Examining the "physics" in geophysics

[gentleman-farmer]

Swansont is giving a new definition for the core of the earth saying that the word core as used on this science forum means the interior of the earth - and not the core of the earth

 

Swansont

I'll leave it to Mr Skeptic to address whether "core" was being used in the technical sense or the colloquial sense of "interior" (though his subsequent post makes it pretty clear it was the latter)

 

gf) This leaves us in wonderment as Swansont also says it is proper and (perhaps expected) that we quote out of context

Well, no, the context really doesn't matter here;

 

If we are at liberty to re-define technical terms to suit ourselves and if we are at liberty to quote out of context - than we are entering a state of anarchy and have dispensed with science

 

gf

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[swansont]

Truncating my quote about context, in order to make an out-of-context point about context has melted my irony meter.

[gentleman-farmer]

Your meters IMO should have melted when you stated ::

Swansont Well, no, the context really doesn't matter here.

 

You are also the only one to have suggested that magma originates in the core ::

Swansont since magma isn't formed in the core

 

Folk here are talking about Heat from the core not magma - I fail to see why you are distorting what is being said or suggesting that it is proper to mis-use scientific terms or quote out of context

 

gf

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[Moontanman]

GF you are misusing the term magma to begin with, the earths mantle is a very thick almost plastic liquid that does indeed rise and spread out under the crust and the friction of this spreading is what causes the earths crust to move as in plate tectonics.

 

Magma, the stuff from volcanoes is often very runny liquid rock, it originates from the earths crust, it is so fluid because it contain far more in the way of more volatile elements than the material of the earths mantle. magma only forms in the earths crust where it is not subjected to the extreme pressure of the mantle.

 

Until you see the difference between magma from volcanoes and the material in the mantle there is no way to understand geophysics...

 

http://en.wikipedia.org/wiki/Magma

 

Environments of magma formation and compositions are commonly correlated. Environments include subduction zones, continental rift zones, mid-oceanic ridges, and hotspots, some of which are interpreted as mantle plumes. Despite being found in such widespread locales, the bulk of the Earth's crust and mantle is not molten. Rather, most of the Earth takes the form of a rheid, a form of solid that can move or deform under pressure. Magma, as liquid, preferentially forms in high temperature, low pressure environments within several kilometers of the Earth's surface.

 

 

The Earths mantle is not magma it is a Rheid

 

http://en.wikipedia.org/wiki/Rheid

 

http://en.wikipedia.org/wiki/Asthenosphere

 

The upper part of the asthenosphere is believed to be the zone upon which the great rigid and brittle lithospheric plates of the Earth's crust move about. Due to the temperature and pressure conditions in the asthenosphere, rock becomes ductile, moving at rates of deformation measured in cm/yr over lineal distances eventually measuring thousands of kilometers. In this way, it flows like a convection current, radiating heat outward from the Earth's interior. Above the asthenosphere, at the same rate of deformation, rock behaves elastically and, being brittle, can break, causing faults. The rigid lithosphere is thought to "float" or move about on the slowly flowing asthenosphere, creating the movement of crustal plates.

[gentleman-farmer]

Thermal processes are chaotic - and if we were to believe you (Moontanman) or the author of that material we'd have to generate another theory for the origin of earthquake which at the moment follows the line of brittle fracture and sliding faults

 

We'd have to give scientific reason for the plates to move in uniform fashion for millions of years (knowing again that thermal processes are chaotic)

 

We cannot have conditions in the asthenosphere wherein rock becomes ductile and moving at rates of deformation measured in cm/yr - and have earthquake too

 

Your Internet material is inconsistent with other & better formulated theories including the temperatures that magma forms: 650 C (1202 F) & 1200 C (2192 F)

 

Best IMO we stop trying to defend a thermal regime that has no merit except in the say so

 

gf

[Bignose]

Thermal processes are chaotic

 

Whether a process is chaotic or not depends greatly upon the time and length scale it is observed on.

 

This is best demonstrated by example -- the water that comes out of my hose is turbulent. The motion of one one molecule of water in the hose is indeed random (what I assume you mean by chaotic, which has a precise mathematical definition, not really applicable here). And, the velocity of water in the exact middle of the hose over time will also be random and fluctuate about.

 

However, the AVERAGE velocity and the AVERAGE movement of the water is very steady. The water only exists the hose, for example. The velocity is not so random as to include forward and backward motion. The turbulence in the fluid only results in the instantaneous velocity to fluctuate about the mean velocity. It is very easy to predict the mean velocity.

 

Randomness in the heating is similar. The exact amount on energy any individual molecule gets will be random. However, the average temperature profile is significantly easier. Over long time, the fluctuations lose meaning.

 

So, while on any one day, there may be a slug of liquid rock that is acting "chatoically", that in no way whatsoever precludes there being an overall average heating or motion that is very steady. That is, while at any moment the exact velocity of a current may fluctuate, the long-term average of that current may be very regular and steady. Thus, the plates can move in a "uniform fashion" despite the "fluctuation". Just like the water comes out of the end of the hose, despite the randomness of the turbulence in the flow. "Millions of years" is plenty of time to use an ensemble average and determine the mean effects, and not get caught up in the random fluctuations.

[gentleman-farmer]

Thermal processes are chaotic - it is impossible to predict the path of movement

 

One of the major tenets advanced by geophysics is that flowing magma propels the plates and causes oceanic plate separation at the mid-ocean ridges. But magma (by definition - being molten, fully expanded - having gone through phase change) has no means, in itself, to move an inch. It is incapable of performing work (force through a distance), except in the formation stage when it is expanding and going through phase change.

 

Magma, by all definition, is a dead by-product of the heat that formed it.

 

Our young are entering the stages of advanced education with the notion of magma propelling plates firmly set in their minds. One might ask further -how it is that the physical interlocks that exist at plate boundaries (and the friction from movement) - never enter the equation?

[swansont]

Is magma under pressure?

 

You still haven't answered this.

[Bignose]

Thermal processes are chaotic - it is impossible to predict the path of movement

 

Just repeating it again, doesn't make it right.

 

I turn on the stove to the high setting. I put a pot of water on that burner. Given the heat flux (from the stove setting), the size, shape and material of the pot, and the volume of water I put in there, I can predict the average temperature of that pot of water in time.

 

What I cannot predict is which molecules will vaporize into steam and which will remain in water. On the molecular scale, the randomness is significant. On the scale of the whole pot, the randomness is insignificant -- the mean temperature of the whole pot can be known.

 

So, AGAIN, whether something is random (or "chaotic") really depends on the scales of interest. Something can be both random and non-random, depending on the scale. In fact, most things in nature seem to be this way.

 

And, AGAIN, on the scale of millions of years, the randomness gets blurred out and the MEAN effects can be seen.

[gentleman-farmer]

Bignose

I turn on the stove to the high setting. I put a pot of water on that burner. Given the heat flux (from the stove setting), the size, shape and material of the pot, and the volume of water I put in there, I can predict the average temperature of that pot of water in time.

 

gf) You are in the wrong section of the physics book. You'll find the temperature of pots of water in the section on heat transfer.

 

And with an earth with a polar radius of 3949 miles I think it could care less if you can predict which molecules will vaporize into steam

 

Thermal processes (by virtue of the inability to define motion, velocity of any stream or section, or viscosity at any point within the system) is chaotic

 

There are over 1,000,000 earthquakes a year - they do not originate in elevated temperature environments - so you got two choices - forget nuclear cores (core meaning at the center of the earth) or earthquake

 

Ya can't have both

 

gf

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[Bignose]

gf, I don't know enough about earthquakes and geophysics to have an opinion about whether or not magma flows and earthquakes and volcanoes are related.

 

All I have said is that things that look "chaotic" at one time scale can look very deterministic and non-random at another.

 

So, just calling magma flows "chaotic" because "all thermal processes are chaotic" isn't right. At the very least, you need to define over what time scale you are observing this.

 

You mentioned millions of years. Over millions of years, no matter what the randomness in the system may be, it is definitely possible that the mean flow and mean processes have an effect. You cannot just dismiss them because they are "chaotic."

 

And, if convection currents is magma isn't heat transfer, what is? Just because my example was water in a pot, and your situation has molten rock, that doesn't mean that they are different. The underlying physics are the same.

 

And finally, in what system can you not define a velocity? And how does not defining a velocity make something chaotic? Or even random?

[Moontanman]

Thermal processes are chaotic - and if we were to believe you (Moontanman) or the author of that material we'd have to generate another theory for the origin of earthquake which at the moment follows the line of brittle fracture and sliding faults

 

How does moving Rheid cancel the idea of earth quakes? Earth quakes occur in the crust, the moving tectonic plates is what generates earth quakes in the ridgid crust...

 

We'd have to give scientific reason for the plates to move in uniform fashion for millions of years (knowing again that thermal processes are chaotic)

 

Do you have thing to back this up other than your opinions? You are still assuming things to be true that just aren't, who says the tectonic plates move in a uniform fashion?

 

We cannot have conditions in the asthenosphere wherein rock becomes ductile and moving at rates of deformation measured in cm/yr - and have earthquake too

 

Why not?

 

Your Internet material is inconsistent with other & better formulated theories including the temperatures that magma forms: 650 C (1202 F) & 1200 C (2192 F)

 

Again you are using the term magma incorrectly, magma does not originate in the mantle, magma forms in the crust.

 

Best IMO we stop trying to defend a thermal regime that has no merit except in the say so

 

gf

 

You first...

[gentleman-farmer]

Bignose

You cannot just dismiss them because they are "chaotic."

 

gf) Yes you can - and you have too - the tectonic plates move in a regular pattern - but the (so called thermal engine) is chaotic. Earthquake is said to be from brittle fracture of cold rock followed by a sliding fault

 

If the earth is warmed from the core upward - the definition of earthquake wouldn't work. We cannot dismiss what must be true - just to satisfy a poorly structured (thermal engine) geophysical tenet

 

 

gf

Edited July 10, 2010 by gentleman-farmer
typo

[Bignose]

Bignose

 

gf) Yes you can - and you have too - the tectonic plates move in a regular pattern - but the (so called thermal engine) is chaotic. Earthquake is said to be from brittle fracture of cold rock followed by a sliding fault

 

If the earth is warmed from the core upward - the definition of earthquake wouldn't work. We cannot dismiss what must be true - just to satisfy a poorly structured (thermal engine) geophysical tenet

 

 

gf

 

One last time -- if the mean pattern underneath the chaotic pattern is non-zero, it could very well be significant. Do you know that the mean pattern is zero? If not, you cannot just dismiss because you say you can.

[gentleman-farmer]

There are two well defined layers that follow the surface contours. The first is the MOHO (or Mohorovicic discontinuity) the other is a plastic layer. The term was coined by Don L. Anderson, in "The Plastic Layer of the Earth's Mantle," Scientific American, July 1962, No 1, Pg. 52-9.

 

The permanence (and extent) of these layers stand in testimony that magma does not intrude to move surface plates

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CAPTION: the famous Moho seismic discontinuity. Named after a Yugoslav seismologist who discovered it in 1909, the Mohorovicic Discontinuity, which reflects the different densities of the crust and the mantle, normally occurs at a depth of 35 km beneath the continents and about 10 km beneath the oceans. But here you can literally stand with one foot on the gabbro of the ocean crust and the other on the peridotite of the ocean mantle. It is because of this unusual sequence of rocks and other aspects of Gros Morne's geology and landscape that in 1988 Gros Morne was declared a UNESCO World Heritage Site

 

gf

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Edited July 10, 2010 by gentleman-farmer
typo

[insane_alien]

The permanence (and extent) of these layers stand in testimony that magma does not intrude to move surface plates

 

well, this is semi-correct. in that of course magma doesn't move tectonic plates as its a product of tectonic movement.

 

but the permanence of layers (espetially when one of them is solid) does not mean that they can't be dragging each other round.

 

for an example, lets say you have some oil floating on water. you submerge a rotor into the water an turn it on so the water rotates in the container.

 

viscous friction will drag the oil around with it with little disruption to the interface.

 

we know the mantle undergoes convection(we've measured it) so there is movement of the mantle. which means there will be viscous drag forces on the tectonic plates. MASSIVE viscous drag forces. easily enough to overcome the mechanical strength of the rock.

 

from this it seems illogical that there wouldn't be distortion of the crust.

[gentleman-farmer]

In the late 1960's five Saturn first stage engines (each producing 1.5 million pounds of thrust) were clustered together to launch the Apollo to the moon.

 

I entered this extraordinary program fresh out of engineering school, and went on to teach college physics nights.

 

Apollo taught all involved how fragile this earth really is - leading me to add an earth sciences section to my physics classes. The first semester was a disaster - because these were physics students, and they were quick to point out that the leading tenet of the earth sciences (tectonics) was in violation of every physical principle in the book. It was contrived - it was nonsense

 

I restructured the earth sciences section with an aim to solve the problem by defining the forces that are actually in play

 

that will be forthcoming

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\

As a matter of note we brought back every single astronaut we launched into space

 

gf

Edited July 10, 2010 by gentleman-farmer

[D H]

Apollo taught all involved how fragile this earth really is - leading me to add an earth sciences section to my physics classes. The first semester was a disaster - because these were physics students, and they were quick to point out that the leading tenet of the earth sciences (tectonics) was in violation of every physical principle in the book.

Once again, I call bull. I suspect that is was you pointed out to your students that the stuff in the textbooks "was in violation of every physical principle". Just because you don't understand something doesn't mean it is wrong.

 

Regarding the non sequitur you posted in the very first post in this thread,

An article appeared on CNN.com not long ago that discusses the issue, stating ::

"..U.S. students placed below average in both math and science.

 

Too many teachers in the US come into the system with a bias against what they are teaching. This is particularly so in the south. You are a part of the problem.

[gentleman-farmer]

D H)

Too many teachers in the US come into the system with a bias against what they are teaching. This is particularly so in the south. You are a part of the problem.

 

gf) You have a credibility problem D H - I'm from Michigan - I even said so in the opening page of this post - and that is where I taught college physics

 

gf

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[DJBruce]

gf) You have a credibility problem D H - I'm from Michigan - I even said so in the opening page of this post - and that is where I taught college physics

 

gf

 

I am guessing that DH's southern remark was possibly made with your statement

 

I'm a new member - originally from Michigan and now in the land of hurricanes and alligators with my wife of many years, and our two horses.

/

 

in mind. As for your ad hominem on DH's credibility, I would say that DH, like all of the experts on this forum, is a really credible person on many topics. Also as an aside you can never attack your way to proving you are right.

 

 

In the late 1960's five Saturn first stage engines (each producing 1.5 million pounds of thrust) were clustered together to launch the Apollo to the moon.

 

I entered this extraordinary program fresh out of engineering school, and went on to teach college physics nights.

 

Apollo taught all involved how fragile this earth really is - leading me to add an earth sciences section to my physics classes. The first semester was a disaster - because these were physics students, and they were quick to point out that the leading tenet of the earth sciences (tectonics) was in violation of every physical principle in the book. It was contrived - it was nonsense

 

I restructured the earth sciences section with an aim to solve the problem by defining the forces that are actually in play

 

that will be forthcoming

 

As a matter of note we brought back every single astronaut we launched into space

 

gf

 

What does all of the astronaut, NASA, and biographical information have anything to do with your position on geophysics? As far as I can tell it simply tells me that you had this idea. Not what evidence you are actually using to support your claims. Also what did your department and colleagues think when you rewrote the entire geophysics curriculum to match your believes?

[Mr Skeptic]

I'm from Michigan - I even said so in the opening page of this post - and that is where I taught college physics

 

What school did you teach at?

Edited July 11, 2010 by Mr Skeptic

[gentleman-farmer]

Mr Skeptic

What school did you teach at?

 

gf) Give me your folk's home phone number and I'll call and let ya know

 

DJBruce

Also as an aside you can never attack your way to proving you are right.

 

gf) Good point - that's why I found it so surprising that D H would resort to that tactic

D H wrote :: Too many teachers in the US come into the system with a bias against what they are teaching. This is particularly so in the south. You are a part of the problem.

 

P.S. No point in trying to close the door around D H's regional comments - the horse has already left the barn

 

gf

Edited July 11, 2010 by gentleman-farmer

[pioneer]

Here is a theoretical consideration about water, at the high temperatures and pressure and high metal oxide concentrations within the mantle. The water will be induced to dissociate into OH- and H+, with the OH- interacting with the cations of the metal oxides.

 

Below is an elemental and compound analysis of the mantle.

 

Element Compound

O 44.8

Si 21.5 SiO2 46

Mg 22.8 MgO 37.8

Fe 5.8 FeO 7.5

Al 2.2 Al2O3 4.2

Ca 2.3 CaO 3.2

Na 0.3 Na2O 0.4

K 0.03 K2O 0.04

 

Sum 99.7 Sum 99.1

 

 

The H+ from the dissociated water/metal oxide interactions will follow a concentration gradient toward lower concentration. Since it initially forms in the upper mantle the H+ flows toward the core simply because this is the direction of lower concentration.

 

The acid flux in conjunction with oxide, corrodes the iron core to generate magnetic FeO. The result is a flow of electron current toward the surface (opposite to the H+ current downward); pH of oceans is slightly basic. This is also reflected by the current direction in lightning; negative up.

 

Mars which also has an iron core is not magnetic to the same degree due to a disruption in H+ flux.

[gentleman-farmer]

Newton's second law, f = ma (or f = m(the time rate of change of velocity) - or simply (f = m dv/dt) tells us with absolute clarity that only forces have the capacity to move the tectonic plates (or anything, for that matter).

 

As it relates to this thread - magma can exert a force during expansion and phase change. Beyond that magma is dead as a prime mover. And adding heat will not change the physics - all it'll do is cause the magma to go to the next phase - vaporization.

 

The earth sciences require a system of forces that are verifiably uniform world wide, that are unchanging through the ages, that are based on the principles of physics that we know to exist - and can be quantified mathematically.

 

This system of forces must account for not only the movement of the tectonic plates, but for earthquake and mountain building, for the observed rise and fall of land masses. It must account for the existence of volcanoes, and hot springs, and the huge deposits of lava as found in the states of Washington, Oregon, and Idaho in the United States known as the Columbia Plateau and the lava floods of India, known as the Deccan Traps or those in the Pacific Ocean north of the Solomon Islands called the Ontong Java Plateau

 

It is insufficient to base science on "well-observed fact" as D H proposed in the 6 th post of this thread. If we accept that notion some might be pre-disposed to accept the Ptolemaic geo-centric view of the universe - for what is more obvious than the sun crossing the sky? (& please swansont - don't quote that out of context - context matters)

 

Science (as does physics) relates to physical principle and mathematical verifications. I'm going to open a new thread soon, Examining the "physics" in geophysics (mountain building). A new thread will be necessary because the arguments against current (mountain building theory) follow the path (of the dissipation of compressive forces (stresses) though shear)

 

gf

[insane_alien]

Newton's second law, f = ma (or f = m(the time rate of change of velocity) - or simply (f = m dv/dt) tells us with absolute clarity that only forces have the capacity to move the tectonic plates (or anything, for that matter).

 

this isn't in dispute, where have we suggested otherwise?

 

As it relates to this thread - magma can exert a force during expansion and phase change. Beyond that magma is dead as a prime mover. And adding heat will not change the physics - all it'll do is cause the magma to go to the next phase - vaporization.

 

i suggest you look up convection. a much studied area of fluid dynamics.

 

not to mention we can measure it moving which means the situation is moot, it exherts viscous drag on the crust or physics doesn't exist.

 

The earth sciences require a system of forces that are verifiably uniform world wide, that are unchanging through the ages, that are based on the principles of physics that we know to exist - and can be quantified mathematically.

 

actually, the earth sciences do not require constant forces, they realise and take into account that the forces will change with time and expect it. what you said there is just false.

 

and you are showing no consideration of timescale either. just because they're not jittering around and changing direction completely every few minutes doesn't mean that they are static. timescales for geologic processes are typically in the millions to billions of years.

 

It is insufficient to base science on "well-observed fact" as D H proposed in the 6 th post of this thread. If we accept that notion some might be pre-disposed to accept the Ptolemaic geo-centric view of the universe - for what is more obvious than the sun crossing the sky? (& please swansont - don't quote that out of context - context matters)

 

eh? all of science is built on well-observed facts. well observed facts contradict a geo-centric viewpoint for variety of reasons even without an outside perspective.