I have just finished reading a very detailed book that has half convinced me that the earth (and other planetary bodies) are hollow. I know this sounds ridiculous, and if someone here gives a good answer why not, I’ll change my mind, (and get very annoyed that I read a 500 page page book that can be disproved!) but I can’t think of a good reason to disprove it.I read the previous topic on this site on the hollow earth theory, but no-one raised the points that were in this book so I’ll have a go.You can see the book at: https://www.amazon.com/gp/product/0620219637/?tag=pfamazon01-20&tag=pfamazon01-20 , its written by Jan Lamprecht who says the book is a Lateral Thinking exercise along the lines advocated by Kurt Godel.When I started reading I had three problems I could see with the hollow earth concept;1. Gravity2. Seismology3. The origin of volcanoesI found his rebuttals to these points hard to flaw, which he answered in the very first section:1. Newton's Law of Gravity; one of the most useful mathematical formulae ever devised. This little formula has made space travel and the exploration of the Solar System possible. It made satellites possible. . . . Scientists use this little formula to gain an understanding of galaxies far away, and indeed the behaviour of the universe as a whole. It is now more than 300 years since Newton devised this little formula; and we still do now know what causes gravity.Newtonian gravity is accurately measured and proven with the bounds of the solar system. However, Newtonian gravity remains untested in other areas. All we have is a formula. This formula has been used to determine the mass of the Earth. This is based on the concept that for each mass of M inside the Earth, it exerts and attractive force of F. We do not know the valid range for Newtonian gravity. Inside Newton's formula is G. G is the "universal gravitational constant". It is assumed, and assumed is the correct word here, that each mass of M exerts the same force of F regardless of where in the universe it may be placed. It is also assumed that each mass of M exerts the same force F whether it lies on the surface of the Earth or whether it be deep inside the Earth. When using the Cavendish balance to determine the mass of the Earth, it is assumed that each particle exerts a fixed force upon all others. This assumption rules out the very real possibility that particles near the surface of a planet might exert a force greater than those deep down. The key to all of our gravity is the mass of the Earth. If the mass of the Earth is wrong, then so are our estimates for those of other bodies. If the mass of the Earth has been overstated, then it follows that the masses of all other bodies in the solar system have also been overstated. If the Earth is hollow, then so too is every other planet in the solar system.How can we be sure that the Earth really has the mass accorded it by Newtonian gravity? As gravity is so unbelievably weak, is an experiment using two lead balls really representative of the entire Earth? No, of course not. There is electrical charge to account for, and also magnetic forces and electromagnetic forces, that are a lot stonger than gravity, that the current theory does not take into account.[He then proceeds to go into detail about Newton’s shell theorem, which is too mathematically complex for me to understand, but I think proves that gravity is always 0 at the centre of any spherical body]..then seismology2. The only "reliable" method we have of knowing what goes on in the Earth beneath our feet comes from the science of Seismology. However, there are many examples of actual findings being different from what was predicted. The science of seismology contains two very broad assumptions which no one has ever been able to verify: 1. The speed of seismic waves beneath the Earth is ultimately inferred from our understanding of the structure of the Earth based on Newtonian Gravity. We have no way of being certain that these waves really are reaching these depths or travelling at these speeds. 2. We cannot be sure that speed changes are due to the changing constitution of the Earth. Our view of the inner Earth might be very skewed. Much of the predicted structure changes have never turned out to be real. If we find such errors at depths of just a few kilometres, how much less can we trust our ideas when dealing with rock which is hundreds and perhaps thousands of miles beneath the surface?The fact that the deepest man has ever gone into the earths crust is 25 miles, theres still hundreds of miles to go until we can have any sort of proof...then geology3. What do we really know about the Earth's interior? And how trustworthy is our knowledge of it? Many people (mistakenly) think that the lava which pours out of volcanoes comes from a large reservoir of molten material which makes up the greater part of the Earth. Scientists have discovered that lava comes from within the Earth's crust. The lava comes from approximately 20 miles down. The existence of lava does not affect the passage of earthquake (seismic) waves. This indicates to scientists that the crust is largely solid. So where does the heat come from which melts the rock locally? Scientists have advanced two theories. Some say that the melting is due to high concentrations of radioactive elements in a particular area. These decaying radioactive elements generate enough heat to melt rock. Much lava is slightly radioactive and that lends support to this theory. Other geologists have argued that shearing and faulting are adequate heat generating mechanisms via friction. The evidence supports both theories. Lava cannot possibly be rising from the centre of the Earth as some may be tempted to think. It would cool down and become solid on its long, slow journey upwards. Lava is therefore a surface phenomenon and does not in any way reflect what the Earth is like 50 or 100 or more miles down.The author then gives some reasons to believe the earth may be hollow. He mentioned what seismologists call the 'shadow zone' which is the large area in the centre of the earth that no P or S waves ever penetrate, and he has concluded that it is more likely that they cannot penetrate that because there is nothing there to penetrate (seismology does not work in gas). He also explains the earth’s magnetic field with a counter rotating dynamo effect which involves a burning hydrogen core. He postulates that as Hydrogen is the lightest element, due to Newton’s shell theorem making g = 0 at the centre, it would naturally diffuse to the centre and would burn in a reaction similar to the suns.I was surprised to read a review of the book from Dr Tom Van Flandern (astronomer, formerly U.S. Naval Observatory) who said: “For merely showing us all that the inferred density profile of Earth's interior is not a unique solution of seismic data -- an important constraint for all theoreticians working in that area -- the book had already made itself worthwhile.”And also a review from Richard Baum (Director Mercury & Venus Sections, British Astronomical Association) which said: “I must say you have stored your book with an enormous amount of information; much quite surprising, all stimulating. Essentially you are not only obliging us to take a fresh look at things but to observe from an unsuspected different position - the presumed impossible.”It all sounded quite scientifically sound to me, so I decided to put it in this debunking section, as I can’t debunk it, especially the points 1, 2, 3 he makes.Is there anything that really puts a nail in all this theory? i'd be eager to hear it.some diagrams: http://www.bibliotecapleyades.net/tierra_hueca/esp_tierra_hueca_9.htm