Density and buoyancy prove that gravity exists. 
How so? The theory of gravity has never been proven, you'll be the first!
The Theory of Gravity doesn't need proof that it exists. All you have to do is look in thousands of books and thousands of websites to see that the Theory of Gravity exists all over the place.
Same with gravity, only more so. All you have to do is hold your car keys above the table and let them go. They fall to the table. Gravity does it. Gravity is in use all over the world by all people.
And, as some of these recent people have posted right in this thread, gravity proves density exists. And the second proof is centrifugal force, a force which actually opposes gravity.
The two things you are trying to do are:
1. Show a crazy, mixed up FE science that can easily be proven wrong;
2. Use semantics to mix up word meanings just to throw off novice scientists so that they doubt science.
The question is, why are you doing this?
Do you really believe your own nonsense?
Are you trying to form a minority group to get government funding?
Are you simply trying to see how long you can get this thread to go?
Are you trying to start a religious cult of some kind?
Are you trying to prove to yourself that you can actually be so strong that you have no shame?
What are you really all about?
Some things don't need proof to be real, just like the magnetism we can't see it at all but there it is. About gravity, we already have some theories, but we are not sure if it's a particle or a wave, but time will give us the answer.
The science still searching the gravity as a particle on the CERN, and if they don't find it we can deduct it was a wave all the time. If you want to learn more about the particle, take a look to the next link: https://en.wikipedia.org/wiki/Graviton
I think it will be a thing like Higgs boson, no one believes until they see it.