Expanding Earth
The expanding Earth or growing Earth
Although the hypothesis was suggested historically, since the recognition of plate tectonics during the mid 20th century, scientific consensus has rejected the idea of any significant expansion or contraction of Earth.[2][3][4][5][6]
Different forms of the hypothesis
Expansion with constant mass
In 1834, during the second voyage of HMS Beagle, Charles Darwin investigated stepped plains featuring raised beaches 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 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" [of the Earth] "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 Mountains as part of a curved enlargement of the Earth's crust due to "the action of one connected force". Not long afterwards, he abandoned this idea and proposed that as the mountains rose, the ocean floor subsided, explaining the formation of coral reefs.[7]
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 caused 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.[8][9] 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.[10]
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 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. By their hypothesis, expansion caused cracks and joints in Earth's interior that could fill with magma. This was succeeded by a cooling phase, where the magma would freeze and become solid rock again, causing Earth to shrink.[11]
Mass addition
In 1888
After initially endorsing the idea of continental drift, Australian geologist
To date no scientific mechanism of action has been proposed for this addition of new mass. Although the earth is constantly acquiring mass through accumulation of rocks and dust from space[23] 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 suggested in 1938 that the universal gravitational constant had decreased during the billions of years of its existence. This caused German physicist Pascual Jordan to propose in 1964, a modification of the theory of general relativity, that all planets slowly expand. This explanation is considered a viable hypothesis within the context of physics.[24]
Measurements of a possible variation of the gravitational constant showed an upper limit for a relative change of 5×10−12 per year, excluding Jordan's idea.[25]
Formation from a gas giant
According to the hypothesis of
Main arguments against Earth expansion
The hypothesis had never developed a plausible and verifiable mechanism of action.
The scientific community finds that significant evidence contradicts the Expanding Earth theory, and that the evidence used for it is explained better 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.[2] The main 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".[28]
- The motions of
- Imaging of lithosphere fragments within the mantle is evidence for lithosphere consumption by subduction.[4][30]
- Examinations of data from the Paleozoic and Earth's moment of inertia suggest that there has not been any significant change of Earth's radius during the last 620 million years.[3]
See also
- Category:Plate tectonics
- Timeline of the development of tectonophysics (before 1954)
- Timeline of the development of tectonophysics (after 1952)
Notes
- ^ Ott Christoph Hilgenberg: Vom wachsenden Erdball. Berlin 1933.
- ^ .
- ^ S2CID 51948507, archived from the original(PDF) on 24 December 2015, retrieved 23 November 2007
- ^ S2CID 129874595
- ^ Buis A.; Clavin W. (16 August 2011). "NASA Research Confirms it's a Small World, After All". Archived from the original on 3 January 2019. Retrieved 23 July 2018.
- ^ .
- .
- ^ Mantovani, R. (1889), "Les fractures de l'écorce terrestre et la théorie de Laplace", Bulletin de la Société des Sciences et Arts de l'Île de la Réunion: 41–53
- ^ Mantovani, R. (1909), "L'Antarctide", Je M'instruis. La Science Pour Tous, 38: 595–597
- ISBN 978-0-486-61708-4 See Online versionin German.
- ^ Hohl, R. (1970), "Geotektonische Hypothesen", Die Entwicklungsgeschichte der Erde. Brockhaus Nachschlagewerk Geologie mit Einem ABC der Geologie, Bd. 1 (4. ed.): 279–321
- ^ Yarkovsky, Ivan Osipovich (1888), Hypothèse cinétique de la Gravitation universelle et la connexion avec la formation des éléments chimiques, Moscow
{{citation}}
: CS1 maint: location missing publisher (link) - ^ Ott Christoph Hilgenberg: Vom wachsenden Erdball. Berlin 1933, page 29–35.
- Bibcode:1933vwe..book.....H
- ISBN 978-3-510-50011-6
- ^ Tesla, N. (1935), Expanding Sun Will Explode Someday Tesla Predicts, New York: New York Herald Tribune – via WikiSource
- ^ a b c d Ogrisseg, Jeff (22 November 2009), "Dogmas may blinker mainstream scientific thinking", The Japan Times, archived from the original on 3 March 2015
- .
- ISBN 978-0-8047-1364-1
- ISBN 0813341329
- ISBN 978-0-521-27560-6
- ^ Wills, Matthew (8 October 2016). "The Mother of Ocean Floor Cartography". JSTOR. Retrieved 14 October 2016.
While working with the North Atlantic data, she noted what must have been a rift between high undersea mountains. This suggested earthquake activity, which then [was] only associated with [the] fringe theory of continental drift. Heezen infamously dismissed his assistant's idea as "girl talk." But she was right, and her thinking helped to vindicate Alfred Wegener's 1912 theory of moving continents. Yet Tharp's name isn't on any of the key papers that Heezen and others published about plate tectonics between 1959-1963, which brought this once controversial idea to the mainstream of earth sciences.
- ^ "What's Hitting Earth? | Science Mission Directorate". Archived from the original on 25 May 2020. Retrieved 16 September 2016.
- Bibcode:1971eesc.book.....J
- ISBN 978-3-540-00470-7
- ^ JSTOR 24111129.
- arXiv:1307.1692.
- ^ It's a Small World, After All: Earth Is Not Expanding, NASA Research Confirms, ScienceDaily (Aug. 17, 2011)
- ^ Fowler (1990), pp 281 & 320–327; Duff (1993), pp 609–613; Stanley (1999), pp 223–226
- ^ S2CID 4340130
- S2CID 4258162
Bibliography
- Carey, S.W.; 1976: "The Expanding Earth", Developments in Geotectonics (10), Elsevier, ISBN 0-444-41485-1; digital edition 2013: ASIN B01E3II6VY.
- Carey, S.W.;1988: "Theories of the Earth and Universe: A History of Dogma in the Earth Sciences", Stanford University Press, ISBN 0-804-71364-2.
- ISBN 0-412-40320-X.
- ISBN 0-521-38590-3.
- Stanley, S.M.; 1999: Earth System History, W.H. Freeman & Co, ISBN 0-7167-2882-6.
External links
- Media related to Expanding Earth at Wikimedia Commons
Historical
- Ott Christoph Hilgenberg:
- 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: Warren Carey, Last of the Giants Archived 21 August 2016 at the Wayback Machine