Sunday, May 25, 2008

Study: Sun not special - therefore alien life should be common?

New Scientist's Hazel Muir tells us (May 22, 2008), reporting on recent research: "Sun's properties not 'fine-tuned' for life", adding
The finding adds weight to the idea that alien life should be common throughout the universe.

I am not sure how one can add "weight" to an idea, but never mind. Re the sun:
With his ANU colleague José Robles and others, Lineweaver has now analysed 11 features of the Sun that might affect its ability to have habitable planets. They included its mass, age, rotation speed and orbital distance from the centre of the Milky Way.

Then they compared these with well-measured statistics for other stars to answer the question – overall, does the Sun stand out from the crowd any more than some other randomly chosen star would?

The Sun did stand out in two ways: it is more massive than 95% of nearby stars and its orbit around the centre of our galaxy is more circular than those of 93% of nearby stars.

This research (in press at Astrophysical Journal) contradicts Guillermo Gonzalez's "privileged planet" hypothesis concerning the sun, so I asked him about it:
Lineweaver concludes that even though the Sun is obviously exceptional in two properties he considers (mass and Galactic orbit -- both of which I have pointed out in previous papers), it is not exceptional when you consider it in the context of 11 properties. Of course, this is not the correct conclusion. Not only is the Sun exceptional in these two properties (and probably one or two others), there are good reasons to believe that the Sun's mass and Galactic orbit need to be close to their actual values for life.

It's not clear whether Muir thinks that the alien life that should be common throughout the universe would be intelligent, complex (but perhaps not intelligent), or simple.

Lineweaver's approach is reminiscent of Carl Sagan's Copernican Principle (there must be lots of Them out there by definition, because otherwise, we would be unique). And - to judge from the Top 10 admittedly "controversial" pieces of evidence for extraterrestrial life accumulated so far (September 4, 2006) - the New Scientist staff can survive on regular infusions of hope.

One underlying assumption is that life will evolve under favourable conditions. The doctrine of the common ancestry of life on Earth would seem to suggest, however, that even where conditions are favourable, it is hardly a common event.

Also: Science and ethics: When the devil offered a no strings research post.

Nature's IQ: Intelligent design from a Hindu perspective

Science journalist warns against the "institutionalised idolatry of science"

Expelled film pre-trashed by United Kludgies of Canada (Trashing a film you haven't seen is way less work.)

Is everything determined by forces over which we have no control?

On Jane Goodall, apes, human uniqueness, and God