PLEASE NOTE:
*
CCNet 123/2000 - 28 November 2000
---------------------------------
"The discovery of new strains of bacteria is practically a
daily
event and does not constitute evidence for an extraterrestrial
origin."
-- Matthew Genge, The Natural History Museum,
London, 27 November
2000
"To claim an extraterrestrial origin, a microbe needs to be
captured
hundreds (preferably thousands) of kilometers away from Earth by
a
sterilized spacecraft."
-- Andrew Glikson, Australian National
University, 27 November
2000
"With the rapid accumulation of data that goes generally in
the
direction of supporting panspermia, the adoption of an
intransigent
Earth-bound view of life would surely be a risky business!"
-- Chandra Wickramasinghe & Sir Fred
Hoyle, 27 November 2000
(1) ALIEN MICROBE REPORTED FOUND IN EARTH'S ATMOSPHERE
Space.com, 27 November 2000
(2) THIS COMET SHOWS WHY WE NEED SOUTHERN-HEMISPHERE SEARCHES
http://cfa-www.harvard.edu/iau/cbat.html
(3) COMET UTSUNOMYA-JONES: A SECOND BINOCULAR COMET FOR
CHRISTMAS?
NearEarth Net, 26 November 2000
(4) LIFE UNDER BOMBARDMENT
Ilan Manulis <ilan@trendline.co.il>
(5) LIFE UNDER BOMBARDMENT
NASA Astrobiology Institute
(6) LOOK INSIDE MARS' FROSTY CRATERS
MSNBC News, 27 November 2000
(7) DUST AND THE ENVIRONMENT OF THE EARTH: CALL FOR ABSTRACTS
(8) NO EVIDENCE FOR COMETARY BACTERIA IN THE ATMOSPHERE
Matthew Genge <M.Genge@nhm.ac.uk>
(9) EARTH-BOUND VIEW OF LIFE IS A RISKY BUSINESS
Chandra Wickramasinghe & Sir Fred Hoyle
<xdw20@dial.pipex.com]
(10) MICROBES FROM OUTER SPACE AND THE EARTH MANTLE? ...
Andrew Glikson <geospectral@spirit.com.au>
(11) AND FINALLY: BAD NEWS FOR TECHNOPESSIMISTS - INTERNET
SURPRISINGLY
ROBUST
Physics News <physnews@aip.org>
===================
(1) ALIEN MICROBE REPORTED FOUND IN EARTH'S ATMOSPHERE
From Space.com, 27 November 2000
http://www.space.com/cgi-bin/email/gate.cgi?lk=T5&date=001127&go=/searchforlife/alien_bacteria_001127.html
By Robert Roy Britt
Senior Science Writer
A group of scientists says it has collected an alien bacterium 10
miles
above Earth, plus signatures of other extraterrestrial microbes
even higher
in the atmosphere. The claims were met with immediate skepticism
by other
scientists.
The bacterium was collected 10 miles (16 kilometers) high by
balloon
operated by the Indian Space Research Organization. Chandra
Wickramasinghe,
who leads a study into the results, called the microbe a
previously unknown
strain of bacteria and said it likely came from a comet.
Wickramasinghe and a colleague, Fred Hoyle, say the findings
support an idea
they pioneered, called panspermia, which holds that the seeds of
life are
everywhere in space and are the source for life on Earth.
Matthew Genge, an expert on meteorites and cometary debris at
London's
Natural History Museum, said he was flabbergasted by the claim.
"I don't believe the authors have provided the kind of
evidence that would
be needed to support their claim," Genge said. "Their
announcement appears
premature."
Genge, who does not rule out panspermia as a possibility, said
nonetheless
that the supposed alien bacteria could have been previously
unknown strains
of terrestrial bacteria.
"Hitherto unknown strains of bacteria are found virtually
every day," Genge
told SPACE.com. "If no one had ever seen or heard of an
elephant and
suddenly one was discovered this wouldn't be evidence that it
comes from
space."
Wickramasinghe countered that procedures precluded the
instruments aboard
the balloon from being contaminated on the ground or on the way
up, but he
acknowledged the possibility of contamination at the point where
the
collection was made.
"Earthly bacteria could get up to 15 kilometers from several
sources,"
Wickramasinghe told SPACE.com. "Also there is a chance that
unknown strains
of bacteria were lofted from the heights of the Himalayas."
Wickramasinghe said his group wouldn't reveal details until the
microbe is
studied further.
High-flying bacteria
Genge echoed the cautions of other scientists in saying that dust
carrying
terrestrial bacteria had been found in found the collection
filters of NASA
U2 aircraft doing similar research for 15 years.
"There is in fact enormous amounts of dust from the Earth's
surface at high
altitude, both artificial and natural in origin, and some of it
undoubtedly
carries bacteria," Genge said.
"Another possible form of contamination could also be human
waste," Genge
said. "Passenger aircraft fly at 10 miles altitude and eject
human waste
into the atmosphere. A fine spray of such liquid released into
the
atmosphere at high altitude will form tiny ice grains containing
bacteria
these will become widely dispersed."
NASA also commented on the claim, pointing out that living spores
have been
found previously as high as 10 miles.
"While NASA's astrobiology effort has certainly not come
down on the side of
panspermia, it has identified panspermia as worthy of serious
investigation,
along with more conventional ideas about the origin of life on
Earth," said
a press release out of NASA's Ames Research Center.
Other scientists also urged caution in interpreting the results.
Meanwhile,
recent studies by other groups have boosted panspermia into the
spotlight,
and many leading researchers are warming to the idea that
microbes may be
hardy enough to endure the rigors of space travel.
More evidence of alien microbes
Wickramasinghe and his colleagues, based at the recently formed
Cardiff
Centre for Astrobiology in Wales, also studied data from a 1999
Leonid
fireball, collected at 52 miles (83 kilometers) altitude. The
original study
on this data, produced by a team led by Ray Russell of the
Aerospace
Corporation, found organic compounds indicating that the building
blocks of
life could have survived a trip from space to Earth.
Working with the Leonid fireball data in a separate study, the
Cardiff team
concluded that the fireball actually did contained a signature of
microbes
that rained down from space. The study analyzed the infrared
light emitted
by the fireball, which the researchers say showed signs of
burning bacteria.
Further, they say this signature resembled the infrared spectra
of comet
dust.
"There is little chance if any of Earthly bacteria resident
at such great
heights," Wickramasinghe said.
But Genge flatly refuted the group's analysis of the Leonid
fireball data.
"The infrared spectra of the Leonid meteors are not evidence
for bacteria,
nor are the infrared spectra of comets," Genge said. He
added that the data
show a feature that is common in all organic material.
"If you took me, put me in an oven, dried me at 300 degrees
and then took my
infrared spectra, I'd have (this feature) too. This would
certainly not be
evidence that you'll find Matt Genges on comets.
The whole debate is reminiscent of claims of microscopic fossils
in a
meteorite from Mars, reported by NASA scientists in 1996.
Scientists are
still debating that finding.
Copyright 2000, Space.com
==============
(2) THIS COMET SHOWS WHY WE NEED SOUTHERN-HEMISPHERE SEARCHES
From http://cfa-www.harvard.edu/iau/cbat.html
Circular No. 7526
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA
02138,
U.S.A.
IAUSUBS@CFA.HARVARD.EDU
or FAX 617-495-7231 (subscriptions)
CBAT@CFA.HARVARD.EDU
(science)
URL http://cfa-www.harvard.edu/iau/cbat.html
ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)
COMET C/2000 W1 (UTSUNOMIYA-JONES)
On Nov. 19, S. Nakano, Sumoto, Japan, reported the visual
discovery on Nov.
18 by Syogo Utsunomiya (Aso, Kumamoto; 25x150 binoculars) of a
possible
comet with coma diameter 5' moving
rapidly southeastward in Vela. Attempts by several observers
(including A.
Hale, D. Seargent, J. Biggs, T. Urata, and J. Kobayashi) to
confirm the
object, at the request of Nakano and the
Central Bureau, were unsuccessful. On Nov. 25, A. C.
Gilmore (Mount John
University Observatory) reported the visual discovery of an
apparent comet
by Albert F. Jones (Nelson, New Zealand,
0.078-m f/8 refractor, 30x) while observing the variable star T
Aps at dawn;
Jones reported the comet as being diffuse with coma diameter
about 4' in
morning twilight. The possibility that Jones' object might be the
same as
that reported by Utsunomiya was explored by the Central Bureau,
and a search
ephemeris from plausible parabolic orbital elements fitted to the
Nov. 18
and 25 approximate positions was circulated to numerous
southern-hemisphere
observers. Confirming CCD astrometry was made by Gilmore
with the 1.0-m
f/7.7 reflector at Mt. John.
2000
UT
R.A. (2000) Decl.
m1 Observer
Nov.
18.817 9
04.0 -41
22
8.5 Utsunomiya
18.833 9
04.2 -41
27
8.5 "
18.847 9
04.4 -41
31
8.5 "
25.64 13
49.8 -77
05
8 Jones
26.42295 15 36 22.31 -76 23
51.5
Gilmore
26.42506 15 36 37.51 -76 23
31.7
"
26.42772 15 36 57.31 -76 23
05.1
"
26.42998 15 37 13.94 -76 22
43.8
"
26.55906 15 52 38.76 -76 00
58.0
"
26.56010 15 52 46.20 -76 00
47.4
"
26.56126 15 52 54.24 -76 00
34.8
"
26.56207 15 52 59.84 -76 00
25.6
"
The following preliminary parabolic orbital elements by B.G.
Marsden are
heavily weighted toward the Mt. John accurate positions:
T = 2000 Dec. 26.56
TT
Peri. = 51.52
Node = 10.81 2000.0
q = 0.3214
AU
Incl. = 160.16
(C) Copyright 2000 CBAT
2000 November
26
(7526)
Daniel W. E. Green
=========================
(3) COMET UTSUNOMYA-JONES: A SECOND BINOCULAR COMET FOR
CHRISTMAS?
From NearEarth Net, 26 November 2000
http://meteors.com/cometlinear/on_november_18th.html
By Mark Kidger
On November 18th a Japanese amateur astronomer found a moderately
bright
comet with 25x150 binoculars. Syogo Utsunomiya said that the
comet was
magnitude 8.5 and moving rapidly, indicating that it was close to
the Earth.
Utsunomiya is not a beginner in this as he had already discovered
the
moderately bright Comet C/1997 T1. A whole series of very
experienced
observers tried to confirm the discovery and failed. This is not
actually an
unknown situation as some comets move so fast that they can be
extremely
difficult to relocate, particularly when close to Earth so that
parallax may
even shift the comet significantly for one observer with respect
to another.
Then, at dawn on November 25th, a New Zealand amateur astronomer,
Albert
Jones, saw what appeared to be a comet in the field of the
variable star T
Aps when observing with his 3-inch reflector. Jones is a
reputable comet
observer and was well-prepared for this moment even though he had
never
discovered a comet himself. Even though Jones's comet was some 90
degrees
away from the one seen by Utsunomiya, it was immediately
suspected that they
might be one and the same.
The following morning, Mount St. John observatory in New Zealand
recovered
the comet using an ephemeris prepared assuming that the two
comets were one
and the same. In just 18 hours, it had moved another 6 degrees.
At present there are just three positions for the comet and only
one of
those - the Mount St. John confirmatory CCD observation - is an
accurate
position. The very rough orbit suggests though that this comet is
unusually
close to the Earth and will reach perihelion at the orbit of
Mercury.
According to this orbit, closest approach was 0.280AU (41 million
kilometres) on November 25th. The comet is expected to reach
perihelion
around midday on Boxing Day - December 26th - at 0.32AU (48
million
kilometres) from the Sun.
By mid December the comet should be slightly brighter than
magnitude 7,
having brightened only slightly from its current magnitude 7.5.
Although
currently near the South Pole, it will rise rapidly in
declination a s it
approaches perihelion and will be north of the Sun in
mid-December and
observable from the northern hemisphere. However, additional
observations
may change this orbit substantially and, almost certainly will
change it.
However, this is a very small and diffuse object. Its absolute
magnitude is
estimated to be 10.5 - this would be its theoretical brightness
when
simultaneously at 1AU from the Sun and the Earth. This is nearly
50 times
fainter than an "average" new comet and 400 times
fainter than Comet Halley.
Such comets often fail to even reach perihelion, let alone
survive it. My
best guess is that the comet will probably disappear before
perihelion
unless we are unusually lucky. This doesn't mean a LINEAR-type
fragmentation
- such disappearances usually involve a comet getting larger and
diffuser
until it finally fades out of sight. Comet C/1997 N1 (Tabur) had
an
identical absolute magnitude and just vanished four weeks after
discovery
and well before reaching perihelion at almost the same distance
from the
Sun.
-----
MODERATOR'S NOTE: I wish to make one correction to Mark's report:
I
understand that Albert Jones actually has been credited with the
discovery
of a comet before. He discovered a comet in August 1946, and in
being
credited with comet discoveries more than 54 years apart, he has
broken a
new record. Furthermore, at the age now of 80, be seems to be the
oldest
person credited with the discovery of a comet, the previous age
record being
held by Lewis Swift, who was 79 when he found his last comet in
1899.
Congratulations, Albert!
=============
(4) LIFE UNDER BOMBARDMENT
From Ilan Manulis <ilan@trendline.co.il>
Dear Benny,
I think the information provided in the following Web page might
interest
the readers of CCNet. It portraits a possibility that life, in
its most
primitive form, might have existed even during the Late Heavy
Bombardment
period (between 4.1 and 3.8 billion years ago).
http://nai.arc.nasa.gov/index.cfm?page=lifebombard
Best regards,
Ilan Manulis
Chairman, Solar System Small Objects Section
The Israeli Astronomical Association
================
(5) LIFE UNDER BOMBARDMENT
From NASA Astrobiology Institute
http://nai.arc.nasa.gov/index.cfm?page=lifebombard
No-one knows when life first established a firm foothold on
Earth. Ask
around in the scientific community, though, and you'll probably
hear that
the surface of early Earth, before about 3.8 billion years ago,
was too
hostile an environment for even a lowly microbe to set up shop.
The main problem, as the conventional argument goes, was that
between around
4.1 and 3.8 billion years ago, Earth was constantly being
bombarded by
comets and asteroids. The disastrous effects of these impacts
would have
rendered the Earth's surface uninhabitable.
Not necessarily so, say a team of astrobiologists who are
studying the
oldest known sedimentary rocks on Earth. They have come to the
conclusion
that conventional wisdom on the subject may need some revision.
Their
conclusions will be published in a forthcoming issue of the
Journal of
Geophysical Research.
The rocks in question appear to be a banded iron formation, or
BIF, from
Akilia Island in West Greenland. BIFs were deposited on Earth's
ocean floors
during the first 2 billion years of the planet's history. Iron
and oxygen
present in the oceans combined to form rust, which settled to the
sea floor
in layered sediments. Movements of the Earth's crust later pushed
some of
these sediments to the surface, where they can now be studied.
It's not possible to date the Akilia BIF sediments directly
because they
have undergone metamorphism - pressure cooking - so that
traditional
radioactive dating techniques cannot be used to determine their
age. But
jutting into these sediments are younger igneous rocks that can
be
accurately dated with these techniques.
An earlier analysis of this igneous rock, performed by a group
headed by Dr.
Allen Nutman of the Australian National University, put its age
at 3.85
billion years. And because the igneous rock intrudes into the
banded iron
formation, it must have formed later than the sediments did. So
the Akilia
sediments must have been formed at least 3.85 billion years ago.
Exactly how
old they are, there is no way to know. But they are more ancient
than any
other sedimentary rocks found so far on Earth.
Rocks this old are rare on Earth because tectonic recycling
action has
crushed, buried and melted all of the material that formed the
Earth's crust
during its first half-billion years of existence. Finding
sedimentary rocks
this old is important to geologists because they provide
invaluable clues
about what Earth was like in its early years.
Few people dispute the notion that between 4.1 and 3.8 billion
years ago,
our planet was heavily bombarded by debris from space, a period
known as the
Late Heavy Bombardment. If you look up at a full moon on a clear
night, you
see that its surface is riddled with impact craters. Scientists
who study
the size and distribution of those craters see clear evidence
that the Moon
underwent an intense period of impacts between 4.1 and 3.8
billion years
ago. Although no craters from this time remain on Earth, because
the Earth
and Moon are so near each other, the assumption is that Earth
suffered a
similar fate.
Ariel D. Anbar, an Assistant Professor in the Department of Earth
and
Environmental Sciences at the University of Rochester, working
with Gail L.
Arnold, a graduate student, decided to look for traces of this
bombardment
in the Akilia sediments. Comets and asteroids contain greater
quantities of
the chemical element iridium than does the Earth's crust. So
Anbar and
Arnold, members of the NASA Astrobiology Institute (NAI), probed
the Akilia
sediments for abnormally high traces of iridium.
They didn't find them. "Our naive expectation going
in," explained Anbar,
was that "these sediments date from this bombardment period,
so we should
see evidence of the bombardment in them, right? So we looked for
iridium in
these rocks and didn't find any. They were clean as a
whistle."
But earlier study of the Akilia sediments by one of Anbar's
collaborators,
Steve Mojzsis, had turned up a very different type of signature
in the
Akilia formation - a signature of biological activity. Mojzsis,
also a
member of the NAI, performed his analysis of the Akilia sediments
while at
the University of California San Diego.
Carbon atoms come in two distinct forms, or isotopes. Carbon-12
atoms, the
lighter of the two, contain 6 neutrons; carbon-13 atoms contain 7
neutrons.
Microorganisms that take in carbon dioxide prefer to use the
lighter
carbon-12 atoms to construct the organic building blocks of which
they are
made.
When ancient ocean-dwelling organisms died, the carbon that was
formerly
part of their living tissue settled to the ocean floor, becoming
part of the
sedimentary material deposited there. When Mojzsis found that the
Akilia
sedimentary rock samples contained higher-than-normal quantities
of
carbon-12, he concluded that biological activity must have been
taking place
at the time the sediments were formed - at least 3.85 billion
years ago.
So Anbar, Arnold and Mojzsis were faced with seemingly
contradictory
evidence. Life appeared to have been flourishing during the
period of the
Late Heavy Bombardment, at a time when Earth's surface was
thought to be
uninhabitable. And traces of the bombardment were nowhere to be
found in the
Akilia rocks.
The solution lay in quantifying more carefully the effects of
bombardment,
using models developed by NAI member Kevin Zahnle at the NASA
Ames Research
Center. The essence of these models is that they treat the
bombardment as a
series of impact episodes, rather than assuming continuous
pummeling of the
Earth. They also take into account that smaller impact events are
far more
common than larger ones.
The Akilia sediments would not be expected to contain telltale
traces of
extraterrestrial iridium unless a massive asteroid had slammed
into the
Earth, spewing iridium into the global environment, precisely
during the
period when the Akilia formation was being deposited. Zahnle's
models
indicate, however, that even during the Late Heavy Bombardment,
such massive
impacts were rare - too rare for there to be much chance of
seeing their
signs in sediments like those found on Akilia Island. So it made
perfect
sense that the sediments didn't contain elevated levels of
iridium.
Anbar and his colleagues reason that if the bombardment had a
smaller-than-expected effect on the composition of sediments, it
may also
have had a smaller-than-expected effect on early life. Although
small
impacts were more common during the Late Heavy Bombardment than
at any time
since then, each such impact would destroy life at the surface
only in one
small area, not globally. Only the rarest, most massive impacts
had the
potential to wipe out all life on the planet's surface.
Zahnle's models indicate such impacts occurred only once every
ten to one
hundred million years. Moreover, the worst of their effects
lasted for only
about ten thousand years, after which time conditions on the
Earth's surface
returned to normal. "So during most of this violent period
of Earth's
history," says Anbar, "the Earth's surface - if you're
a microbe, anyway -
was a perfectly balmy place to be. Which runs contrary to this
picture that
is out there that this was a very inhospitable period of time for
life."
That still leaves open one important question: Where could life
hang out in
safety during those rare, massive impact events that caused the
surface
literally to boil away? One suggestion is that hydrothermal vents
might have
filled that role. If life migrated down to these vents - or
perhaps even
began there - it could have continued on during major impact
events,
oblivious to what was going on the surface. And when the
environment topside
returned to habitability, life could have moved back up and
recolonized the
surface.
"So as long as microorganisms had places on the Earth where
they'd be
sheltered from really massive impact events," concluded
Anbar, "there's no
reason that they couldn't have repopulated the surface multiple
times. And
therefore there's no reason not to expect to find evidence of
life if you
find sediments from the earth's surface during the period of
heavy
bombardment."
Web-links
* Radioactive dating techniques are explained about halfway down
the
Web page, "Solar System Fluff."
* For an introduction to crater-counting techniques
* Information about life in deep-sea hydrothermal vents
* Stephen J. Mojzsis's research, which detected signs of ancient
life
in the Akilia sediments
* For a look at the instruments and laboratories used by Ariel D.
Anbar and Gail L. Arnold to measure iridium in the Akilia
sediments
=================
(6) LOOK INSIDE MARS' FROSTY CRATERS
From MSNBC News, 27 November 2000
http://www.msnbc.com/news/463318.asp
Nov. 27 - New images from the orbital camera aboard NASA's
Mars Global
Surveyor have documented the change of seasons on Mars, with
eerie patches
of frost within craters in the north and south.
IT IS SPRING in Mars' northern hemisphere, and the frost that
accumulated
during the most recent six-month-long winter has been retreating
since May.
The examples of frost-rimmed craters include Lomonosov and an
unnamed crater
farther north.
The unnamed crater has a patch of frost on its floor that is
expected to
persist through the Martian summer, based on how it looked during
the 1970s
Viking missions. Meanwhile, it's autumn in the southern
hemisphere, and
frost was seen as early as August in some craters. Later in the
season, the
southern frost line crept farther north, and a dusting of frost
began to
appear in Lowell Crater in mid-October.
FULL STORY at
http://www.msnbc.com/news/463318.asp
===============
(7) DUST AND THE ENVIRONMENT OF THE EARTH: CALL FOR ABSTRACTS
Call for abstracts for the Mineralogical Society Spring Meeting
"Mineral
particules and the Environment", Kingston, Surrey, April
19-20th, 2001.
This meeting will include a session on the effects cosmic and
volcanic dust
on the terrestrial environment. Papers on climatic change caused
by cosmic
and impact-related dust are particularly encouraged. Selected
papers from
the meeting will form the basis of a mineralogical society
special
publication.
Abstract deadline: 31 Jan, 2001.
For more information see the meeting website at http://www.minersoc.org. To
discuss your abstract before submission contact Matthew Genge,
The Natural
History Museum M.Genge@nhm.ac.uk
============================
* LETTERS TO THE MODERATOR *
============================
(8) NO EVIDENCE FOR COMETARY BACTERIA IN THE ATMOSPHERE
From Matthew Genge <M.Genge@nhm.ac.uk>
Dear Benny,
There are three reasons why the recent unpublished data of
Wickramasinghe
and Hoyle (CCNET, 27 Nov 2000) do not represent evidence for the
presence of
bacteria on cometary dust in the atmosphere.
(1) Contamination during balloon collection.
Even though contamination can be avoided during preparation and
launch it
cannot during collection of dust particles at altitude. In the
collections
of dust on inertial impactors mounted on U2 aircraft (flown at 20
km) the
majority of particles are terrestrial in origin (both natural and
artificial). Some of these particles will carry terrestrial
bacteria and
will definitely be collected along with cosmic dust at altitude.
Contamination by terrestrial materials is thus unavoidable. NASA
abandoned
the collection of cosmic dust particles in preference to U2
aircraft in the
mid 1970s because of the higher yields and lower contamination
from the
collection vehicle that the U2's offer.
Commercial passenger aircraft also fly at altitudes ~11 km and
eject human
waste. This is an excellent means of introducing aerosols
containing
bacteria at high altitude.
(2) Nothing new in new bacteria.
The discovery of new strains of bacteria is practically a daily
event and
does not constitute evidence for an extraterrestrial origin.
(3) The 3.4 micron band in infra red spectra.
Bacteria do show a 3.4 micron feature in the infra red, so do
many other
things including the abiotic macromolecular carbonaceous
materials found in
cometary dust particles collected by NASA in the atmosphere. The
presence of
this band in the infra red spectra of comets and the leonid
meteors is thus
merely evidence for the presence of organic compounds with
appropriate C-H
bonds not bacteria.
Matthew Genge
The Natural History Museum, London, UK.
================
(9) EARTH-BOUND VIEW OF LIFE IS A RISKY BUSINESS
From Chandra Wickramasinghe & Sir Fred Hoyle <xdw20@dial.pipex.com]
Dear Benny:
We cannot respond in detail to (1) and (2) of Matthew Genge's
comment
because the details are still under embargo. On point (3) the
relevant
question is how one could have organic dust that mimics the 3.4
micron
profile of a bacterium in the material around the persistent
meteor trail.
A similar question relates of course to the detection of 3.4
micron
bacterial features in cometary and interstellar dust. In these
latter cases
we have argued in extenso that the simplest way to account for
the fact that
nearly one third of the carbon in interstellar space is tied up
in the form
of particles that are spectroscopically indistinguishable from
bacteria, is
to invoke well-attested processes in biology (eg replication)
rather than
some ill-defined chemical processes. It is in such a much broader
cosmic
context that we attempted to model the Leonids data, which of
course would
not be easily understood by a person ideologically antagonistic
to
panspermia.
With the rapid accumulation of data that goes generally in the
direction of
supporting panspermia the adoption of an intransigent Earth-bound
view of
life would surely be a risky business!
Yours sincerely
Chandra Wickramasinghe
Fred Hoyle
==============
(10) MICROBES FROM OUTER SPACE AND THE EARTH MANTLE? ...
From Andrew Glikson <geospectral@spirit.com.au>
Dear Benny,
I refer to recent "news" (CCNet 27.11.2000) purporting
to claim the capture
by a scientific balloon of an "extraterrestrial
bacteria" some 16 km high in
the stratosphere. The following comments may be relevant, with
full respect
to proponents of the panspermia theory:
1. Unsterilised rockets and satellites, as well as scientific and
weather
balloons, routinely pass through stratospheric and higher
altitudes,
inevitably contaminating the stratosphere and outer space. A
small fraction
of the finest grained terrestrial carbon soot can also rise to
significant
altitudes, conceivably carrying microbes. To claim an
extraterrestrial
origin, a microbe needs to be captured hundreds (preferably
thousands) of
kilometers away from Earth by a sterilized spacecraft.
2. It is claimed that the bacteria is "unlike any known
strain on Earth",
but I am unaware of any molecular biological evidence regarding
this
absolutely critical point. To date only a small part of
terrestrial microbe
species have been identified and classified. To substantiate an
"extraterrestrial" claim, the microbe will need to be
shown to be distinct
from known terrestrial microbes in some fundamental sense, for
example if
its nucleic acids and proteins show different structural symmetry
(chirality) such as distinguishes meteoritic from terrestrial
amino acids
(Zhao and Bada, 1989).
3. Since microbe spores are known for their remarkable resilience
under a
range of pressure, temperature, pH and radiation conditions -
which is the
very basis for the panspermia hypothesis of their space transport
- why
can't such microbe spores be released from the Earth surface for
as short
distances as 16 km upward? After all - the microbes have to be
originally
released from SOMEWHERE (i.e. another planet? or a comet?) - why
not from
Earth?
4. According to Okham's Razor principle - central to scientific
research -
while working hypotheses can always be entertained, where a
simpler
explanation (one invoking fewer unknown variables) exists for an
observation
it is to be preferred to a novel explanation - at least until
clear evidence
emerges. To claim an extraterrestrial origin of a 16 km-high
bacterium is,
in principle, no different than claiming that nanobacteria which
have
actually been documented in drill cores several kilometers
beneath the Earth
surface (e.g.. Uwins et al., 2000) are derived from the Earth's
mantle ...!
"Extraordinary claims require extraordinary evidence"
(Carl Sagan).
Sincerely
Andrew Glikson
A.N.U.
Canberra, ACT 0200
===========
(11) AND FINALLY: BAD NEWS FOR TECHNOPESSIMISTS - INTERNET
SURPRISINGLY
ROBUST
From Physics News <physnews@aip.org>
PHYSICS NEWS
UPDATE
The American Institute of Physics Bulletin of Physics News
Number 513 November 22, 2000 by Phillip F. Schewe and Ben
Stein
THE INTERNET IS SURPRISINGLY ROBUST, and it remains connected on
a global
scale even if a randomly chosen 99% of its connection points
break down.
However, it is relatively fragile if
its most highly connected points are selectively knocked
out. These are the
conclusions of researchers applying physics principles and
precise
mathematical models to the study of the
worldwide computer network. The Internet consists of computer
networks (most
commonly, "local area networks") connected by various
devices, known as
routers and hubs. For simplicity's sake,
researchers consider each connection point as a generic
"node." Previous
work suggests the fraction of Internet nodes having k connections
is
proportional to k^-a, for some number a. This is a
"scale-free power law
distribution," which occurs commonly in nature and appears
in the frequency
of earthquakes and the size distributions of clouds and
mountains. Unlike an
exponential distribution, a scale-free power law distribution
decays very
slowly, meaning in this case that there is a large proportion of
computers
that still have a significant amount of connections. Recent
computer
simulations of scale-free networks have shown that the Internet
is resilient
for this reason (Albert et al., Nature, 27 July; Albert-Laszlo
Barabasi,
Notre Dame, 219-631-5767, alb@nd.edu;
see also The Industrial Physicist,
December 2000). The latest work now puts this conclusion on a
firm
mathematical footing. Two independent groups (Reuven Cohen, Bar
Ilan
University, Israel, 011-972-8-9370131, cohenr@shosji.ph.biu.ac.il;
Duncan
Callaway, Cornell, 607-255-9174; dc52@cornell.edu) apply
percolation theory,
developed by geophysicists interested in estimating how much oil
they could
extract from reservoirs in a porous medium. Percolation theory
deals with
systems containing points ("sites") and connections
between them, and it
analyzes the behavior of the system when one removes some of the
sites or
connections. Combined with the insights from the scale-free
distribution,
the powerful percolation-based approach may help Internet
architects to
maximize resistance against Internet attacks, by controlling the
distribution of nodes having certain numbers of connections.
(Cohen et al,
Phys. Rev. Lett, 20 Nov (Select Articles); Callaway et al., Phys.
Rev.
Lett., upcoming.)
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