On Tuesday, November 17, 2015 at 5:24:15 PM UTC-5, eridanus wrote:
> El martes, 17 de noviembre de 2015, 14:24:13 (UTC), Bob Casanova  escribió:
> > On Mon, 16 Nov 2015 14:49:01 -0600, the following appeared
> > in talk.origins, posted by Bill <
fre...@gmail.com>:
> > 
> > >eridanus wrote:
> > >
> > >> 
> > >> 
> > >> CHICXULUB: THE IMPACT CONTROVERSY
> > >> 
> > >> 
http://massextinction.princeton.edu/chicxulub
> > >> 
> > >> Anyone can dare to retrieve it and to ready.  It is very interesting.
> > >> Well, at least for me for I am a retired man. Other person with a lot of
> > >> work cannot cope with this burden.
> > >> 
> > >> I had been talking with someone yesterday and it was mentioned this
> > >> question
> > >> the famous CHICXULUB crater, or meteorite.  This has resulted in a very
> > >> interesting controversy.  This is the sort of controversies I love.
> > >> It is the equivalent of a football match for me.  I love controversies.
> > >> eri
> > >
> > >I jumped to the last link, "11. Conclusions - Based on 30 Years of Research 
> > >" and found: ""How could so many be so wrong for so long" is the frequently 
> > >asked question. The answer is an exuberant belief in the impact hypothesis 
> > >as the only explanation for the KTB mass extinction led many scientists to 
> > >throw out the baby with the bathwater. The evidence was always there, but 
> > >disregarded, thrown out or re-interpreted as impact-generated."
There were many other explanations for the K-T extinctions besides the
asteroid impact, the Deccan Traps, and the draining of the continents
and much of the continental shelves. [These three get star billing in 
the Wikipedia entry linked by Richard Norman.] 
One that was popular for a long time was a supernova occurring close
enough to our solar system to cause massive radiational and perhaps
even thermal damage. There were many others, but none of them 
survived the triple impact of these three now-favored hypotheses.
> > >We know the KTB hypothesis is true because it's become popular with 
> > >scientists
> > 
> > No, we know it's "true" because we've found evidence that it
> > (the massive bolide impact) occurred.
For a long time the evidence was circumstantial, in the form of 
shocked quartz and an anomalous amount of iridium. But even this,
combined with the sheer drama of the asteroid impact story, was
enough to make it the most popular theory. Of course, the search
for a large enough crater began immediately, and lack of success
even caused some to hypothesize that Iceleand is the surviving 
remnant of the impact site. The age of Iceland, so it was claimed,
was just right.
Finding that Yucatan crater did convince some doubters, but not
very many, IIRC: its main role was that now it was clear that an 
asteroid impact HAD taken place at the right time.
> > Whether it was the
> > sole cause of the extinctions is a separate issue, one which
> > is still under discussion and investigation; the consensus
> > seems to be "no, but it was a major contributor". And all
> > based on evidence.
<snip for focus>
> one question is a crater and even the signs of a meteorite.
> This is not in dispute, but perhaps the exact dating of the
> crash. Then, you must not hasten on to say "this is the truth"
> because things could be a little more complex that they look.
> What have you read about this case?
> Why exist a controversy?  A controversy does not exist by a work
> of the Holy Spirit. 
> Then, you must read the case.  The data would tell you if this is 
> the truth, half the truth, or a quart of the truth.
> Things are not very often odd or evens, sometimes the truth is more
> complex to determine. 
> Eri
Indeed. My impression is that the supernova hypothesis was never 
discredited -- it just fell out of fashion.  
Scientists in general are too ready to jump on bandwagons or embrace 
hypotheses on analogy by what they know. It is now fashionable to 
write long stories about Lowell's hypothesis about the canals of Mars, 
because few people took it seriously even at its height of popularity.
But there is very little mention of the fact that many astronomers,
perhaps even a majority, were convinced that there were regular 
seasonal changes on Mars and that they were due to vegetation. I remember
at least one book from my boyhood, written by a professional astronomer,
that flat-out proclaimed "We know there is life on Mars." Arguments were
mainly about its nature. Some opted for something similar to lichens,
while others argued that the recovery from dust storms was so quick that
it had to consist of tall plant-like things from which dust readily blew off.
Peter Nyikos
Professor, Dept. of Mathematics         -- standard disclaimer--
University of South Carolina
http://people.math.sc.edu/nyikos/