ASTROBIOLOGY - Extraterrestrial
" Is Life a random accident, or is the Universe in some way designed to produce it?
In an infinite Universe...everything that can happen will happen,
an infinite number of times" ... Authur C. Clarke
Throughout human history man has wondered about the stars
and possibility of extra-terrestrial life.
"Beyond the known World"
Man has always striven to expand his known territory.
In our current age, we have begun a serious
Search for Extra-Terrestrial Intelligence.
The discovery of extraterrestrial life would have significant
biological and philosophical implications
Our world view is very ANTHROPOMORPHIC
Our science and religions are based on a Humans only beliefs
The Question: Is our world (LIFE) unique or
is there animal life elsewhere in the Universe?
How Many ? of you believe that life exists elsewhere in the galaxy?
RARE EARTH Hypothesis vs DRAKE EQUATION...
is supposition that procaryotic-like organisms are common in planetary
systems of the universe, but animal life (INTELLIGENT) is very rare... based upon:
1. bacteria evolved on Earth as soon as environment allowed it,
and they inhabit extremely hostile terrestrial environs,
not unlike what might be found in other planetary systems
2. larger, complex (animal) life occurred late in Earth history
(Cambrian Explosion) under restricted environmental conditions
and higher life required a unique set of circumstances that
MAY NOT be common in other planetary systems
Single celled procaryotic extremeophiles may exist everywhere, but a transition
to multicelluar animals can occur only on a small fraction of planets, & only a
few of those might lead to extraterrestrial intelligence. EX: the dinosaurs
survived for 150 m.y., yet without their chance extinction human life might
not have evolved.
The Rare Earth supposition conforms to the Scientific
in that it is a TESTABLE hypothesis
a) use telescopes (Hubble) to find planetary systems
b) we can search for procaryotes (Mars missions)
c) we can search for SETI via radio-telemetry
d) we can send probes (satellites - Voyager)
Likely Ways (3) in which we might Discover Extra-Terrestrial Life.
IN METEORITES (& rocks from MARS
Murchison Meteorite - (Australia in 1969) - 1st real attempt...
contained many amino acids & things that look-like fossilized single cells.
Moon Rocks - a 2nd real attempt at search for extra-terrestrial life... nothing.
1976 VIKING Probes to Mars - were next attempts - mostly unsuccessful/inconclusive.
1997 - McKay Group of NASA & ALH 84001 meteorite
holds polycyclic aromatic hydrocarbons...
Even if life were discovered in a extra- terrestrial meteorite, it doesn't mean life evolved independent of Earth... ricochette Idea (see figure)
Swedish chemist, Svante Arreheinus,
suggested that microbiological life arose elsewhere in the universe and
was seeded onto our planet by meteorite...
2) SENTIENT RADIO SIGNALS FROM THE UNIVERSE
Radiotelescope eavesdropping SETI - Search for Extraterrestrial Intelligence
Arecibo - largest radio dish (Puerto Rico) - effective to 4,000 light years
False alarms - 1967 - Jocelyn Bell, Ph.D. candidate at Cambridge,
detected regularly pulsating radio signal (called LGM - little green men)
that was finally identified as rotating neutron stars
Distances/probabilities of success are slim to none
nearest star 4 light years away
our measurable universe is about 100,000 light years wide
and it would take a radio signal 100 years to go that far
Marconi - (1895) - so we've been broadcasting for 100 years
imagine - our first message is "I Love Lucy"
Milky Way - 400 billion stars
impossible to listen to all with radio-telescope or
look at each with Hubble Space telescope
Nov. 16, 1974 - Arecibo sends signal
at 2.38 GHz at 3 trillion watts
(strongest man made signal ever), which was aimed at M13 star cluster some 25,000 lya.
Other Earth signals might include...
Pioneer 10 (Mar 2, 1972 satellite) 1st man made object to leave solar system
will reach another star system in about 1,000 years
maybe a better idea... why not an alien artifact - ala 2001:
A space Odyssey
could be.... set to signal us when we reach certain technological level...
could be... interrogate-able directly, like an interactive computer
DIRECT CONTACT VIA ALIENS &/or UFO's ...........
well why not ?
CLOSE ENCOUNTERS OF THE
Reasons we've Never Seen an ET
DRAKE EQUATION and Radio Astronomy
The current astrobiology paradigm is the view that alien civilizations do in fact exist and are
numerous enough likely to be scattered among all the stars, but isolated from one another
by the emptiness of interstellar space. Just for Earth's own galaxy, the Milky Way,
experts have estimated that there might be up to one million advanced societies.
The notion that alien civilizations are ubiquitous arose about forty years ago.
The possibility of searching for ET's by radio astronomy was proposed by Giuseppe Cocconi
and Philip Morrison in journal Nature in 1959. First project was called OZMA, when
Dr. Frank D. Drake, then a young astronomer at a federal radio observatory in West Virginia,
in 1959 was the first to scan the skies for faint alien signals, from 2 nearby stars. He was
quickly joined by like-minded experts, including Cornell astronomer Dr. Carl Sagan.
Dr. Drake laid out his ideas in 1961, in what came to be known as the Drake Equation.
The equation made educated guesses for the rate at which stars form, the fraction of stars
with planets, the number of those planets on which life arises and so on, including the average
lifetime of technological civilizations. By his equation Drake estimated that the Milky Way had
about 10,000 civilizations capable of interstellar communication.
Later, Carl Sagan revised the calculations and raised the estimate to a million alien worlds.
Since the cosmos holds hundreds of millions of galaxies, by that analysis the total number
of alien societies could be astronomical. One estimate put the number at roughly 10 trillion
alien intelligent societies.
Theory of PLURALITY and PLAUSIBILITY...
given that : the Milky Way has
of stars -
many stars may have planetary systems like our own... none discovered yet
given that : Cosmology believes that the
portion of the Universe we can see and measure
is a typical (represntative sample) of ALL the UNIVERSE
and an infinite abundance of matter is present in an infinitely vast universe...
given that : same physcial laws that lead
to formation of life on Earth
are present EVERYWHERE,
THEN : LIFE &
CONSCIOUSNESS should emerge elsewhere
as they have here ?????
Some WILD GUESSES: Drake Equation
OBSERVABLE UNIVERSE = 100,000,000,000 galaxies
if only 1% have planets = 1,000,000,000 planets
if only 1% are Earth-like 10,000,000 Earth's..... etc
|PROPERTIES of EXTRATERRESTRIAL LIFE|
IDEAS on ALIEN LIFE FORMS
might even look like us -
Law of Biological Convergence......
states similar organs have evolved independently in widely different species
EYES, in many species have same function, but different evolutionary origins
LIMBS, in fish/mammal are for motion, but evolved from different structures
WINGS, in bats/birds have similar functions, but different evolutionary origins
THUS Aliens and Man may look alike for they evolved under same physical laws
So what will the ET's look like ?????
- A sentient alien might have...
a spherical brain encased in a protective shell located above the ground
with sense organs situated near brain to reduce need for long information channels
with limbs for locomotion
limbs... even in number for balance/stability
few in number for efficiency
with biochemistry similar to us......based upon DNA/RNA/proteins
Likely to be non-human, i.e., some sort of "BORG"
artificial intelligence is very likely to appear & quite soon
Big Blue - May 12, 1997 beats the World's Chess Champion
machines translate text, play chess, neural nets = microchips implants
a SETI signal is likely to be machine based.
some evolutionists believe biological intelligence is in transitory phase...
a conscious, intelligent machine could have human intellect (STARTREK)
WHY DOES MODERN MAN LIKE TO BELIEVE IN
Some Religious Reasons:
a beneficient God would desire to endow other worlds with life
God would not have made so many stars just for the purpose of MAN alone
An infinite God could scarcely find the opportunities to enjoy himself,
to exercise his Godhead, if a single planet were the sole seat of His activities
Some Contemporary Human Beliefs:
1877, Giovanni Schiaparelli, describes Martian Canals...
Lowell Observatory (AZ) founded to view engineering society that made the canals
1898, H.G.Wells - War of the Worlds - Martians invade Earth 1930's
Orson Wells broadcast on Halloween is believed by Eastern seaboard
WWII - Warner von Braun - missles and rockets = ability to leave Earth 1940's
popularity of UFO's rises... (UFO's are common throughout history of mankind)
1950's to present --> Superman to Star Wars and Star Trek popularity
1953, Miller/Urey (Chicago) - Origin of Life Experiments... aa's to life route is possible
for further information I recommend the book... Are We Alone? Philosophical Implications of the Discovery of Extraterrestrial Life. by Paul Davies, professor of Natural Philosophy at University of Adelaide, Basic Books, Orion Productions, Harper Collins Publishers, Inc., 1995
back last update - 14 May 2003
Department of Biology,
University of Miami,
Coral Gables, FL 33124-4621
14 May 2003
GREATEST SCIENTIFIC REVELATIONS...
If we were to discover extraterrestrial sentient life,
it would be THE greatest scientific revelation in the history of man.
Some of the Great Revelations of Science have included...
1) Copernicus... Earth is not center of astronomical universe
2) Darwin... the processes of evolution and natural selection
3) Watson/Crick... DNA is the chemical basis of life
4) ??? "Evolution of animal "LIFE" is independent of
a consequence... if we believe that ET's do exist,
wouldn't it be best for the human
species to be politically unified and speak with a single united voice.
The Cambrian Explosion... tbl 5.1 pg 467
a period of geological time [from roughly 543 mya to 490 mya]
marking the emergence of (sea) ANIMAL life
see great diversity of fossilized animals absent in late Precambrian
an adaptive radiation due to (?) unique circumstances (?)
most extraordinary biological event on our planet
by 505 mya... majority of all animal phyla (between 28-40) had appeared
all basic animal body plans had been established
Possible causes of rapid evolution of animal life in Cambrian Explosion...
1. O2 levels reached some critical value - favored oxidative metabolism
favored biochemical evolution allowing making of hard skeletons
2. large amounts of nutrients became available
phosphorites, nitrates, & Fe (via deep sea upswellings)
3. temperatures become moderate
4. continental drift (which lasted 10-15 my) was occurring at this time
Extremophiles (bacteria that live in very hostile environments)
the origin of microbial life elsewhere in the
DOES NOT mean that Natural Selection will inevitably lead it onto
intelligent animal life.
While bacteria have been on Earth since the beginning, animal life
only appeared recently (500 million years ago).
The Widely Held View is that ET's do Exist.
FERMI PARADOX: in 1950 Enrico Fermi, a prominent nuclear physicist,
if ET's are common place, "WHERE ARE THEY ?" Shouldn't their presence
5 Reasons we have never seen an ET...
1. inter-stellar travel is NOT feasible
ans: no principle of physics say interstellar travel is not feasible
even at 20% of the speed of light, we could get to nearby
stars in a decade
2. ET's are searching for us, but are not here yet...
ans: an civilization with rocket technology should be able to cross
the galaxy eventually (in the 12 billion year history of the
universe someone should have been here by now)
3. ET's don't like to travel to far from home...
ans: human nature has always been one of expansion and colonization.
colonization grows exponentially (see article)
the time limits to colonizing the Universe are the
speed of rocketry and the rate of establishing the new colony.
Let use a trip rate of 100 years and 400 years to establish a colony
The universe if about 100,000 light years across...
humans could leap frog (planet to planet) across the known Universe
in 3.75 to 5.0 million years, a mere "second" in a 12 billion year old
Universe. Humans took 5,000 years to go from caveman to space
flight, thus the upper limits of colonization might be only
50 million years
4. ET's are here, but don't like us (or have a 'Prime Directive')
have a policy of non-interference, or they came & left
5. We are ALONE and are the most advanced life-form in the galaxy