Shiva hypothesis

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The Shiva hypothesis, also known as coherent catastrophism , is the idea that global natural catastrophes on Earth, such as extinction events, happen at regular intervals because of the periodic motion of the Sun in relation to the Milky Way galaxy.

Contents

Initial proposal in 1979

William Napier and Victor Clube in their 1979 Nature article, ”A Theory of Terrestrial Catastrophism”, [1] proposed the idea that gravitational disturbances caused by the Solar System crossing the plane of the Milky Way galaxy are enough to disturb comets in the Oort cloud surrounding the Solar System. This sends comets in towards the inner Solar System, which raises the chance of an impact. According to the hypothesis, this results in the Earth experiencing large impact events about every 30 million years (such as the Cretaceous–Paleogene extinction event).

Later work by Rampino

Starting in 1984, Michael R. Rampino published followup research on the hypothesis. Certainly Rampino was aware of Napier and Clube's earlier publication, as Rampino and Stothers' letter to Nature in 1984 references it. [2]

In the 1990s, Rampino and Bruce Haggerty renamed Napier and Clube's Theory of Terrestrial Catastrophism after Shiva, the Hindu god of destruction. [3] In 2020, Rampino and colleagues published non-marine evidence corroborating previous marine evidence in support of the Shiva hypothesis. [4]

Similar theories

The Sun's passage through the higher density spiral arms of the galaxy, rather than its passage through the plane of the galaxy, could hypothetically coincide with mass extinction on Earth. [5] However, a reanalysis of the effects of the Sun's transit through the spiral structure based on CO data has failed to find a correlation. [6]

The Shiva Hypothesis may have inspired yet another theory: that a brown dwarf named Nemesis causes extinctions every 26 million years, which varies slightly from 30 million years. [7]

Criticism

The idea of extinction periodicity has been criticised due to the fact that the hypothesis assumes that most or all extinction events have the same cause, when evidence suggests that extinctions are likely the result of a variety of causes that are unlikely to be cyclically induced. [8]

See also

Related Research Articles

<span class="mw-page-title-main">Extinction event</span> Widespread and rapid decrease in the biodiversity on Earth

An extinction event is a widespread and rapid decrease in the biodiversity on Earth. Such an event is identified by a sharp fall in the diversity and abundance of multicellular organisms. It occurs when the rate of extinction increases with respect to the background extinction rate and the rate of speciation. Estimates of the number of major mass extinctions in the last 540 million years range from as few as five to more than twenty. These differences stem from disagreement as to what constitutes a "major" extinction event, and the data chosen to measure past diversity.

<span class="mw-page-title-main">Impact event</span> Collision of two astronomical objects

An impact event is a collision between astronomical objects causing measurable effects. Impact events have physical consequences and have been found to regularly occur in planetary systems, though the most frequent involve asteroids, comets or meteoroids and have minimal effect. When large objects impact terrestrial planets such as the Earth, there can be significant physical and biospheric consequences, though atmospheres mitigate many surface impacts through atmospheric entry. Impact craters and structures are dominant landforms on many of the Solar System's solid objects and present the strongest empirical evidence for their frequency and scale.

Nemesis was a hypothetical red dwarf or brown dwarf, originally postulated in 1984 to be orbiting the Sun at a distance of about 95,000 AU, somewhat beyond the Oort cloud, to explain a perceived cycle of mass extinctions in the geological record, which seem to occur more often at intervals of 26 million years. In a 2017 paper, Sarah Sadavoy and Steven Stahler argued that the Sun was probably part of a binary system at the time of its formation, leading them to suggest "there probably was a Nemesis, a long time ago". Such a star would have separated from this binary system over four billion years ago, meaning it could not be responsible for the more recent perceived cycle of mass extinctions.

<span class="mw-page-title-main">Catastrophism</span> Geological theory of abrupt, severe change

In geology, catastrophism is the theory that the Earth has largely been shaped by sudden, short-lived, violent events, possibly worldwide in scope. This contrasts with uniformitarianism, according to which slow incremental changes, such as erosion, brought about all the Earth's geological features. The proponents of uniformitarianism held that the present was "the key to the past", and that all geological processes throughout the past resembled those that can be observed today. Since the 19th-century disputes between catastrophists and uniformitarians, a more inclusive and integrated view of geologic events has developed, in which the scientific consensus accepts that some catastrophic events occurred in the geologic past, but regards these as explicable as extreme examples of natural processes which can occur.

<span class="mw-page-title-main">Impact winter</span> Hypothesized climate effects due to an asteroid or comet impact on Earth

An impact winter is a hypothesized period of prolonged cold weather due to the impact of a large asteroid or comet on the Earth's surface. If an asteroid were to strike land or a shallow body of water, it would eject an enormous amount of dust, ash, and other material into the atmosphere, blocking the radiation from the Sun. This would cause the global temperature to decrease drastically. If an asteroid or comet with the diameter of about 5 km (3.1 mi) or more were to hit in a large deep body of water or explode before hitting the surface, there would still be an enormous amount of debris ejected into the atmosphere. It has been proposed that an impact winter could lead to mass extinction, wiping out many of the world's existing species. The Cretaceous–Paleogene extinction event probably involved an impact winter, and led to mass extinction of most tetrapods weighing more than 25 kilograms.

<span class="mw-page-title-main">Rare Earth hypothesis</span> Hypothesis that complex extraterrestrial life is improbable and extremely rare

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<span class="mw-page-title-main">Chandra Wickramasinghe</span> British astronomer (born 1939)

Nalin Chandra Wickramasinghe is a Sri Lankan-born British mathematician, astronomer and astrobiologist of Sinhalese ethnicity. His research interests include the interstellar medium, infrared astronomy, light scattering theory, applications of solid-state physics to astronomy, the early Solar System, comets, astrochemistry, the origin of life and astrobiology. A student and collaborator of Fred Hoyle, the pair worked jointly for over 40 years as influential proponents of panspermia. In 1974 they proposed the hypothesis that some dust in interstellar space was largely organic, later proven to be correct.

The Shiva crater is the claim by paleontologist Sankar Chatterjee and colleagues that the Bombay High and Surat Depression on the Indian continental shelf west of Mumbai, India represent a 500-kilometre (310 mi) impact crater, that formed around the Cretaceous-Paleogene boundary. Chatterjee and colleagues have claimed that this could have contributed to the K-Pg extinction event. Other scholars have questioned the claims, finding that there is no evidence of an impact structure.

<span class="mw-page-title-main">Milky Way</span> Galaxy containing the Solar System

The Milky Way is the galaxy that includes the Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. The term Milky Way is a translation of the Latin via lactea, from the Greek γαλαξίας κύκλος, meaning "milky circle". From Earth, the Milky Way appears as a band because its disk-shaped structure is viewed from within. Galileo Galilei first resolved the band of light into individual stars with his telescope in 1610. Until the early 1920s, most astronomers thought that the Milky Way contained all the stars in the Universe. Following the 1920 Great Debate between the astronomers Harlow Shapley and Heber Doust Curtis, observations by Edwin Hubble showed that the Milky Way is just one of many galaxies.

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William M. (Bill) Napier is the author of five high tech thriller novels and a number of nonfiction science books.

<span class="mw-page-title-main">Galactic tide</span> Tidal force experienced by objects subject to the gravitational field of a galaxy

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<span class="mw-page-title-main">Cretaceous–Paleogene boundary</span> Geological formation between time periods

The Cretaceous–Paleogene (K–Pg) boundary, formerly known as the Cretaceous–Tertiary (K–T) boundary, is a geological signature, usually a thin band of rock containing much more iridium than other bands. The K–Pg boundary marks the end of the Cretaceous Period, the last period of the Mesozoic Era, and marks the beginning of the Paleogene Period, the first period of the Cenozoic Era. Its age is usually estimated at 66 million years, with radiometric dating yielding a more precise age of 66.043 ± 0.011 Ma.

Stace Victor Murray Clube is an English astrophysicist.

<span class="mw-page-title-main">Hills cloud</span> Vast theoretical circumstellar disc

In astronomy, the Hills cloud is a vast theoretical circumstellar disc, interior to the Oort cloud, whose outer border would be located at around 20,000 to 30,000 astronomical units (AU) from the Sun, and whose inner border, less well defined, is hypothetically located at 250–1500 AU, well beyond planetary and Kuiper Belt object orbits—but distances might be much greater. If it exists, the Hills cloud contains roughly 5 times as many comets as the Oort cloud.

<span class="mw-page-title-main">Future of Earth</span> Long-term extrapolated geological and biological changes of Planet Earth

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<span class="mw-page-title-main">Galactic habitable zone</span> Region of a galaxy in which life might most likely develop

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<span class="mw-page-title-main">Michael R. Rampino</span>

Michael R. Rampino is a Geologist and Professor of Biology and Environmental Studies at New York University, known for his scientific contributions on causes of mass extinctions of life. Along with colleagues, he's developed theories about periodic mass extinctions being strongly related to the earth's position in relation to the galaxy. "The solar system and its planets experience cataclysms every time they pass "up" or "down" through the plane of the disk-shaped galaxy." These ~30 million year cyclical breaks are an important factor in evolutionary theory, along with other longer 60-million- and 140-million-year cycles potentially caused by mantle plumes within the planet, opining "The Earth seems to have a pulse," He is also a research consultant at NASA's Goddard Institute for Space Studies (GISS) in New York City.

References

  1. Napier, WM; Clube, SVM (1979). "A theory of terrestrial catastrophism". Nature. 282 (5738): 455–459. Bibcode:1979Natur.282..455N. doi:10.1038/282455a0. S2CID   35238984.
  2. Rampino, Michael R; Stothers, Richard B (1984). "Terrestrial mass extinctions, cometary impacts and the Sun's motion perpendicular to the galactic plane". Nature. 308 (5961): 709–712. Bibcode:1984Natur.308..709R. doi:10.1038/308709a0. S2CID   4256690.
  3. Rampino, Michael R.; Haggerty, Bruce M. (February 1996). "The ?Shiva Hypothesis?: Impacts, mass extinctions, and the galaxy". Earth, Moon, and Planets. 72 (1–3): 441–460. Bibcode:1996EM&P...72..441R. doi:10.1007/BF00117548. S2CID   189901526.
  4. Rampino, Michael R.; Caldeira, Ken; Zhu, Yuhong (2020). "A 27.5-My underlying periodicity detected in extinction episodes of non-marine tetrapods". Historical Biology. 33 (11): 3084–3090. doi:10.1080/08912963.2020.1849178.
  5. Gillman, M.; Erenler, H. (2008). "The galactic cycle of extinction" (PDF). International Journal of Astrobiology . 7 (1): 17–26. Bibcode:2008IJAsB...7...17G. CiteSeerX   10.1.1.384.9224 . doi:10.1017/S1473550408004047. S2CID   31391193.
  6. Overholt, Andrew C.; Melott, Adrian L.; Pohl, Martin (2009). "Testing the Link Between Terrestrial Climate Change and Galactic Spiral Arm Transit". The Astrophysical Journal. 705 (2): L101–L103. arXiv: 0906.2777 . Bibcode:2009ApJ...705L.101O. doi:10.1088/0004-637X/705/2/L101. S2CID   734824.
  7. Leslie Mullen. "Getting WISE About Nemesis". Astrobiology Magazine. Archived from the original on 2010-03-14. Retrieved 11 February 2021.
  8. Algeo, Thomas J; Shen, Jun (2023-09-08). "Theory and classification of mass extinction causation". National Science Review. doi: 10.1093/nsr/nwad237 . ISSN   2095-5138. PMC   10727847 .