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Saturday, July 6, 2013

Twinkle, Twinkle


It seems that the rate of supernova occurrence (black line) is pretty much a dead match for biodiversity -- the normalized marine invertebrate genera count (blue line).  The gray is the error band around the biodiversity count. 



When Sagan said we were made of star-stuff, he had only half the picture.  Apparently, the stars really do affect life on earth.  The Permian extinction falls right in:
Svensmark notes that the Late Permian saw the largest fall in the local supernova rate seen in the past 500 million years. This was when the Solar System had left the hyperactive Norma Arm of the Milky Way Galaxy behind it and entered the quiet space beyond.
Through a variety of mechanisms, too few supernovae resulted in warmer air, reduced circulation, poor nutrient mixing, ending with a shortage of oxygen in the atmosphere.  Nearly all life on earth went extinct.
But once upon a time an abundance of nearby supernovae chilled the earth so badly it kicked into Snowball Earth.   So, Goldilocks, human life arose in a period of "just right" insofar as supernovae are concerned. 





7 comments:

  1. Read this to my wife. Her comment: That is freakishly, wonderfully great!

    Yep.

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  2. Looking at that graph, how can anyone possibly refute evolution? I suppose the most stubborn of the stubborn could say the black and blue lines don't match up perfectly, but come on...

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  3. Well do I remember that gorgonopsid skull, photographed in the Karoo where it had been lying since South Africa was south of the Antarctic Circle...

    Undergrad palaeontology at the University of the Witwatersrand, Johannesburg, was fascinating. We were taught by James Kipling, a rare old, self-taught fossil hound with an Afrikaans accent you could cut with a knife (God rest him).

    Anyway, it's an interesting idea. I read some time ago that the end of the Permian was marked in Russia by thick deposits of decaying vegetation, with abundant fungal spores. Just how heavy did that Cosmic Ray bombardment have to be, to trigger cloud formation that would cut out the sun for up to a year?! It seems a little tenuous.

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  4. So, obviously, biodiversity drives supernovae. Life on Earth causes nearby stars to commit suicide. Am I reading that right?

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    Replies
    1. Eek. A new argument for a) population control and b) clear-cutting rain forests!

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  5. Interesting. The abstract doesn't mention the connection I first thought of: an increase of radiation correlating to a greater number of mutations, hence more species.

    Another blow to the over-specialization in modern science.

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  6. What I find most interesting about that graph is that the supernova rate correlates so strongly with the total number of marine genera, rather than the rate of new genera coming into being. My expectation would've been that the downturns in supernova rate wouldn't have correlated as tightly with the total number as the upturns, as many existing genera that originated during the upturn would adapt rather than go outright extinct. That seems to suggest that rather than being a direct cause, the supernova rate sets some sort of upper limit on marine biodiversity, with the more direct causes generating or maintaining biodiversity up to that level.

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