Wading in after several days away. Occam's Razor was the topic right?
The Tamarak experiment vs a ton of other evidence. Well let us apply the razor shall we? The Tamarak has been shown to have troubles in many ways. And on the other side at this point thousands of experiments that confirm gravity and a basically spherical, spinning Earth. Guess which OR suggests is the winner?
Vauxhall, last I checked Earth contains lead, so it is indeed made of lead. Definitely not exclusively, nor even in majority. But it is not devoid of the stuff.
The Cavendish experiment has been replicated with other materials, not just lead. The same results occur. The moon orbiting the Earth was Newton's main inspiration for the basic equation F=(G*M*m)/r^2. If you think lead is a problem then fine, the Earth is made up of many different things, all of which have been shown to have MASS and mass is the relevant property here. See the two m's in the equation? Those stand for mass. And we also know what the sun is composed of and those also have mass, therefor there was no illogical assumption made. Now I am sure you will now go on about assumptions of mass or some other tomfoolery. Have at it.
I see that Mikey mentioned he is not a physicist. Well I am. No one will do the Tamarak experiment again, see above. There is no reason for working scientists and engineers to want to. There was a time when the idea of universal gravitation was a new and relatively weak idea. The preponderance of evidence that is now in hand would require some incredible event to occur for engineers and scientists to question it. Because there is a plethora of evidence.
Flat Earth types seem to come in two flavors. Those who are clueless as to how science really functions. It is primarily a set of methods that are used to determine the way nature works and to produce hypotheses and to test those. An experiment is not done once and never replicated, especially one that is relatively easy to replicate and has important value, as the Cavendish one did. Something costing billions might not be replicated. But even at the LHC two different detectors were involved in the search for the Higgs Boson and the discovery of it was only accepted after the results from both detectors (essentially two different experiments) were show to confirm one another. The second flavor of Flat Earthers are the same as a great number of anti-scientific types. Their mantra is, "this is too hard for me to understand therefore it must be incorrect." Well tough. Accept that some people are brighter than you and have worked for years to acquire the knowledge and know how to become scientists and engineers.