The Earth is hollow.

Seismologic unreliability There is a huge difference between accuracy and directness. Seismographs are finely tuned instruments, giving accurate and reliable readings of seismic tremors. These tremors are mechanical energy given off by certain events, and the point of the seismograph is to record that energy. Full stop. That's it. My opponent seeks to discredit the findings of modern geophysics by casting doubt on the primary instrument of research in this area by repeatedly mischaracterizing the seismograph as an instrument for predicting earthquakes, rather than measuring them. The fact that they are primarily on land and far-spread has little to do with the enormous discoveries they have allowed us to make about the structure of the earth - namely, that tremors travel faster through certain parts of the earth than others, allowing us to calculate the density of parts of the mantle and core. We can tell that the tremors are traveling through liquid rock, for instance, rather than through air or a vacuum, because of the speed. We can hear when they echo off abrupt temperature or structure changes, giving clues as to the form of the interior. We can tell that there is a solid core because of the way the waves are deflected. Were the earth hollow, the readings we'd get would be entirely different. That is why my opponent has to discredit these instruments; because the informationn they give directly contradicts the teachings of the hollow earth fiction. Satellite photographs The simpler explanation, especially considering that the very presence of the oceans proves that there is no arctic hole, is that these white specks are either parts of the ice cap or artifacts from the image compositing process. The orbit information I provided for the ESSA-7 is almost identical to that for all the other ESSA satellites, who all were on arctic-avoinding orbit for the reasons I gave last round. I gave images from satellite photos, two of which were not composites, but direct photographs of the norther section of the earth. The "sea ice" my opponent refers to happens to be the entire polar ice cap; if there is a hole, I challenge my opponent to find it. Furthermore, these are only a few of a very large number of photos available from various sources, both public and private, that show the unblemished polar cap. I am not obligated to provide every single image of the North Pole to prove this point; my opponent is leaning on two very grainy photos with an unusual but perfectly logical compositing artifact, and if he were to use any other photo of the pole he would have no basis for his claims. This is cherrypicking at its most blatant. Crater formation My opponent concedes that no meteor craters have been observed in formation, and once agian misunderstands the nature of the seismograph. Since we do not have any observations, direct or indirect, of the the event in progress, My opponent mischaracterizes my argument by saying "The argument that there is a planet is unable to rebound is contrary to observable evidence," This is a strawman. I provided a mechanism by which the magma-filled planet would rebound - an explanation the hollow earth lacks. The pressure of the mantle are quite sufficient to explain the rebounding of the crater floor, as well as explaining the lack of radial fractures. My opponent had no adequate explanation as to why a hollow planet would not exhibit these fractures, or holes into the inner void in particularly large craters. He also did not give any real reason why the hollow earth would spring back into shape after a large meteor strike, rather than shattering or puncturing. Volcanoes Magma, and consequently volcanoes, continental drift, and plate tectonics, is logically incompatible with a hollow earth. With an internal void, there is no reason for the magma to escape upwards; the slightest opening in the inner surface would allow the draining of the magma to the center, and any volcanic activity we may have once had should have ended eons ago. Not to mention the fact that the thinness of the shell doesn't provide a plausible reason for the existence of magma; the pressures involved are far less intense than the mantle and core, and you presumably have another solid crust on the inner surface, which makes no sense at all considering magma is rock under great pressure and heat, both of which should be lacking from the hollow earth. This is a fatal inconsistency for the hollow earth idea. Without vast amounts of liquid rock, the whole observed process of continental drift cannot take place, as the expansion of the plates at the ridges (such as the massive Mid-Atlantic Ridge) cannot take place without generation of new crust from magma. Oceans My opponent's chart is proof that there is no such hole, at least in the Arctic. Water will seek the lowest possible level, and the North hole is supposedly directly on the axis of the earth, placing it on the abbysmal plain. This area of the arctic ocean is more than 5000 feet deep [1], placing it as deep or deeper than the vast majority of the oceans. Any hole here into an inner void would open a direct path for the water to flow down farther than any other point in the ocean, and would open up a space large enough to hold the water from all the oceans of the world. WEre there such a hole, there would be no visible oceans, as they would have already disappeared into the inner void. [1] . http://en.wikipedia.org... Core Halley's model is both patently ridiculous and physically impossible. By no conceivable process of planetary evolution could a series on concentric spheres form, when during the aggregation stages they would be both deformable and attracted into the common center. Far more incredible is the idea that a core of super-dense material could form free-floating within these spheres, absent from the enormous pressures that are necessary to crush matter into that state. Our planet has over over 26000 tons of pressure per square inch bearing down on the center from every angle, allowing for such a core; a hollow planet would not. Halley's was a thought experiment, nothing more; it does not represent a physically possible form of planetary development. Earth mass and volume 75% hollow is hardly unreasonable for most models, especially considering the multiple-shell models face insuperable difficulties with planet formation, even more so than the rest of the hollow spheres. The problem of density stands. Even Halley's model, which posits a central core but has no mechanism for compressing it, faces a severe density problem; any model with more space has worse issues with reconciling the known density of the earth. To recap: We have ample photographic evidence of the unbroken poles. The presence of a hole into the inner void at the north pole would drain the oceans. The speed with which mechanical energy passes though the mantle proves it is not hollow. The presence of magma, volcanic activity, and continental drift defies the ability of the hollow earth model to explain. These models also cannot support a super-dense core, which is necessary to Earth's magnetic field. These models also fail to adequately explain the rebound of large crater floors, and the absence of radial fractures and holes. The Earth's mass/volume is far too great to allow for any significant fraction of it to be hollow. I thank my opponent, and return him the debate. -C