The Earth is more flat than it is spherical.

I'd ask that from this point on, that the opponent both defend his own arguments while rebutting my arguments. Five rounds is not ample space to debate if we are to alternate between defense and rebuttals each round. Beyond that, I'd like to thank my opponent for his thorough response. I'll begin with a short rehashing of one point of my case that was briefly mentioned, then address the opponent's arguments, finally closing with some "questions" I'd like the opponent to answer in is next speech. A Note on My CaseThe opponent briefly mentioned that we are not to trust that other planets exist just because NASA says so. I would again like to say that I was very careful with my arguments such that I could avoid this. When I refer to other planets, it is based upon the information that any private citizen with a telescope could glean. If my opponent would like to seriously suggest that this is somehow an illusion created by "wet space", then it would behoove him to support this with evidence. Argument 0: The Curvature of the EarthThe opponent's number here are largely correct, as it concerns how the curvature of the earth is mathematically described. His assumptions about what this curvature entails, however, are largely misguided. He argues that this curvature should be noticeable when on the ocean, as water on a globe should mostly form a curved, globular shape. He reasons that we do not notice flying over a "760 mile high hump of water" when flying from California to Hawaii. The opponent's difficulty in this is assumably due to his lack of perspective.For the purposes of this explanation, assume the Earth is round. "Height" is a measurement of the distance from the surface of the earth/ocean to some reference point above it. In other words, if one were to draw an arrow perpendicular to the ground upwards at many points along the Earth, the arrows would all face in different directions and away from the center of the earth. (Think sea urchin.) Because of this, person A could be 10 miles above Texas and person B could be 10 miles above China, but they would objectively be about 8,000 miles away from one another. Similarly, when a plane flies it attempts to maintain a constant altitude. Because of the curved Earth, this means the flight path of a plane is actually curved -- it is not literally flying in a straight line from California to Hawaii, else it would pass through water. We know the "hump" exists because we cannot stand on a tower in California, pull out a telescope and see Hawaii. If the world were flat, as the opponent contends, such an action would be possible. (Technically it would not, as the density of the atmosphere would obscure Hawaii. But we would at least see a white fuzz instead of the sky.)While the maths regarding the Earth's curvature are correct, the opponent's belief that this disproves a round Earth is unfounded. On the contrary -- the fact that from hawaii one cannot see any other landmass is indicative that it is indeed surrounded by a "hump". (Though from the perspective of a citizen on the island, it just looks like the sea extends infinitely in all direction, because as the opponent mentioned -- the curvature of the Earth is too slight for us to notice it when on the ground. People are unable to tell that the ocean is 6 feet lower from 10 miles away. Our vision is nowhere near that good.)Argument 1: Distances SightedThe opponent brings up an instance in which the Chicago skyline was visible from Michigan, something that should be impossible if the Earth were curved. This was explained as being what is called a "superior mirage". Instead of trying to explain the exact science behind mirages, I'll take a different approach. Let us assume that the Earth is flat and that the Chicago skyline was visible because of this. This would imply that the Chicago skyline is always viewable from Michigan from that particular spot, if weather conditions are normal. This simply isn't the case. Normally, one cannot see the skyline from Michigan. What's more, the mirage often does show up as inverted and mirrored. [1] This conundrum can be explained in one of two ways. Either the opponent is correct and the Earth is flat, but Chicago itself regularly pops into and out of existence, with the occasional horizontal inversion or the referenced video is indeed a superior mirage. The most *reasonable* conclusion is that the image seen is a superior mirage. It is highly unlikely that Chicago is flitting in and out of existence. Argument 2: Reflection of Light on Flat WaterFor the first part of this, the opponent maintains that water always attempts to be "level", which he concludes is not possible on a spherical Earth. This is easily understood when one understands that "level" means "having the same relative height". As I explained earlier height is measured from the center of the Earth. If you placed a two buoys are different, random positions in the ocean and measured the distance of said buoys from the center of the Earth, you would get similar measurements. This is because water is affected by gravity and on Earth gravity pulls all things toward the center of the Earth. This is why water can maintain a "curved" shape. (The opponent is fond of physics engines, so I recommend that he creates a gravitational point and then fills the container with a liquid. He will see the water comes to equilibrium in the shape of a globe.)As for the second part, I'm not quite sure the opponent's point regarding sunsets. [2] I've provided an image of a sunset and it is exactly what one would see in a physics simulation if you recreated the helio-centric model and looked at a sunset from a zoomed in portion of the water sphere you created earlier. (I own a physics simulator, so if the opponent is not pleased I can further demonstrate that this is actually the case.)Argument 3: Flight pathsThere are two reasons for the effect you're describing. The first is demand -- there aren't that many people looking to go from argentina to sydney. There are very many people looking to go to and from north america.Outside of this, the flight paths of planes don't really do much to indicate the shape of the Earth, in most instances. Planes have limited fuel, must deal with demand and must account for various weather structures and wind patterns. If the opponent provided said map and flight paths, I could provide a more specific rebuttal. But as this argument stands, it isn't saying much or proving much. QuestionsHere I'm simply outlining some questions for the opponent to answer. These are not arguments -- just questions. 1. Why has no one document the "edge" of the Earth?2. Why is it night in some places and daytime in others, simultaneously?3. Why can't you see Hawaii from California?4. What's on the "other side" of Earth? If someone's seen it, why isn't there evidence of their journey "over and around the edge?"5. Why would this conspiracy exist? Who does it benefit?6. Why do ships sail below the horizon? 7. Why can I skype someone in China and see the moon when I cannot see the moon from where I am? 8. How do you explain Rayleigh scattering?9. How do satellites work if the Earth is flat? If satellites are a myth, why does my cell phone work? How does google maps have accurate images of my neighborhood from space?ConclusionI've demonstrated that the opponent's arguments do not hold up. I expect that he will rebut my arguments in the next round, as well as defend his own. Hopefully he will answer my questions as well. Sources:1 - http://www.freep.com...;2 - http://wp.lps.org...;