KT Bolide--Comet or Meteorite?

[George Leonard <gl91bciiLt@earthlink.net>]

Within the last two days (that's already 80 messages back) some of us 
have made appropriately careful references to the KT "bolide". I've spent 
some time now, guided by Mary, going through our archives back to 96 and 
that thread, before posing this question. Assuming for the moment that 
there was a bolide: what was its nature? Alvarez is careful to use the 
term "bolide" in his popular 1997 summation, T Rex and the Crater of 
Doom. Since a comet would have become part of the vapor plume on impact, 
he seems to think we can never discover if the bolide was comet or 
meteorite. But by the next year, J. L. Powellin Night Comes to the 
Cretaceous, almost always says "meteorite" without discussing why.  We've 
spoken a great deal on this list about leaps of logic and standards of 
proof. 1. Has anyone else noticed an unexamined consensus forming, among 
believers, that it was a meteorite? 2. Was there any discussion? Now I'm 
well aware that our archives include two news stories about a fragment of 
"the KT meteorite" supposedly found. My point is, Alvarez's believers 
(like myself) had ever agreed it was a meteorite. Mary, again, graciously 
forwarded me Frank Kyte's Nature article about his find, and the only 
evidence that Dr. Kyte presented was that since it was a meteorite and it 
was at/near the KT, well, what else could it be? Though it was 5000 miles 
from Chicxulub. Here's my point: I wanted to believe Kyte. And that's not 
good, logically. But there are inducements. If I stick to comet, no 
fragment, no proof ever will be found. But if I say, meteorite, a 
fragment can be found; and apparently any fragment we do find, anywhere, 
now becomes "proof." So I have a motive to start to say meteorite. On the 
other hand, saying it was a comet is a non falsifiable statement, isn't 
it? It has to have become part of the vapor plume in the great heat 
generated by impact. Wouldn't Popper rebuke me for saying comet, since it 
can never be falsified or verified? Our list is very fond of Popper, but 
that's a problem, isn't it? It interests me how "science" here is coming 
down to an issue of analytic philosophy, and even of psychology, the 
human motivation to support one's argument. I would be grateful, then, if 
anyone can inform me of any evidence they've heard presented that it was 
comet or meteorite; or even of discussions about it. Thanks. 
Best, 
George
George J. Leonard
Professor of Interdisciplinary Humanities
530 Humanities Hall
San Francisco State University
San Francisco, CA