Rare Earth; compared to others (Introduction)

by David Turell , Friday, February 26, 2016, 01:15 (3194 days ago) @ David Turell

The source of this latest claim that the Earth is very special is in tis article:-http://blogs.discovermagazine.com/d-brief/2016/02/22/earth-is-a-1-in-700-quintillion-kind-of-place/#.Vs-mRCr2Zdi-"A new study suggests that there are around 700 quintillion planets in the universe, but only one like Earth. It's a revelation that's both beautiful and terrifying at the same time.-"Astrophysicist Erik Zackrisson from Uppsala University in Sweden arrived at this staggering figure — a 7 followed by 20 zeros — with the aid of a computer model that simulated the universe's evolution following the Big Bang. Zackrisson's model combined information about known exoplanets with our understanding of the early universe and the laws of physics to recreate the past 13.8 billion years.-"Zackrisson found that Earth appears to have been dealt a fairly lucky hand. In a galaxy like the Milky Way, for example, most of the planets Zackrisson's model generated looked very different than Earth — they were larger, older and very unlikely to support life. The study can be found on the preprint server arXiv, and has been submitted to The Astrophysical Journal.-***-"But according to Zackrisson, most planets in the universe shouldn't look like Earth. His model indicates that Earth's existence presents a mild statistical anomaly in the multiplicity of planets. Most of the worlds predicted by his model exist in galaxies larger than the Milky Way and orbit stars with different compositions — an important factor in determining a planet's characteristics. His research indicates that, from a purely statistical standpoint, Earth perhaps shouldn't exist.-***-“'It's certainly the case that there are a lot of uncertainties in a calculation like this. Our knowledge of all of these pieces is imperfect,” co-author Andrew Benson told Scientific American.“It was only recently that we even had enough exoplanet data to make a model of this kind possible.”-"Nevertheless, the researchers are confident in the broader implications of their model: Earth is more than your garden-variety planet."-Comment: Same story. we are special.