Overcoming Bias : A Galactic Garden

Description

A Galactic Garden

In August I wrote :

A few years ago PCW Davies persuasively argued that Earth life more likely started on Mars. Last year, Napier and coauthors argued that comets are an even more likely source:

A single comet of radius 10 km and 30% volume fraction of clay contains as much clay, to within a factor of around 10, as that of the early Earth. However, our Solar System is surrounded by about 10 comets forming the Oort cloud … Whereas the average persistence of shallow clay pools and hydrothermal vent concentrations of clay on the Earth can range from 1 to around 100 years, a cometary interior provides a stable, aqueous, organic-rich environment for around 10 years.

The larger the region from which life could plausibly have started and then come to Earth, the more likely Earth life becomes in that scenario, and the more believable is whatever theory suggested that scenario. The latest Scientific American suggests to me an even larger plausible region of orgin: life’s origin may go back to the tight warm mixing cluster of stars where the Sun formed. Simon Zwart :

[The Sun] was one of 1,000 or so siblings all born at nearly the same time. Had we been around at the dawn of the solar system, space would not have seemed nearly so empty. The night sky would have been filled with bright stars, several at least as bright as the full moon. …

The cluster into which the sun was probably born is ...

Original URL

http://www.overcomingbias.com/2009/11/where-to-find-life.html

http://www.overcomingbias.com/2009/11/where-to-find-life.html