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The expanding Earth or growing Earth hypothesis argues that the position and relative movement of
continents A continent is any of several large landmasses. Generally identified by convention rather than any strict criteria, up to seven geographical regions are commonly regarded as continents. Ordered from largest in area to smallest, these seven ...
is at least partially due to the volume of Earth increasing. Conversely, geophysical global cooling was the hypothesis that various features could be explained by Earth contracting. Although it was suggested historically, since the recognition of plate tectonics in the 1970s, scientific consensus has rejected any significant expansion or contraction of Earth.


Different forms of the hypothesis


Expansion with constant mass

In 1834, during the second voyage of HMS ''Beagle'',
Charles Darwin Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all species of life have descended fr ...
investigated stepped plains featuring
raised beach A raised beach, coastal terrace,Pinter, N (2010): 'Coastal Terraces, Sealevel, and Active Tectonics' (educational exercise), from 2/04/2011/ref> or perched coastline is a relatively flat, horizontal or gently inclined surface of marine origin, ...
es in Patagonia which indicated to him that a huge area of South America had been "uplifted to its present height by a succession of elevations which acted over the whole of this space with nearly an equal force." While his mentor
Charles Lyell Sir Charles Lyell, 1st Baronet, (14 November 1797 – 22 February 1875) was a Scottish geologist who demonstrated the power of known natural causes in explaining the earth's history. He is best known as the author of ''Principles of Geolo ...
had suggested forces acting near the crust on smaller areas, Darwin hypothesized that uplift at this continental scale required "the gradual expansion of some central mass"
f the earth F, or f, is the sixth letter in the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is ''ef'' (pronounced ), and the plural is ''efs''. Hist ...
"acting by intervals on the outer crust" with the "elevations being concentric with form of globe (or certainly nearly so)". In 1835 he extended this concept to include the Andes as part of a curved enlargement of the earth's crust due to "the action of one connected force". Not long afterwards, he moved on from this idea and proposed that as the mountains rose, the ocean floor subsided, explaining the formation of coral reefs. In 1889 and 1909
Roberto Mantovani Roberto Mantovani (25 March 1854 – 10 January 1933), was an Italian geologist and violinist. He proposed an early model of continental drift in which a single continent broke up and the continents were displaced by thermal expansion and volc ...
published a hypothesis of Earth expansion and continental drift. He assumed that a closed continent covered the entire surface of a smaller Earth. Thermal expansion led to volcanic activity, which broke the land mass into smaller continents. These continents drifted away from each other because of further expansion at the rip-zones, where oceans currently lie. Although
Alfred Wegener Alfred Lothar Wegener (; ; 1 November 1880 – November 1930) was a German climatologist, geologist, geophysicist, meteorologist, and polar researcher. During his lifetime he was primarily known for his achievements in meteorology and ...
noticed some similarities to his own hypothesis of
continental drift Continental drift is the hypothesis that the Earth's continents have moved over geologic time relative to each other, thus appearing to have "drifted" across the ocean bed. The idea of continental drift has been subsumed into the science of pl ...
, he did not mention Earth expansion as the cause of drift in Mantovani's hypothesis. A compromise between Earth-expansion and Earth-contraction is the "theory of thermal cycles" by Irish physicist
John Joly John Joly FRS (1 November 1857 – 8 December 1933) was an Irish physicist and professor of geology at the University of Dublin, known for his development of radiotherapy in the treatment of cancer. He is also known for developing techniques to ...
. He assumed that heat flow from radioactive decay inside Earth surpasses the cooling of Earth's exterior. Together with British geologist Arthur Holmes, Joly proposed a hypothesis in which Earth loses its heat by cyclic periods of expansion. In their hypothesis, expansion led to cracks and joints in Earth's interior, that could fill with magma. This was followed by a cooling phase, where the magma would freeze and become solid rock again, causing Earth to shrink.


Mass addition

In 1888
Ivan Osipovich Yarkovsky Ivan Osipovich Yarkovsky ( pl, Jan Jarkowski) (24 May 1844, Asveya, Vitebsk Governorate – 22 January 1902, Heidelberg) was a Polish Russian civil engineer. Born from a Polish family in Asveya (Russian Empire, now Belarus), he worked for a Ru ...
suggested that some sort of aether is absorbed within Earth and transformed into new chemical elements, forcing the celestial bodies to expand. This was connected with his mechanical explanation of gravitation. Also the theses of
Ott Christoph Hilgenberg Ott, OTT or O.T.T. may refer to: Entertainment * OTT (group), a pop band from the late 1990s * Ott (record producer), British record producer and musician * "O.T.T" (song), a song by Fugative * ''O.T.T.'' (television series), a UK TV programme f ...
(1933, 1974) and Nikola Tesla (1935) were based on absorption and transformation of aether-energy into normal matter. After initially supporting continental drift, the late Australian geologist S. Warren Carey advocated expansion from the 1950s (before the development of plate tectonics provided the generally accepted explanation of the movement of continents) to his death, demonstrating that
subduction Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, ...
and other events could not balance the
sea-floor spreading Seafloor spreading or Seafloor spread is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge. History of study Earlier theories by Alfred Wegener an ...
at
oceanic ridge A mid-ocean ridge (MOR) is a seafloor mountain system formed by plate tectonics. It typically has a depth of about and rises about above the deepest portion of an ocean basin. This feature is where seafloor spreading takes place along a diver ...
s, and piling yet unresolved paradoxes that continue to plague plate tectonics. Starting in 1956, he proposed some sort of mass increase in the planets and said that a final solution to the problem is only possible in a
cosmological Cosmology () is a branch of physics and metaphysics dealing with the nature of the universe. The term ''cosmology'' was first used in English in 1656 in Thomas Blount's ''Glossographia'', and in 1731 taken up in Latin by German philosopher ...
perspective in connection with the
expansion of the universe The expansion of the universe is the increase in distance between any two given gravitationally unbound parts of the observable universe with time. It is an intrinsic expansion whereby the scale of space itself changes. The universe does not e ...
.
Bruce Heezen Bruce Charles Heezen (; April 11, 1924 – June 21, 1977) was an American geologist. He worked with oceanographic cartographer Marie Tharp at Columbia University to map the Mid-Atlantic Ridge in the 1950s. Biography Heezen was born in Vinton, I ...
initially interpreted his work on the mid-Atlantic ridge as supporting S. Warren Carey's Expanding Earth Theory, but later withdrew his support, finally convinced by the data and analysis of his assistant,
Marie Tharp Marie Tharp (July 30, 1920 – August 23, 2006) was an American geologist and oceanographic cartographer. In the 1950s, she collaborated with geologist Bruce Heezen to produce the first scientific map of the Atlantic Ocean floor. Her cartograp ...
. The remaining proponents after the 1970s, like the Australian geologist James Maxlow, are mainly inspired by Carey's ideas. To date no scientific mechanism of action has been proposed for this addition of new mass. This is a big obstacle for acceptance of the theory by other geologists. It is a well known fact that the earth is constantly acquiring mass through accumulation of rocks and dust from space, as are all other planetary bodies in our system. According to NASA, "Every day about 100 tons of meteoroids -- fragments of dust and gravel and sometimes even big rocks – enter the Earth's atmosphere." The majority of this debris burns up in the atmosphere and lands as dust. Such accretion, however, is only a minuscule fraction of the mass increase required by the growing earth hypothesis.


Decrease of the gravitational constant

Paul Dirac Paul Adrien Maurice Dirac (; 8 August 1902 – 20 October 1984) was an English theoretical physicist who is regarded as one of the most significant physicists of the 20th century. He was the Lucasian Professor of Mathematics at the Univer ...
suggested in 1938 that the universal gravitational constant had ''decreased'' in the billions of years of its existence. This led German physicist Pascual Jordan to a modification of general relativity and to propose in 1964 that all planets slowly expand. This explanation is within the framework of physics considered as a viable hypothesis. Measurements of a possible variation of the gravitational constant showed an upper limit for a relative change of per year, excluding Jordan's idea.


Formation from a gas giant

According to the hypothesis of J. Marvin Herndon (2005, 2013) the Earth originated in its protoplanetary stage from a Jupiter-like
gas giant A gas giant is a giant planet composed mainly of hydrogen and helium. Gas giants are also called failed stars because they contain the same basic elements as a star. Jupiter and Saturn are the gas giants of the Solar System. The term "gas giant" ...
. During development phases of the young
Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
, which resembled to those of a
T Tauri star T Tauri stars (TTS) are a class of variable stars that are less than about ten million years old. This class is named after the prototype, T Tauri, a young star in the Taurus star-forming region. They are found near molecular clouds and ide ...
, the dense atmosphere of the gas giant was stripped off by infrared eruptions from the sun. The remnant was a rocky planet. Due to the loss of pressure from its atmosphere would have begun a progressive decompression. Herndon regards the energy released due to the lack of compression as a primary energy source for geotectonic activity, to which some energy from radioactive decomposition processes was added. He calls the resulting changes in the course of
Earth's history The history of Earth concerns the development of planet Earth from its formation to the present day. Nearly all branches of natural science have contributed to understanding of the main events of Earth's past, characterized by constant geologi ...
by the name of his theory ''Whole-Earth Decompression Dynamics''. He considered the seafloor spreading at
divergent plate boundaries In plate tectonics, a divergent boundary or divergent plate boundary (also known as a constructive boundary or an extensional boundary) is a linear feature that exists between two tectonic plates that are moving away from each other. Divergent b ...
as an effect of it. In his opinion
mantle convection Mantle convection is the very slow creeping motion of Earth's solid silicate mantle as convection currents carrying heat from the interior to the planet's surface. The Earth's surface lithosphere rides atop the asthenosphere and the two form ...
used as concept in the theory of plate tectonics is physically impossible. His theory includes the effect of
solar wind The solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the corona. This plasma mostly consists of electrons, protons and alpha particles with kinetic energy between . The composition of the sol ...
( geomagnetic storms) as cause for the reversals of the Earth magnetic field. The question of mass increase is not addressed.


Main arguments against Earth expansion

The hypothesis had never developed a plausible and verifiable mechanism of action. During the 1960s, the theory of plate tectonics—initially based on the assumption that Earth's size remains constant, and relating the subduction zones to burying of lithosphere at a scale comparable to seafloor spreading—became the accepted explanation in the Earth Sciences. The scientific community finds that significant evidence contradicts the Expanding Earth theory, and that evidence used in support of it is better explained by plate tectonics: *Measurements with modern high-precision geodetic techniques and modeling of the measurements by the horizontal motions of independent rigid plates at the surface of a globe of free radius, were proposed as evidence that Earth is not currently increasing in size to within a measurement accuracy of 0.2 mm per year. The lead author of the study stated "Our study provides an independent confirmation that the solid Earth is not getting larger at present, within current measurement uncertainties". * The motions of
tectonic plates Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large te ...
and subduction zones measured by a large range of geological, geodetic and geophysical techniques supports plate tectonics.Fowler (1990), pp 281 & 320–327; Duff (1993), pp 609–613; Stanley (1999), pp 223–226 * Imaging of lithosphere fragments within the mantle supports lithosphere consumption by subduction. *
Paleomagnetic Paleomagnetism (or palaeomagnetismsee ), is the study of magnetic fields recorded in rocks, sediment, or archeological materials. Geophysicists who specialize in paleomagnetism are called ''paleomagnetists.'' Certain magnetic minerals in rock ...
data has been used to calculate that the radius of Earth 400 million years ago was 102 ± 2.8 percent of today's radius. *Examinations of data from the Paleozoic and Earth's moment of inertia suggest that there has been no significant change of Earth's radius in the last 620 million years.


See also

* :Plate tectonics * Timeline of the development of tectonophysics (before 1954) * Timeline of the development of tectonophysics (after 1952)


Notes


Bibliography

* ; 1976: "The Expanding Earth", Developments in Geotectonics (10), Elsevier, ; digital edition 2013: ASIN B01E3II6VY. * ;1988: "Theories of the Earth and Universe: A History of Dogma in the Earth Sciences", Stanford University Press, . * ; 1993: '' Holmes' principles of physical geology'', Chapman & Hall (4th ed.), . * ; 1990: ''The Solid Earth, an introduction to Global Geophysics'', Cambridge University Press, . * ; 1999: ''Earth System History'', W.H. Freeman & Co, .


External links

* {{Commons-inline, Expanding Earth, Expanding Earth


Historical

*
Ott Christoph Hilgenberg Ott, OTT or O.T.T. may refer to: Entertainment * OTT (group), a pop band from the late 1990s * Ott (record producer), British record producer and musician * "O.T.T" (song), a song by Fugative * ''O.T.T.'' (television series), a UK TV programme f ...
: * G. Scalera
Roberto Mantovani an Italian defender of the continental drift and planetary expansion
* Giancarlo Scalera
Variable Radius CartographyBirth and Perspectives of a New Experimental Discipline
* G. Scalera, Braun
Ott Christoph Hilgenberg in twentieth-century geophysics
* G. Scalera
Samuel Warren Carey – Commemorative memoir
* Andrew Alden


Contemporary


Database of Expansion Tectonic Scientists, living and deceased
Structure of the Earth Geophysics Geodynamics Obsolete geology theories