You are making a semantic argument, so let's clear it up.

Gravity is the natural phenomena, or experimental observation, whereby bodies with mass appear to gravitate towards each other. One model and explanation of this phenomena is Newton's Law of Gravity used within the framework of Newton's dynamics (or laws of motion). The Law claims that gravity is a force, with a very specific formula we are all aware of.

If you ignore Newton's third law (about action-reaction pairs) for the gravitational phenomena of small bodies near a planet, and assume that the planet doesn't move at all, then we call the force on the small body its weight.

Now, returning to your question, in daily lingo, physicists use the word gravity to refer to the phenomena, the force law, or the weight. You have ascertain from context. In summary, gravity is a force is a perfectly valid and understandable statement within the slang of physics.

Heavy objects are made of many light objects[0], so no, they would still accelerate at the same rate.

[0] with the exception of light, which is very light[1], but made of light particles rather than light particles.

[1] Homographs ahoy

There are heavy objects that are not made of lighter objects as far as we can tell, such as the Higgs boson or quarks. As far as we currently know, they should also fall at the same speed near the earth.

Fair point — I was just rehashing a very simple thought experiment that showed why the acceleration should be the same for heavy and light objects alike, but you are totally correct, it isn’t really ok for me to count all bradyons as equivalent.

The thing is that this thought experiment is interesting, but it is wrong. It is true that it is not logically possible for a system of two objects to fall faster than both of its constituent parts, but that does not mean that it is a priori logically impossible for heavier objects to fall faster than lighter objects - the lighter object would slow down the heavier object somewhat, so the new "combined" object would fall slower than the heavier of the two objects, but it would fall faster than the lighter of them.

In fact, the fact that heavy and light objects fall at the same speed is a profoundly special property of the gravitational interaction. No other fundamental force behaves this way: in an electric field, objects with more charge will accelerate more quickly than objects with less charge (and the same is true for the weak and strong forces).

In fact, the acceleration of an object or particle in a field is proportional to its field-specific charge divided by its inertial mass. The really interesting thing about the gravitational interaction is that the "charge" associated with the gravitational field is exactly equal to the inertial mass of that object, so all objects accelerate at the same rate because of the gravitational field.

This truly special property of the gravitational field had no explanation until Einstein's theory of general relativity, which discarded the idea that the gravitational field is a field at all, and described the motions of objects only in terms of rectilinear movement in a curved space-time (the reason why inertial mass curves space time is still unexplained though - it seems to simply be a property of the universe).

> that does not mean that it is a priori logically impossible for heavier objects to fall faster than lighter objects

Right, but if this were the case, a dumbbell would fall about twice as fast when its axis is perpendicular to the ground, than when it's parallel to the ground. Realizing this is not true from lived experience completes the thought experiment.

The difference between the total force acting on the horizontal dumbbell and the total force acting on the vertical dumbbell is 2/(height-dumbbell_length)^2. Given that height should be measured from the center of the Earth, this is ~0 for any length of dumbbell you can conceivably imagine. So even if lighter objects fell more quickly than heavier objects, you wouldn't expect to see oriented dumbbells fall at different rates.

However, what you could expect to see is that dumbbells with different weights for the two parts would never fall horizontally, they would tend to reorient vertically, with the heavier end first. Not sure how likely it would be to have noticed that this is not the case from lived experience.

suppose you have an electric field described by a potential \phi, the force is

F = - q * d\phi/dx

where q is the electric charge

now suppose you're in a gravitational potential \phi_g, the force is

F_g = - m * d\phi_g/dz

where m is the mass. as you can see it's like the newton equation, so yes looks like an acceleration :)

Physics does not magically become different outside the confines of a good school.

On the other hand, the Internet is black with the ink of people who think they understand physics but do not. Credentials do help you to distinguish someone who has a chance of knowing what they're talking about.

I mean, it's… true? My own (very highly upvoted) comment on the main thread of this article contains the text "I only took four lectures of General Relativity before I gave it up in favour of computability and logic", which is helpful context for anyone who reads it, because it lets the reader know in a fairly objective sense that I am familiar with some of the concepts of GR but am unlikely to understand everything in detail. You can't know whether someone on the Internet knows what they're talking about, but they can give you some of their context to help you decide. Admittedly "a good school" is not the most useful context, but it's better than no context.