The Propositions previously set out are generally attempts to explain observed data. Ones in this chapter mostly suggest mechanisms. Even if all the mechanisms suggested here should later be discredited, this does not affect the earlier Propositions.
PART 1 -- DOMAIN MOVEMENT
In NU005 we saw that there was clear evidence of movements of parts of the Earth's crust relative to one another -- already accepted as 'Continental Drift' and 'terranes' -- and that it also appears that smaller parts (microdomains) have moved bigger distances relative to larger ones. Moreover, it appears that the direction of movement has been strongly away from the equator. We will first look more closely at a possible reason for this result.The Fugitive Domains
We have seen that the earlier Continental Drift theories and the later Expanding Earth concept are not mutually exclusive, one is a more developed case of the other. It is clear that pieces of the crust do actually move relative to one another on the surface of the Earth, as in the case of India colliding with northern Asia. Even though the Earth is expanding, these domains are not completely passive subjects of the expansion occurring beneath them; they do actually move.What drives the movement of these domains? Earlier we have seen that the suggestions of 'convection cells', with floating land masses being pushed aside by uprising currents of hot rock, are just not supported by any real evidence. So what causes the movement?
The explanation lies, I believe, in the principle of conservation of momentum. If a body (or a group of bodies) is in motion, its momentum (the figure got by multiplying its mass by its velocity), remains constant or 'conserved' in spite of events it undergoes.
If a series of flat bodies is connected loosely to the surface of a rotating sphere, and that sphere expands under them, what would we expect to happen to the flat bodies?
If the underlying expanding sphere continues to rotate at the same angular rate (same number of revolutions per day), and to a first approximation we can take this to be the case with the Earth in the recent geological past, then 'floating' land masses originally situated near the equator may be expected to move away, towards the poles, so that their momentum remains the same.
This is because if the rate of rotation is the same, the actual velocity of a point on the Earth's equator must increase in direct proportion to its radius if it expands. A floating body may be expected to move away from the equator with a sort of 'centrifugal force', towards a latitude where the surface velocity is the same as in its original position.
Proposition 16A
Domain flight away from the equator occurs on an expanding
Earth in an effort to conserve the momentum of the individual
domains
This suggestion could be tested physically, for example with magnetized discs sliding on the lubricated surface of a metal sphere, or theoretically, through computer simulation.
There are some other factors to consider here. One is the the point that smaller domains appear to have moved longer distances than larger ones. The other is the actual position of the Equator from time to time.
Effect of Domain Size on Movement
Evidence has been given that the microdomains and smaller domains have moved greater distances than larger domains to which they were once attached (Proposition 5H). The reasons for this are not entirely clear.One possible line of reasoning is based on momentum conservation. A large domain extending right over the equator will have a centre of gravity on, or fairly close to, the equator.
If the effect of momentum conservation is to cause movement away from the equator, such movements will be balanced or minimized by the fact that the two halves of the domain are pulling in opposite directions. Of course this only holds while the domain stays in one piece.
On the other hand, a microdomain on the outer edge of such an equatorial megadomain will have its centre of gravity some way from the equator, and the effects of 'centrifugal flight' will be greater. Also, close to the equator the Earth's surface is close to parallel with its axis, so there will be a difference in the degree of change in momentum with radius expansion, compared to a domain in middle latitudes (Figure 16.1).
Fig. 16.1. Changes in momentum at
different latitudes
In this diagram, a microdomain M is shown attached to a large equatorial domain D on an unexpanded Earth, and in various positions relative to D on an Earth of larger radius.
On the expanded Earth, M1 is the position of the microdomain if it remains attached to D. However, we would expect that if it broke away from D and just kept its own position relative to the underlying core it would have appeared to 'move' relative to D, down to M2. If the expanded sphere continued to rotate at the same speed as the unexpanded one, then to move to a position where its rotational speed and momentum were preserved, the microdomain would have to travel right down to M3.
There other considerations. As already noted (Proposition 7F), it seems that domain flight becomes less marked or disappears altogether as the Poles are approached. We have also seen (Proposition 5K) that domain flight may be affected by the gravitational influence of adjacent large domains. There is also a philosophical consideration.
If the Earth is expanding, and smaller domains are ending up further from the Equator than previously adjacent larger domains, this situation could be viewed as larger domains moving further from the Poles than smaller ones. This is an alternative model which deserves consideration. However, it is a model which does not seem as satisfactory as the one already looked at, in that it does not explain the preponderance of equator-pointing peninsulas, or the apparent large shifts of isolated islands such as Iceland.
Domain Blocking
Whatever the basic mechanisms involved in domain movement, whenever you look at the position of a particular area, the important factor may just be one of physical blocking of movement. The Italian, Iberian, and Indian peninsulas are clear examples of domains which were moving north but whose movement was stopped when they ran into larger domains.The highest large area on Earth is the Tibetan Plateau, which stands more than 4 km above sealevel. This domain is reasonably central in the east Asian landmass. Rather than being pushed up, as is usually assumed for high areas, it may be that this plateau never had the chance to slide down; while other parts of the holodomain may have slid away into hollows created by Earth expansion, this may have happened to have been blocked from movement by adjacent domains.
It is usually assumed that India, breaking off from the Gondwanan continent low in the south, travelled a long way north before colliding with Laurasia. In fact, it is possible that the Indian megadomain was never more than a few hundred kilometres from Laurasia, so that the relative movement leading to creation of the Himalayas was only of this order, and the long 'skid marks' down the Indian Ocean actually represent the Earth expanding away under India. We have seen, in NU005, that the Himalayas could have been formed from only 2-3 km of domain material pushed together, so the actual 'run up' of India to the impact need not have been very long.
Thickness of Domains
At the end of NU009 we arrived at a picture of the Earth (Fig. 9.2) in which the old broad, massive 'tectonic plates', extending down some 100 km or more in the 'lithosphere', were replaced by a mass of smaller domains and sub-domains beneath them, of very varying thicknesses.Another feature of the old 'tectonic plate' approach was the idea that these huge plates were floating on a layer of liquid rock within the Earth, like icebergs in the ocean. I have suggested that there is no such liquid layer. I also strongly suspect that actual calculations of the influence of any such liquid layer on movements would show them to be quite insignificant. It is as if the demolishers of an office tower on a hill would expect quite different results from a controlled implosion according to whether it had been raining or not.
Whatever, the tectonic plate idea assumes more or less uniform-thickness massive plates everywhere on the Earth. The domain approach does not. It is possible that the smaller microdomains, such as Rottnest, may be, like Laputa, only a few hundred metres or less thick.
What this implies is that these surface microdomains may be moving quite unsuspectedly, like snails on a slab of rock, without creating any obvious effects such as heating or rock metamorphism. The slab of rock may itself be inching its way downhill as soil is washed away under it, and the whole hillside may be part of a microdomain moving over a larger subdomain.
Proposition 16B
Microdomains may be moving independently on underlying
domains which are themselves in motion
This Proposition is at the stage where it could be verified by careful actual measurements of relative movements; surveying instruments have now been developed which are just about capable of this level of accuracy. Let us revert briefly to the quotation about Rottnest which appeared at the head of NU002. We have already shown how the earth movements suggested by the plant relationships in that quotation do appear to actually occur; now we can see their speed.
The basement limestone rocks on which Rottnest is situated are believed to be about 1.5 my old. If Rottnest has moved 300 km south in this period, simple calculation shows the average rate of movement to have been 20 cm/yr. This is quite a large amount, which should be easily detectable with properly-designed measurements.
Of course, Rottnest may not be currently moving at all, it may be blocked on its undersea pedestal. The basement rock on which it moved could be above or below the level assumed, and hence of different age, and the reference point on the coast from which the 300 km was measured could itself be moving, although variations here tend to increase the calculated speed rather than reduce them. Whatever, if the domain movements suggested actually exist, it should be possible to observe and measure them somewhere.
The Position of the Equator
There is quite a lot of geological evidence (e.g. [17]) that the position of the Earth's equator has varied somewhat in the past. This is not a new thought, such suggestions predate even the development of Continental Drift ideas. And of course the reasoning in this book makes the equatorial position almost a philosophical question -- if domains and subdomains are moving freely about the Earth, like people milling in a crowd, what relevance is there in a line drawn across this crowd at some arbitrary point in the past?There is, in fact, some relevance. We have seen, in the phenomenon of domain flight, that these movements have apparently been away from the equator of the time when movement began. It has been suggested that when the split of the Holodomain into Laurasia and Gondwanaland occurred, this took place along the equator of that day. The Tethyan Girdle formed round the Earth by that event has had a strong influence on the Earth's subsequent history.
It is very obvious that the distribution of land between the northern and southern hemispheres is currently quite uneven, with far more in the north than in the south. This reflects the fact that the old Tethyan equator ran along a line between domains which is mostly much further north relative to its original position. As the jostling domains have moved to different extents, the line has become rather broken up, but appears most northernly in the Mediterranean, at about 35°N, and most southernly around southeast Asia.
In Table 6 there was a list of families suggested as originating in Laurasia, and of ones from Gondwanaland. There were far more in the Gondwanan section, presumably because more intense evolution occurs in the tropics, and almost all the current tropics were once part of Gondwanaland. Much more of Laurasia has ended up in cold polar regions where the opportunity for development is much poorer.
Proposition 16C
More modern species are of Gondwanan origin than
Laurasian because species development is more marked in the
tropics, which were predominantly parts of Gondwanaland
The reason for the uneven distribution of land in the two hemispheres is not clear at present. It could be pure chance. However, there is another unevenness, more recent than the Tethyan one, which is happening because of the opening up of the Pacific Ocean.
The Pacific is very large, covering around a third of the entire Earth's surface, and it has opened up relatively recently and quickly. As a result, the hemisphere centered on a point in the South Pacific off New Zealand contains only 15% of the Earth's land surface. This does suggest that there have been at least two episodes of unevenness of domain redistribution, and that their cause is not related to the Earth's spin, as the Pacific episode has affected both hemispheres more or less equally.
There is some suggestion from plant family distributions of different early equator positions. In particular, the layout of the cycads (Fig. 4.13) leads to speculation about an equator which once dipped down towards southern Africa and Australia then up again to the Americas. The cycads are much older than the other plant groups featured, and could have originated under different conditions -- but more evidence is needed on this one.
The Final Answer
As almost all of the concepts of domainography have only now been introduced with this book, it is not reasonable to expect that the whole field can be advanced to the stage of giving final answers in one go. In particular, much more detailed calculation is needed of the parts amenable to mathematical analysis. For the moment we must be content with pointing out that such calculations can be made.In this work, we also need to keep in mind at every stage whether the assumptions used are justified. For example, it was assumed above, as a first approximation, that the Earth is rotating at the same rate as it did in the past. In fact there is evidence that the rate of spin is slowing down.
Most of this evidence comes from studies of growth patterns in fossil corals. Some of these show patterns, similar to the growth rings in trees, but with one 'ring' for each day rather than year. They indicate that in the past, the Earth had more than 400 days in a year.
This is usually taken to mean that the Earth turned more quickly on its axis in those days (an alternative, that the Earth took longer to go round the Sun, is much less likely). The implications of all the matters raised are going to need a lot of exploring!
PART 2 -- WITHIN THE PLANET
In Chapter 9 we had a good look inside the Earth, and a number of Propositions were made which differed greatly from accepted views. We can now go to develop some of these, and see some of the mechanisms for change which they imply. The first area to look at is the Earth's inner structure and composition.Phase Changes and Density
Working from the conventionally-accepted data and figures given in Fig. 9.1, we arrived at a new scenario for the inner structure of the Earth. The idea that the Earth's density increases from the surface to the core, and does so through a number of abrupt changes or discontinuities as well as gradually, was not disputed. The idea that the Earth's temperature increases hugely towards the core, reaching several hundred thousand degrees at the centre, was rejected. The idea that our planet has an iron-rich core was rejected. The observation that the upper layers of the Earth's crust are the source of heat which rises to the surface is undisputed, and a source for this heat was suggested.The density of the Earth's inner substance is believed to increase from an average of around 2.7 at the surface to around 13.6 at the centre. The density of iron metal is around 7.9, and of its oxides and compounds a good deal less, so this density of itself gives no explanation for the high value at the Earth's centre. I have put forward part of an explanation (Proposition 9D), in suggesting that the density discontinuities are due to phase changes in the Earth's substance caused by the great pressures. We can make the picture more explicit.
It seems reasonable to suggest that the entire reason for density increasing as you approach the Earth's centre is that the rock substance is progressively more compressed as the weight of the overlying layers gets larger. At certain threshold pressures, the substance will undergo a specific rearrangement, a phase change. Between these key pressures, the substance will become progressively more compressed and hence of higher density, but stay in the same phase.
Proposition 16D
Both the progressive and the abrupt increases in density
encountered on approaching the Earth's centre are due to the
increasing pressure of the overlying material
If, then, the increase in density towards the centre is purely the outcome of the increasing pressure, this raises another possibility, concerning the composition of the Earth's substance. We have abandoned the iron core, we have suggested that the density discontinuities are due to pressure thresholds. We are left with nothing which necessarily requires the composition of the Earth substance to change with depth. The simple conclusion -- and we will see in the next Chapter that we should always take the simplest way -- is that it does not change.
Proposition 16E
The composition of the Earth's solid substance is more or less
uniform from the centre to the surface
Of course this Proposition does not apply to the Domainosphere, the outer layer of the Earth where, as we have seen, the interaction of domains has led to segregation of components. This segregation has occurred directly, through domain rubbing and natural zone-refining (Propositions 14C, 14D). It has occurred indirectly, through domain uplift or land exposure, by erosion and leaching of rock components. And it has occurred biologically, through the action of life, as in the formation of fossil fuels.
What the Proposition suggests is that the primeval composition of the Earth's solid material was uniform. Only in the Domainosphere, the top 500 km or so where domainographic processes are active, has this uniformity of composition been disturbed.
But hold on a minute -- what about the Sial and the Sima layers, described at the start of Chapter 9, which are known to differ in chemical composition? Let us look more closely at these.
The Sial and the Sima
The Sial is the lighter layer of rock (density 2.7) which forms the majority of the Earth's continents. It is discontinuous, up to about 30 km thick below the continents, but grading away to nothing at their edge. The Sima is slightly denser (2.9), is exposed at the deeper ocean beds, and is believed to underlie the Sial where the latter exists. The situation, as conventionally accepted, was illustrated in Figure 9.1.| Silicon | Aluminium | Iron | Calcium | Magnesium | Other | |
| SiO2 | Al2O3 | Fe2O3+FeO | CaO | MgO | -- | |
| SIAL | 69 | 14 | 4 | -- | -- | 13 |
| SIMA | 48 | 15 | 11 | 11 | 9 | 6 |
Both layers consist essentially of igneous rocks, although of course both may be overlaid by sedimentary or metamorphic ones. These rocks are not of a fixed composition, but both are basically made up of metal silicates -- compounds of silicon and oxygen with various metals. Where the two differ is in their respective contents of the metals.
It is conventional to represent the compositions in terms of the oxides of the elements. Table 16 (based on [64]) shows the approximate percentage compositions of the Sima and the Sial in this form.
It should be noted that these are average compositions. Most igneous rocks fall fairly easily into one group or the other, but it is possible to find examples which grade from one type into the other.
The main differences are that the Sial has much more silica, less iron, and almost none of the calcium and magnesium of the Sima. Iron and calcium are considerably heavier than silicon, and the higher proportion of these in the Sima accounts for its higher density.
The conventional view is that the Sial, being lighter, floated out and condensed first in the early days of the Earth, when it was all molten. Conventionally, also, the heat which currently flows out of the Earth was believed to come, at least in part, from this 'primeval' heat. I have already suggested (Proposition 9F) that the idea that the Earth now has a very hot core is wrong. I have also suggested (Proposition 8E) that igneous rocks are all produced locally, from domain rubbing, and do not well up from deep inside the Earth.
If we put all these points together, we end up with a scenario very different to the conventional one. This leads to a number of important propositions, the first of which concerns the Sial and the Sima. It seems likely that the Sial was never formed separately to the Sima, but instead represents only worked-over and re-melted Sima.
Proposition 16F
The acidic igneous rocks classed as Sial have been derived by
the re-melting of worked-over and leached basic Sima rocks
This Proposition explains the occurrence of the iron-rich ore beds formed in the early, Precambrian era, and the calcium- and magnesium-rich deposits (limestones) of the Paleozoic and later eras. It also explains the silica-rich deposits (sands and sandstones) of all ages. The implication is that the Sima is the 'primeval' rock, which, as already suggested, extends throughout the Earth.
Proposition 16G
Rock of 'Sima-type' composition has extended throughout
the Earth since it was first formed, and has only been modified
near to the surface by domainographic processes
An implication of this (which can be tested) is that the average composition of all rocks, sedimentary, metamorphic, and igneous, in the upper layers above the Sima, should when summed together be identical to that of the Sima (after allowing for the mainly atmosphere-derived components such as carbon).
Heat and the Earth
If we do not need the inner Earth to be molten to explain such things as floating tectonic plates, heat rising to the surface, or segregation of the Sial or other layers, then we might as well assume that it never was molten.Proposition 16H
The Earth was never molten
Instead, in the absence of a better story, we can take it that the primeval Earth accumulated at a temperature not too different to now. After all, if the Earth condensed from part of a solar=system wide disc of gas, as one proposal has it, there is no need to assume this gas was hot. Even if the Earth was formed from material thrown out from the hot Sun, this material could radiate heat freely, and need not still be hot by the time it reached Earth's orbit. If the material was very fine, close to the molecular level, the concept 'heat' in fact means nothing; heat is a measure of the interaction of particles close enough to interact.
The same reasoning applies also to the other planets of the Solar System.
Composition of the Other Planets
In Table 15, values were given for the densities of the planets and major moons of the Solar System. There are some conclusions to be drawn from these densities.The density values given for the Outer Planets and most of their moons are irrelevant, because those values include unknown proportions of atmospheric components, whether as gas, liquid, or solid. The only values we can use here are for the large bodies with known rocky surfaces, that is, the four Inner Planets and our own Moon.
In order of decreasing size, these values are: Earth - 5.50; Venus - 5.25; Mars - 3.91; Mercury - 5.41; and Moon - 3.35. There is a clear progression here, with the smaller bodies having lower densities -- the only hiccup is with Mercury. Notice also that as the bodies get smaller, their densities approach those of the upper few hundred kilometres of Earth, 2.7-3.3 (see Figure 9.1).
It seems worth examining the proposition that all the rocky planets, and probably the rocky cores of the giant planets, are made up of Sima-type material like Earth, which material shows the same compression and increase in density with depth as on Earth.
Proposition 16I
All the Solar System planets and major moons have rocky
centres made up of the same Sima-type material as Earth, subject
to the same increase in density with depth
The situation is best illustrated by noting the radius of the planet or moon and imagining it superimposed on the higher layers of the Earth shown in Figure 9.1, with the surfaces matching. Thus our Moon, with a radius of 1738 km, would extend down to halfway down the Lower Mantle, with a density at its centre of between 4.3 and 5.5, and one at its surface of around 2.7. The fit with the actual average density of 3.34 is really quite good, particularly when you allow for the fact that more of a sphere's volume is closer to its surface than its centre (seven-eighths is above the half-radius mark, only one-eighth below).
Mars, with a radius of 3393 km, would extend on Fig. 9.1 some way into the Outer Core, with a small part of its volume having a density of 10.0-12.3. Again this looks as if it fits in quite well with an average density of 3.95. Probably this area would benefit from detailed and careful calculations.
As to the apparent Mercury hiccup, which causes it to vary from the pattern, there are a number of possibilities. One is that there are exceptional circumstances with Mercury which cause it to vary from the pattern This may well be the case, although I cannot think of any reasons at the moment.
Another possibility is that there may be errors in the quoted figures. For example, in the case of Mercury, the mass may be somewhat in error. Usually planetary masses are calculated, with good accuracy, from observations of the orbits of their moons. Mercury does not have a moon, and it is also so close to the Sun it is difficult to make good observations. The mass may therefore be in error; earlier figures havein fact suggested that its mass was higher, with a density more than that of Earth. From the general sequence, we would expect Mercury to have a density of about 3.6. Time will tell what the real position is.
At least at the moment, the evidence available favours the suggestion in Proposition 16I. If, in fact, the rocky components of all the planets are made up of very similar material, it also seems likely that all the planets were formed in the same event and at the same time.
Proposition 16J
All the Solar System planets were formed in the same event
and at the same time
Before leaving this area, we should look more closely at the phase changes in the Sima material, and their role in planetary expansion.
Sima Phase Changes and Expansion
In Figure 9.1, the values shown for the density of the Earth's substance vary from 2.7 at the surface to 13.6 at the core. There are a number of abrupt changes or discontinuities, the biggest being at the Mantle/Core boundary, where the density leaps from 5.5 to 10.0. Is it possible to compress rock with a 'natural' density of around 2.9 to one of 10.0 or more? The answer is yes, if the pressures are great enough. There may be two quite different stages in this compression.Many substances will alter to denser phases, when high pressures are applied, by rearrangement of their crystal lattice structures. For example, of the two main forms of the element carbon, the normal-pressure one is graphite, which has a density of 2.25. All the atoms are packed in flat sheets, with some separation between the sheets. These sheets give graphite its ability to slip and lubricate, and also its ability to conduct electricity.
On the other hand, diamond is a 'frozen' high-pressure form of carbon. Its density is 3.52, more than 50% higher than graphite, and its atoms are all interlocked in a compact, three-dimensional construction. This structure gives diamond its great hardness.
We can number the Sima phases from I to V downwards from the surface, with I being the crustal phase, II and III the upper and lower Mantle, and IV and V the outer and inner Core. It seems possible that the densities for phases I-III, up to 5.5, could be achieved by appropriate crystal lattice structure rearrangements. But the leap to 10.0 looks less possible.
However, under very great pressures, matter can be compressed to an enormous degree, not by lattice rearrangements, but by actually crushing down the atoms themselves. Material crushed in this manner is called 'degenerate matter', and its density may be truly enormous. The example usually quoted is that of degenerate matter in the heart of 'black dwarf' stars, where one matchbox full would weigh more than our Earth.
A possible explanation for the high density of the phase IV and V Sima is that it consists of the lowest grades of degenerate matter.
Proposition 16K
At the Mantle/Core boundary, phase III normal-matter Sima
changes to phase IV degenerate-matter Sima
This Proposition is not in conflict with an observed feature of the Mantle/Core boundary. Below this boundary, in the upper Core, earthquake waves behave similarly to what they do in liquid, while above it they do not. For this reason, the outer Core has been assumed to be liquid in the past. It now seems quite possible that this liquid-mimicking behaviour is a feature of phase IV degenerate matter. Certainly, at the enormous pressures involved, the normal concepts associated with 'liquid' and 'solid' begin to lose meaning.
It is worth pointing out that if the Earth once had half its current radius, for the same mass, its density would average eight times as much -- that is the ratio of the two volumes of the current and unexpanded spheres. This density, around 44.16 instead of the current 5.52, would have to involve the use of degenerate matter. It is far higher than the density of the the most compact normal substances known, the densest element being osmium, at 22.59.
It is also now clear that the mechanism for planetary expansion involves changes in the planet's inner phases, progressively from denser to less dense forms.
Proposition 16L
Planetary expansion occurs via the conversion of higher-density
Sima phases into lower-density ones
In some senses this is another way of looking at Proposition 9E, on the change in position of density discontinuities with pressure. It provides a mechanism for planetary expansion, but not a reason. For that, we must look at the next section.
PART 3 -- GRAVITY RULES, OK?
Heating in the Earth
In Chapter 9 we looked at the question of the heat which flows from the Earth, and concluded (Proposition 9G) that it was mainly derived from the frictional heat of domain rubbing. We will now look at this area again, a bit more closely.Proposition 9G is all right as it stands, but it does not explain everything. Heat flows up from beneath the Earth's surface even in places where the domains are not apparently active, where it is tectonically quiet. Of course the average sub-ground temperatures are higher in places where the domains are currently shifting -- in fact close studies of these temperatures would be a good way to trace domain boundaries -- but we still need a mechanism for the spread of the frictional heat throughout the rest of the Earth's surface.
This mechanism is to be found in earthquake waves. We already know that these travel throughout the body of the Earth -- our knowledge of the Earth's interior is based on a study of these waves. And we have seen, in NU014, that around a million earthquakes occur on our planet each year. This number is fairly arbitrary; if we took into account weaker and weaker earth-twitches, the number would be two, ten, or a hundred million.
It seems obvious that it is these vibrational waves which carry the heat energy derived from domainographic processes throughout the Earth.
Proposition 16M
Heat derived from domain movements in the Domainosphere
is distributed around the Earth by earthquake waves
Heat is itself a form of vibrational energy, so the transfer of this energy from the earthquake waves would be quite normal. Where, in the Earth's upper layers, is the energy originally produced? This must be in the area of active domains, in what I have called the Domainosphere. This is the same as the area in which earthquakes are active, from the surface down to about 700 km below.
Here is another area where the current treatment gives an improved explanation of observed facts. In the old tectonic-plate idea, these plates were assumed to be about 100 km thick, and floating at this depth on a mushy or semi-liquid layer called the Aesthenosphere (Fig. 9.1). Movement of these plates has been suggested as the cause of shallower earthquakes, but till now there has been no accepted cause of origin for the deeper ones.
As the Earth expands, the effects will be most apparent near to the surface, where most of the volume lies. Setting the Domainosphere to 700 km deep is arbitrary, that is just the level where domainographic activities have faded away close to nothing.
We can, however, try to identify a band in the Domainosphere where activity, and hence temperature, is highest. We have good information on the depths and strengths of larger earthquakes which have occurred over many years. If we assume as a first approximation that the Domainosphere's maximum activity band lies at the same depth over the whole Earth, its position can be found by summing together the energies of these earthquakes at the different depths, and seeing where the energy level is highest.
Proposition 16N
The Domainosphere has a maximum activity band, with a
position derivable from measurements of earthquake depths and
energies
It seems that the position of this band must be more than 10 km down, because measured temperatures from oil wells increase to this sort of depth. Presumably underneath the band, and right down to the centre of the Earth, the temperature should be fairly uniform and close to that of the activity band -- there is nowhere for the heat to escape to -- at least in parts where the concept of temperature still has meaning.
Ultimately, all the domainographic energy stems from gravitational forces. A simple mind model of Earth Expansion is that the crust splits apart under the expansionist forces and top material falls down the split to fill it, with the potential energy given up by the falling material providing the source of heat. However, there are other models, for processes which are not quite as simple. We will pass on now to one of these.
The Moon Masseur
In Chapter 15 we looked at the Earth-Moon system, and saw that the double-planet situation which existed or was approached there may have led to the loss of much atmosphere (Proposition 15D). This close coupling between our planet and our moon has a further implication.We saw that the centre of gravity of the system formed by our planet and its moon lies some 1400 km below the surface, or around 5000 km above the actual centre, of the Earth. Now this point is obviously not fixed in the Earth. Instead, it moves around the Earth as the planet rotates, staying always on the line joining the centres of gravity of the two bodies.
The gravitational attraction of the Moon has a very noticeable effect on our lives. Together with the attraction of the Sun, it controls the tides. The Moon is both much closer to the Earth and much lighter than the Sun, and the outcome of these two opposing influences is that the Moon has a little more than twice the effect of the Sun on tides. Tides have greatly influenced biological matters on Earth, as well as physical ones, and have set 'biological clocks' which are still ticking millions of years later, as in the menstrual periods of women.
There is a lot of energy in tidal movements, and commercial tide-power stations have been built in some parts of the world. Ultimately this energy is mostly derived from the rotational energy of the Earth, which is tending to slow down to present the same face to the Moon, as the Moon now does to the Earth.
Tidal energy, like most forms of energy, ends up as heat, so one effect of the tides is to heat up the oceans. But there are other tides. One is the tide of the atmosphere, the reason why weather patterns tend to move from west to east, and this also must result in some heating of the atmosphere.
But a far greater tide is the tide of the solid Earth. Every day, the Earth-Moon centre of gravity travels more than 30,000 km round inside the Earth, at that depth of 1400 km below the surface. The gravitational forces act like a giant fist, massaging the ball of the Earth. Because the solid Earth is hugely more massive than its oceans or atmosphere, even a small effect will release a lot of energy from this massage, and this energy will also appear as heat.
Proposition 16O
The Earth is being continually heated up by gravitational
massage exerted on its mass by the Moon
It should be possible to calculate the amount of heat released in this way. It may or may not be significant compared to the energy released by Earth expansion. However, the forces involved are by no means minor, we know that they have been able to stop the rotations of planets and moons in their tracks.
As far as the Earth is concerned, the heating happens because its rotating gravitational system with the Moon is 'lopsided'. This point is true for when the rest of the Universe is considered, too.
The Lopsided Universe
As already mentioned, the Sun also has an effect on tidal processes in the Earth, if a lesser one than that due to the moon. As the Earth rotates each day, the Sun attempts to raise tides, not only in the seas and the atmosphere, but also in the solid Earth. The straining of the Earth's inner substance towards the direction of the Sun may be very small, but will still add up, and again contribute to 'tidal heating'.Gravity reaches right throughout the Universe. As the Solar System is not at the centre of our local galaxy, but out towards the rim, the sum of the gravitational pulls of all the stars in this galaxy will also be lopsided, and have its effect on the Earth. The effect may be extremely tiny, but even so, over periods of billions of years, it may produce a measurable result.
Killed by an Apple
Another matter which will be affected by changes in the Earth's radius is its surface gravity. If the Earth had half its present radius but still the same mass, the gravitational force at its surface would be about four times as great as it is now, other things being equal. This is because gravitational forces decrease as the square of the distance.A variation of this sort would have many effects on the Earth, for example erosion would be more active, stable mountain slopes would not be as steep (that is why Mars has a mountain twice as high as Earth, its surface gravity is lower), and taller plants and animals would be less feasible. Against this, the atmosphere would be drawn in closer to the surface, making it much denser and able to buoy up tall plants. Here is a further reason for assuming a much denser atmosphere on the early Earth.
According to legend, Isaac Newton first developed the theory of gravitation when he thought about what had caused an apple on a tree he was sitting under to fall on his head. If gravity was four times higher, he might not have been in any condition to think afterwards.
When the rule for the variation of gravity with distance was mentioned above, the rider 'other things being equal' was added. It is possible that they weren't equal.
The Gravitational Constant and the Nuclear Strong Force
Just over 50 years ago, the Nobel Prize-winning physicist P.A.M. Dirac published a paper [27] which suggested a number of basic relationships existed between the fundamental physical constants of the Universe. In particular, he suggested that these 'constants' were not actually fixed, but varied with the age of the Universe. Among these constants was included the gravitational constant, G, which defines the amount of gravitational attraction between two bodies of given mass and separation.The effect of Dirac's Proposition was that G was decreasing in size with time, and so the gravitational forces holding together a body such as the Earth were also decreasing as time went on. Dirac was active at a time when the currently-accepted ideas of an expanding Universe were being worked out. Whether the relationships and numbers suggested by Dirac are 'true' or not, it does seem at least feasible that, in a Universe held together by gravity, the fundamental forces of gravity might alter as the Universe expanded.
Variation in the gravitational constant would also have many other effects, for example the planets would be expected to move out further from the Sun under weaker gravity. This would make them receive much less radiation from the Sun, unless there was some compensating effect, and get much colder. I know of no evidence to support such an occurrence.
Another, possibly more likely, cause concerns the Nuclear Strong Force, or some other force responsible for holding atoms together. A reduction in the strength of one of these forces, which are of relatively recent discovery and were not known when Dirac was active, might cause atoms to expand in average size. This need have no connection with gravity, and could explain planetary expansion without any changes in planetary orbits.
Here then is a possible root cause for the expansion observed in the Earth and our neighbouring planets.
Proposition 16P
Planetary expansion has occurred because the nuclear forces
acting between the components of the planet have become weaker
as time progressed
Of course, making such a bold assumption as that the fundamental constants of the Universe may vary with time really is opening a huge can of worms. So much of modern science depends on the assumption that some things really are permanently fixed. Once one starts questioning whether the rate of decay of a given radioactive substance, or the speed of light in a vacuum, or the rate of progression of time, are fixed quantities, the resulting chaos is more one of philosophy than of science. We will not venture further into these heavily mined areas, but instead will now sit back and review the ground already covered.
(Full list of references at NURefs)
[17]. S W Carey. Lecture. Geology Department, University of Western Australia, 1987.
[27]. P A M Dirac. A new basis for cosmology. Proc Roy Soc London/ A165 p199-208, 1938.
[64]. The Physical Earth. Mitchell Beazley.
NU017: Looking Back: the Final Synthesis
NU015: The Moon and the Planets
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Version 2.0, 2004, PDFs etc on World Wide Web (http://www.aoi.com.au/matrix/Nuteeriat.htm)
Version 3.0, 2014 Oct 1, Reworked from Chapter 16 of "Nuteeriat" as one article in a suite on the World Wide Web.