Binary Stars WR 25 and Tr16-244 in the Carina Nebula. Hubble Photo. Credit: NASA, ESA, and J. Maíz Apellániz (Instituto de Astrofísica de Andalucía, Spain).
MIT's Technology Review reported on July 12 that Adrian Melott at the University of Kansas and Richard Bambach at the Smithsonian Institute in Washington DC have reviewed the past 500 million years of earth's paleo-record to try to explain mass extinctions that have occurred like clockwork every 27 million years. Their work has shown "an excess of extinctions every 27 million years, with a confidence level of 99%."
Since the 1980s, one theory for these events has been that our sun, Sol, is in fact a binary star and crosses paths with its twin, Nemesis, every 27 million years, thereby showering our system with comets. Lynn Yarris, science writer at the Lawrence Berkeley National Laboratory, has cited Norse sagas to find human confirmation of Nemesis's influence on life on Earth for signficantly shorter periods. She quotes the "Fimbul Winter" from the saga, Twilight of the Gods:
"Heavy snows are driven and fall from the world's four corners; the murder frost prevails. The Sun is darkened at noon; it sheds no gladness; devouring tempests bellow and never end. In vain do men await the coming of summer. Thrice winter follows winter over a world which is snow-smitten, frost-fettered, and chained in ice."Wiki on the Fimbul Winter: "There have been several popular ideas about whether or not this particular piece of mythology has a connection to the climate change that occurred in the Nordic countries at the end of the Nordic Bronze Age, about 650 BC. Before this climate change, the Nordic countries were considerably warmer."
Melott's and Bambach's research argues against the existence of Nemesis because normally Nemesis's path (if it exists) would alter over time, causing variations in the 27 million year timeframe. If they are correct in confirming this startling regularity, that means that something else is causing these periodic catastrophes. The Technology Review: "It's not easy to imagine a process in our chaotic interstellar environment that could have such a regular heart beat; perhaps the answer is closer to home."
So this is another jaw-dropping confluence of palaeontology and astronomy. Mind you, as usual the comments section of the Technology Review article is full of raging critics who cite articles that argue against the proof of periodic extinctions in the fossil record. A typical comment: "Anyone who claims a 99% confidence level over a 500 million year period with a straight face loses all credibility immediately, and is unlikely to ever regain it in my eyes." And a comment on Nemesis: "Always put it somewhere up there in the if-you-don't-believe-in-fairies-Tinkerbell-will-die category. Seemed it was missing a few necessary variables - like, how does a medium-sized G0 hold on to something that far out? What is the maximum orbital diameter observed between binary stars? Can you even call it a binary star if it's that far off? Even Proxima Centauri takes only 500 000 years to orbit Alpha Centauri."
If Melott and Bambach are wrong, does that mean we have to go back to looking for our Sun's evil twin? Their findings still may mean that there is something else out there, running on an approximate 27 million year rotation. Considering Yarris's discussion of shorter timeframes, and the unlikelihood that something in the universe is so perfectly regular, there may be some other cosmic pattern at hand. Somewhere between the Astronomers, the Paleo-biologists, the Palaeontologists, the Archaeologists, and now the Literary and Linguistic analysts, we are having trouble comprehending the points at which our human, planetary, solar and universal clocks all match up.