Movements of the continents as the Earth expands. Left: Atlantic Ocean centered; right: Pacific Ocean centered.

Expanding Earth or Growing Earth is a hypothesis asserting that the position and relative movement of continents is at least partially due to the volume of the Earth increasing. Conversely, geophysical global cooling was the hypothesis that various features could be explained by the earth contracting.

While suggested historically, since the recognition of plate tectonics in the 1970s scientific consensus has rejected any expansion or contraction of the Earth.

Different forms of the hypothesis

There are 3 forms of the expanding earth hypothesis.

  1. Earth's mass has remained constant, and thus the gravitational pull at the surface has decreased over time;
  2. Earth's mass has grown with the volume in such a way that the surface gravity has remained constant;
  3. Earth's gravity at its surface has increased over time, in line with its hypothesized growing mass and volume;

The late Australian geologist S. Warren Carey suggested expansion in the 1950s and 60s, before the development of plate tectonics provided the generally accepted explanation of the movement of continents.[1] The remaining proponents after the 1970s are mainly inspired in Carey's ideas.[1]

Expansion with constant mass

During the second voyage of HMS Beagle, in 1834–1835 Charles Darwin hypothesized 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.[2]

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.[3][4] 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.[5]

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.[6]

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.[7] Also the theses of Ott Christoph Hilgenberg (1933, 1974)[8][9] and Nikola Tesla[10] 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.[11]

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. [12]

Measurements of a possible variation of the gravitational constant showed an upper limit for a relative change of 5•10−12,[Over what period? clarification needed] excluding Jordan's idea.[13]

Scientific consensus

The theory had never developed a plausible and verifiable mechanism of action, but neither had any of its competing theories.[1] By the late 1970s the theory of plate tectonics made all other theories obsolete following the discovery of subduction, which was found to be an important part of a mechanism of action.[1]

Generally, the scientific community finds that there is no evidence in support of the Expanding Earth theory, and there is evidence against it:

  • Measurements with modern high-precision geodetic techniques show that the Earth is not currently increasing in size to within a measurement accuracy of 0.2 mm per year.[14] The motions of tectonic plates and subduction zones measured by a large range of geological, geodetic and geophysical techniques supports plate tectonics.[15][16][17]
  • 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. 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. The value of g (the Earth's gravitational attraction) is known and would change considerably with any such gains in the Earth's mass or volume, along with the Earths orbit around the Sun.
  • 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.[18][19]
  • 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.[20]

Present day advocates

Australian Geologist James Maxlow has produced a series of twenty-three reconstructions of a smaller Earth suggesting a 99%[21] matching of all the continental boundaries. Italian Geologist Giancarlo Scalera has written several papers[22] in support of evidence for an expanding Earth.

In 2005 J. Marvin Herndon postulated what he calls whole-earth decompression dynamics, which he describes as a unified theory combining elements of plate tectonics and earth expansion. He suggests that Earth formed from a Jupiter-sized gas giant by catastrophic loss of its gaseous atmosphere with subsequent decompression and expansion of the rocky remnant planet resulting in decompression cracks at continental margins which are filled in by basalts from mid-ocean ridges.[23]

Another present day advocate of an expanding Earth is comics artist Neal Adams, who suggests the Earth is growing and not merely expanding, and proposes his ideas within a "Growing Earth-Growing Universe" Theory.[24] Adams has made video animations that graphically illustrate his hypothesis, in which new mass is manufactured by a hypothesized electron/positron pair production process within the core of the Earth and all celestial bodies.[25]

See also

Notes

  1. 1.0 1.1 1.2 1.3 Jeff Ogrisseg (2009), "Dogmas may blinker mainstream scientific thinking", The Japan Times, http://search.japantimes.co.jp/cgi-bin/fl20091122x2.html
  2. Herbert, Sandra (1991), "Charles Darwin as a prospective geological author", British Journal for the History of Science 24 (2): 159–192 [184–188], doi:10.1017/S0007087400027060, JSTOR 4027165, http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=A342&pageseq=26, retrieved 24 October 2008
  3. Mantovani, R. (1889), "Les fractures de l’écorce terrestre et la théorie de Laplace", Bull. Soc. Sc. Et Arts Réunion: 41–53
  4. Mantovani, R. (1909), "L’Antarctide", Je m’instruis. La science pour tous 38: 595–597
  5. Wegener, A. (1929/1966), The Origin of Continents and Oceans, Courier Dover Publications, ISBN 0486617084 See Online version in German.
  6. Hohl, R. (1970), "Geotektonische Hypothesen", Die Entwicklungsgeschichte der Erde. Brockhaus Nachschlagewerk Geologie mit einem ABC der Geologie Bd. 1: 279–321
  7. Yarkovsky, Ivan Osipovich (1888), Hypothese cinetique de la Gravitation universelle et connexion avec la formation des elements chimiques, Moskau
  8. Hilgenberg, O.C. (1933), Vom wachsenden Erdball (The Expanding Earth), Berlin: Giessmann & Bartsch, Bibcode 1933QB981.H6.......
  9. Hilgenberg, O.C. (1974), "Geotektonik, neuartig gesehen", Geotektonische Forschungen 45: 1–194, ISBN 978-3-510-50011-6
  10. Tesla, N. (1935), Expanding Sun Will Explode Someday Tesla Predicts, New York: New York Herald Tribune, http://en.wikisource.org/wiki/The_New_York_Herald_Tribune/1935/08/18/Expanding_Sun_Will_Explode_Some_Day_Tesla_Predicts
  11. Samuel Warren Carey (1988), Theories of the earth and universe: a history of dogma in the earth sciences (illustrated ed.), Stanford University Press, p. 347-350, ISBN 9780804713641, http://books.google.es/books?id=l_0l0KOdHLoC&pg=PA347&lpg=PA347&dq=sam+elton&source=bl&ots=GaxCPuvbKl&sig=uQCezu2rHiSzTeMy6Y1TuiSoR6w&hl=en&ei=x2ToTvTvJMnJhAev_cHcCg&sa=X&oi=book_result&ct=result&redir_esc=y#v=onepage&q=sam%20elton&f=false
  12. Jordan, P. (1971), The expanding earth: some consequences of Dirac's gravitation hypothesis, Oxford: Pergamon Press
  13. Born, M. (1964/2003), Die Relativitätstheorie Einsteins (Einstein's theory of relativity), Berlin-Heidelberg-New York: Springer-publisher, ISBN 3-540-00470-X
  14. Script error
  15. Fowler (1990), pp 281 & 320–327; Duff (1993), pp 609–613; Stanley (1999), pp 223–226
  16. 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
  17. Van Der Lee, Suzan; Nolet, Guust (1997), "Seismic image of the subducted trailing fragments of the Farallon plate", Nature 386 (6622): 266, doi:10.1038/386266a0
  18. 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 (5643): 316–321, doi:10.1038/271316a0
  19. Schmidt, P. W. and Clark, D. A. (1980), The response of palaeomagnetic data to Earth expansion, Geophysical Journal of the Royal Astronomical Society, 61: 95–100, 1980, doi:10.1111/j.1365-246X.1980.tb04306.x
  20. Williams, G.E. (2000), "Geological constraints on the Precambrian history of the Earth’s rotation and the moon’s orbit" (PDF), Reviews of Geophysics 38 (1): 37–59, Bibcode 2000RvGeo..38...37W, doi:10.1029/1999RG900016, http://www.eos.ubc.ca/~mjelline/453website/eosc453/E_prints/1999RG900016.pdf
  21. "Refer to half-way down first paragraph", by James Maxlow
  22. [1]
  23. J. Marvin Herndon, Whole-earth decompression dynamics, Current Science, V. 89, No. 11, 10 Dec. 2005 http://cs-test.ias.ac.in/cs/Downloads/article_39535.pdf
  24. Jeff Ogrisseg (2009), "Top artist draws growing global conclusions", The Japan Times, http://search.japantimes.co.jp/cgi-bin/fl20091122x3.html
  25. O'Brien, Jeffrey (March 2001), "Master of the Universe", Wired (9.03), http://www.wired.com/wired/archive/9.03/adams_pr.html, retrieved 2 June 2008

Bibliography

  • 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.

External links

Historical

Contemporary

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