Belief in Earth's Iron Core still puzzling

[Boerseun]

I think a big obstacle to your understanding is in trying to compare the centrifugal force created by a spinning disc on Earth to what would be experienced in the accretion disc surrounding the infant sun.

 

A spinning disc on your desk will create centrifugal force, because the reason objects on the disc might be spinning, is because they are physically connected to the disc and are rotating because of that.

 

An object being part of an accretion disc will not experience centrifugal force, because as far as that particular object is concerned, it will be traveling in a straight line. Every object in an orbit is in a "stable" orbit, i.e. it is following a line that is the resultant of all forces working in on the object.

 

Another big difference in the image of spinning discs you have in your head and an accretion disc, is that the spinning disc stays static (apart from the rotation) - all the objects on that disc will have the same positional relationship towards all other objects on the disc, regardless of rotational speed. In an accretion disc, following Kepler's laws, objects closer to the centre of the system's mass will orbit faster, and objects further away will orbit slower. Any accretion disc will start to form a spiral as all objects in it find their stable orbits, with objects close to the centre orbiting much faster than those towards the rim. So, it doesn't matter at all what the object is made of, if its velocity is suitable to maintain an orbit around the centre of the system's mass, it will stay right there. If its velocity is any slower than what Kepler would demand given its distance from the centre, it would fall towards the centre. If its velocity is greater, the object will fall away from the centre, towards the rim. This could result in an orbit like a comet's, being highly elliptical, or, given sufficient velocity, it will leave the system altogether.

 

My point is that the composition of whatever might be orbiting the accretion disk is irrelevant. All that matters, is velocity and distance from the center.

 

As a matter of fact, the Laws of Gravity and Kepler's Laws have been the same since the disc accreted till today. Which means that Jupiter, having a much lower density than the Earth (demonstrably so) should fall into the sun, and the Earth would fly outwards - if your argument regarding the initial conditions under which they've formed, holds.

 

Which it clearly does not.

[stereologist]

I was taught Earth formed from within a spinning cloud of elements, mainly hydrogen, and, as with any rotating fluid, gaseous or semi-solid mass, the heaviest elements will always be forced outward, leaving the lightest elements in the center. Thus, Earth originally having a hydrogen core is what I was taught in the 1950s and then again in the 1970s, albeit seldom clearly stated; usually mentioned as lighter elements.

 

This is not necessarily true. A centrifuge can be used to separate materials in this manner.

 

On the other hand the oceans have the denser waters at the center of the gyre. The solar system ends up with the denser materials towards the center, not farther out.

 

I was also taught that an enormous swarm of iron-rich micro-planets later attacked a smaller proto-Earth in a concentrated bombardment, adding to its mass and making it totally molten. Then, even though early Earth was still spinning to the extent that many believe it was still largely disk shaped, only iron, with some nickel, somehow flowed inward against centrifugal force and displaced the original hydrogen core, vaporizing it and forcing it to vent to the surface where it was blown away by solar winds. Have I got this right?

 

There would not have been an original hydrogen core. To form a hydrogen core large pressures would have been required. The idea that forces would have kept denser materials from flowing towards the center of the earth are wrong.

[maddog]

To date, two imaginative theories seem to be most popular as explanations for how the theorized enormous excess of iron came to be in Earth's core:

 

The Grand Bombardment Theory assumes a swarm, consisting of billions and billions (?) of iron-rich planetesimals (micro-planets) bombarded a smaller proto-Earth over a short (?) period of time. These iron-rich planetesimals supposedly added considerable mass and made Earth completely molten through their concentrated impacts within the short (?) period of time. Then, gravity supposedly forced (only) molten iron and nickel into Earth's core, vaporizing the hydrogen originally deposited there when Earth condensed within a spinning mass of dust and gases; largely hydrogen. The vaporized core hydrogen is then assumed to have been blown away by solar winds.

 

I hope I stated the Bombardment assumption correctly. This is what I was taught in college.

Description fine enough, so far. It is what you do with it. :naughty:

However, it seems to me Earth is a relatively insignificant mass in an immense volume of space, orbiting between Sun and Jupiter; whose individual gravitational attractions greatly exceeds that of proportionately minuscule Earth. Therefore, it seems to me the vast majority of iron-rich planetesimals wandering within our galaxy would much more likely have been attracted to either the Sun or Jupiter and largely ignored Earth.

 

This appears evident in the fact that neither the Sun or Jupiter contain much iron; apparently even less than the cosmic proportion. This fact alone appears to make it impossible for any swarm of planetesimals to have even existed; iron-rich or stony. It also appears to me that it is more likely for a swarm of planetesimals to be only a figment of someone's imagination; fabricated to support a logical assumption which lacks physical proof.

Then we are left with the problem of where did all these billions of planetesmials come from and how were they formed largely of iron. All of which just seems just like more assumptions to prove an assumption to me.

 

:umno:

 

Your conclusion only takes have of the Nebular Hypothesis into account. You neglect all

the asteroids and comets which are numerous in our solar system. Asteroids come in

three varieties: Irons, Stony-Irons, Carbonaceous Chondrites (carbon rich). There are

a lot of Irons in our asteroid belt (as much as 25 % composition). It is from these that

likely pummeled the Early Earth near its beginning to form an iron rich core.

 

BTW, our sun was formed from a gaseous medium that was rich in iron (Pop II) so our

sun will be rich in iron. So will all the other gaseous (Jovial) planets. Terestrial planets

typically have solid/molten liquid cores depending on mass.

 

In fact were our planet to have Hydrogen at the core, there were be insufficient pressure

to form Metallic Hydrogen as Pyrotex has already so eloquently explained to you. This means

that no electrical current can flow at the core. Thus no Van Allen Radiation belt. Since

this does exist, you have a contradiction embedded in your assumptions. Earth thus does

have an molten Iron core.

 

Does anyone know of a more plausible theory of how Earth developed a core containing such a enormous excess of iron?

Standard model fits fine with all the pertinent results.

 

I found the following interesting, especially since no swarms of planetesimals were observed:

 

Scientific FrontLine / Hubble Observations Confirm that Planets Form from Disks Around Stars

 

May 3, 2009: Hubble Observations Confirm that Planets Form from Disks Around Stars

 

More than 200 years ago, the philosopher Emmanuel Kant first proposed that planets are born from disks of dust and gas that swirl around their home stars. Though astronomers have detected more than 200 extrasolar planets and have seen many debris disks around young stars, they have yet to observe a planet and a debris disk around the same star.

 

Now, NASA's Hubble Space Telescope, in collaboration with ground-based observatories, has at last confirmed what Kant and scientists have long predicted: that planets form from debris disks around stars.

 

The Hubble observations by a team of astronomers led by G. Fritz Benedict and Barbara E. McArthur of the University of Texas at Austin show for the first time that a planet is aligned with its star's circumstellar disk of dust and gas. The planet, detected in 2000, orbits the nearby Sun-like star Epsilon Eridani, located 10.5 light-years from Earth in the constellation Eridanus. The planet's orbit is inclined 30 degrees to Earth, the same angle at which the star's disk is tilted. The results will appear in the November issue of the Astronomical Journal.

You are just adding more fuel to benefit your opponent's (correct POV). :shrug:

 

I f you really wish to think something that is already been resolved for years, then just

subscribe to the Flat Earth Society. They might be still accepting members. :eek: :eek_big: :hihi:

 

maddog

[Pyrotex]

CharlieO,

thanks ever so much for all the appreciative and flattering things you say about my posts.

But then you turn around and start 'tagging' parts of the theory I presented as being 'lucky' and 'unexplained'. You say no one has ever observed an 'iron-rich ring of dust' around other stars, as if that meant something. Charlie, we CANNOT do spectrometry of dust rings around other stars, YET. The technology doesn't exist, YET. So it doesn't matter.

 

Get a clue Charlie. If there ever was an accepted theory that the Earth began with a Hydrogen core, it was LONG GONE by the time I was in high school. I'm 62, and our high school science curriculum was one of the best in the state. I read all the excellent science books by Isaac Asimov. No Hydrogen core. My two research papers in my senior year (1965) were on the Birth and Evolution of Stars, and the Formation of Planets. No Hydrogen core.

 

If there ever WERE a 'Hydrogen core theory' of the Earth, it had already been invalidated by the 1960's, and probably a lot earlier.

 

Now, it could be that YOUR science teacher(s) in high school or even college were mistaken and gave you some bad information. Sorry about that! I had a biology teacher who swore that Pythons could swallow an adult water buffalo! Wrong! But I went to the encyclopedia and got the facts. Had you gone to the encyclopedia in the 1960's you would have gotten the facts, too: no Hydrogen core.

 

If you want us to take you seriously, drop all the BS about the 'Hydrogen core theory'.

 

Let's just take it that you were misinformed, and leave it at that. Iron was a major constituent of all inner-most planets before and during their formation. This has been the mainstream opinion since the 1960's.

[Cold-co]

A MATTER OF GRAVITY

 

Some two hundred years ago, scientists longed to break free from Church control. To break free, they needed to unseat the Church approved, cold-core cross section that had been taught for over 5000 years. The sleight of hand they devised was so well disguised even the Jesuits, who the Pope directed to derail their efforts, could find no fault in their logic. In time, the Jesuits came to teach the scientist’s view. Today, we perpetuate the scientist’s sleight of hand every time we teach gravitational forces at work within Earth.

Gravity is a bidirectional (elastic) force—Earth pulls you with the same amount of force that you pull the Earth. But since Earth is so much larger than any freely moving body, on or above her surface, we treat her gravity as a directional force. This makes the force of gravity relatively simple, so we teach gravity before we teach elasticity. But in reality, elastic cohesion (the drawing together of particles) is the force identified by Newton in his law of universal gravitation, “Every particle of matter in the universe attracts every other particle with a force that is directly proportional to the product of the masses of the particles and inversely proportional to the square of the distance between them.”

In addition to our less than accurate treatment of gravity, seismic wave data show Earth’s upper shells to be solids down to her core. Yet, we treat her as a large liquid drop to calculate her moment of inertia from her rotationally induced flattening (f). Since she is thought to at least act like a liquid, her flattening is believed to be held on check solely by the equatorial acceleration of gravity (ge); hence, our flattening equation becomes f = 1.5(C-A/Ma2) + 0.5 rate of rotation squared times Earth's radius (a)/ge). In so doing, we conclude she has a low moment of inertia. In turn, she must have a molten interior to allow heavier particles to sink deep into her core to achieve the low moment of inertia demanded by our flattening equation. However, our hot-core model is valid only if we ignore horizontal elastic cohesion.

Elastic cohesion in a solid imparts a constant pull between all its parts. But, no one ever bothered to calculate the strength of that pull in Earth’s shells, because in a schematic of forces diagram the improper use of directional forces (the scientist’s sleight of hand) makes them appear to cancel out; but a gravitational pull cannot cancel out another gravitational pull—only balance. Their pulls are still present.

Now, if we treat Earth’s outer shell as a structurally sound, hollow sphere, subject to horizontal elastic cohesion; then the mass movement, created by her rotation, must also overcome that shell’s elastic cohesion before she will flatten. Trigonometric calculations of Earth’s gravitational forces show horizontal cohesion in her outermost shell to be an acceleration of equal value to the acceleration of vertical gravity on her surface, thus our flattening equation needs another component, +0.5 rate of rotation squared times earth's radius/gh. Or, since this acceleration is of equal value to the acceleration of vertical gravity, that vertical equatorial acceleration can be doubled to obtain Earth’s moment of inertia. When doubled, our flattening equation yields a moment of inertia equal to the summation of moments of inertia mathematically derived for the individual shells of a condensed, cold-core model, whose shell densities are proportional to the speeds of seismic waves passed through them. Serendipity!!!

The squeeze afforded by horizontal elastic cohesion, gives us a unique way to look at Earth’s mechanics—one of a contracting pressure vessel driven by an ever increasing packing pressure provided by horizontal cohesion. A pressure vessel capable of producing a natural heat-pumping cycle—like the heat-pumping cycle employed in diamond anvil devices used to determine the physical characteristics of solid hydrogen. Just as the test sample in a diamond anvil gives up heat to move to a denser phase, so too does the hydrogen crystal in Earth’s pressure vessel give up heat—heat that shows up as geothermal energy in or on her surface.

 

Moderation Note: Subsuquent discussion of Cold-co's model of the Earth's structure has been moved to 19755 so that it may be explored without the constraints of this thread's topic.

[CraigD]

The composition and structure of the Earth is an old and profound scientific subject. Science, like philosophy, thrives as a process, the ongoing consideration of a series of “what if”, hypothetical questions. “What if the Earth’s core was mostly hydrogen by mass?” is such a question, and despite it’s having been championed pseudoscientifically by various more and less well known people, some with conventionally religious agendas, some not, deserves sound scientific consideration.

 

First, it’s necessary to decide what’s meant by the question. “The Earth’s core” is, thanks to years of seismographic experimentation and analysis, well defined: one of two spherical regions centered at the Earth’s center, with radii of about 1200 and 3500 km, or about 1 quarter and 2 thirds of the radius of the Earth. As CharlieO notes, these regions have never been directly sampled – a hole bored down to them and their stuff examined – so their composition can only be decided indirectly.

 

Next, it’s necessary to decide what’s meant by “mostly hydrogen”. In ordinary conditions, hydrogen is a very low-density (about [math]0.9 \mbox{kg/m}^3[/math]) gas. It can be fairly easily liquefied or frozen (at around 20 and 14 K), increasing its density to about 70 (about [math]70 \mbox{kg/m}^3[/math]). Neither of these densities is nearly sufficient for the Earth’s core, as the Earth’s average density is about (about [math]5500 \mbox{kg/m}^3[/math]).

 

If the Earth’s core is mostly hydrogen, the hydrogen must be in a very chemically strange state where its nuclei – mostly single protons – are packed more densely than the lowest-energy spacing of their electrons allows in normal atomic matter, a state known as metallic hydrogen, because in this state, it’s electrons conduct electricity – almost certainly superconduct, with zero resistance. Several experiments have produced small quantities of metallic hydrogen, notably the “Nellis experiment” in 1996 and a 2008 experiment by Silvera and Deemyad, which metalized hydrogen at

[math]1.4 \times 10^{11}[/math] to [math]1.8 \times 10^{11}[/math] Pa at 3000 K

and

[math]6.4 \times 10^{10}[/math] to [math]6.5 \times 10^{10}[/math] Pa at 1025 to 1055 K

, respectively. In this state, there is practically no limit to how dense hydrogen, or any other fully electron degenerate matter, can be (densities approaching [math]10^{16} \mbox{kg/m}^3, where matter becomes neutron degenerate).

 

These temperatures and pressures are within the range theoretically predicted for the Earth’s core. So it is, in principle possible for Earth to have a metallic hydrogen core.

 

An important point needs to be made here: although some hydrogen core proponents emphasize a “cold core”, it’s not necessary for hydrogen to be cold to be a very dense. It is necessary for it to be electron degenerate – a metal – rather than a liquid or ice, where each nucleus retains its electron. Liquid and solid (ice) hydrogen are associated with very low temperatures because, at standard atmospheric pressure, its boiling and melting point are very low (as mentioned above, about 14 and 20 K).

 

Science, however, can’t stop with finding a hypothesized thing in principle possible. It must provide an explanation for how the thing came to be. Here, our investigation turns from high-pressure chemistry to planetary astrophysics.

 

From observing stellar systems in earlier stages of development than our own, we know with high certainty that they form from gas and dust clouds, passing through a stage when the young star is surrounded by a protoplanetary disk. Many-bodies computer simulations strongly suggest that these disks accrete into distinct planets of various sizes and compositions. For the same fundamentally mechanical reasons that the average speed of lighter molecules in a gas are greater than that of heavier ones, light elements such as hydrogen, helium, and pretty much all the elements that are gasses at standard pressure and temperature, are the most difficult to accrete, so are accreted in large proportion only by the large accretions that become gas giant planets. Accretions that form smaller planets and other bodies are able to accrete in large proportions only heavy elements, and relatively small amounts of light elements compounded into dense solids, such as H2O ice and, because of oxygen’s strong chemical tendency to compound with heavier elements, various oxygen compounds.

 

It is because of this fundamental dynamic that “the Earth has a hydrogen core” hypothesis is unlikely. Although there’s was a lot of gaseous hydrogen in the solar system’s protoplanetary disk, it was accreted mostly by the 4 gas giants. The inner planets, and the large moons of the gas giants accreted mostly iron, silicon, and, due to its above mentioned tendency, oxygen.

 

It’s helpful to compare the composition of the galaxy on average, the solar system, and the Earth. Here’s a table I put together from a variety of sources and approximations:

[font="Fixedsys"][noparse]
              Atomic   Abundance by mass                       Abundance Earth
Element        Mass     Galactic     Solar Sys  Earth           /Solar Sys
1  Hydrogen    1.0079   .922927968  .909850951  .000045         .00004945865028
2  Helium      4.0026   .075479649  .088702314  .0000000000045  .00000000005073
8  Oxygen      15.9994  .000818257  .000776145  .301            387.81400488814
6  Carbon      12.0108  .000482111  .000329372  .0000000066     .00002003809870
10 Neon        20.1798  .000083589  .000112182  .000000000004   .00000003565623
7  Nitrogen    14.0067  .000086277  .000102072  .00000068       .00666190637715
12 Magnesium   24.3051  .000030039  .000035024  .139            3968.6652529153
14 Silicon     28.0855  .000029133  .000032611  .151            4630.3188397575
26 Iron        55.8452  .000024569  .000029350  .321            10936.956199868
16 Sulfur      32.0655  .000017273  .000016794  .029            1726.7311303667
18 Argon       39.9481              .000003293  .000000011      .00333968311830
13 Aluminium   26.9815              .000002768  .014            5056.5498760992
20 Calcium     40.0784              .000001992  .015            7528.0760664162
11 Sodium      22.9898              .000001871  .00012          64.106682600422
28 Nickel      58.6934              .000001607  .018            11195.913533258
24 Chromium    51.9962              .000000440  .00000046       1.0448597823342
15 Phosphorus  30.9738              .000000339  .002            5896.9929186927
25 Manganese   54.9380              .000000311  .0000046        14.770269174359
17 Chlorine    35.4532              .000000169  .0000042        24.767370258509
19 Potassium   39.0983              .000000122  .00011          894.71616697406
22 Titanium    47.8671              .000000078  .000029         370.52772172452
[/noparse][/font]

In summary, while it’s conceivable that Earth, in its present form, could have a metallic hydrogen core, there’s no scientifically plausible explanation of which I’m aware of how a protoplanetary disk can eventually form such a planet.

[modest]

several experiments have produced small quantities of metallic hydrogen, notably the “nellis experiment” in 1996 and a 2008 experiment by silvera and deemyad, which metalized hydrogen at

[math]1.4 \times 10^{11}[/math] to [math]1.8 \times 10^{11}[/math] pa at 3000 k

and

[math]6.4 \times 10^{10}[/math] to [math]6.5 \times 10^{10}[/math] pa at 1025 to 1055 k

, respectively. In this state, there is practically no limit to how dense hydrogen, or any other fully electron degenerate matter, can be (densities approaching [math]10^{16} \mbox{kg/m}^3[/math], where matter becomes neutron degenerate).

 

These temperatures and pressures are within the range theoretically predicted for the Earth’s core. So it is, in principle possible for Earth to have a metallic hydrogen core.

 

The pressure in Earth's core cannot be much higher than 300 Gpa. The experiments you reference constrain the possible density of hydrogen at this pressure:

-

source

It seems reasonable to preclude the possibility of an hydrogen core by noting that it doesn't have the necessary density at earth's core pressure.

 

~modest

[Pyrotex]

If I'm reading that chart right, Modest, then the experiments quoted by Craig took place at, say:

 

150 GPa and 65 GPA

 

which can be read off the left axis of the chart.

Using the dashed line for shock reverberations, this would give us densities of:

 

0.7 gm*cm-3 and .53 gm*cm-3

 

Now, the Earth's core has a density of 5500 kg*m-3

 

That translates to .55 * 10^6 g*m-3

 

.......................or .55 * 10^6 * 10^-6 g*cm-3

 

.......................or .55 g*cm-3

 

The first density listed above (.7) is indeed higher than .55 :shrug: :confused:

and the second one is spot on.

 

So... why do you say the chart demonstrates that the Earth's core cannot be MH???

[modest]

If I'm reading that chart right, Modest, then the experiments quoted by Craig took place at, say:

 

150 GPa and 65 GPA

 

which can be read off the left axis of the chart.

Using the dashed line for shock reverberations, this would give us densities of:

 

0.7 gm*cm-3 and .53 gm*cm-3

 

Now, the Earth's core has a density of 5500 kg*m-3

 

That translates to .55 * 10^6 g*m-3

 

.......................or .55 * 10^6 * 10^-6 g*cm-3

 

.......................or .55 g*cm-3

 

The first density listed above (.7) is indeed higher than .55 :shrug: :confused:

and the second one is spot on.

 

So... why do you say the chart demonstrates that the Earth's core cannot be MH???

 

I believe 5500 kg/m^3 is 5.5 g/cm^3:

 

[math]\frac{5500 \ kg}{m^3} \left( \frac{1000 \ g}{1 \ kg}\right) \left( \frac{1 \ m^3}{1000000 \ cm^3} \right) = 5.5 \ g/cm^3[/math]

 

You perhaps multiplied by 100 rather than 1000 from kg to g. I do that a lot thinking m -> cm. The inner core is more realistically 12.6 - 13 g/cm^3 while hydrogen at that pressure/temp can't really be above 1 g/cm^3:

 

What is the best estimate of the densities of the various layers of the Earth?

 

~modest

[HydrogenBond]

If we look at the first ionization potential of atoms iron is in the middle between Si and Ca, Ca=6.113, Fe=7.87, Si=8.151, C=11.26, O=13.16,

 

MIT 3.091 Periodic Table of the Elements: First Ionization Potential"]http://web.mit.edu/course/3/3.091/www3/pt/pert9.html]MIT 3.091 Periodic Table of the Elements: First Ionization Potential

 

If we started with the earths assumed atoms, ionized, the iron should oxidize before the Si with the available O. Something doesn't add up. The work around this is to assume the earth was formed with asteroid bombardment to isolate the iron.

 

If we look at the composition of asteroids we have found on the earth and what we can see based on luminosity,

Asteroids: Zoom Astronomy

 

Type Composition Percentage of Asteroids

 

Carbon (C-type) Carbon over 75 percent

 

Silicate (S-type) Metallic iron mixed with iron-silicates and magnesium-silicates 17 percent

 

Metallic (M-type) Iron/ nickel less than 7 percent

 

Dark (D-type) Water ice/frozen carbon monoxide mixed with rock

less than 1 percent

 

If we assume random asteroids encounters, the earth should have much more C. Carbon can display ferro magnetic properties. Carbon has the highest melting point of all the elements being solid up at 3678 C at atmospheric temperature. The asteroid scenario actually gives us a C core. Carbon has a higher ionization energy than any of the major metals and would be the last the oxidize after the metals and might be able to remain elemental. But that changes the earth's composition.

[Moontanman]

So you are assuming the earths elements ionized at some point after they came together? Carbon is not present as elemental carbon but mostly as hydrocarbons and Co2. Silicates already have the oxygen tied up. Silicon is almost always in combination with oxygen. iron occurs in pure form in meteors as does nickle. I think your premise of the atoms being free to combine at will needs to be rethought.

[RevOfAllRevs]

However, it seems the more I learn, the more I discover I don't know or understand. Help is needed. I don't know if Earth has an iron core or a hydrogen core, albeit the latter seems more likely to me; given the constant loss of hydrogen into space which appears to be physical evidence that some sort of hydrogen reservoir exists within Earth. It is the unquestioning belief of many that Earth has an iron core that is puzzling to me.>>>>>Breivty Snip<<<<< Does anyone know of a more plausible theory of how Earth developed a core containing such a enormous excess of iron?>>>another snip<<<

I found the following interesting, especially since no swarms of planetesimals were observed:

May 3, 2009: Hubble Observations Confirm that Planets Form from Disks Around Stars

 

I was wondering what is the latest in the idea that 'fission' or something close is happening in the earths core. If it was true would that have any effect on your belief that the earths core isn't mainly 'iron' ? Thanks in advance.

 

; }>

[Moontanman]

Radioactive decay releases helium 3, there can little doubt that chemically bound hydrogen is being released by heat and contact with catalysts deep within the Earth.

[CraigD]

I was wondering what is the latest in the idea that 'fission' or something close is happening in the earths core.

Nuclear fission – more commonly referred to as radioactivity – has a very important affecting on the Earth’s history, and the understanding of it an important event in the history of science.

 

In 1862, using the best science of his time, Kelvin calculated from the temperature of the Earth at various depths that it had formed about 100,000,000 years ago. His calculations were sound, but his results wrong (present-day theories, via many means, place the formation of the Earth about 4,500,000,000 years ago) because they don’t account for the heat produced by nuclear fission.

 

By the 1930s, the role or radioactivity in the various sections of the Earth was well understood and accepted by mainstream science.

 

(sources: Engines of our Ingenuity: The Age of the Earth; Wikipedia article “age of the Earth”)

If it was true would that have any effect on your belief that the earths core isn't mainly 'iron' ?

Though very important to geophysics, I don’t think radioactivity has much relevance to the “Earth’s hydrogen core” or other fringe theories.

 

Fringe and mainstream geo and planetary physics theories alike focus heavily (or should – fringe theories often focus on strange and unexpected theoretical details) on how planets form, which in turn depends heavily on what mater was present when the planets formed, and the dynamics of how different elements in different forms can form planets. This is why mainstream physics favors an iron-nickel core for Earth, Earth-like, and even un-Earth-like planets, such as gas giants like Jupiter – iron and nickel are abundant throughout solar systems, and easily gravitationally captured and pulled to the center of accreting bodies. Even though hydrogen is the most abundant element in the solar system, it’s not easily captured by Earth-size planets, so according to mainstream theory, exists in large fractions only in much larger, giant planets.

 

Radioactivity becomes significant as planets age, after their formation.

[RevOfAllRevs]

Thanks so much for the great responses. I have often wondered why the heavier (including the radio active elements) elements wouldn't 'settle out' to the most central part of the earths core. I am aware that there are fluid dynamics and other processes at work which would disrupt simple settling, and that the core is a rather poorly understood area of the planet.

 

One more question? How do we know (how do we sample for) He-3 and other by products of fission in the core ?

 

; }>

[Moontanman]

Thanks so much for the great responses. I have often wondered why the heavier (including the radio active elements) elements wouldn't 'settle out' to the most central part of the earths core. I am aware that there are fluid dynamics and other processes at work which would disrupt simple settling, and that the core is a rather poorly understood area of the planet.

 

One more question? How do we know (how do we sample for) He-3 and other by products of fission in the core ?

 

; }>

 

Actually Rev, there is a school of thought that says the heavy elements, ie uranium, thorium, plutonium etc, did indeed migrate to the center of the earth forming a ball approximately 5 miles across that is a liquid metal reactor, gravitational pressure and the poisons (in this case poisons mean elements that slow down or stop the fission reactions) naturally moderate the reactions. Additionally, much like the gravitational pressure that keeps the sun from exploding in a runaway reaction the same pressure keeps the ball of uranium from exploding inside the earth.

 

Georeactor - Wikipedia, the free encyclopedia

 

Helium exiting from the earth is detected by various instruments, it is found in lava and from the areas of deep under ground faults and interestingly enough from oil wells. Since He doesn't chemically react with other elements it migrates to the surface unimpeded by chemical reactions that would or could stop other elements. the percentage of He3 to He4 varies but it is always a very small percentage. Most He3 from inside the Earth is thought to be the by product of the decay of Tritium which is one of the by products of fission reactions.

 

Helium-3 - Wikipedia, the free encyclopedia

[RevOfAllRevs]

Wonderful. I did wonder how the reaction would be moderated having no control rods to slow the reaction, and simply assumed that the pressure and thousands of miles of iron etc would allow a crazy wide open reaction with no need for control (its a good thing that the critical mass wasn't huge I suppose).

 

And thanks for the info of how the He3 is detected. I wonder how we know that is coming from the core and not the mantel? In any case thanks for explaining it, its incredible what we can do with so little information.

 

; }>