Cavendish, using lead spheres and carefully recorded observations, determined the gravitational constant and the weight of the world. He placed the density of our rock at 5.45 times the density of water, a number that matches well with today’s estimation of 5.51. Cavendish’s calculations of Total Mass were also pretty accurate, 5.97 × 10²⁴ kilograms.
Cosmologists pondered those speculations for 100 years until 1915 when Albert Einstein published the theory of general relativity, predicting spacetime and gravitational curvature or warpability.
A 19-year-old mathematician named Chandrasekhar mathematically proved a star just 1.4 times solar mass (the mass of our sun) will collapse. In 1939, Oppenheimer predicted at a collapsing star, provided it retained enough mass, would collapse all the way down to a black hole.
Back in 1916, Karl Schwarzschild had predicted a flat black hole without charge. Such a black hole probably does not exist. If it exists, a single proton striking it off-center would impart the customary spinning rotation. In 1963, Roy Kerr published the Kerr solution which correctly painted the more correct picture of a violently spinning monster pulling everything inward.
In 1971, the first black hole, Cygnus X-1, was first spotted. Stephen Hawking famously played the devil’s advocate and lost a bet as to whether Cygnus X-1 actually was a black hole. Cygnus X-1 is about 21 solar masses and is 7,000 light years away in the northern sky.
Super-massive holes, like Sagittarius A at the heart of the Milky Way, first came into view via the Hubble Space Telescope in 1994.
Be thou aware! We are on the precipice of some amazing revelations.
Black Holes
Imagine the vacuum cleaner in a giant sphere with dust in the air. Suppose that the sphere is in orbit around the Earth, and inside the sphere, all the dust is weightless, and there is no static cling to the walls of the sphere. And the vacuum cleaner runs for billions of years. The concentration of dust in the air will eventually get close to absolute zero, but there will always be a vanishingly small chance that a mote or a few could remain unsucked.
We do not, at this time, have the capability to answer such questions, Eter Null. However, we are on the verge of finding effective answers through experimental simulations, careful observations, and AI enhanced calculations.
As I understand it, one question is what happens to matter absorbed by black holes. Does it accumulate or pass on through, perhaps to another dimension.
But your question is will one just keep sucking up matter until everything is absorbed. It’s a good question. A vacuum cleaner, as far as we know, cannot pull in the dirt from the other side of town, or could it, if left running for a time so long it is hard to imagine?
Why would black holes ever stop absorbing matter? Maybe all galaxies are eventually doomed to fall into their central, growing supermassive black holes, and the far distant future is nothing but black holes. Even Hawking radiation gets reabsorbed.