Ben Franklin Centre for Theoretical Research
PO Box 27, Subiaco, WA 6008, Australia.
"No tricks or fancy calculations will suffice to solve the problem. The only way will be to guess the outline, the shape, the quality of the answer."
-- Richard Feynman
Inside the Earth
With the advent of the Hubble Space Telescope and an array of remarkably capable instruments to look outward into space, we are learning more and more about the planets, our Galaxy, and other astronomical objects, some many billions of light-years away. But our knowledge of the Earth we live on, and what lies inside it, is still very limited compared to these astronomical discoveries.
This may be because we do not have the equivalent of modern telescopes to look inside the Earth, we lack instruments with which to discover Earth's secrets. So the facts, data analysis, and conclusions and opinions we have obtained so far are still at a much lower level of certainty.
In this article we'll look at the tools and techniques which are currently available to us, and describe the picture or pictures of the Earth which these methods and measurements suggest. But it must be acknowledged that these pictures are based on much weaker and scarcer evidence than is available for the Universe outside the Earth, and many current assertions are really rather speculative.
First we'll look at all the various lines of evidence which do exist, and try to put together a new picture of the interior of the Earth and its workings, as a scientific model. We'll call this model the Heartfire Model of the Earth.
As with all good scientific models, the aim is to erect a structure which gives the best correspondence between observed data and a theoretical set of rules and laws which are suggested to underlie the data. As newer information is gained, the model may need modifying to accommodate this, and perhaps eventually may need replacing completely with a better one. But it gives a starting point, and very importantly, allows us to massage the model to generate predictions about things which may be then tested, and in so doing, see how good the model actually is.
It doesn't matter whether the model is 'true' or 'real' or not, all that matters is whether it is self-consistent and gives the best match with the data. This is a useful approach, because it allows critics to suggest improvements to bits of the model, to make it better reflect new data.
The Earth as a sphere
The Earth is a solid spherical object, with a circumference very close to 40,000 kilometres (this round figure is not a coincidence, it is because the metre was defined as one ten-millionth of the distance from the pole to the equator). It is not an exact sphere, because rotational forces make it bulge at the equator, but it is close enough to spherical for our purposes here.
All the evidence shows that the Earth is made up of layers, layers which abruptly change in nature as you go down from the surface to the centre.
Figure ITE1. Diagram of layers within the Earth. From .
The top, surface, layer, called the Crust, is very thin compared to the others -- averaging about 30 km, compared to thousands of kilometres for the others. It is also the least dense, at around 2.7-2.9 (gm /cm3).
9. 3-D Earth Structure Model - Purdue University.
10. World's First Realization of Ultrahigh Pressure and Ultrahigh Temperature at the Earth's Center - Finally reaching the Earth's Core.
11. Scientists Recreate Ultra-High Pressure and Temperature of Innermost Earth. http://www.jamstec.go.jp/e/about/press_release/20100405/ .
12. David Noel. Temperatures of the Earth -- a globe in space. http://www.aoi.com.au/bcw/EarthTemp/index.htm .
13. John Woodmorappe. Lord Kelvin Revisited on the Young Age of the Earth. http://www.answersingenesis.org/articles/tj/v13/n1/kelvin.