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Cambridge Conference Digest - January 29, 1998

CAMBRIDGE-CONFERENCE DIGEST, 29 January 1998
--------------------------------------------

(1) WHY IMPACT PROBABILITY CALCULATIONS ARE STILL GUESSWORK

(2) NEW EVIDENCE FOR MAJOR PUNCTUATION OF GLOBAL CLIMATE AT THE 
    PLEISTOCENE/ HOLOCENE BOUNDARY

(3) ... AND AN EXTRATERRESTRIAL HYPOTHESIS

=========================================
(1) WHY IMPACT PROBABILITY CALCULATIONS ARE STILL GUESSWORK
     
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 
knew 

* 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 
"low". 

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 
world). 

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. 

=======================

(2) NEW EVIDENCE FOR MAJOR PUNCTUATION OF GLOBAL CLIMATE AT THE 
    PLEISTOCENE/ HOLOCENE BOUNDARY

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 
Hemisphere.  

"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..

=========================================================
(3) ... AND AN EXTRATERRESTRIAL HYPOTHESIS

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]

RUSSIAN ACADEMY OF SCIENCE, SIBERIAN DIVISION, JOINT INSTITUTE
OF GEOLOGICAL GEOPHYSICS & MINERALOGY, NOVOSIBIRSK 630090, RUSSIA

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 <> disaster is comparable with the so-called 
<> 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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