Every 27 million years, just like clockwork...

[n2doc]

Monday, July 12, 2010
The Death of Nemesis: The Sun's Distant, Dark Companion
The data that once suggested the Sun is orbited by a distant dark companion now raises even more questions

Over the last 500 million years or so, life on Earth has been threatened on many occasions; the fossil record is littered with extinction events. What's curious about these events is that they seem to occur with alarming regularity.

The periodicity is a matter of some controversy among paleobiologists but there is a growing consensus that something of enormous destructive power happens every 26 or 27 million years. The question is what?

In this blog, we've looked at various ideas such as the Sun's passage through the various spiral arms of the Milky Way galaxy (it turns out that this can't explain the extinctions because the motion doesn't have had the right periodicity).

But another idea first put forward in the 1980s is that the Sun has a distant dark companion called Nemesis that sweeps through the Oort cloud every 27 million years or so, sending a deadly shower of comets our way. It's this icy shower of death that causes the extinctions, or so the thinking goes.

more

http://www.technologyreview.com/blog/arxiv/25420/

[MineralMan]

1. Oddly, I don't see any particular 27 year pattern in that chart.

Not at all.

[wtmusic]

2. You're not alone.

The fact is that with modern and better paleontological data any peridocity is rejected, as easily checked with autocorrelation :

"Quantitatively, extinction rates in the Fossil Record 2 family data (3) and Sepkoski’s family and genus data (1, 2) are not correlated with themselves at any time lag (49), which is a necessary condition for periodicity to hold. That said, analyses of origination rates in all three datasets (49, 50) suggest short-term autocorrelation. However, the current dataset shows no autocorrelation in either kind of rate (Fig. S1), and a standard spectral analysis (Fig. S2) also suggests purely random variation through the time series (i.e., white noise)."

(from the comments)

[Odin2005]

3. Not this BS again.

Read some of Peter Ward's books. the K-T extinction is the ONLY major extinction caused by an impact.

[laconicsax]

4. So far...

:scared:

:rofl::rofl::P