Nir Shaviv

Nir Shaviv Joseph (Hebrew ניר יוסף שביב; born July 6, 1972 in Ithaca, New York) is an Israeli- American physicist. He's since 2013 Full Professor at the Racah Institute of Physics, Hebrew University of Jerusalem.

Life

Shaviv studied physics from 1987 to 1990 at the Israel Institute of Technology in Haifa and completed his BA degree as valedictorian from. During his military service in the IDF ( 1990-93 ), he continued his studies in 1992 and was co-author with first releases for Astrophysics. He obtained in 1994 a Master of Science in Physics and his PhD in 1994 and 1996. 1996 to 1999 he was Lee DuBridge Prize Fellow at the TAPIR ( Theoretical Astrophysics Group ) at the California Institute of Technology. 1999 to 2001 he worked as a postdoctoral fellow at the Canadian Institute for Theoretical Astrophysics at the University of Toronto and from 2001 to 2006 as a lecturer at the Racah Institute of Physics, Hebrew University of Jerusalem.

Astrophysics

Within astrophysics, he became known for his work on the Eddington limit. He showed that astrophysical objects can be brighter than the Eddington limit pretending. He was able to interpret the mass loss in the Eta Carinae and classical novae better.

Contribution to climate history and reconstruction

Shaviv has already investigated the influence of cosmic rays on iron meteorites and their isotopic distribution and thereby posits a link between times relatively cool climate in Earth's history and increased cosmic radiation. This he used to be an interpretation of the paradox of the weak, young sun as the temperature curve over the entire Earth's history. Shaviv identified four peaks in the flow of cosmic radiation (CRF, Cosmic Ray Flux ) on the earth in the last 500 million years ago, about a distance of 143 plus / minus 10 million years ago, which he in four passages of the sun through the spiral arms in our galaxy connection brought in which more supernovae occur due to higher density of stars, the sources of cosmic radiation. The peaks in CRF corresponded to minima in the global temperature curve. Shaviv worked here together with Jan Veizer.

He refers to the hypothesis Henrik Svensmark to a cooling effect cosmic rays on climate. Thus, had shielded as an explanation of the paradox of the weak young sun the stronger solar wind, the young sun the Earth from galactic cosmic rays. Experimental results from the CLOUD experiment at CERN and other experiments could not find a greater influence of cosmic rays on aerosol formation ( nuclei for cloud formation ) in the lower atmosphere.

A published study in 2009 by Andrew C. Overholt et al. examined the excitation Shavivs using a different model of the Milky Way. Adopted by Shaviv correlation between the Spiralarmdurchgängen the earth and the ice ages in the Earth's history is excluded here with reference to recent work and theories to a different mechanism of Spiralarmdurchgänge. A 2012 published by the Royal Astronomical Society study by Henrik Svensmark, however, recognizes a correlation between cool climate periods on Earth and marine biodiversity on the one hand and the reconstructed in the study course of the frequency of supernovae in the solar neighborhood in the last 500 million years ago on the other. He relied less on a reconstruction of the passages of the sun through the spiral arms ( the structure of which is uncertain ) of the galaxy, as in the analysis of star clusters in the solar neighborhood.

While Overholt criticized the context of spiral arm passages, expressed Stefan Rahmstorf fundamental criticism of the methodological approach ( and the derivative of CRF data from the iron meteorites ) and the conclusions of the work of Shaviv and Veizer, where Rahmstorf only at best a similarity in the Periodiziäten of wants to recognize temperature history and the course of the CRF.

Shaviv 2012 signed with a number of other scientists an open letter, published in the Wall Street Journal. Thus, neither a nor decarbonisation other drastic action was needed.

Private

Shaviv comes from Haifa and grew up in a family of scientists at the Technion there. This also affected his parents' house, which was designed by his mother Edna Shaviv, a professor of architecture and urban planning in the context of their research. Nir's father Giora Shaviv was a physicist Dean of the Physics Faculty at Technion and was the Israeli Physical Society ago. Due to his youth Shaviv was occasionally asked a professor to the student ID when he took out books from the library.

Shaviv lives with his wife Hila in Jerusalem. They have two sons.

Awards

Publications (selection)

• C. Elphick, O. Regev and Shaviv NJ: Dynamics of Fronts in Thermally Bistable fluid. In: The Astrophysical Journal. Volume 392, 1992, p 106
• NJ Shaviv and O. Regev: Interface Dynamics and Growth in Thermally Bistable fluid domain. In: Physical Review E. Volume 50, 1994, p 2048
• NJ Shaviv and A. Dar: Gamma Ray Bursts from mini jets. In: The Astrophysical Journal. Band 447, 1995, p 863
• NJ Shaviv and A. Dar: Fireballs in Dense Stellar Regions as in Explanation of gamma - ray bursts. In: Mon. Not. of the Royal Astr. Soc. Band 277, 1995, p 287
• NJ Shaviv: The Eddington Luminosity in multi- phased Media. In: The Astrophysical Journal Letters. Volume 494, 1998, p 193
• A. Dar, A. Laor and NJ Shaviv: Life extinctions by cosmic ray jets. In: Physical Review Letters. Belt 80, 1998, p 5813
• NJ Shaviv: The Porous Atmosphere of eta Carinae. In: The Astrophysical Journal Letters. Volume 532, 2000, pp. L137
• NJ Shaviv Cosmic Ray Diffusion from the Galactic Spiral Arms, Iron Meteorites and a possible Climatic Connection. In: Physical Review Letters. Volume 89, 2002, pp. 051 102
• NJ Shaviv: The Spiral Structure of the Milky Way, Cosmic Rays and Ice Age Epochs on Earth. In: New Astronomy. Volume 8, 2003, p 39
• SP Owocki, Gayley KG and NJ Shaviv: A Power Law Porosity Formalism for Continuum - Driven Mass Loss from Stars above the Eddington limit. In: The Astrophys. Journal. Volume 616, 2004, p 525
• NJ Shaviv: On Climate Response to Changes in the Cosmic Ray Flux and Radiative Budget. In: J. Geophys. Res - Space Phys. Volume 110 (A8 ), 2005, A08105, doi: 10.1029/2004JA010866

Articles and conference papers (selection)

• NJ Shaviv: Climate Change and the Cosmic Ray Connection. In: International Seminar on Nuclear War and Planetary Emergencies - 30thsession. Erice, Italy, August 2003. ( Ed. R. Ragaini, World Scientific, 2004)
• Nir Shaviv: The Role of the Sun in Climate Change of the 20th century. In: The cold sun. Why the climate catastrophe does not occur. By Fritz Vahrenholt and Sebastian Luning. Hoffmann und Campe, Hamburg 2012, ISBN 3-455-50250-4, pp. 86-95.