Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: FuzzyUK on 03/02/2011 22:35:05
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I see this at Wikipedia:
http://en.wikipedia.org/wiki/Expanding_Earth
"Scientific consensus
There is no evidence supporting expansion of the Earth: measurements with modern high-precision geodetic techniques show that the Earth is not currently increasing in size, and there is no source of energy to power expansion."
Next I look at a theory by Neal Adams that the Earth is growing:
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The expanding earth hypothesis was one of the ideas put forward before plate tectonics became established to explain the similarities in the structure of the edges of many continental areas. It is now totally discredited and the drift of the continents has been measured and is now totally consistent with the theories of the way that tectonics works. The way the continents moved over the earth's surface has been estimated over many millions of years. It appears that it is a very slow oscillation with the continents grouping to form one super continent land mass and then splitting apart as this extra insulation creates a hot spot in the interior of the earth.
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I notice the shrunken Earth as depicted by Neal Adams is devoid of oceans are they supposed to have formed to fill in the gaps as the earth expanded ?
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The theory was that the earth somehow expanded in the ancient past before the oceans formed. Ohter theories were related to the collision hypothesis of the formation of the moon (which was also around at that time) and that the earth was melted and the residual crust (continents) moved at that time. This may have much more truth in it because the collision hypothesis is now well established as the most likely route for the origin of the moon. However the concept of continents moving continuously was considered to be impossible at that time. It's amazing how things change.
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It's amazing how things change.
I'm old enough to remember when plate tectonics was just becoming accepeted [:I]
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Neal Adams says the world is expanding.
The measurements say it isn't.
Neal Adams is wrong.
What's complicated about that?
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Don't forget that all substances have an expansion coefficient.
So, for example, the thermal expansion coefficient of water is somewhere around 0.02% per degree Celsius (varies with temperature, and density). I suppose everything on the crust will expand with temperature shifts.
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Expansion coefficients for typical solids are about 10 ppm/C
How cold would the Earth have to have been for the shrinkage imagined in Neal Adams' ideas?
How far below absolute zero would that be?
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How far below absolute zero would that be?
I'm not sure numbers are quite on, but I figured about -147K.
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The video cited in the first post suggests that the earth has roughly doubles in size. (that's about the right ballpark for the disappearance of the oceans which cover about 70% of the Earth).
With a change of 10 ppm/degree that needs a change of something like 50,000 degrees. It would have had to get to something like ten times hotter than the surface of the sun to do that. Obviously, it would boil long before that but it illustrates the magnitude of the problem.
Neal Adams is not just a little bit wrong.
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There have been proposals that the Earth is hollow I believe that some of the NAZI leaders subscribed to that idea.
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Sorry... I read the Wikipedia article that indicated that the theory of a (grossly) expanding earth was largely discounted. My comment was more directed that there are some theories that part of the sea level rise is a very slow warming & expansion of the oceans, and is not wholly due to melting of arctic ice.
That brings up the point...
In the video, he discussed the gross expansion in the last 100 to 200 million years.
yet the current hypothesis of the age of Earth is 4.5 Billion years. It doesn't make a lot of sense that all the oceans grew from nothing in the last 100 million years or so.
When you read about the theory of evolution, the theory is that the majority of the life developed as ocean marine biota. The beginning of aquatic multicellular life was during the late Precambrian era, followed by the Cambrian Explosion about 540 million years ago. There were fish during the Silurian period 443 million years ago, and very simple mossy life on land.
http://en.wikipedia.org/wiki/Silurian (416-443 million years ago)
Fish were common early, but land animals were mainly limited to insects during the Denovian period.
http://en.wikipedia.org/wiki/Devonian (359-416 million years ago)
More insects and amphibians during the Carboniferous period
http://en.wikipedia.org/wiki/Carboniferous (299 to 359 million years ago)
During these periods when the dry land was beginning to be colonized, the marine plants and animals were rapidly growing and expanding.
Anyway, it would go against many evolutionary theories to conclude that the oceans did not exist before the dinosaurs.
I'm trying to think of a mechanism for such dramatic expansion.
Earth has was likely very HOT when it first aggregated, and has been slowly cooling throughout its life. So, one should expect early thermal shrinking, rather than thermal expansion.
The only other possible mechanism that I can think of is a shift of density. So, perhaps if density was evenly distributed over the earth during early development, the earth might have been slightly more compact. Volcanism might slowly pour light materials on the surface, and heavy materials might slowly sink to the middle of the earth. But, undoubtedly, this would not just wait for the first 4 billion years to pass by, then suddenly start happening less than a half billion years ago. In fact, my guess is that it would have occurred during the planet formation.