- NEW YORK, N.Y., and HAIFA -- Jets of cosmic rays from colliding stars can produce
lethal amounts of muons in the earth's atmosphere, destroy the ozone layer
and radioactivate the environment. The three astrophysicists who first
proposed that some of the earth's great extinctions were caused by such
events -- Arnon Dar, Ari Laor, and Nir Shaviv from the Technion-Israel
Institute of Technology -- now propose that the radiation produced would
also cause mutations that create new species in surviving life. Their doom
and creation theory is published in the June 29 Physical Review Letters.
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- Other causes proposed to explain past
extinctions include asteroids or comets hitting the earth, volcanoes, nearby
supernovae, and rising sea levels. Cosmic ray jets, however, explain key
characteristics of the most massive extinctions, the authors maintain.
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- One feature explained by cosmic ray jets
is the abrupt repopulation of the earth with completely new species that
occurred after some extinctions. New species would be created through rapid
mutations caused by radiation. Thus, these cosmic events could radically
change the nature of existence on earth by both destroying and creating
life. Furthermore, the extinction by cosmic ray jet theory explains why
radiation resistant species, including many insects and plants, survived
through all but the greatest extinctions. It also explains why species
sheltered from the mouns in canyons, caves and underground habitats were
not destroyed. Sea life in deep water also survived, while life in shallow
waters and on the surface was wiped out. For example, tiny marine creatures
called foraminafera displayed this selective survival; one type that lived
in shallow waters disappeared, while most species of a type dwelling deep
in the ocean survived.
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- Dar, Laor, and Shaviv suggest ways to
gather more substantial evidence for their doom and creation theory. Energetic
particles would have left tracks in earth and moon rocks, and left behind
particular forms of some chemical elements in rocks. Sensitive instruments
can be used to search for these traces of past catastrophes.
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- Neutron stars whose collisions create
cosmic rays are the extremely massive and dense remnants of some supernova
explosions. They contain several times the mass of the sun crammed into
a space only about 12 miles across (compared to 864,000 miles for the sun).
Some neutron stars come in pairs; these stars circle each other at closer
and closer range until they spiral into each other. In an earlier paper,
Dar and Shaviv suggested that when they collide, a brilliant disk forms
briefly and spews enormous jets of high-energy particles known as cosmic
rays.
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- If the earth were in the path of a jet
and less than 3,000 light years away, it would experience an intense bombardment,
up to a month long, of fast-moving muons. Muons would flood the earth,
penetrating hundreds of yards underwater or underground, destroying an
organism's central nervous system and causing death within days. Chemical
compounds that form would deplete the earth's ozone layer, increasing the
amount of ultraviolet light that reaches the surface, which together with
the radioactivity produced would be deadly to many plants, disrupting the
food chain.
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- Astronomers have identified five pairs
of neutron stars in our galaxy, two of which are within 3,000 light years
of earth. They calculate that it will be several hundred million years
before any of them collide. But they estimate that there are hundreds more
pairs in the Milky Way. As these pairs are discovered, their orbits can
be measured to determine when they can be expected to collide. The stars
approach each other slowly enough that humankind will probably have time,
possibly hundreds of thousands of years, to prepare for such events.
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- The Technion-Israel Institute of Technology
is the country's premier scientific and technological center for applied
research and education. It commands a worldwide reputation for its pioneering
work in communications, electronics, computer science, biotechnology, water-resource
management, materials engineering, aerospace and medicine, among others.
The majority of Israel's engineers are Technion graduates, as are most
of the founders and managers of its high-tech industries. The university's
11,000 students and 700 faculty study and work in the Technion's 19 faculties
and 30 research centers and institutes in Haifa.
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- The American Technion Society (ATS) is
the university's support organization in the United States. Based in New
York City, it is the leading American organization supporting higher education
in Israel. The ATS has raised $650 million since its inception in 1940,
half of that during the last six years. Technion societies are located
in 24 countries around the world.
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