tell that to climate change
the US military doesn't give a stuff about friend politicians, and openly states that climate change is a threat to national security
It makes sense to me. If your sandwhich was comprised of something like helium then it would float. I guess "gravity" only applies to certain sandwiches.It is very much theory, and no
So your telling me that you would believe my words over a perfectly legit scientific article I just linked you to? Your suggestion does not sound like it would work very well
the density of an object being greater than the medium it is in will result in it sinking. this is true. however, this doesn't disagree with the newtonian definition of gravity at all. denser materials sink in less dense materials because of pressure. a lead weight exerts more downward force (due to gravity) over a given area than a similar volume of air, because there's more mass in that given volume - equal masses of lead and air would both exert the same downward
force, but the lead would still sink right down because the volume of air is far greater, meaning the overall downward pressure is severely reduced. i can get more in-depth and account for more factors, e.g. the actual details of gravitational forces, but this is a simplified answer as to why "muh density" is technically correct but not a good answer (and also does nothing to discredit gravity)
also, "it is very much theory"- a scientific theory is not defined by the colloquial definition outside of science. a colloquial theory is known as a hypothesis in science. a scientific theory is a hypothesis which has substantial evidence, has been thoroughly tested and reviewed, and has no substantially superior alternative scientific theory known in the scientific community.
scientific theories do not claim to be the absolute truth. they are a scientific approach to moving towards the truth - during every scientific revolution, or breakthrough, we simply replace a theory with a more accurate theory.

(longer flaw lines = bigger flaws, number of flaw lines irrelevant)
in the case of the amsterdam scientist you linked to, he's not actually saying there's no such thing as gravity. he's simply attempting to refine the current theory, and move it towards the slot of "future theory". perhaps one day we will actually create a perfect model of reality, but it'll take a while