[meteorite-list] Periodicity of Extinctions

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Thu, 4 Aug 2011 17:23:16 -0500
Message-ID: <CA4182A92C9341468FDE347D7E1A5C4B_at_ATARIENGINE2>

Richard, E. P., Listoids,

OK, into the Great Dismal Swamp...

First we have to make sure everyone is talking about
the actual Nemesis hypothesis, not the universal
misconception of both scientists and science writers.
The idea was that we were originally a double star
with a normal dim companion (more of them then
solo stars in our neighborhood) in a mildly distant
but circular orbit. Then, less than a billion years
ago, maybe only half a billion, a passing star greatly
perturbed our little buddy into a new crazy, highly
eccentric orbit that can't last from which it generates
showers that produce extinctions now, but didn't
until 500-700 Ma ago.

So, Periodicy very Yes, Nemesis... Naaaah, not so much.
Melott and Bambach, "Nemesis Reconsidered," accepted
by Monthly Notices of the Royal Astronomical Society
http://arxiv.org/ftp/arxiv/papers/1007/1007.0437.pdf

"Hut (1984) was specific that irregularity of the period
of revolution of such an object [Nemesis] over the past
250 My should be about 20% due to perturbation from
the Galaxy tidal gravitational field and by passing stars,
and sharp peaks should not be expected in Fourier
analysis. Torbett & Smoluchowski (1984) reached the
same conclusion, but with a somewhat larger estimate
of the fluctuations from the Galactic tide alone,
dependent on the inclination of the Nemesis orbit with
respect to the Galactic disk. Hills (1984) estimated a
period change of 4% per Nemesis orbital period from
the effects of passing stars. Using a t1/2 amplitude
scaling expected from a random walk, the orbital
period should drift by 15 to 30% over the last 500 My.
This change in the period will broaden or split any
spectral peak in a time series frequency spectrum,
so Nemesis as an extinction driver is inconsistent
with a sharp peak." Melott and Bambach say their
new enlarged data set raises the likelihood of
periodicy to 99%.

Of course, nobody agrees with anybody else. That's
science. Oddly, the very regularity of the extinction
timing argues against its being the result of Oort
Cloud perturbations caused by a Nemesis-like object
because Nemesis' orbit couldn't be that stable.

MIT's Technology Review (07/12/2010)
http://www.technologyreview.com/blog/arxiv/25420/?ref=rss
    "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?"

A fascinating example of parallax: the Solar System
looks difference from the East Coast and the (near)
West Coast!

J. John Sepkoski, one of the co-discoverers of the
apparent cyclic nature of mass extinctions says that
"here is an intriguing observation that no one knows
how to explain. Researchers formulated a number
of very interesting astronomical hypotheses" but none
convince. It is an hypotheses does not suggest tests.
"This situation is not conducive to scientific effort or
to intellectual curiosity, so interest in the question
of periodic extinctions has died down." In other words,
the idea is an orphan fact that no one wants to take
home
http://www.scientificamerican.com/article.cfm?id=what-ever-happened-to-the

The Earth does pass back and forth through the galactic
plane in a sinusoidal fashion of poorly constrained period.
That has also been suggested as the cause of the periodicy:
http://articles.adsabs.harvard.edu/full/1996EM%26P...72..441R
The full PDF can be downloaded from here:
http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1996EM%26P...72..441R&defaultprint=YES&filetype=.pdf
This article does contain some very "spikey" plots and
nice Fourier plots of periods for those who "don't see it."

Predicted Extinctions (27,000,000 period):
11 mya: Miocene, Serravillian
38 mya: Eocene, Bartonian
65 mya: KT Extinction
92 mya: Cretaceous, Turonian
119 mya: Cretaceous, Aptian
146 mya: Jurassic, Tithonian
173 mya: Jurassic, Aalenian
200 mya: Triassic-Jurassic Boundary
227 mya: Triassic, Carnian
254 mya: Permian, Wuchuapingian
281 mya: Permian, Artinskian
308 mya: Carboniferous, Moscovian
335 mya: Carboniferous, Visean
362 mya: Devonian, Famennian
389 mya: Devonian, Givetian
416 mya: Silurian-Devonian Boundary
443 mya: Ordovician-Silurian Boundary
470 mya: Ordovician, Dapingian
497 mya: Cambrian, Furongian

Actual Extinctions:
14.5 mya: Middle Miocene Disruption (off by 3 my)
33.9 mya: Late Eocene Extinctions (off by 4 my)
65 mya: KT Extinction.
93.5 mya: Cennomanian-Turonian (off by 1.5 mya)
117 mya: Aptian Extinction (off by 2 my)
145 mya: End Jurassic: often considered regional only (off by 1 my)
183 mya: Toarcian Turnover (off by 10 my)
200 mya: Triassic-Jurassic Extinction (spot on)
228 mya: Carnian Extinctions? Questionable, supported, iirc, by Benton
(off by 1 my)
251 mya: PT Extinction (off by 3 my)
260 mya: Guadelupian Mass Extinction (off by 6 my)
Devonian extinctions: one damned thing after another,
for a perdiod of 20 to 30 million years...
360 mya: Carboniferous-Devonian Boundary/Hangenberg Event (off by 2 my)
375 mya: The Frasnian-Famennian/Kellwasser Event (off by 13 my)
420 mya: Lau event (off by 4 my)
423 mya: Mulde event (off by 7 my)
426 mya: Irevikean event (off by 10 my)
443 mya: Ordovician Mass Extinction (spot on)

How do I explain the temporal irregularities?

The process of perturbing the Oort Cloud is very
slow. It can take ip to a million years to stir it and
inject a body into the inner system, where it may
persist for up to a million years before it hits
anything at all, and it may not hit the Earth but
disrupt a lesser body (asteroid) that takes more
millions of years for a big enoug fragment to hit
the Earth and do damage.

It's a mixture of the Periodic and the Stochastic.

I am not bothered by a few million years of "slop"
in so contingent a process. It's not like an Oort
resident hops on a high-speed rail line that says
"Next Stop: Earth." Oortie can take the scenic route.

As for the "missing" or "extra" extinctions... Well,
hate to tell you, Apocalypse Fans, sometimes big
impactors MISS. If you draw a straight line that
passes closer to the Sun than the Earth, going
through the solar system like a bullet from any
random angle, the odds of it intersecting the Earth
at any given moment is 1 in 1,363,000,000. If you
restrain the impactor to the general plane of the
solar system, the odds improve, but the Oort Cloud
is a sphere (we think).

As for, "extra" extinctions, like my grandmother
used to say, "It's Always Something..." There could
be other, less common causes, couldn't there?

Interestingly, the bio-believers in Periodicy don't
like impacts, just as the paleontologists hated the
Chicxulub Hypothesis when it WAS an hypothesis.
Jim Bakker said the dinosaurs all died from bad
colds... Some blamed the extinction on parasites;
some on climate change (cooling of course; we didn't
have warming yet); some favored supernovae; and
on and on, and nobody liked astronomers sticking
their nose in where it didn't belong!

The Missing and the Extra increase dramatically
as you go back in time. The crater evidence vanishes.
These time wobbles are more likely artifacts of a
planet that keeps itself tidied up geologically. If
there really were no periodocy, there would be as
many bad data points in the last 200 million years
as there are in the 200 million years before that.

Not so. Human Error and Aggressive Tectonics do
the rest.


Sterling K. Webb
----------------------------------------------------------------

----- Original Message -----
From: "Richard Kowalski" <damoclid at yahoo.com>
To: <meteorite-list at meteoritecentral.com>
Sent: Wednesday, August 03, 2011 3:17 PM
Subject: Re: [meteorite-list] Periodicity of Extinctions


My last comment on this ongoing non-sense. The radio program Coast to
Coast AM is a much better venue for it.


Unlike you, I am not obsessed with my colleagues. I know them too well!
:)

Morrison's article you cite was publish more than 14 years ago. I'd be
very interested if anyone can see a 26my periodicity in that plot. I
can't

The second plot you cite is older still, 1984.

Science moves forward with time as we learn more.

I stand by my statements that there is no Nemesis or periodicity.

--
Richard Kowalski
Full Moon Photography
IMCA #1081
______________________________________________
Visit the Archives at 
http://www.meteoritecentral.com/mailing-list-archives.html
Meteorite-list mailing list
Meteorite-list at meteoritecentral.com
http://six.pairlist.net/mailman/listinfo/meteorite-list 

Received on Thu 04 Aug 2011 06:23:16 PM PDT