Subject: CC DIGEST, 29/01/98
Date: Thu, 29 Jan 1998 14:31:59 -0500 (EST)
From: Benny J Peiser






A brief comment on the Kobres/Chapman controversy

From: Benny J Peiser

What is the probability of throwing a "six" when the die is cast? You
may think that this is a rather simple exam question which does
not require complex mathematics. In reality, however, you cannot
even begin your calculations without some additional information.

In order to calculate the probability of "throwing a six", you
have to obtain a number of known facts first on which to base
your maths. What you need to know is

* how many dice are included in one throw?

* are all dice regular cubes with six faces?

* have all dice the same numbers on their faces, ranging from
  1 to 6, or some other numbers?

* are there dice with different shapes and different numbers on
  their faces?

There are, thus, some essential requirements for any probability
theory to be considered tenable. The main requirement, as I have
shown, is the existence of an  e s s e n t i a l  number of  k n o w n
variables on which to base any calculation of probability.

What, then, is the probability of on "impact event" with "civilisation
threatening effects" occurring in the next two hundred years (or
tomorrow)? All impact probability calculations, as I understand
this complex mathematical theory, would only be  v a l i d  if we

* that the currently observed asteroidal and cometary flux is more or
  less constant over time

* the number and orbital dynamics of all (or most) of the long
  period comets

* the nature and extent of all (or most) meteor streams

* the actual effects and the chronology (and perhaps periodicity)
  of past impacts

* the number and dynamics of most of the giant asteroids

* the absolute dates of the last four or five cosmic catastrophe
  of global extent.

Since most of this vital information about our cosmic environment
is simply not available to mankind at this stage of human
evolution and scientific exploration (mind you, the above list is
not comprehensive by any means), I remain rather sceptical about
assurances by researchers who claim that the probability of a
civilisation threatening impact in the foreseeable future is

There are doubts whether such claims are based on sound scientific
evidence and reasoning. It also appears that our current
astronomical, geological and historical knowledge is not nearly as
thorough enough yet as to arrive at a   r e l i a b l e
calculation of impact probabilities. After all, all papers on the
complex issue of impact probability are based, necessarily so,
on what little is known about the currently observable asteroidal
and cometary flux (including our limited knowledge of the number
and ages of impact events in the geological record). This
relatively modest amount of data together with its inherent
vagueness is, as far as I can see, not enough for any reliable
calculations about future impact events.

Let's face it: during the last couple of centuries, mankind has
only obtained a glimpse of the real cosmic picture. The entire
panorama will most likely look quite different from what we
currently know or believe (just think about what most
scientists told us 20 years ago about the main features of our

I do sympathise with the philosophical concerns and psychological
re-assurances of some people involved in NEO research. However,
scientists who wish to be truthful to interested lay-people and
the general public, should readily admit that mankind will
continue to live in a world of cosmic uncertanties as long as
we fail to spent more time, more research and much more money on
gathering the vital information which is not only necessary for
any tenable calculation of impact probabilities but, moreover,
for the establishment of a global system of planetary defense.



From: Clark Whelton

The New York Times Science Section, January 27, 1998

If Climate Changes, It May Change Quickly.

William K. Stevens

"...A growing accumulation of geological evidence is making it ever
clearer that in the past the climate has undergone drastic changes in
temperature and rainfall patterns in the space of a human lifetime, in
a decade or in even less time."

"....In uncovering one of the latest pieces of evidence of abrupt
climate change, American scientists led by Dr. Jeffrey P. Severinghaus
of the University of Rhode Island examined climatic clues taken from
corings of ancient ice in Greenland.

"The Severinghaus team determined that when the world began its final
ascent out of the last ice age more than 11,000 years ago,
temperatures in Greenland initially spiked upward by about 9 to 18
degrees F. -- at least a third, and perhaps more, of the total
recovery to today's warmth -- in, at most, mere decades and probably
less than a single decade. They also found that the impact of the
sudden warming had been felt at least throughout the Northern

"That amount of heating, coming so quickly, is astounding," said Dr.
Richard Alley of Pennsylvania State University, a member of the study team.
Another recent study, by Dr. Peter deMenocal, a paleoclimatologist at
Lamont-Doherty, examined clues in Atlantic Ocean sediments off sub-tropical
North Africa.  He discovered that every 1,500 years or so since the end of
the ice age, ocean temperatures there have fluctuated wildly and abruptly.

"In a cold phase, they fell by 5 to 15 degrees, and seasonal rains
on the continent were severely curtailed -- all within no more than 50 to
100 years, and possibly less (the sediment analysis is not fine enough to
tell).  Then, in another 1,500 years, the picture reversed just as abruptly,
causing flooding rains and creating widespread lakes in what is now the Sahara.

"The transitions are sharp," Dr. deMenocal said.  "Climate changes
we thought should take thousands of years to happen occur within a
generation or two," at most.  The changes may have wreaked havoc on nascent
civilizations in Africa and the Middle East.  "It was certainly something
that would have rocked somebody's world," Dr. deMenocal said..


E. P. Izokh: Australo-Asian tektites and a global disaster of about
10,000 years BP, caused by collision of the Earth with a comet.
GEOLOGIYA I GEOFIZIKA, 1997, Vol.38, No.3, pp.628-660
[in Russian]


About 10,000 years ago, at the Pleistocene-Holocene border, some
important events occurred: the glaciation stopped abruptly; the
sea level elevated, and quick (for 20-50 years) climatic and
ecological changes took place, leading to the extinction of the
so-called mammoth fauna and exerting a direct effect on the
mankind's evolution and appearance of civilizations. These and
other disastrous events providing a distinct boundary between the
Pleistocene and the Holocene received no relevant explanation in
the Quaternary geology until now.

It is shown in the paper that the disaster under study was caused by
the collision of the Earth with an eruptive comet, brought various
volcanic tektite glasses from a remote planetary body. This extra-
terrestrial source of tektites is proven by the well-known but not
adopted paradox of tektite age, i.e. a difference in hundreds of
thousands and millions of years between the radiogenic age of
tektites (time of formation) and time of their fall onto the Earth.
The volcanic nature of tektites is supported (by analogy with
volcanic bombs, lavas, tufflavas, and extrusive formations taking
into account extraterrestrial conditions) by their long and many-
stage formation, by ordered trends of composition variability
inherent only in magmatic differentiation, etc. Relying on a
diversity of forms, structure, and composition of tektites, we made
an attempt to reconstruct various types of volcanic eruptions. Most
likely, the place of volcanic activity was a small or light planetary
body of the type of Io, Callisto, Triton, etc. with ice crust, acid
upper and relatively basic lower mantle, with small gravitation,
without atmosphere, etc., situated somewhere on the periphery of the
Solar System. It is supposed that a very powerful explosion ejected
into space some part of a stone-ice volcanic construction, i.e.
eruptive comet, according to S. K. Ysekhsvyatsky.

The comet hypothesis permits explanation of main features of
distribution of tektites over the Earth's surface, various forms of
their connection with impact craters as well as many other features
of tektites. The common Earth impact hypothesis for tektite origin is
not able to explain all these facts; it is deeply perplexed and is
severely criticized in this paper.

The <<mammoth>> disaster is comparable with the so-called
<<dinosaur>> catastrophe at the Cretaceous-Paleogene border, which
also was accompanied with impact craters and fall of tektites. An
analogy is traced with the collision of the Shoemaker-Levi comet with
the Jupiter. Thus, a special class of eruptive comets, cosmic bodies the most
dangerous for the Earth, which are beyond attention of investigators,
is discussed for the first time.


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