Hollow/ expanding Earth theory

[paigetheoracle]

Could the mechanism that might explain the expanding Earth theory be simply 'gas'?

 

Consider the following points. What if the earth is like burning plasticine? When I was a child we regularly set fire to this stuff and it expanded, filling with gas and forming a multitude of chambers (There was also a joke material around in junior magic tricks that did the same thing - meant to look like animals doing their business). Think of pumice, the multitude of caves in the world (not all underground river flows) and the theory from experiments carried out in the sixties that 'seemed' to indicate the moon was hollow.

 

What if the Earth is just a great big balloon, full of expanding gas and volcanic vents are its only means of escape but they cannot release it all because there aren't enough to do this? (Without them if this is true, the planet would explode (think of calderas like in Yellowstone) or shrink to a solid rock if peppered with them (empty balloon).

 

What if continental drift is actually caused by released gas in the form of volcanic vents (like burning plasticine) pushing the world apart and these are transient seams (weaknesses) where this happens, rather than sliding plates on a sea of magma, being pushed around by seismic energy (This to me seems even more implausible as I've seen no other mechanism in nature to cause this and it implies the Earth is of a fixed 'size', which I find equally as unlikely: The only constant in the universe is change and that means growth (expansion) or decay (collapse)). I see the crust and its cracks as more of a souffle than dodgem cars, moving around on a surface (What's their mechanism for doing this I wonder and why does it happen, I'd like to know?)

 

Nobody has been to the centre of the Earth, so it's all theory what is actually down there - so what actual arguments are there for or against this idea?

[Boerseun]

Very unlikely, in my opinion. The Earth's dimensions are well-known, as well as the Earth's density. If you take any regular surface-occuring rock, which is solid to begin with, and measure it's density, then you'll see that the planet's density as a whole is actually higher than that of surface-occurring rock. This points to a very dense core, and the magnetic field points to a churning, molten mantle. Current theory points to a solid iron core, because the density, electrical and seismic signatures all fit. Whilst the only constant might be change, as per your post, that change might simply be mantle convection as opposed to growth or shrinkage. A bubbly or hollow core would decrease the planet's density quite severely. This is clearly not the case.

 

Seismic data also completely and utterly torpedoes a "hollow Earth" theory.

[paigetheoracle]

I too believe the core is solid and the mantle may well be liquid Boersun but convection implies loss through bleeding out of heat and that means shrinkage, unless as I say heat manufacture without sufficient escape routes, creates expansion (That is the logic of my argument but your may better informed about the facts than I am. This is just an attempt to explain the theory, if it has validity).

 

By the way what is the mechanism by which the plates are supposed to move? Are they floating and do they slide sideways or are you saying that they are levered into position as solids, by liquid magma pressure or even escaping gas? As a layman I'm trying to make sense of all the various theories from my own base of experience and trying to make sense of apparent paradox's.

 

This is why I'm still having difficulty with the idea behind continental movement, if you get my drift? I see detritus floating on water and milling about but it sticks together, where there isn't sufficient water to keep the objects apart and that is what I see with the crust. I don't see great big gaps, sufficient to move the masses apart through wave motion (eruptions as a force), only minor cracks in the crust, where liquid magma breaks through, like as I say a souffle or are you saying that when the Earth was younger, the liquid mantle was on the surface with very little crust in evidence and that was why the continents clumped into Gondwanaland or whatever and now as it's cooled, they've spread and settled into their present positions? That would make more sense to me.

 

Thinking about it perhaps another analogy would fit the situation even better. Think of a saucepan of boiling water with meat boiling away at the bottom. What happens is that after a while scum floats to the surface because of the cooking process and it all clumps together too as with just waves in the sea or a river as mentioned above but here you have 'boiling magma' (water) as a more appropriate mechanism for driving the clumping. So while the idea of the continents seeming to drift away because the planet is expanding, seems reasonable as an idea, this heating and clumping/ cooling and separation might equally explain it as a valid theory, to fit in with the facts. Now that would seem a very reasonable view of the facts but I've never heard anyone put it like that before, hence my initial scepticism of continental drift and consideration of the alternative theory as possibly having validity (Draw the continents on a balloon and blow it up and it seems a very convincing way of showing how they could have gotten into their present positions).

[Hill]

By the way what is the mechanism by which the plates are supposed to move? Are they floating and do they slide sideways or are you saying that they are levered into position as solids, by liquid magma pressure or even escaping gas? As a layman I'm trying to make sense of all the various theories from my own base of experience and trying to make sense of apparent paradox's.

 

This is why I'm still having difficulty with the idea behind continental movement, if you get my drift? I see detritus floating on water and milling about but it sticks together, where there isn't sufficient water to keep the objects apart and that is what I see with the crust. I don't see great big gaps, sufficient to move the masses apart through wave motion (eruptions as a force), only minor cracks in the crust, where liquid magma breaks through, like as I say a souffle or are you saying that when the Earth was younger, the liquid mantle was on the surface with very little crust in evidence and that was why the continents clumped into Gondwanaland or whatever and now as it's cooled, they've spread and settled into their present positions? That would make more sense to me?

 

Originally, when the earth's surface began to develop a solid surface, the rock was probably homogeneous. As the molten surface cooled enough for rain to fall, the rock cycle (weathering, erosion, deposition, metamorphism) began to produce sort out new kinds of rock. The original crust was rich in iron and magnesium (called ferro-magnesian, mafic, or femag) The newly evolving rock were progressively rich in silica and aluminum (sialic). The newer rock is lighter and "floats" on the heavier rock. Because of heat remaining from the Earth's formation, and due to radioactive minerals at depth, the earth's surface still is affected and in motion. Most of the volcanic activity occurs along ocean spreading centers - the mid-oceanic ridges - and along continental margins where the heavier mafic ocean crust is forced beneath some continental margins. The thicker but lighter continental crust rides upon the upper mantle and is either pushed by or overrides the oceanic crust.

 

This is all highly simplified and still all details of the process are not understood. But new evidence continues to modify the theory which is less than 50 years old. There is no doubt among geologists of the reality of continental drift but there is still much healthy debate as the model is refined.

 

For instance, recent evidence hints that the crust may have solidified sooner than previously thought. http://www.nytimes.com/2007/08/28/science/28obdiam.html

(NYT article may require free registration)

[paigetheoracle]

Speaking as a non-scientist, I can understand volcanic ridges pushing the plates apart but I have difficulty with finding an analogy (or even photographic proof as supplied by science for the former) of subduction zones. If the Earth is shrinking, you'd expect material to be squeezed out - if it was expanding, you'd expect material to be sucked in, logically but what is the mechanism, I want to know, pushing the plates around and under each other? As I said earlier, I can see the continents originally clumping together as scum of flotsam on the surface of a liquid rock sea but that doesn't exist now, as obviously, so where is the evidence of the mechanism to move the surface matter - that is all I want to know?

[Hill]

Speaking as a non-scientist, I can understand volcanic ridges pushing the plates apart but I have difficulty with finding an analogy (or even photographic proof as supplied by science for the former) of subduction zones. If the Earth is shrinking, you'd expect material to be squeezed out - if it was expanding, you'd expect material to be sucked in, logically but what is the mechanism, I want to know, pushing the plates around and under each other? As I said earlier, I can see the continents originally clumping together as scum of flotsam on the surface of a liquid rock sea but that doesn't exist now, as obviously, so where is the evidence of the mechanism to move the surface matter - that is all I want to know?

 

A more detailed explanation of sea floor spreading at oceanic ridges can be found here: Developing the theory [This Dynamic Earth, USGS]

 

 

There is no "photographic" evidence because the spreading evidence is found in measurements of the magnetism in the rocks.

 

The evidence for subduction is also not in photographs, but in analysis of deep focus earthquake epicenters.

 

Earthquake epicenter diagram from the Gorda Plate area of the Pacific Northwest of the U.S. From AGU Web Site:Pulling the Rug out From Under California: Seismic Images of the Mendocino Triple Junction Region

[Tormod]

The only constant in the universe is change and that means growth (expansion) or decay (collapse)).

 

This is a fallacious argument in that "the only constant is change" is inherently not true, it is a mere tautology. Also, it does not necessarily mean growth or decay - you also have changes in energy levels, force fields, temperature etc (which again are expressions of various changes in other things). But change itself is not a constant.

 

Nobody has been to the centre of the Earth, so it's all theory what is actually down there - so what actual arguments are there for or against this idea?

 

Again a fallacious argumentation. "Nobody has been there" is not a good argument. You are correct that it's all theory as to *what's down there*. The tectonic movements can however be observed (The West coast of Norway and the East coast of Canada are drifting apart, for example, which is measured by GPS). We still have to theorize about what causes it, but that is after all what science is for.

 

Here's a bit about the development of the continental drift theory:

Developing the theory [This Dynamic Earth, USGS]