First, “Is the observed attraction phenomenon of a mass really caused by a force?” The short answer might be: yes. All of the observed motions, actions and reactions of opposing gravitational masses are empirically consistent with Newton’s three laws of motion. This, of course, includes his first law of inertia and resistance; his second law of force and acceleration; and his third law of action and reaction motions (Sections H, I and J).
Such gravitational motions, actions, and reactions are also substantially consistent with his law of Universal Gravitational Attraction:
“[E]very body in the universe attracts every other body toward its center with a force that is proportional to the mass of each body and is inversely proportional to the square of their distance apart.”
Such motions are also consistent with the empirical natural law of Relative Gravitational Acceleration, which is nothing more than an application of Newton’s laws to the observed and theoretical gravitational accelerations of all opposing masses. On the other hand, the natural law of Relative Gravitational Acceleration completely contradicts Einstein’s theories of gravitation, vis. equal gravitational acceleration regardless of mass, gravity without force, his Principle of Equivalence, and curved spacetime.
Gravity acts exactly the way a force caused by energy should act. It holds masses in reciprocal orbits in the same way that an Olympic hammer thrower and his weight at the end of a chain move in reciprocal orbits, or a bandleader twirls a weighted baton around its center of mass. It causes masses to reciprocally move toward each other, often to impact, like the Shoemaker-Levy comet and Jupiter, or a bullet and an approaching terrestrial target. The Cassini-Huygens planetary spacecraft dramatically picked up speed like a magnet, as it approached its rendezvous with the planet Saturn. The oceans are pulled by the Moon, stronger on the side of the Earth facing the Moon, and to a lesser extent on the other side; which demonstrates the inverse square law of attraction relative to distance. The result is simultaneous higher tides on both sides of the Earth. When Galileo’s cannonballs were released at the top of the Leaning Tower they immediately accelerated toward Earth. When we try to pick up a heavy object, its weight (mutual attraction with respect to the Earth) greatly resists our attempt. All of our massive buildings are held fixed to the Earth, despite the Earth’s rotational speed of 1,000 miles per hour. The Moon remains in orbit despite its inertial straight-line speed of about 3,750 km/hr. How can there be any doubt?
There is an old proverb of logic: If something looks like a duck, and walks like a duck, and flies like a duck, and quacks like a duck, then most likely it is a duck. Likewise, all of such gravitational motions, observations and natural laws are consistent with, and lead us directly to, the conclusion that gravitational attraction is caused by some kind of force.
Thus, we have the following laws of nature:
1. The attracting (pulling) phenomenon of a gravitating body is a force which is proportional to the mass of such attracting (pulling) body.
2. The inertial resistance of an attracted (pulled) gravitating mass is inversely proportional to the applied force of the attracting (pulling) mass.
3. The gravitational acceleration (motion) of an attracted (pulled) mass is proportional to the applied force of the attracting (pulling) mass, and inversely proportional to its own pulled mass.