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Dead Zones in the Search for

80_2New findings from diverse fields are are being brought to bear of the central question of the 21st century: How common is life in the universe? Where can it survive, Will it leave a fossil record, How complex us it. The list below moves several key features of the Universe off the chart of likely places to search for life.

In our recent post "Cruising the Goldilocks Zone -The Search for Super Earths" we described the hot zones and habitats with highest probability of supporting complex life.

In stark contrast, the zones and regions of the known universe listed below are the ones that astrobiologists have concluded have little or zero chance of supporting life as we know it. The listing of "dead zones" was compliled for Rare Earth -Why Complex Life is Uncommon in the Universe by Uinversity of Washington scientists Peter D. Ward (Professor of Geological Sciences and Curator of Paleontology) and Donald Brownlee (Professor of Astronomy and member of the National Academy of Sciences).

Early Universe: The most distanct known galaxies are too young to have enough metals for formation of Earth-size inner planets. Hazards include energetic quasar-like activity and frequent super-nova explosions.

Elliptical Galaxies: Stars are too metal-poor. Solar mass stars have eveloved into giants that are too hot for life o inner planets.

Globular Clusters: Although they contain milllions of stars, the stars are too metal poor yo have inner planets as large as`earth. Solar mass stars have evolved to gaints that are too hot for life on inner planets.

Small Galaxies: Most of the stars are too metal deficient.

Centers of Galaxies: Energetic star building and black-hole processes prevent development of complex life.

Edges of Galaxies: Most stars are too metal poor.

Planetary Systems with "Hot Jupiters": Inward spiral of the giant planets drives the inner planets into the central star.

Planetary Systems with Giant Planets in Eccentric Orbits: Unstable environments. Some planets lost to space.

Future Stars: Uranium, potassium, and thorium too rare to provide sufficent heat to drive plate tectonics.

Posted by Casey Kazan.

Be sure to check out the fascinating Great Debate on the Odds of Complex Life in the Universe at Astrobiology Online which includes Ward and Brownlee and several other renowned scientists.

Prior Posts:

Cruising the Goldilocks Zone -The Search for Super Earths

Comments

Interesting article, but did anyone run a spell check on this ? Honestly.

Great Debate on the Odds of Complex Life in the Universe: should be http://www.astrobio.net/news/article239.html
without the
extra h in http

1)Why are scientist assuming that every solar system operates like all others? It may be that these "dead zones" have metal poor stars and high incidents of radiation but who knows what kind of magnetic field these planets have? If a super Earth (say..2xEarth) has the same kind of plate tectonics and mantle system as our planet, would it not have a magnetic field double the size and strentgh of ours? This would offer protection to the life forms on the planet and it would also prevent the atmosphere from being stripped from the planet by solar radiation.

2)If it is true that the elements of metal rich stars are forged from the supernova of larger, metal poor stars, then why do we believe these areas in the early universe would not form metal rich stars after a few billion years of supernova? They may not have an abundance of planet forming material like the milkyway but they would have some. Even a tiny fraction of what we have still means a couple of million planets!

3) Why are we assuming that life needs a rocky planet to form? could life not start in a molecular cloud of hydrogen and oxygen, warmed by nearby star activity to a few degress above zero with enough mass to keep the cloud together but not enough for it to compress into a star? I know a cloud such as this has not been discovered but is it not possible?

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