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Expanding Earth

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The hypothesized spreading apart of continental masses as Earth's size increases by the creation of new ocean floor material.
Movements of the continents as the Earth expands. Left: Atlantic Ocean centered; right: Pacific Ocean centered.

Expanding Earth is a pseudoscientific hypothesis asserting that the position and relative movement of continents is due to the volume of the Earth increasing. While suggested historically, since the recognition of plate tectonics in the 1970's, the scientific consensus has rejected any expansion of the Earth. In fact, on very long timescales the Earth is slowly shrinking, due to thermal contraction.

Disproof

There is no evidence supporting expansion of the Earth: the Earth is not currently increasing in size, and there is no source of energy to power expansion. This is in contrast to plate tectonics, which is supported by a large range of geological and geophysical measurements, including direct measurements of plate motions by geodesy and of subduction at plate boundaries[1][2][3].

Paleomagnetic data has been used to calculate that the radius of the Earth 400 million years ago was 102 ± 2.8% of today's radius.[4] Furthermore, examinations of earth's moment of inertia suggest that there has been no significant change of earth's radius in the last 620 million years.[5]

Different Forms of the Hypothesis

There are various forms of the expanding earth hypothesis, including some proposals which say that the Earth's mass has remained constant (and thus the gravitational pull at the surface has decreased over time), that Earth's mass has grown with the volume in such a way that the surface gravity has remained constant, or that the earth's gravity at its surface has increased over time, in line with its growing mass and volume. Many of the remaining expanding Earth adherents have been inspired by the ideas of the late Australian geologist S. Warren Carey, who suggested expansion in the 1950s and 60s - prior to the development of tectonics.

Historical Versions

Expansion with constant mass

During the second voyage of HMS Beagle, in 1834–1835 Charles Darwin theorised that an expanding earth could explain the elevation of the landmass of South America as shown by mountain building in the Andes and stepped plains featuring raised beaches in Patagonia. Later in 1835 he abandoned this idea, and proposed that as mountains rose, the ocean floor subsided.[6]

In 1889 and 1909 Roberto Mantovani 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. [7] [8] Although Alfred Wegener noticed some similarities to his own hypothesis of continental drift, he did not mention earth expansion as the cause of drift in Mantovani's hypothesis. [9]

A compromise between earth-expansion and earth-contraction is the "theory of thermal cycles" by Irish physicist John Joly. He assumed that heat flow from radioactive decay inside the Earth surpasses the cooling of the Earth's exterior. Together with British geologist Arthur Holmes, Joly proposed a hypothesis in which the Earth loses its heat by cyclic periods of expansion. In their hypothesis, expansion led to cracks and joints in the 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 the Earth to shrink. [10]

Expanding Earth models based on thermal expansion contradict most modern principles from rheology, and fail to provide an acceptable explanation for the proposed melting and phase transitions.

Mass accretion

In 1888 Ivan Osipovich Yarkovsky suggested that some sort of aether is absorbed within the earth and transformed into new chemical elements, forcing the celestial bodies to expand. This was connected with his mechanical explanation of gravitation. [11] Also the theses of Ott Christoph Hilgenberg (1933, 1974)[12][13] and Nikola Tesla[14] were based on absorption and transformation of aether-energy into normal matter.

S. Warren Carey, starting in 1956, proposed some sort of mass increase in the planets and said that a final solution to the problem is only possible in a cosmological perspective in connection with the expansion of the universe.

Mass accretion on a scale required to change the Earth's radius is contradicted by the current accretion rate of the Earth, and by the Earth's average internal temperature: any accretion releases a lot of energy, which would warm the planet's interior.

Decrease of the gravitational constant

Paul Dirac 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. Contrary to most of the other explanations this one was at least within the framework of physics considered as a viable hypothesis. [15]

Measurements of a possible variation of the gravitational constant showed an upper limit for a relative change of 5•10−12, excluding Jordan's idea.[16]

Present day advocates

One prominent present day advocate of an expanding Earth is comics artist Neal Adams,[17] who calls his ideas "Growing Earth Theory". Adams has made video animations that graphically illustrate his hypothesis, in which new mass is created by a hypothesized electron/positron pair production process within the core of the Earth[18][19][20]

Additional current advocates of similar ideas have organized themselves as the "Growing Earth Consortium"[21].

See also

Notes

  1. ^ Fowler (1990), pp 281 & 320-327; Duff (1993), pp 609-613; Stanley (1999), pp 223-226
  2. ^ Bucher, K. (2005), "Blueschists, eclogites, and decompression assemblages of the Zermatt-Saas ophiolite: High-pressure metamorphism of subducted Tethys lithosphere", American Mineralogist, 90: 821, doi:10.2138/am.2005.1718
  3. ^ Van Der Lee, Suzan; Nolet, Guust (1997), "Seismic image of the subducted trailing fragments of the Farallon plate", Nature, 386: 266, doi:10.1038/386266a0
  4. ^ McElhinney, M. W., Taylor, S. R., and Stevenson, D. J. (1978), "Limits to the expansion of Earth, Moon, Mars, and Mercury and to changes in the gravitational constant", Nature, 271: 316–321, doi:10.1038/271316a0{{citation}}: CS1 maint: multiple names: authors list (link)
  5. ^ Williams, G.E. (2000), "Geological constraints on the Precambrian history of the Earth's rotation and the moon's orbit", Reviews of Geophysics, 38 (1): 37–59, doi:10.1029/1999RG900016 {{citation}}: External link in |title= (help)
  6. ^ Herbert, Sandra (1991), "Charles Darwin as a prospective geological author", British Journal for the History of Science, no. 24, pp. 184–188, retrieved 2008-10-24
  7. ^ Mantovani, R. (1889), "Les fractures de l'écorce terrestre et la théorie de Laplace", Bull. Soc. Sc. Et Arts Réunion: 41–53
  8. ^ Mantovani, R. (1909), "L'Antarctide", Je m’instruis. La science pour tous, 38: 595–597
  9. ^ Wegener, A. (1929/1966), The Origin of Continents and Oceans, Courier Dover Publications, ISBN 0486617084 {{citation}}: Check date values in: |year= (help) See Online version in German.
  10. ^ Hohl, R. (1970), "Geotektonische Hypothesen", Die Entwicklungsgeschichte der Erde. Brockhaus Nachschlagewerk Geologie mit einem ABC der Geologie, Bd. 1: 279–321 {{citation}}: Unknown parameter |auflage= ignored (|edition= suggested) (help)
  11. ^ Yarkovsky, Ivan Osipovich (1888), Hypothese cinetique de la Gravitation universelle et connexion avec la formation des elements chimiques, Moskau{{citation}}: CS1 maint: location missing publisher (link)
  12. ^ Hilgenberg, O.C. (1933), Vom wachsenden Erdball, Berlin: Giessmann & Bartsch
  13. ^ Hilgenberg, O.C. (1974), "Geotektonik, neuartig gesehen", Geotektonische Forschungen, 45: 1–194
  14. ^ Tesla, N. (1935), Expanding Sun Will Explode Someday Tesla Predicts, New York: New York Herald Tribune
  15. ^ Jordan, P. (1971), The expanding earth: some consequences of Dirac's gravitation hypothesis, Oxford: Pergamon Press
  16. ^ Born, M. (1964/2003), Die Relativitätstheorie Einsteins (Einstein's theory of relativity), Berlin-Heidelberg-New York: Springer-publisher, ISBN 3-540-00470-X {{citation}}: Check date values in: |year= (help)
  17. ^ Neal Adams' New Model of the Universe
  18. ^ New Model of the Universe, Neal Adams, retrieved 2008-06-02
  19. ^ Video clip of continental matching, Continuity Studios, retrieved 2008-06-02 {{citation}}: External link in |publisher= (help)
  20. ^ O'Brien, Jeffrey (2001), "Master of the Universe", Wired (9.03), retrieved 2008-06-02 {{citation}}: Unknown parameter |month= ignored (help)
  21. ^ Growing Earth Consortium

Literature

  • Duff, D.; 1993: Holmes' principles of physical geology, Chapman & Hall (4th ed.), ISBN 0-412-40320-X.
  • Fowler, C.M.R.; 1990: The Solid Earth, an introduction to Global Geophysics, Cambridge University Press, ISBN 0-521-38590-3.
  • Stanley, S.M.; 1999: Earth System History, W.H. Freeman & Co, ISBN 0-7167-2882-6.

Historical

Contemporary

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