What causes black holes and stars to spin?

[Taormina]

Did it ever occur to anyone that space, itself, is mass-less, i.e., that it is pure emptiness, and therefore cannot be curved?
There are other explanations for the (gravitational) phenomena that physicists are are using "curved space" to explain.
But does anybody also realize that Einstein was never able to explain what CAUSED mass to curve space?
Einstein only used calculus to describe curved paths that objects take, but never said how mass causes space to curve!
Einstein's theory is actually full of "holes" (errors and gaps), so according to Einstein, we really must doubt his theory:
As Einstein (1950) explained: “The great attraction of the [relativity] theory is its logical consistency. If any deduction from it should prove untenable, then it must be given up; a modification of it seems impossible without destruction of the whole” (p. 110).

[Syne]

Well, it would help if you knew that it was "curved spacetime", not just "curved space". It's basically the gradient, in space, of how fast time moves that causes curved paths. Somewhat like a car taking a corner, where the wheels on the inside of the curve rotate slower than those on the outside of the curve. But instead of the curve causing the difference in speeds, it's the difference in rates of time that cause the curvature of the path. So it's more about time than it is space. Space is just where the time rate gradient occurs. And due to the equivalence principle of relativity, this time rate gradient is the same whether caused by gravity or acceleration. This is because the total velocity of an object is always the sum of it's motion through both time and space. IOW, the faster something moves through space, the slower it moves through time, and vice versa.

[Taormina]

Nonsense! Einstein's theory is full of errors. Space and time are NOT inherently related. Neither one can be "stretched." That is only a delusion.
Einstein had to say very peculiar things about space and time in order for his mathematical equations to balance.
Did you ever notice how physicists, when they are caught in a conundrum that they cannot resolve, always say the math only works on a large scale?
Not sure where you got that info, but physics today has reached a point where many of the more open-minded scientists realize there are too many anomalies, such that those few individuals are saying that we really DO need a new theory. Using the so-called "space-time" idea is like a child who, when asked a question that he/she cannot answer, just says "God made it happen!" Time is a constant throughout the entire universe. It cannot be slowed down or speeded up. And i never heard anyone say that "space is just where the time rate gradient occurs." That gives you an out (like using God to explain something that can't be explained) because that statement allows you to revise the nature of the universe, and avoid defining what space is. Did you know that Einstein never really understood what space is? He thought it was "an ether." But he never defined what he meant by an "ether."
You could try to use textbook physics with its numerous conundrums and explanations that do not offer satisfactory definitions of important concepts, but the textbooks are merely repeating what the authors of those textbooks were told in their physics classes. I had a physics teacher once who, when I proposed a new way of looking at light and asked him to comment on my theory simply said "Oh! Just read the textbook." Sorry, but that is NOT how science is supposed to work.
I challenge you to look much, much deeper into the reality of what space and time really are, in and of themselves. NOT merely use Einstein's mathematics for his fantasy of so-called "space-time," which is an idea that is flawed in its underlying conceptualizations.
Has this made you angry enough at me to actually try to DEFINE (i.e., give a scientific, operational definition of) what "space" and "time" are, without saying that they are one interchangeable dimension? There can be no meaningful scientific discussion if the parties in the discussion do not agree on the definitions of the concepts that they are trying to discuss.

[Syne]

No, you're just completely ignorant of the physics. Space and time are inherently related, even in something as rudimentary as speed, where speed = distance/time. You can't derive a speed without both a measure in space and a measure in time. And the difference in the rate of time due to elevation and speed has been repeatedly verified by experiment:

Newly developed optical clocks are so precise that they register the passage of time differently at elevations of just a few dozen centimeters or velocities of a few meters per second
https://www.scientificamerican.com/artic...-dilation/

That's not large scale. But from the trash you spew, I can only assume you deny such science. "Open-minded" is a crackpot excuse for pure woo. Macro physics moved on from an absolute time once Einstein's predictions proved far more accurate than Newton's. The number of times you compare standard, well-tested physics to God proves you're only a crackpot who simply doesn't understand the physics. Yes, anything far enough beyond your comprehension could appear to be magic, but it's only willful ignorance that keeps you from actually learning it. I don't really give two craps what you've never heard anyone say, as it's pretty clear you haven't been able to digest much of what you've heard at all.

Einstein's use of the description "aether" never corresponded to the classical concept. He only borrowed the term to express that spacetime had a geometry.

The only similarity of this relativistic aether concept with the classical aether models lies in the presence of physical properties in space, which can be identified through geodesics. As historians such as John Stachel argue, Einstein's views on the "new aether" are not in conflict with his abandonment of the aether in 1905. As Einstein himself pointed out, no "substance" and no state of motion can be attributed to that new aether. Einstein's use of the word "aether" found little support in the scientific community, and played no role in the continuing development of modern physics.
https://en.wikipedia.org/wiki/Luminifero...the_aether

And again, you keep saying "space" where the modern physics of gravity requires spacetime. You really need to learn some basic physics before you try to rewrite it or listen to crackpots who are the blind leading the blind.

Here's an epiphany for you. Physics is not ontology. Ontology is a branch of philosophy because ontological questions cannot be answered by the scientific method. Pretending they can be is a fundamental misunderstanding of how science works. Your physics teacher not having the patience to deal with your special brand of unscientific woo is exactly how science is supposed to work. Until you have experimental evidence to support your little proposals, it's a complete waste of everyone's time.

No one in physics has ever called space and time "one interchangeable dimension". Physics definitions are practical descriptions, nothing more. They are descriptions of observations, not ontological deep dives for ultimate "truth", which are the domain of philosophy. The simple answers are that space is an extent and time is a duration. Neither is "made of" anything but arbitrarily defined units of extent and duration. Because when "matter tells spacetime how to curve and spacetime tells matter how to move" there is no chicken and egg problem. Matter is the source. The extent of space and duration of time are only ever measured by and relative to matter.

But go ahead, try explaining these results without a Lorentz invariant spacetime: https://www.scientificamerican.com/artic...-dilation/