Posted by Amzer Zo
(here)
[...]
Excerpts from a paper by Lynn Yarris, LBL Research Review / Science Beat Berkeley Lab,
http://www.lbl.gov/Science-Articles/...s-nemesis.html, Mon, 13 Apr
1987 11:02 CDT
[...]
The evidence for Nemesis-triggered periodic comet storms based on cosmic ray exposure ages was drawn primarily from reviews of existing data. "In these days of tight budgets," observes Muller wryly, "the cheapest way to do research is in the library." Another review of existing data, this time by Muller and LBL physicist Donald
Morris, uncovered evidence for periodic comet storms in the Earth's magnetic field.
Volcanic rock, as it cools from the lava state, aligns itself with the Earth's magnetic field. In 1906, French physicist Bernard Brunhes discovered volcanic rock magnetized in the opposite direction of today's field. It is now known that the
Earth's magnetic field has reversed itself many times throughout the planet's history, and at times has even been switched off. Muller and Morris felt that at least
some of these geomagnetic flips were caused by comet impacts, and they developed a model to explain how it happened.
The Earth's magnetic field is generated by slow eddies in its molten nickel-iron core that are the product of the heat flow out of the core, modified by the planet's rotation. When a crashing comet plunges the world into darkness, temperatures on the land drop much faster than those in the sea because water retains heat much longer than soil. According to the model of Muller and Morris, water near the equator evaporates and is redistributed as ice and snow on the polar caps. The result is a sudden (within a few hundred years) drop in the level of the oceans.
In accordance with the conservation of angular momentum, the redistribution of mass alters the rotation rate of the Earth's crust and mantle with respect to the liquid core and leads to a disruption of the magnetic field.
"It is the same as when figure skaters go into a spin with their arms extended, then draw their arms in to increase their rotational speed," says Muller.
"The Earth's magnetism is so sensitive to the motions of the liquid core that it doesn't take much of a change in rotational rate to affect the field."
Prior to the work of Muller and Morris, Chicago's
Raup had examined the frequency of 296 geomagnetic reversals that took place during the last 170 million years and found peaks in the rate of reversals occurring approximately every 30 million years.
Deposits of microtektites were also found in volcanic and seabed rocks from times when reversals took place. There was a sudden drop in sea level during the die-out of the dinosaurs, but there is no evidence of a geomagnetic reversal. This does not blemish
the model of Muller and Morris, however, for it
predicts that magnetic excursions, during which the field is turned off,
would result from half of the impacts. Magnetic excursions are difficult to detect in volcanic rock.
"Our model readily explains observed geophysical correlations, and accounts for the behavior of the Earth's magnetic field during a reversal," says Morris. "Although somewhat speculative, it is based on assumptions that are considered plausible by experts in the relevant scientific fields."
A geomagnetic reversal could also take place should the polar caps melt and cause a sudden swelling of the seas. This, too, would alter the rotation of the Earth's crust and mantle with respect to the core and disrupt the dynamo.
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Perhaps the most important aspect of the Nemesis theory, and the one for which we as a species can be most grateful, is that the deadly little companion star is not due to return until the year 15 million A.D.
Re: Intel assessment, YouTube, Dr Sal's video, and geomagnetic pole reversal
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But do any of the scientists on Avalon have a good guess about what might really happen in either case?
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