Well, first of all, your question is awkward, because "theory" doesn't mean "not fact".
Newton's law of universal gravitation can't be proven, but it's a very very very very
successful theory, in many ways.
-- When you take Newton's formula for gravity, and use calculus and geometry
to stroke it and squeeze it and massage it and roll it around in your hands, it
tells you what the shape and size of planetary orbits must be, and how the
planets must move in their orbits . . . and then when you measure the real
motions of the real planets, you find that they actually move as the formula
for gravity says they should.
-- When you take Newton's formula for gravity and use it to program the maneuvers
of a TV satellite, a moon landing, and a space probe to Pluto, those things work just
as you want them to.
None of this "proves" that the formula for gravity is correct in every possible way.
But so far, for more than 300 years, it has been the best formula we have, as long as
we don't try to use it for things that are very very tiny ... like smaller than atoms.
The theory that Einstein developed which pertains to gravity is called general relativity.
It will be replaced by a new theory when enough evidence is collected
This is a fact.
Newton
Newton's Law of gravitation
The theory of gravity is very, very old, in fact Plato was discussing it. However, it was Newton who formulated the theory of universal gravity, that the same "force" that causes things to fall to the floor keeps planets in orbit around the sun.
The best way to respond to this is to explain that there is the fact of evolution and the theory of evolution. Evolution is defined as genetic change within a population. This is an easily observable fact both in nature and the laboratory. The theory of evolution is an explanation for the diversity of life on earth based on the observable facts that evolution does indeed occur. It is exactly the same situation with gravity. Gravity is a fact, an easily observed physical phenomenon. But there is also a Theory of Gravitation, an explanation for the phenomenon itself and how it works. That there is a theory for both evolution and gravity does not mean the facts of evolution and gravity are any less true.
Yes, Einstein did produce a theory of gravity, and it is more accurate than Newton's theory of gravity.
The theory that Einstein developed which pertains to gravity is called general relativity.
The theory that gravity is instable
Gravity- The force that attracts a body toward the Earth, or toward any other physical body having mass. For most purposes Newtons laws of gravity apply with minor modifications to take the general theory of relativity into account. FACT= *Gravity is measured by Acceleration.
They didn't; the big bang theory is just an idea or a theory, not a fact. The empirical evidence that our Universe was, 13.7 billion years ago, much more dense that it is now, is overwhelming. No other explanation even begins to explain what we observe in our Universe. Saying the Big Bang is a "just an idea or theory" is like saying gravity is "just an idea or a theory, not a fact."
Gravity is not well understood. It is a property of matter.
The theory of gravity is important because humans need explanations to things they do not understand. The theory breaks a possibilty down to where it becomes understandable.
Relativity is a theory of gravity, and gravity governs the motion of planets. This is your answer in a nutshell. If you want a detailed answer, then I suggest you start studying general theory.
The Church has always promoted science, I can find no evidence that they ever had a problem with the theory of gravity.
Gravity was Newton's most famous theory.