Posted 13 November 2012 - 01:38 AM
"the earth is roughly spherical in shape"
"you have no proof for that"
"our laws of gravity tell us objects as heavy as earth have to attain a spherical shape"
"your laws for gravity are bollixed up. You apparently are unaware of three fundamental problems. Firstly, your theory has not been tested when gravity is extreme. Secondly, you need a quantum theory of gravity before you can conclude anything about the shape of earth. And thirdly, your theory violates energy conservation."
"None of the points you raise are valid objections against a round earth. Firstly, our theory of gravity has been tested under extreme gravity conditions. But that is not even relevant here. Earth mass objects collapse into spherical shape under very mild gravity conditions, with the gravitational acceleration at surface staying at very low values. Secondly, quantum effects are completely irrelevant in the description of earth mass objects collapsing into spherical shape. And finally, your point on energy conservation brings to surface a subtlety in our theory of gravity. The theory of gravity tells us energy conservation is not an issue, every local experiment you do will demonstrate energy conservation. However, if you look at faraway phenomena, it becomes less clear how energy conservation should be accounted for. This is no different from the fact that concepts like simultaneity break down when trying to apply these to distant phenomena. None of these subtleties lead to any inconsistencies in the theory. The theory is sound."
"Show me energy is locally conserved. Give it your best shot. Give a local law of energy momentum conservation right here. I don't care where you get it from, just tell me or write it down, or whatever"
"You focus on energy conservation only. I take it that means I have convinced you on the other two points you raised? Anyway, your request is easy to fulfill. Any textbook on general relativity will clarify the point. Let's take the textbook by Wald that is used all over the world in postgrad courses. Equation 4.3.6 on page 70 expresses local energy and momentum conservation."
"You miss the point. If you take a large volume, energy is not conserved. Baez has a web page that says so. Oh, and by the way, Wald sucks."
"I already told you that at large distances things work out in a more complex way. We were discussing local conservation laws. Maybe you actually should read Baez, he is very explicit on local energy conservation. And by the way: haven't you spotted that Baez refers to Wald?"
"I didn't say Baez gave a correct argument, just a better one than Wald. There is no conservation law of any kind, local or global, without additional assumptions, and they preclude the strong field regime. There is no evidence for a spherical earth!"
"I thought we had closed that part of the discussion. You have not reacted to my statement that the collapse of large objects into spherical shape does not require a strong gravitational field. You classify earth being round as a fantasy. Fine with me. I am done discussing."
"Did I say it is a fantasy? I said there was no evidence of an actual spherical earth, and there is not."
"What is your alternative?" What shape do you assign to earth, and what theory of gravity supports such a shape? Can you give me references that support your claims"
"Listen. I know all about it. Don't be fooled, there is no evidence for a spherical earth."