The Earth is more flat than it is spherical.

A great many ideas are currently being discussed here and I believe if I tried to address each of them as individual arguments, the debate would become muddied, hard to follow and difficult to judge. Instead, I'll be defending some specific concepts, the very nature of which imply the falsehood of my opponent's claims. These concepts specifically are: gravity, satellites and arguments concerning the inconsistency of a Flat Earth. Gravity and SatellitesThe opponent seems to have a fundemental misunderstanding of what gravity is, in that he repeatedly attempts to show gravitational ideas are inconsistent by referring to properties of gravity that are not considered to be true. The opponent begins by attempting to explain gravity as a faulty assumption that is actually explained by density and buoyancy.Density in and of itself is simply defined as the amount of mass (not weight, mass) that a given thing has per cubic unit. Ie, water has a density of 1000 kg / m^3, which is to say that every cubic meter of water contains exactly 1000 kg of water. Density itself does not define any particular physical behavior, but rather a physical characteristic. Bouyancy, on the other hand, does define a behavior in many ways. It's definition is "the upward force exerted by a fluid that opposes the weight of a submersed object". Weight is defined as "the force on an object due to gravity". In noting this, we see that the opponent is assuming the existence of gravity by claiming to believe in buoyancy. Without gravity, the concept of buoyancy would not exist. What's more, buoyancy deals with fluids -- not gases or solid matter. We are currently being "held to the Earth" in a gas atmosphere, meaning no liquid is involved. This means that even if buoyancy didn't already assume the existence of gravity, it still would not explain our current dillema.The opponent's referenced FAQ uses a cute picture of various color liquids being suspended on one another in a beaker. The characterstic of density does play a role here, as more dense matter is pulled beneath less dense matter. If we were to hypothetically assume that this account for us staying on the planet, then we run into a consistency when considering the "Vomit Comet".For those who don't know, the Vomit Comet is any plane that flies in a specific parabolic, largely vertical flight path whose purpose is to introduce people to what it feels like to be free of gravity. In the opponent's view, the density of the air inside the plane is less than the density of a human, so the human should remain on the ground. We find, however, that when the plane enters a controlled fall, the people and object inside begin to "float" and can move around the plane in any direction without being pulled towards the Earth. In the opponent's view, this should be impossible. Clearly the flight path of the plane does not change the density of the objects inside, but we still see that the behavior of these objects changes.This counter-example effectively disproves the opponent's "density" argument. We are, again, left with the idea that object possess an innate attraction toward all other objects and that particularly large objects exert this force to a noticeable degree. We should also note that the opponent ignore the evidence I presented that clearly shows a science experiment in which the gravitational pull between two relatively small objects was able to be measured. This evidence is an actual observable measurement of the gravitational pull between two things which are not celestial in size. Next, the opponent attempts to provide "gravitational counterexamples", which I will address here. 1. "Gravity causes some things to stick to other objects, some things to orbit, pulls on some objects and pushes on others."Barring the last behavior (pushes on objects), which has never been demonstrably observed, the other behaviors are all the same.Gravity causes things of mass to be drawn toward one another. The strength of this force depends on the distance between the two objects and the mass of the objects. Two grains of sand in a vacuum, void of any other matter, would be attracted toward one another and would eventually meet. This would take a considerable amount of time, however, since grains of sand are very small.As far as Earth is concerned, we can think of the Earth's gravity as "causing things to fall". Objects in orbit are literally falling toward Earth, but their horizontal velocity is great enough such that they effectively remain at the same altitude, even though from a fixed perspective they are clearly falling. All satellites eventually will fall to earth, if left untouched, as they slowly lose their horizontal velocity over time due to minute frictions. Gravity pulls on all objects and there is no observable behavior that violates this idea. 2. "How can we do space walks on the ISS."As was mentioned, things in orbit are falling. Just as you can do a "space walk" on a Vomit Comet, you can do one on the ISS, since both are falling. It is a common misconception that gravity is "too weak" on the ISS that it allows floating. Rather, the ISS and other satellites are in a constant state of falling, which allows for the sensation of weightlessness.3. "How do elliptical orbits work."Perfectly circular orbits are nearly non-existent in nature. All orbits are elliptical to greater or lesser extents. An elliptical orbit "works" because an objects relative velocity changes dependent upon its location in the orbit. If you think of the "portion of the orbit" where the object is coming back to the larger body from its long leg, it is moving at a very fast speed. The satellite moves past the planet, then loses velocity as it reaches the far end of the other leg, then comes back. A highly elliptical orbit is basically an object that is falling toward the planet, but has the horizontal velocity to just barely miss hitting the planet. Again, all orbits are elliptical to some extent. And to further make clear an important idea here, if something has a velocity that it going against the direction of gravity, that object can still move for some time in that direction, though gravity is decelerating it. Consider that you can "jump" on Earth. You jumping gives you a vertical velocity against gravity. This velocity is reduced because of gravity's acceleration in the opposite direction, so eventually you stop moving up and come back down. I hope this clarifies gravity for the opponent. Doing something as simple as reading the "gravity" wikipedia page clearly answers many of the opponent's questions, as gravity is a very understood phenomenon. (I say understood in that we know how objects are affected by gravity. The nature of what actually causes gravity to occur is not understood at this time.)Flat Earth CounterexamplesI'll providing some counterexamples, either based in logic or based on what any person can do themselves. I'm not going off any "video evidence" or "photo evidence", as the opponent believes that these could be part of some epic conspiracy.1. You can't see Hawaii from California.Let's be clear -- I understand that the atmosphere would not allow one to see 2,500 miles in one direction. However, I title the point this to harken back to the points mentioned earlier. If the Earth were flat, one would expect that you could look at the horizon and either a) see very distant earthly objects or b) see a white "fuzz" caused by the atmosphere. We see, however, that whenever we look over any horizon at night, we can clearly see stars. If the world were flat, we would expect to see a "fuzziness" that goes up for a while, which then turns to star light once we are looking through little enough atmosphere to see.This is clearly not the case. I say any horizon because I want the opponent to understand that this ability to see the stars has nothing to do with local geography, but is a global phenomenon. Consider this gourgeous image that I have provided. It illustrates a portion of a flat Earth. The distance between the penguin and the city is some 2,500 miles and he is looking in the direction of that city, over the horizon. He should see an atmospheric blur in a flat earth, but he is in reality able to see the stars directly over the horizon. This reality is completely inconsistent with the flat Earth model. 2. The Flat earth is inconsistent with gravity.As I have already demonstrated, gravity is a real force that even the opponent unwittingly used to describe the behavior of objects in his "buoyancy" claims. A flat earth could not maintain its shape under gravity and people near the "edge" of the flat earth would not be pulled down but rather at an angle between "down" and "over". Let's explore both of these ideas briefly.Just like water, the earth generally attempts to rest at the "lowest point", which is to say it attempts to exist in the state in which it has the least potential energy. Just as if one built a sufficiently high skycraper it would eventually crumble under its own weight, so would a flat earth's edges crumble toward its gravitational center. This is why celestial bodies are generally round -- gathering matter during planet formation attempts to rest in the position in which it has the least potential energy. This shape is a sphere, in which every point on the surface is roughly as distant from the gravitational center as every other point. (This is also why water forms a sphere -- it is at its "lowest" point when the surface of the water lies along the radius of a sphere, as it is as close as it can be to the "center".)Additionally, the gravitational center of the earth would still be at the "middle of the plate" in a flat earth. This means objects near the edge of the plate would be pulled in that direction and would, based upon the size of the earth, literally slide in that direction, since they are not affixed to the earth.ConclusionUnfortunately, I'm out of space. I look forward to the opponent's response.