The Earth is hollow.

Seismology For purposes of space, I will not be quoting my opponent's entire argument; hopefully my summary will not mangle his points too much. His points are, roughly, these: - We do not have observational evidence of the interior of the earth, as our deepest direct measurement did not even reach the mantle; - Seismographs give an indirect, incomplete, and imprecise picture of the earth's interior. His point, I believe, is to cast doubt on the conventional picture of the Earth as a solid sphere of molten rock with a super-dense core and a thin solid crust. This picture is our interpretation of these same indirect measurements of seismic vibrations, after all. If the seismographs are unreliable, then we have little idea what the earth looks like below 40,000 feet. The problem with this argument is that, although it is true that seismographs are indirect and cannot give us direct images of the interior of the planet, we can tell the density of the materials through which the waves pass by their speed. Mechanical vibrations travel through different substances at different speeds, depending on the density of the medium; hence the difference in the speed of sound at sea level and in the upper atmosphere. The speed of sound through the air is about 670 mph; through granite, it travels at almost 13,500 mph. [1] By timing the passage of waves from recorded earthquakes to stations at various parts of the globe, scientists can determine the density of the materials these waves passed through on the way. A hollow earth would give a completely different reading than a solid earth; and the whole reason we have the crust/mantle/core model is because the waves revealed progressively denser layers beneath the surface. [1] . http://books.google.com... Satellite photographs "As you can see, the photographs of the ESSA-3 and ESSA-7 both show a rather large hole at the North Pole. Hollow Earth theory necessitates, in most cases, an entrance to the inner Earth. " These photographs are composites from many passes of satellites in semi-polar orbits. IS specific, the image in the right was captured by the ESSA-7, which had a sun-synchronous 102-degree inclination retrograde orbit. [1] This gave it an orbit that almost passed over the poles, but not quite. "If one is interested in imaging from LEO [Low Earth Orbit], one might wish to view the Earth under fixed lighting conditions. This can be done with a near-polar, retrograde orbit whose inclination depends on the altitude of the spacecraft. This is called a sun-synchronous orbit. Due to gravity torques this orbit plane precesses just the right amount to keep the spacecraft viewing a fixed local time on each of its two (north and south passes). " [2] As you can see, there is a space around the pole where the satellite will not pass. The black circle in this and other images are artifacts created by this dead spot where the satellite simply never crossed. "These bird's eye photographs of the entrance to the Hollow Earth at the North Pole show, without a doubt, an entrance to the hollow Earth. " Circular reasoning works because circular reasoning works. As counter examples, please accept these photographs as a small token of the vast number of existing images of the poles taken from space that show no such circles. . http://i.telegraph.co.uk... . http://marinesciencetoday.com... Crater formation My opponent writes, "The imprints left behind by planetary collisions, craters, are inconsistent with the physics of a solid Earth. " The fact is that there is little to no observational evidence of crater formation. Apart from laboratory experiments in sand, which hold only a vague relation to the reactions of a full-size planet, we have not observed craters forming, and certainly not the size craters that my opponent bases this argument on. This point is, therefore, firmly in the realm of hypothesis and conjecture. He questions how a solid planet could show large craters with central uplifts; but in reality, the solid crust with magma under pressure underneath is the only good explanation for such phenomena. The hollow model has no mechanism sufficient to uplift the weakened crater floor; and in fact, faces significant problems from the existence of craters. For instance, why would a object capable of making the large craters he discussed not punch through the crust? Without a solid planet, there seems to be no real reason to not observe gaping holes instead of craters. Also, if the planet were hollow and had to rebound after a significant strike, why do we not observe spiderweb fractures radiating outward from the craters? If the planet walls were forced to absorb the full impact without any support underneath, one would expect to see significant radial fracturing; but this is not the case. With a magma-filled planet, the pressure of the mantle provides a reasonable explanation for the uplift seen in the crater floors; with a hollow planet, craters should exhibit radial fractures and the occasional hole or missing fragment, none of which have been observed. [1] . http://science.nasa.gov... [2] . http://www-ssc.igpp.ucla.edu... Minor Counter Arguments The trans-polar voyage of the USS Nautilus is proof that no Arctic hole exists on or near the North Pole, as the submarine passed directly over the pole without incident. . http://www.nytimes.com... The presence of volcanoes is fairly compelling evidence for large quantities of magma under high pressure, something the hollow earth has no real explanation for. The global distribution and activity of volcanoes along the edges of tectonic plates makes perfect sense if the plates are thin beds of solid rock floating on a liquid sphere, but none at all if the crust is thick and monolithic. For the same reason, the hollow earth theory is incompatible with continental drift, a phenomena that can be measured. The Mid-Atlantic Ridge has no place on a hollow planet, as it would lack the internal pressures that could create such a fracture, or the magma to build the spreading plates. The presence of the oceans is incompatible with a central void and polar openings, as the oceans would drain into the center in a matter of hours. Without a churning central magnetic core, the hollow earth cannot explain the drifting magnetic poles; nor can it explain the geomagnetic reversals the Earth experiences roughly every 450,000 years. The current theory is that this is caused by convection currents in the molten core, which of course the hollow earth would lack. . http://en.wikipedia.org... Argument from mathematics and the mass/volume of the Earth The Earth has a volume of 2.598ï¿½10^11 cubic miles [1] and a mass of 1.3166444ï¿½1025 lb. [2] The problem arises when claims are made that much of that volume is empty. A solid earth gives an average density of 344.3 lb/ft3 [3], which is comfortable for a planet made of mostly dense stone with a super-dense core of nickel in the center. An Earth with 75% empty space inside, which is much less than most hollow earth theories posit, has the problem of far too much mass in far too little space. This gives us a solid volume of 6.495ï¿½10^10 mi3, which still sounds like a lot but isn't nearly enough. You end up with an average density of 1377 lb/ft3, over four times the density of the solid-earth model. [4] At only 75% hollow, the Earth's crust would have to be twice as dense as lead; and from