Earth dimensions

[Spyman]

It is just a matter of what you want to hear.

What I 'hear' when I am told that "paleomagnetic data has been used to calculate that the radius of the Earth 400 million years ago was 102 ± 2.8% of today's radius" is that the tolerance of the estimate is good enough to falsify whether the Earth has expanded to TWICE its radius during the last 400 millions of years, but does not have the accuracy for making claims that the circumference of Earth is shrinking with millimeters per year.

 

The tolerance level tells me that the Earth could have been slightly smaller 400 million years ago.

[michel123456]

Fair enough.

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I will continue gathering information.

 

from http://en.wikipedia.org/wiki/Jupiter

 

"Theoretical models indicate that if Jupiter had much more mass than it does at present, the planet would shrink. For small changes in mass, the radius would not change appreciably, and above about four Jupiter masses the interior would become so much more compressed under the increased gravitation force that the planet's volume would decrease despite the increasing amount of matter."

 

 

 

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from http://jgslegacy.lyellcollection.org/cgi/content/abstract/109/1-4/217

 

The evolution of a shrinking earth (1953, old stuff)

George Martin Lees, M.C. D.F.C. Ph.D. F.R.S.

 

Contraction of the earth's surface due to shrinkage of the interior is the only adequate explanation of the compression zones, but the amount attributable to cooling is thought to be inadequate. Estimates of the extent of compression during the Alpine, Hercynian, Caledonian and at least three Pre-Cambrian phases give a contraction of the earth's circumference of at least 3000 km. and perhaps much more. The processes of compression, mountain-forming and erosion were already an established regime at the time of the oldest exposed Archaean rocks, and in consequence there is no geological evidence on the nature of the primordial crust and certainly no hint that it was at one time molten. Assuming no important change in the mass of the earth since the Archaean, the average density at that, already advanced, stage of compression may have been about 4–5 g/cm3 compared with the present value of 5–517.

 

Note: the 3000km value for the circumference equals about 477 km of radius decrease at the last phase of the precambrian period, about 500 millions years ago, or approximatively 3 times more than the previous estimation.

 

And more contemporary stuff

http://rt.com/Sci_Tech/2009-10-05/scientist-earth-shrinking-waistline.html

 

"Our planet is shrinking, says a Russian geologist. Since its early days the Earth’s average radius has reduced by 585 kilometers.

Vyacheslav Orlenok, professor of geology at the Kant Russian State University in Kaliningrad, compared ancient relief structures to those of today, he reports in a paper.

 

He says 4.5 billion years ago, when Earth’s surface had just started to solidify, the little blue ball was a bit bigger. Its average radius was 6,956 km, and has since reduced by 585 km."

 

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And to show you how impartial I can be, a counter-example:

 

from http://www.apqj64.dsl.pipex.com/sfa/id59.htm

"In Theory …

There have been many theories (ideas) about why the Earth has a wrinkled surface (mountains and ocean tranches). One of the popular ones of the last century was the `Shrinking Earth' theory. It was imagined that the Earth started off as a molten ball of rock material, orbiting the Sun. As this cooled, a skin was formed, much like skin forms on cooling custard! This skin is referred to as the Crust. When things cool down, it is well known that they shrink. This would cause the solid crust to buckle, in the same way that the skin of an apple wrinkles when it has been left for too long without being eaten. The mountain ranges of the Earth were thought to be the wrinkles on the Crust. This idea was well accepted in scientific circles. As with all scientific ideas, eventually someone challenged it. Eventually it was replaced with the `Plate Tectonics' theory, which explains more facts accurately. The shrinking Earth theory would predict that mountain ranges would appear at random, all over the Earth. They are not, they are found only in narrow belts e.g. the Alps or Himalayas. Plate Tectonics predicts that mountains are only found in narrow belts, where two plates collide - this is what is observed. It would predict that mountains would constantly grow higher. They do not, they are eventually worn down e.g. the Scottish mountains are all less than 1500m in height, they were once the size of the alps at about 4000m high. Plate tectonics predicts this since mountains would cease to grow when the plates stop moving in that area. The shrinking Earth theory predicts that volcanoes and Earthquakes would occur at random, all over the surface of the Earth. They do not, they only occur in narrow belts. This is predicted by plate tectonics. Accurate measurements of the positions of countries can now be made using satellite technology. These show that countries are moving around the surface of the Earth. This can not be explained by the shrinking Earth theory. The rocks of Derbyshire contain fossil corals, indicating that tropical conditions once existed here. This can easily be predicted by plate tectonics. India is a sub tropical country. There is evidence that it has been covered in ice, millions of years ago. This is easily explained by plate tectonics."

 

All information welcome.

Edited June 14, 2010 by michel123456
Consecutive posts merged.

[D H]

orrection:From wiki at

 

http://en.wikipedia.org/wiki/Expanding_earth_theory#Current_status

 

"Modern measurements have established very stringent upper bound limits for the expansion rate, which very much reduces the possibility of an expanding Earth. For example, paleomagnetic data has been used to calculate that the radius of the Earth 400 million years ago was 102 ± 2.8% of today's radius.[2] Furthermore, examinations of earth's moment of inertia suggest that no significant change of earth's radius in the last 620 Million years could have taken place and therefore earth expansion is untenable."

 

What is the pure scientific mathematical conclusion of this?

The conclusion I would draw from the first reference is that the null hypothesis cannot be rejected. The null hypothesis here is that the Earth has neither expanded nor contracted over the last 400 million year. The second reference, which you have ignored, is a much more stringent test. No significant change in the Earth's radius has changed over the last 620 million years.

 

It does stand to reason that the Earth has changed shape/size to some extent over the last 4.5 billion years (i.e., since the formation of the Moon). The Earth was much hotter way, way back then than it is now and the Earth was rotating much faster then than it is now. It also stands to reason that the vast majority of whatever gross changes in size/shape did take place occurred very, very early in the Earth's history. That very early shrinking does not explain the shape of the continents and it does not explain plate tectonics.

 

Plate tectonics is driven primarily by the continued cooling of the Earth, not by the more-or-less stagnant gross size/shape of the Earth. By way of analogy, think of heating a pot of water on a stove to near boiling. You can see a lot of roiling and eddies in that nearly-boiling pot of water. While the water does expand very slightly due to that heating, that slight expansion does not explain all the turbulence you are seeing. Heat transfer does.

[michel123456]

Plate tectonics is a confirmed observation. I agree with it.

 

But it's another thing to measure & observe, and another thing to explain.

 

IMO you cannot explain plate tectonics through the cause of motion of tectonic plates.

Whether plate tectonics is caused by convection in the mantel or core, by contraction or expansion, is wrong.

IMO the observed fact, those gigantic plates slightly moving, is caused by the structure of the crust.

When you take a body, a structure, or a construction; the way it breaks under some specific effect, is mainly an outward sign of its internal structure.

When you smash a

it breaks into pieces, large & small, with cutting edges. When you smash a

, it breaks into a huge amount small pieces with rounded edges. The internal structure of the glass makes the way it breaks. The same symptoms are used in particle physics: scientists break tiny particles to understand their internal structure.

For Earth's crust, it is the same. If it breaks into gigantic plates, it is caused by its internal structure, and by the way it is broken. The statement "The shrinking Earth theory would predict that mountain ranges would appear at random, all over the Earth" is a false argument, IMO.

 

As for the null hypothesis, of course it cannot be rejected: it is the mainstream concept.

Edited June 15, 2010 by michel123456

[D H]

Plate tectonics is a confirmed observation. I agree with it.

Then why do you argue with it?

 

What causes the plates to move, the upwelling and downwelling at boundaries? What causes vulcanism?

 

As for the null hypothesis, of course it cannot be rejected: it is the mainstream concept.

You misunderstand what I and others have said. Suppose that the cited study showed that the Earth's radius 400 million years ago was 102±0.28% of today's radius (instead of the cited 102±2.8%). The null hypothesis would then have to be rejected were that the case. The null hypothesis cannot be rejected on the basis of the actual study because no change (100%) is within the uncertainties of the results.

[John Cuthber]

If you don't ask the question in the first place you won't find any evidence.

The only elements I could find are summarized in my first post. Evidentally not enough to make a claim. It is one of my few "theories" I use to keep in a drawer. Maybe some day it will find some support.

 

You asked the question and sought evidence. Fair enough.

I provided the evidence- the constancy of the length of the day. This disproves your idea.

Your "theory" is dead, if you keep hold of it you will just end up smelling bad.

It would be better to clear out that "drawer" and throw away the rubbish.

It will never find support because it does not agree with reality.

[D H]

You asked the question and sought evidence. Fair enough.

I provided the evidence- the constancy of the length of the day. This disproves your idea.

Except that what you are claiming is not true. A day was considerably shorter 4.5 billion years ago than it is today, perhaps as short as six or so hours long. The length of a day has increased since then and continues to increase to this day. A day was about 15 hours long 3.8 billion years ago, 18 hours long 900 million years ago, 22 hours long 400 million years ago.

 

Your "theory" is dead, if you keep hold of it you will just end up smelling bad.

I agree with that, but not for the reason you cited.

[insane_alien]

yes, but the day getting longer does not add weight to the theory that the earth is shrinking.

 

if the earth was shrinking then the day would get shorter. or at least get longer from tidal forces slower than it would un impeded.

[michel123456]

yes, but the day getting longer does not add weight to the theory that the earth is shrinking.

 

if the earth was shrinking then the day would get shorter. or at least get longer from tidal forces slower than it would un impeded.

 

Correct.

That is a very good argument.

 

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Then why do you argue with it?

 

What causes the plates to move, the upwelling and downwelling at boundaries? What causes vulcanism?

 

 

You misunderstand what I and others have said. Suppose that the cited study showed that the Earth's radius 400 million years ago was 102±0.28% of today's radius (instead of the cited 102±2.8%). The null hypothesis would then have to be rejected were that the case. The null hypothesis cannot be rejected on the basis of the actual study because no change (100%) is within the uncertainties of the results.

 

Sorry for the misunderstanding. I do not see the shrinking earth as a replacement of plates tectonics. I think both can happen, these are 2 different things, maybe the one causing the other.

And I have well understood all of your post about null hypothesis.

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(...)Your "theory" is dead, if you keep hold of it you will just end up smelling bad.

It would be better to clear out that "drawer" and throw away the rubbish.

It will never find support because it does not agree with reality.

 

Hi John.

Edited June 15, 2010 by michel123456
Consecutive posts merged.

[D H]

Sorry for the misunderstanding. I do not see the shrinking earth as a replacement of plates tectonics. I think both can happen, these are 2 different things, maybe the one causing the other.

While detailing the causes of plate tectonics remains a work in progress, the basic mechanisms are fairly well understood. The key underlying mechanisms are heat transfer and gravity. A shrinking Earth is not a part of the picture. You are the one proposing a new model, so you are the one who needs to explain why this new theory is needed. What problems does your model fixing? What predictions does your model make that distinguish it from the existing model? Does your model agree with known facts? What are the theoretical underpinnings of your model?

[michel123456]

why this new theory is needed.

As I said before, I am evolutionist. I think everything is an state of evolution. Not only the living beings, but the stars, the galaxies, the universe, and as a matter of coherence, the planet. We know from observation that the earth considered as a whole is not in a stable situation: there are earthquakes, eruptions, tsunamis, and also hurricanes, floods, etc. We know that the Moon is getting away, we know that the length of the day was different in the past. We know that the magnetic poles happen to change from time to time. we know that the Earth at some period did not exist at all, and was formed in some way, that the Earth surface was hot, then cooled. In a few words, we know things have changed, and we know that things are continuing to change now. I think if you want to remain in an evolutionist spirit, you must admit the possibility that EVERYTHING can change, including all things we use to consider as a standard, for example Earth's dimensions.

What problems does your model fixing?

I think it provides a simple mechanism that explains the source of those gigantic forces that mave the tectonic plates move & collide. I cannot understand how it is possible to explain tectonics only through convection currents without any bigger change in Earth's structure.

What predictions does your model make that distinguish it from the existing model?

Gravity was less in the past, and will increase in the future. Relief will increase, in the past the surface was smoother. Almost the entire Earth was covered with a thinner ocean in which life appeared. Slowly, very slowly, the ground raised, and life began to come out of water. After some time, because gravity was increasing, some of these animals could not bear their weight anymore, and got back to the waters. The others dissapear, letting the place free for other living beings, smaller and more adaptaded to the increasing gravity. We are one of those, and slowly, we will feel being attracted by water.

Does your model agree with known facts?

That's what I am looking for. As i said before, if you are not interested in a specific question, you won't find any answer.

What are the theoretical underpinnings of your model?

we know through physics that everything is interconnected. You cannot change the position of the Moon without any influence on a bunch of other parameters. So, when so many parameters are constantly changing, in don't see any reason why some others must remain stable.

There are 3 possibilities:

1._Earth's radius is stable

2._Earth's radius is increasing.

3._Earth's radius is decreasing.

 

1 is the mainstream conception, no comment.

2 is the expanding Earth Theory, with some supporting and contradictory aspects.

3 is the shrinking Earth. No other comment.

[michel123456]

To put in the drawer.

http://www.russia-ic.com/education_science/science/breakthrough/985/

[D H]

As I said before, I am evolutionist. I think everything is an state of evolution.

What precisely do you mean by this statement? You need to be very careful here. You risk falling into the same kind of nonsense that ensues from people who do not understand the uncertainty principle.

 

To put in the drawer.

http://www.russia-ic.com/education_science/science/breakthrough/985/

That's the same crap you posted in #27. And it is crap. There is no way to trace the Earth back to 4.5 billion years ago through crustal markers. The Earth was molten 4.5 billion years ago. The Earth had to cool for 400 million years before the crust formed. His amazingly precise results, a radius of 6956 kilometers 4.5 billion years ago and an outgassing of 3.22×10²⁵ grams of hydrogen, are signs that this is utter nonsense. Those are numbers pulled out of a lower body orifice. Another sign of nonsense is the statement "Average compression speed of our planet was 1.46x10^-2 cm per year." The shrinking, if it did exist, would have be anything but uniform. It would have been much closer to exponential. Using an average rate to describe an exponential process is bad form at best.

 

This has the look and feel of crackpot analysis. A word of advice: Don't put much credence in what Russian biologists and geologists say. Several sciences, and those two in particular, suffered immensely in the old Soviet Union. Russia is still recovering from the damage done by communist ideology to those sciences. Twenty years is not near enough time to undo that damage.

 

It stands to reason that the Earth did indeed shrink somewhat in the last 4.5 billion years. It also stands to reason that the vast, vast majority of that shrinkage occurred shortly after the Earth formed. Some of that initial shrinkage resulted simply from cooling. Cooling is roughly an exponential decay process. Most of the cooling occurred during that first 400 million years when the Earth was still molten. Another factor is gravitational collapse. Most of that happened prior to 4.5 billion years ago. The outgassing? We don't know enough about planet formation or about early planetary chemistry to be able to say anything close to a number as precise as "3.22×10²⁵ grams of hydrogen."

 

There are some secondary effects that did happen after that initial cooling. It took quite a whole for the Earth's solid core and post-perovskite layer at the core-mantle boundary to form. Scientists still don't know enough about either of those, and particularly about the post-perovskite layer, to be able to say anything precise about how those affected the size of the Earth. These are secondary effects, however. The vast majority of the shrinkage occurred very early on in the Earth's history.

[michel123456]

Why are you so angry? We are in speculations, aren't we?

What is that makes the idea so outrageous?

 

I don't have the background to judge a Professor of any University. And I don't make a judgment on the basis of nationality. There are some russians around who can answer.

This post was not intended to raise any other comment, that's the reason I wrote "to put in the drawer".

 

And I don't understand what the uncertainty principle has to do here, nor why do you get

annoyed when I declare myself an evolutionist. The contrary would be much more disturbing.

 

What I ment is that IMHO everything evolutes. Nothing stays the same. The philosoph said "ta panta rei". That's all.

 

And i read all your post. That makes sense.

[Sisyphus]

Generally "evolutionist," like "Darwinist," is a pejorative term used by Creationists for people who believe that Darwinian evolution occurs. It's confusing how you're using it, to refer to yourself in a context that has nothing to do with natural selection. It seems like you just mean that you believe that nothing is completely static, which, if you'll pardon me, is a rather obvious statement. In fact, it's necessary: entropy always increases.

 

Of course, going from that to "every parameter of everything changes significantly over any amount of time" is not really supportable as a philosophical basis for making hypotheses.

[michel123456]

yes, but the day getting longer does not add weight to the theory that the earth is shrinking.

 

if the earth was shrinking then the day would get shorter. or at least get longer from tidal forces slower than it would un impeded.

 

After some deep reflexion...

The day gets longer means the rotation slows down.

And when a body in rotation slows down (decelerates), it gives rise to a centripetal force.

[swansont]

After some deep reflexion...

The day gets longer means the rotation slows down.

And when a body in rotation slows down (decelerates), it gives rise to a centripetal force.

 

Um, no. Centripetal forces are, by definition, directed to the center of rotation. A body that is rotating already has a centripetal acceleration. Changing rotational speed from an external force requires a tangential acceleration.

[michel123456]

You are not aware of the worldwide known

. (1) there was a thread about it on this forum.

 

(1) at the time i made it, i thought it was representing a spiral galaxy.

[swansont]

!

Moderator Note

Casserole experiment discussion moved to the correct thread

http://www.scienceforums.net/topic/44512-deceleration-centripetal-force/page__p__517986__fromsearch__1#entry517986