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From the first spark of life to the first starships

The Rise and Fall of Star Faring Civilizations in Our Own Galaxy

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No human being can truly fathom the immense size of our universe, and the untold trillions of star systems it contains. But what if we narrow the scope way down to a single, solitary galaxy (our own) out of all the hundreds of billions of galaxies in that fraction of the universe we can see?

Sorry. We can't even comprehend that. For it includes possibly a trillion wildly diverse planets, ranging in size from smaller than our Moon, to 50 times larger than Earth. No, most of us can barely list a dozen of the one hundred plus nations on Earth itself. So it's no wonder our home galaxy is beyond our understanding, in most ways.

But still, we can take the meager scraps of knowledge we've so far collected about our galaxy and ourselves, and speculate on the present and future of beings such as we in this vast island universe of ours...

Page table of contents

Likely stages of star farer development

1. Natural processes. Coalescence of a solar system complete with planets.

LOCAL TIMING NOTE: Our own solar system and planets appear to have required no longer than 30 million years to take basic form. END NOTE.

-- Earth formed twice as fast as was thought [""] by Will Knight;; 28 August 02

-- Earth older than thought [""]; 29th August 2002; Ananova

In recent years I've seen wildly varying estimates of how many stars presently exist in our galaxy, from a low of 100 billion to a high of 500 billion. The differing estimates come from a variety of experts and dates, with no clear trend as to whether the 'final' number will be at the low end or high end of the scale. So maybe a number smack in the middle of this range would be appropriate here. Say, 300 billion? We'll also assume that this number is roughly maintained throughout the time range relevant to us here, by virtue of new stars replacing dying ones.

-- SETI Institute and Chicago Sun-Times (found on or about June 30, 1997)

There's an estimated 400 billion stars in our galaxy, and on a clear night in a northern hemisphere desert setting, we can see around 2000-3000 of them in the sky.

-- the Online Newshour (PBS) (8-22-97 datestamp)

It appears likely that any and all star systems in the Universe centered on stars similar to our own will possess a family of planets as well.

-- Contact: Very modern discoveries. A FLORIDA TODAY Space Online special report By Todd Halvorson and Robyn Suriano, FLORIDA TODAY; Contact: Is Anyone Out There? 1999, seems a related or alternative title for the same article;

There appear to be billions of potential Earth-type planets in our galaxy. Not all of them will give birth to life-- but many might.

-- American Association: Starlight 'reveals billions of Earths' By David Derbyshire, Science Correspondent, in San Francisco, ISSUE 2098, 21 February 2001, Telegraph Group Limited,

Our galaxy may host as many as 50 billion 'Earths'.

-- 'Hungry' stars reveal planet presence [the names of both Pallab Ghosh and Jonathan Amos are attached to this article], 20 February, 2001, BBC News Online

-- Universal Earth Planets like Earth are probably commonplace in the Universe, reveals a stellar analysis, by Eugenie Samuel; New Scientist News; 20 February 2001

-- New clue to Star Trek version of the universe by Tim Radford; The Guardian; February 21, 2001

sideways view galaxy

92% of 300 billion is 276 billion.

Where do we get the 92% figure? It stems from the nature of our galaxy itself. Some 8% of the total stars in the Milky Way galaxy may exist in the 'halo' rather than core or luminous disk. As the halo is of immensely greater volume than the core and disk, and the density of stars populating the halo much lower than elsewhere, the distances involved for that 8% of stars within the halo will be wildly out of whack compared to the main bodies of core and disk focused on here. In other words, most civilizations living in the halo will be so far away from everyone else that they may have no hope of practical contact with others at all, forever and ever.

For this reason I will not here consider the possibility of intelligent life in star systems trapped in the vast isolation of the galactic halo. They may well exist, but unless they or we develop some pretty miraculous technologies, we'll never meet or talk with one another-- ever.

While we're at it, let's remove the star systems from the galactic core/bulge from consideration too (some 10% of the total), leaving us with 246 billion systems. Why? Too much happening in the vicinity to allow intelligence a reasonable chance to develop on the worlds trapped there. Too many and frequent hard radiation baths, too many cosmic collisions and explosions, etc., etc. Sure, there'll be microbial life all over there, and maybe even some more complex lifeforms here and there. But any intelligent beings in the vicinity likely didn't originate in such a place.

The central bulge of a particular galaxy may contain up to 10% of the total stars within that galaxy.

-- Hubble Tackles Questions About Cosmic Bulges By Deborah Zabarenko, Yahoo! News Science Headlines, October 7, 1999

-- space : Barren galaxies by PHILIP BALL; 4-10-2000; NATURE NEWS SERVICE

But there's one very important condition to include here: time. For the purposes of this document we need to cut out of the discussion entirely many worlds from both the distant past and the too recent present.

From everything we know today, it'd be darn near impossible for something along the line of intelligent hominids (our own ancestors) to emerge on a given world in a shorter timespan than 4.5 billion years or so. Sure, there could be some worlds much luckier than ours environmental-wise-- but in that case there might be too few challenges to spark the rise of intelligence at all. Intelligence appears to require quite a few problems and hardships to overcome, for evolution to begin favoring it significantly over random mutations. So much 'luckier' worlds might develop no intelligence whatsoever. And even if they did, such worlds would likely be so rare as to be statistically insignificant for the purposes of this effort. So we'll assume 4.5 billion years to be the average time frame required for the emergence of intelligence on a given world.

This means that for our goal here of determining the likely number of technologically advanced civilizations present in our galaxy today, we'll need to dismiss all those worlds likely too young to have produced same by now. For this reason we'll cut out of the running all worlds younger than 4 billion years of age. As star formation then was around 3-5 per year (but has settled since to 1 per year), we'll use the value of three (an average) to find 12 billion 'too young' star systems to strip out of consideration here.

This leaves us with 234 billion systems (246 billion - 12 billion).

Then there's the matter of systems too old to form life-- because they were bereft of sufficient carbon during creation.

It appears that the element carbon, which is critically important to the creation of life as we know it, may not have existed in significant distributed quantity in the universe until around 6.6 billion BC. Thus, the 'clock' on the emergence of life anywhere in space may not have begun ticking until 6.6 billion BC.

There's a few other elements from which life might theoretically form in nature, such as silicon-- but so far research indicates this would likely be a rare event, and where it did occur the chances of it going on to develop into complex forms and then evolving further, to possess intelligence, would be still more remote. For this reason I will not consider naturally evolved silicon-based life or civilizations as statistically significant in this study.

The useful lifespans of stars like ours (apparently the type most conducive to life formation) appears to be only around 5 billion years (after which time they become inimical to life formation or survival). This also marks the natural spans of planetary existence relevant to life and intelligence development. The first planet-like bodies formed around stars perhaps around 12.5 billion BC. So perhaps all the systems formed between 12.5 billion BC and 6.6 billion BC should be taken out of the running for hosting native lifeforms of any significance. As the star system creation rate may have been considerably higher in the far past than more recently, we'll assume a creation rate of 4 stars per year over 5.9 billion years to get 23.6 billion systems which may be too old and carbon-short to have spit out any major lifeforms during their span.

This leaves us with 210 billion systems (234 billion - 23.6 billion).

So now we've stripped out systems created prior to 6.6 billion BC and those created after 4 billion BC, leaving us 210 billion systems.

Note that there's still a potential discrepancy here. Namely, those possibly life-bearing star systems created between 6.6 billion BC and 5 billion BC will have often either already been incinerated by their host star by now, or at least be beginning the cooking process. This would mean that if they haven't already produced intelligence, they probably never will. Or, if intelligence did appear, by now they're likely quite advanced and either moving themselves, their world, or both to more inviting locales-- or else they essentially destroyed themselves long ago.

But should we remove these worlds from the potentials roster? I say no. So they will be included in the proceedings.

It appears likely that the earliest time civilizations could arise in our galaxy may be now, or the relatively recent past. Factors supporting this include the time necessary for the creation of carbon-- an element essential to life as we know it. The Universe's production of carbon may have reached its maximum only around 6.6 billion BC-- or just two billion years before the formation of our own solar system.

Adding to this the time shown by Earth's own evolution to be required for the development of higher lifeforms makes it appear the earliest that carbon-based intelligence may have evolved would have been around 75% of the Universe's present age-- or maybe 3,000,000,000 BC (this is assuming a 12 billion year age for the Universe).

-- The Oldest Life-Form By Ray Villard, Special to, Sep 20 1999,

Silicon-based lifeforms are likely rare, arising primarily in environments too hot for carbon molecules to maintain integrity. The moment these silicon forms attempted to expand beyond their hot environs to other locales, they would probably be met and stopped by robust carbon-based forms, which seem to rule all cooler climes.

-- What Might E.T. Look Like? chat with Seth Shostak; June 30, 1999, and other sources

There appears to be roughly one new star created in our galaxy every year now. However, it appears that a few billions of years ago three to five new stars were being born in our galaxy every year-- along with the planets which would possibly produce the intelligence beings we're speculating about here.

-- The Chance of Finding Aliens: Reevaluating the Drake Equation By Govert Schilling and Alan M. MacRobert (based on an original piece in Sky & Telescope; last updated July 2000; Sky Publishing Corp

Although the majority of star systems in the galaxy are binary or trinary in nature (rather than orbiting a single star like our own), recent discoveries indicate such multiple star systems may be just as capable of forming planets as our own-- maybe even more so. So it would seem reasonable to assume that at least 80% of all the stars in the galaxy offer the potential for hosting a family of planets in their immediate vicinity.

210 billion times 0.8 makes for 168 billion stars with planets in the main disk of the galaxy, outside of the central bulge, and fitting the time frame chosen above.

Binary stars, NOT single stars like our Sun, appear to be the norm in the Universe.

-- SCIENTIFIC AMERICAN October 1995 Volume 273 Number 4 Pages 134-139

Binary and trinary star systems (the majority in the galaxy) may be capable of forming stable planetary systems too (similar to solitary stars).

-- "Planets doubling up" by Dr David Whitehouse, Sci/Tech, BBC News,, September 26, 1998

It's possible for a planet to orbit two or even more different stars at once. This is important because that means binary star systems (which make up a large proportion of galactic systems) or even triple systems are more likely to possess planets than they would otherwise. This new finding adds a third alternative to such systems-- shared worlds for both star A and B, in addition to worlds orbiting only A or only B, or both stars possessing their own exclusive systems of planets.

-- BBC News Online Sci/Tech Planet found orbiting two stars By Dr David Whitehouse, August 18, 1999,

This makes for 168 billion stars with planetary systems approximating our own, within the main parts of the galaxy. Or, 168 billion variations on our own solar system coming into existence in these regions over the past relevant portions of galactic history.

First Spark of Life to the First Starships Contents

2. The environmental lottery and the major life-spawning region of the galaxy. The appearance of at least one planet in a solar system suitable for spawning and/or hosting the simplest lifeforms with which we are familiar today

It could be that only a relatively narrow band of moderately metal-enriched star systems in any particular galaxy is suited to creating planets conducive to the generation of life. Assuming star density is distributed in a somewhat linear fashion from the core outwards to the edges, and that the moderate metal bearing systems are located in a band..."...about halfway out the galactic disk..."[see citation below]...perhaps only somewhere between 1 and 30 percent of the total stars in the galaxy might be expected to form the sorts of planetary compositions desired.

The creation of planets suitable for life may require moderate amounts of metal in their host stars and accompanying proto-system cloud, thereby suggesting that only a narrow band of any particular galaxy is suitable for producing lifeforms.

-- "Here Come the Suns" by George Musser, Science and the Citizen, Astronomy, Scientific American, May 1999

-- The Goldilocks effect: How other earths form just right; EurekAlert!; 27 JUNE 2001; US Contact: Ann Cairns 303-447-2020 x1156 Geological Society of America

A mere 1% of our galaxy may offer the best chances of housing planets highly suitable for the formation of life as we know it. Our own system is located within this 1% region.

-- Astronomers map 'habitable' galactic zone; Ananova Ltd ; Sunday 8th April 2001

As much as 90% of solar systems may be hostile to the formation of Earth-like planets possessing liquid oceans and gaseous atmospheres-- unless planets can form quickly enough to beat the incredibly short 100,000 year lifespan which may be afforded the related protoplanetary discs due to the evaporative effects from nearby rogue stars within perhaps the majority of star generating regions. This evaporative effect may leave many stars surrounded by mostly Mercury-type blasted planetoids.

-- Home alone by Stuart Clark; 26 April 2001; New Scientist Online News

-- "Survivor" Planets: Astronomers Witness First Steps Of Planet Growth - And Destruction [""]; ScienceDaily Magazine; 4/27/2001; Source: Space Telescope Science Institute (;

-- Barren world of stars By Dr David Whitehouse; BBC News Online; 27 April, 2001

-- Latest investigations of Orion nebula lower odds of planet formation; EurekAlert!; 1 MAY 2001; US Contact: David F. Salisbury 615-343-6803 Vanderbilt University

In at least some cases planets may form in a million years or less. At the time this particular reference was written, it was not yet known if faster than usual planet formation was compatible with the creation of Earth-like worlds.

-- Spontaneous creation puts planet development on fast track By Robert Roy Britt,; 12.08.99

-- Early planet formation triggers planet offspring; EurekAlert!; 8 DECEMBER 1999 AT 14:00 ET US Contact: Janet Wong 416-978-6974 University of Toronto

We're still in the process of determining the Earth's own history; so far new discoveries are tending to shorten the time Earth required for formation by leaps and bounds. So far though it appears unlikely the Earth formed in as brief a time as 100,000 years [citations concerning the possible speed of Earth's formation follow below].

One study places the age of the very oldest material formed in our solar system at 4.56 billion years. The scientists said the material appeared to have formed "phenomenally fast".

-- UH team IDs first material in solar system By Helen Altonn; Honolulu Star-Bulletin Hawaii News; May 11, 2000

Scientists have found a zircon crystal measured to be 4.3 to 4.4 billion years old, and declared it to be the oldest solid piece of Earth known to exist today. It is thought to have coalesced not long after the Earth itself was formed. Evidence suggests Earth itself formed some 4.56 billion years years ago.

-- Scientists identify crystal as oldest known solid on Earth By JOSEPH B. VERRENGIA, Associated Press; January 10, 2001; Nando Media/Nando Times;

It appears our solar system formed around 4.567 billion BC, with Mars forming some 13 million years later, and Earth following at 29 million years after the system itself came into existence. Earlier estimates put Earth formation at 60 million years after creation of the system.

-- Earth formed twice as fast as was thought [""] by Will Knight;; 28 August 02

A shock wave from a super nova around 4.6 billion BC may have helped initiate the precipitatation of rocky bodies like Earth and Mars from the gas and dust of the proto-solar system. Earth's core may have formed as early as only 20 million years after the shock wave passed through the vicinity. The rocky planets were basically completely formed within 30 million years of the coalescence of the solar system.

-- Earth older than thought [""]; 29th August 2002; Ananova

The raw materials required to build Earth-like worlds would be more rare in regions of the galaxy much further from the core than our own solar system. This would make the rocky planets formed there smaller than those closer in, as well as render them less likely to possess tectonic processes like the Earth's-- as a dearth of radioactive elements would make the bodies cooler as well. The lack of (or reduced) tectonic action would appear to make these bodies less likely to foster the emergence of life, and/or maintain such life for the lengthy periods required for evolution to work its ultimate magic-- creating intelligence.

Indeed, many other galaxies throughout the universe may just happen to be sufficiently short of the critical elements required so that they are utterly bereft of Earth-like worlds on which life might develop and flourish. Some entire galaxies might resemble the outer reaches of our own, in regards to planet formation.

-- space : Barren galaxies by PHILIP BALL; 4-10-2000; NATURE NEWS SERVICE

Let's go with a 15% figure, which splits the difference, and shouldn't be too far out of the ballpark to what the actual number is.

Note that as of mid-2002 new discoveries and calculations may be expanding the potential life-producing zone considerably-- but as information regarding these matters so far remains scarce and somewhat vague and uncertain in terms of likely consequences, I'm not including those findings in my considerations here just yet.

The heavy elements required for life formation may work at concentrations as low as 10% that found in Earth's Sun and original formative dust cloud.

Stars and planetary systems which theoretically possess similar compositions of heavy elements as our Sun-- plus considerably more time in which life could have developed (up to billions of extra years)-- exist towards the galactic core. With others like 47 Ursae Majoris sprinkled elsewhere too.

-- Scientific American: Feature Article: Where Are They?: July 2000 [""] by Ian Crawford

Of course, being rich in heavy elements and having a multi-billion year head start on Earth may not help much if your home region near the core keeps your world constantly bathed in lethal radiation, thereby preventing the development of complex life.

-- Review: Is anybody out there? [""], July 28, 2000, Review By L.D. Meagher of "Rare Earth: Why Complex Life Is Uncommon in the Universe" By Peter D. Ward and David Brownlee, Copernicus Books

A gamma ray burst from the explosion of an enormous star no further than 300 lightyears away may have aided in the coalescence of our solar system, by melting dust grains of the proto-system cloud to begin the formation of larger clumps of material-- chondrules. All the system's chondrule beads (totally altogether equivalent to the mass of a hundred Earths) may have been formed in about an hour or so by the gamma ray blast.

The researchers go further, speculating that the ratio of Sun-like stars which receive such a treatment in planet formation might be no higher than one out of a thousand. They also expect that such an event would have considerably accelerated the formation of planets in the solar system.

Keep in mind this is but one theory out of many, and yet to be proven or disproven.

-- A violent blast of radiation spawned the planets by Robert Adler, EurekAlert!, New Scientist issue 11th September 99,

AUTHOR'S NOTE: Some of the ideas in the article cited above may conflict with other notions listed elsewhere in this work-- such as those systems which form too quickly perhaps being doomed to form giant planets in eccentric orbits, which will effectively ruin the chances of inner worlds to develop higher lifeforms. If such a rare event did indeed contribute to the formation of our own solar system, it would seem to make our system appear more rare than other information has led us to believe-- and therefore make the evolution of intelligent life even more so (practically impossible, perhaps even unique to Sol system). IF, that is, such early conditions are relevant whatsoever to biological processes occuring much later on in the story. It would seem difficult to prove such a relationship for this particular event, so far as I can see. But the scientists submitting their paper seem to think they can make it relevant in some way. I don't as yet have access to their reasoning for relevancy, and their idea remains untested by the scientific community-- so I am not yet including it as a filter for star faring civilizations in this edition of Contact.

Note too that as we have plentiful proof for the idea that numerous other star systems (including many very far away) possess planets, the mere possession of a planetary system could not be theoretically prevented by other star systems not sharing with our own system a similar gamma burst with which to form their worlds. So it would seem the only place to apply this as a filter (if it did qualify, which I'm not yet satisified that it does), would be in the production of worlds specifically conducive to life formation, such as Earth. END NOTE.

The galaxy disk itself is some 100,000 lightyears wide, with the luminous disk averaging 1,000 lightyears thick and the nuclear bulge roughly 20,000 LY in diameter and 3,000 LY thick [The Natural History of the Universe by Colin A. Ronin, MacMillan Publishing, 1991, page 56]. Based on the speculations above (and references below), the 'life-band' or moderately metal enriched torus embedded within the galactic disk could be estimated to have a cross sectional height of roughly 1000 lightyears, an inner radius of 24,588 lightyears and outer radius of 25,412 lightyears (cross section width about 824 lightyears).

I assumed a distance from Sol to the galactic core of about 25,000 lightyears (a number centered between two varying figures found in references below).

Our galaxy's core is about 26,000 lightyears from our own solar system, according to Florida Today Space Online (datestamp 1-8-98)

Our galactic center is about 24,000 lightyears away from Earth, according to "'Supermassive' Black Hole Found In The Center Of Our Galaxy", National Science Foundation, 7 September 1998

This leaves us with 0.15 times 168 billion star systems, or 25,200,000,000 systems, in a volume of some 84 billion cubic lightyears.

So far as we know today, life-hosting worlds of robust quality must orbit a star within a certain distance-- not too close and not too far-- in order to sustain life (or else be geologically active internally due to gravitic or magnetic interactions with a larger body like a gas giant), and to obtain the correct mix and balance of elements from the proto system cloud mass in initial creation to nurture life's beginning. In our own system Venus seems too near the Sun, Mars just a bit too far, and Earth almost perfect. Planetoids may well have to be within a certain size range as well-- not so small or light in mass as to be unable to hold onto an atmosphere, and yet not too big either, with a gravity too crushing for complex molecules to form. The largest world which might allow the development of life like our own might be ten times larger than Earth.

It is estimated that the largest planet upon which Earth-like life could develop would be one roughly ten times the mass of Earth.

-- New Scientist: Captive moons [""] by Jeff Hecht, From New Scientist magazine, found on or about 1-25-2000

What's the smallest world which might evolve life like ours? One with 80% the Earth's diameter or half its mass, according to the specs for NASA's Kepler mission.

Even rocky worlds similar to Earth may develop harsh atmospheres more like gas giants if they are too large.

-- Stars and Habitable Planets; Sol Company; found on or about 10-4-2000

But keep in mind that life UN-like ours might still develop on worlds as small or smaller than the specs given above-- such as primitive alien microbes in the seas under the ice of Jupiter's moon Europa.

Anyway, we'll assume a 0.95 probability that there'll be a world of suitable mass, composition, and distance from a star (or internal geological heat inspiring gas giant) in any given planetary system to approximate minimal conditions required by life, from among those in the metal bearing band.

0.95 times 25,200,000,000 gives us 23,940,000,000 systems hosting at least one planet conducive to life formation.

As for rogue or 'orphan' planets (those expelled from star systems to drift alone and in the dark among the stars) possibly hosting life-- we'll assume these to harbor neligible chances for the development of anything near to intelligent, star-faring life.

Summary: We now have 23,940,000,000 systems in which life may have formed, in our native galaxy.

4-2-99 Newz&Viewz: The recent flood of new data on distant solar systems is conflicting with established ideas for how systems form and what 'average' system patterns might be

Rather than finding a nice and neat bunch of alien star systems basically similar to our own, instead we're discovering chaos incarnate. Bizzarre warped mutations of our system abound.

Apparently many systems suffer internal mass imbalances or disturbances from large masses passing nearby which prevent them from assuming or maintaining arrangements like our own system enjoys.

For instance, lots of the alien planets suffer scorching orbits nearer their host stars than our own Mercury, while others endure elliptical orbits similar to our own comets which mean part of the time they're baked in the vicinity of their home star and the rest of the time they're frozen in the outer reaches of their system (some worlds may even be thrown out of their home systems entirely by inopportune gravitic slingshot effects). Lots of the planetary bodies we've detected so far appear to be even larger than our own Jupiter (up to eleven times!), which poses a whole new set of challenges for order and potential biosphere development in a planetary system.

Jupiter-like worlds in long period cometary-like orbits could spell doom for smaller planets in a system which otherwise held the potential for developing biospheres. How? Whenever the immense Jupiter peer came careening into the inner system its mass would perturb the orbits of all the other planets, possibly even changing their orbits, throwing them out of the system entirely, or destroying them (a direct collision wouldn't be necessary; gravity alone could do the job in a near-miss, ripping a planet apart like Jupiter did the Shoemaker-Levy comet on that body's near miss of the gas giant in the months preceding the final collision). Fortunately, 95% of star systems may be free of such disasterous conditions...

-- "Search for New Planets Yields Confusion" By JOHN NOBLE WILFORD, March 2, 1999, The New York Times

-- "Lost Worlds? Exiled Planets Might Support Life"By Deborah Zabarenko, (Reuters)Yahoo! News Science Headlines, June 30 1999

Even our own Earth could have a potential rogue sibling or two out there somewhere.

"Scientist says Earth may have a long-lost 'twin'" By WILLIAM McCALL, June 30, 1999,, Nando Media/Associated Press

-- "Lost in Space" by David Watanabe,, July 01, 1999

The total mass of a proto-solar system's dust disk determines the speed by which planets will form. Less mass delivers much slower formation times, such as 10 million years or thereabouts, while more mass leads to more rapidity and violence in formation-- perhaps in as short a time as one million years. By implication, mass would also determine to a great extent the general composition of the resulting planetary system.

-- Early planet formation triggers planet offspring ,8 DECEMBER 1999, EurekAlert! Contact: Janet Wong 416-978-6974 University of Toronto

It appears logical to assume that the more rapid and violent the planetary formation process is, the more unbalanced the resulting system-- with the consquences possibly being inimical to higher lifeforms. So perhaps those systems which tend to form fastest are also those which end up with the Jupiter-like worlds in planet-killing cometary style orbits. And perhaps these conditions only extend to some 5% or so of star systems, as described before.

First Spark of Life to the First Starships Contents

3. The inevitability of life. We will assume the probability of life having begun (within one billion years or more) on any suitable world in the past history of the galaxy to be 1.00-- or absolute certainty.

LOCAL TIMING NOTE: Simple life seems to have appeared on Earth within a billion years or less of the planet's formation. END NOTE.

Extremophiles may have appeared on Earth around 3.8 billion BC or even earlier (Earth only formed around 4.596 billion BC, or 796 million years earlier than the possible appearance of extremophiles).

-- "From Deep in the Earth, Revelations of Life", by Kathy Sawyer, April 6, 1997 Washington Post, Page A01, and Earth formed twice as fast as was thought [""] by Will Knight;; 28 August 02

This may seem highly presumptuous to some. However, life appears inevitable, given the proper conditions-- which we are assuming to exist in some 23,940,000,000 star systems in our galaxy.

[For more on this topic please refer to The Inevitability of Life]

In some cases there may be two or more worlds in the same solar system capable of supporting life. In other systems there may be an asteroid belt existing in the ideal range from a star for life to appear and thrive, boasting a few dozen planetoids of sufficient mass and composition to act as miniature Earths, and the cumulative mass of the belt entire being sufficient to maintain the required gaseous atmosphere for nourishment.

In these cases of multiple life-friendly bodies, despite the 1.00 probability of life developing on them all within a few billion years after outer shell coalescence or hardening of the planetoids, the probability of two or more of these planetoids developing utterly independent and competitive civilizations within a time frame which would put them at odds with one another is so near to zero as to deserve a probability of 0.0 in our speculation here.

Even in those rare cases where such a star system did produce wholly unrelated, multiple intelligent races on two or more worlds, the timing of the appearances would likely be spread tens of millions of years apart-- so the different races would likely never encounter each other in any meaningful way so far as competition or conflict might be concerned.

I'm assuming here of course that when any two or more intelligent variations arise in close proximity to one another on the same world and at the same time, that one takes precedence over all the rest, effectively driving the others to extinction in short order-- just as happened with humanity's ancestors and their intelligent variants.

Summary: 23,940,000,000 star systems in which life most certainly has formed within our galaxy.

-- "NYU Chemist Supports New Theory For Origin Of Life", 12 MAY 1999 Contact: Josh Plaut,, 212-998-6797, New York University

The moons of giant planets throughout the Universe similar to our own Jupiter may often be fertile environments for the development of life. They likely will often fall short in one element however: possessing sufficient gravity to prevent the loss of their atmospheres to space over the long term.

But computer projections indicate that in many cases of natural system development, such giant planets will move deeper into their native systems after formation, possibly capturing a planet as large as Earth as a moon-- in which case the gravity problem would be overcome.

It is estimated that the largest planet upon which Earth-like life could develop would be one roughly ten times the mass of Earth. Even the largest of such worlds could be captured as moons by giant planets up to 10 times as massive as Jupiter-- and numerous such giants have been detected in other star systems.

But the giants may be just as prone to throw such planets completely out of their systems as capture them.

-- New Scientist: Captive moons [""] by Jeff Hecht, From New Scientist magazine, found on or about 1-25-2000

First Spark of Life to the First Starships Contents

4. The tenacious and robust nature of life. The development and survival of higher life forms

LOCAL TIMING NOTE: Complex life seems to have evolved from simpler forms on Earth around 700 million to 600 million BC-- or within 3.2 billion years of the first appearance of simple life on the planet.

Extremophiles may have appeared on Earth around 3.8 billion BC or even earlier (Earth only formed around 4.596 billion BC, or 796 million years earlier than the possible appearance of extremophiles).

-- "From Deep in the Earth, Revelations of Life", by Kathy Sawyer, April 6, 1997 Washington Post, Page A01, and Earth formed twice as fast as was thought [""] by Will Knight;; 28 August 02

-- Oxygen may be cause of first snowball earth, , 27 OCTOBER 1999, Contact: A'ndrea Elyse Messer 814-865-9481 Penn State

-- Snowball earth by Gabrielle Walker, New Scientist [""], 6 November 1999,

-- THE SHORTER, THE STRANGER From Science Frontiers Digest of Scientific Anomalies [""] #90, NOV-DEC 1993 by William R. Corliss, citing Samuel A. Bowring,, et al; "Calibrating Rates of Early Cambrian Evolution," Science, 261:1293, 1993. Richard A. Kerr; "Evolution's Big Bang Gets Even More Explosive," Science, 261:1274, 1993. R. Monastersky; "Siberian Rocks Clock Biological Big Bang," Science News, 144:142, 1993. Carol Kaesuk Yoon; "Biology's 'Big Bang' Took a Mere Blink of the Eye," New York Times, September 7, 1993. Cr. P. Gunkel

-- New Scientist Planet Science: Cast out of Eden [""] by Bennett Daviss, From New Scientist, 16 May 1998


Earth itself provides proof of extremely hardy microbial life that, once in existence, is extraordinarily difficult to kill. Nuclear weapons? You could kill a handful that way-- but only by pin point targeting. And you'd eradicate both mankind and the cockroaches-- plus use up every nuclear weapon on Earth-- before you even began to put a dent in their numbers.

Yeah, that's right-- you could blow up the entire Earth and there'd be at least some of these creatures that never even noticed.

So even gamma bursters aren't much of a worry to these buggers.

4-7-97 Newz&Viewz: Alien Life Found-- on Earth

These eerie creatures give you the impression they're from the planet Krypton-- since they love being pressure-cooked or frozen, can live comfortably under the crushing pressures of the sea bottom, or in the utter blackness and toxicity of crude oil nearly two miles underground, and often swim about in corrosive acid. They're much more difficult to kill off or exterminate than the mightiest monster of Hollywood films-- the Terminators included. You could essentially ram the Moon into the Earth, busting the Earth into just a huge mass of asteroids and comets, and these things would survive the calamity. Yes, even the awesome nuclear war-proof cockroach can't outsurvive these creatures!

Another 'super' aspect of them is that they are super-small: microscopic. Experts are calling them "extremophiles", while their official designation is "Archaea".

Scientists are giving these things a whole new fresh category of life to themselves, being that they are so wildly different from the previous comparatively fragile life forms we've been familiar with, like plants, animals, fungi, and bacteria.

The extremophiles are making us rethink our expectations about the chance for life in the Universe too, as things like extremophiles could live just about anywhere, and under almost any conditions. They'd surely thrive all over Mars or Venus, for example. Maybe even on Jupiter and Mercury. And passing comets could be literally bursting with the things.

Our own Earth-native extremophiles may have actually came to life so early that the planet itself was still being formed out of huge asteroids and comets smashing and melding together in a yet infantile solar system, 3.8 billion years ago or even further back.

-- some information from the Washington Post. The original article was titled "From Deep in the Earth, Revelations of Life", written by Kathy Sawyer, and appearing in the Sunday, April 6, 1997 Washington Post, Page A01

So at least certain types of microbial life will survive almost anything. But more complex lifeforms are far more fragile, requiring a much narrower and more moderate band of temperatures, as well as frequent or even continuous access to liquid water, and in many cases periodic sunshine as well. Many also require a complex infrastructure of other lifeforms in their environment, for a myriad of reasons-- of which only one is food. Complex lifeforms also require huge gobs of time to appear in the first place, evolve, and generate the mutually supporting biospheric infrastructure described before.

-- We Are Not Alone - Or Are We? [""]; 1/26/2000; Source: University Of Washington (

Note that all the above applies to intelligent life as much or more than to lower lifeforms-- but a world has to develop the layer of lower complex lifeforms from microbes first, before intelligent forms themselves can ever evolve. This 'mid-range' or intermediate layer of lifeforms is the one we're looking at here.

This stage takes us into the realm of catastrophic climate changes, which have the potential of spurring mass extinctions of higher lifeforms, and even pushing an entire civilized world all the way back to the microbial stage, in extreme cases. It's actually a toss up as to whether a technological society like ours of the late 20th/early 21st centuries could survive such a global disaster any better than, say, the common coyote-- to randomly select a complex lower lifeform compared to ourselves.

There's quite a few possible natural sources of such awful climate changes. One is a world being captured as a moon by a bigger planet, or physically ejected from its home system by the same gravity forces, as the larger world travels an eccentric orbit in-system, or appears as an unexpected rogue from the depths of space, merely 'passing through'. Similar calamities can occur with the passing of other stars too close to a living world's native system.

I haven't any estimates available on the frequency of planet-robbing stars passing too near other systems, but we might rate that as rare enough to be negligible in overall effect in this edition of Contact.

The gravity effects of system-native giants however has been quantified to be a problem in around 5% of star systems, as covered earlier in this paper.

But this still leaves massive geological upheaval, supervolcanic eruptions, and cosmic impacts of large asteroids and comets to wreak havoc on living worlds. As well as the occasional gamma ray burster. And other, similar disasters may also come from unexpected quarters-- such as enormous tsunamis created by vast underwater landslides, which might affect coastal settlements of half a world at once, and be potentially devastating not only to critically important populations of higher lifeforms which might live exclusively in such areas, but also to intelligent but still primitive cultures such as early man, which tended to settle such regions en mass due to the tempting local resources of food and other items.

[For more on this topic please refer to Critical questions and answers regarding the fate of higher lifeforms on alien worlds, based on Earth's own history.]

Whew! Talk about a litany of calamities! Anyway, keep in mind that higher life forms and intelligent beings universe-wide would likely have to cope with a similar series of challenges, on their own worlds.

And that's if they are lucky.

How on Earth can I say that? Because Earth itself seems to have been protected from suffering a much greater frequency of such catastrophes as outlined above due to the presence of Jupiter, Saturn, and the Earth's large Moon. The giant planets serve to sweep the solar system clean of marauding asteroids and comets (remember Shoemaker-Levy 9?), thereby reducing the number that can strike the Earth.

Just how essential were Jupiter and Saturn's gravity wells to the long term survival of complex lifeforms on Earth? How crucial was the Moon's creation and presence to Earth's higher lifeform's fate? And how common might such conditions be among other star systems? These questions could be important ones in regards to calculating the chances of complex life and living intelligence developing elsewhere in the galaxy.

Earth's Moon is oversized as such things go-- judging from our own solar system few planets anywhere often come to possess a moon as large in proportion to the primary world as the Moon is to Earth. Yes, Pluto's Charon does manage to surpass this ratio, but that may be a special case too, with Pluto perhaps not being a true planet but a planetesimal left over from the solar system's formation (Pluto's pretty small; four planets in our solar system possess moons which are larger than Pluto itself-- including Earth's own Moon). And Charon may merely be a slightly smaller planetesimal caught in the same gravitic currents as Pluto, from a group of similar bodies found in the Kuiper belt.

Anyway, Earth's Moon not only has helped stabilize the wobble of Earth's axis-- thereby maybe making our planet more life-friendly in terms of climate-- but it has perhaps served (like Jupiter and Saturn before it) to intercept some killer comets and asteroids which might otherwise have decimated Earth too.

The assimilation or blocking of comets and asteroids by Jupiter, Saturn, and the Moon is no small feat where the long term preservation and development of higher life forms on Earth is concerned. It probably wouldn't be difficult to support the conclusion that had any one of these bodies been absent in the solar system, humanity might not yet (or even ever!) have evolved. One powerful set of evidence for this consists of the documented results of those comets and asteroids which managed to get to Earth despite this three world obstacle course (refer to Perspectives on Catastrophism, Lost Prehistoric Civilizations, Forgotten Technologies, and More... for dates and damage estimates of substantial comet/asteroid strikes of the past).

Thus, it may well be that such protective blocks might be necessary for many, if not all, of the worlds in the galaxy which might harbor the potential for intelligent life. Throw in the climate-stabilizing effect that a large Moon provides by taming a world's axis wobble and/or tilt (and many worlds might require that as badly as protection against cosmic impacts), and you virtually prove the necessity of all these bodies for the development of higher lifeforms in many cases, and intelligence in the majority-- if not all.

The enormous gravity wells of Saturn and Jupiter may have helped sweep the solar system clean of many asteroids and comets which would otherwise have posed mass extinction level threats to Earth, and by doing so allowed the development of higher life forms on our planet. Earth's Moon also seems to have helped stabilize Earth's climate by substantially decreasing the range of wobble in the Earth's axis.

-- THE EARTH: A DOUBLY CHARMED PLANET From Science Frontiers Digest of Scientific Anomalies [""] #87, MAY-JUN 1993 by William R. Corliss, citing Jihad Touma and Jack Wisdom; "The Chaotic Obliquity of Mars," Science, 259: 1294, 1993, and J. Laskar and P. Robutel; "The Chaotic Obliquity of the Planets," Nature, 361:608, 1993

Without the Moon, the Earth's axis tilt could randomly change over a range of 85 degrees during the course of millions of years, due to gravity effects from other bodies in the solar system. Such chaotic changes would wreak havoc with the seasons and any long term consistency of climate for a given region of the planet, thereby making it much more difficult for complex lifeforms to evolve, and perhaps altogether impossible for intelligence to do so (but maybe among sealife-- for the sea might moderate these climate changes, if it was sufficiently deep and distributed worldwide). There's a good chance that an unstable world like this would end up with a destiny similar to that of Venus or Mars.

The article cited below offers odds on the creation of a large moon like ours for an Earth-like planet to occur around once out of a million cases.

-- Aliens: Are We Alone in the Univers? by ROBERT NAEYE; Astronomy Magazine (July 1996); found on or about 10-2-2000

Some place the odds of an Earth-Moon-like combination taking place at around 0.083-- and also point out that an Earth denied a Moon might keep its original fast spin, and alternatively enjoy some axial stability from that. There's also indications that some stresses actually cause bursts of new species from the evolutionary process-- so a chaotic Moonless Earth might well flourish-- at least in some ways (but develop intelligence? Maybe-- if the climatic changes weren't too much, and didn't happen too often).

-- The Chance of Finding Aliens: Reevaluating the Drake Equation By Govert Schilling and Alan M. MacRobert (based on an original piece in Sky & Telescope; last updated July 2000; Sky Publishing Corp

But having a Jupiter and a Saturn in the system is not enough; they must also be in a certain orbital range from their star, and in stable, non-comet-like orbits. The non-comet-like orbits are necessary to prevent the giant planets from ruining other worlds by flinging them out of system, into the star, or into less hospitable orbits. The particular orbital range is necessary to insure that the giants are positioned in a good spot to intercept many asteroids and comets, as well as not be too near the system star. For if too near, the giants' magnetic field could cause killer super solar flare eruptions from the star to fry many system planets as regularly as once a century, pretty much destroying any opportunity for higher life forms to evolve there.

Computer projections indicate that in many cases of natural system development, giant planets like Jupiter will move deeper into their native systems after formation, possibly capturing a planet as large as Earth as a moon-- but the giants may be just as prone to throw such planets completely out of their systems as capture them.

Numerous such giants have been detected in other star systems.

-- New Scientist: Captive moons [""] by Jeff Hecht, From New Scientist magazine, found on or about 1-25-2000

Stars disturbingly similar to our own have been observed which apparently fry their orbiting planets perhaps once per century with super solar flares-- which can be 10,000,000 times more powerful than the solar flares with which humanity is familiar.

Humanity has not observed such a flare emanating from our Sun for at least the previous 150 years-- and it's unlikely it would pass unnoticed, as the Sun brightened and a short-lived wave of great heat warmed the entire globe, thereafter creating an aurora reaching to the equator from both poles.

Other indicators like various frozen moons about the solar system depict no such superflare activity for at minimum a billion years into the past.

Fortunately it seems a huge planet like Jupiter in a very close orbit about the star (say comparable to Mercury) is required to trigger such events.

-- New Space Fear Killer Superflares On Sun-Like Stars By Deborah Zabarenko, January 7, Reuters/Yahoo! [AUTHOR NOTE: I believe 1999 is the true year this item was posted-- but a contradictory number of 1998 was included in the text. END NOTE]

Our solar system hasn't faced a superflare for at least 2000 years. A superflare striking Earth would decimate the atmosphere's ozone layer, leading to mass extinctions on Earth within months.

-- Death Stars Make Winter Summer by Lindsey Arent, 23.Sep.99, Wired Digital Inc.

Only life in Earth's deep oceans and/or deep caves could survive a superflare from Earth's Sun. Though it seems unlikely the Sun would produce such superflares from everything presently known, there still exists some small possibility that it does, albeit on very rare occasion.

-- BBC News | Sci/Tech | Sterilisation of planets By Dr David Whitehouse, September 22, 1999,

So what's the likelihood of a given star system suffering the permanent calamity of a giant planet so closely orbiting its central star(s) that regular superflares roast all the otherwise livable planets?

Note that eccentrically orbiting gas giants may represent the first stage of a two stage process, perhaps mostly involving stars unlike our own Sun: that is, systems which are formed too rapidly and violently, which tend to develop giant worlds in eccentric orbits that tend to play pinball with smaller inner worlds which might otherwise be life-friendly, but after a while settle down (perhaps by capturing smaller planets as moons, ejecting them from the system, or throwing them into the star), with the giants finally ending up in very close orbits about their home stars. In stage two, if there's any potentially living worlds still in-system, they are fried once a century by superflares caused by the kissing distance between the giant and the star. So indeed the 5% figure may account for both these deadly circumstances.

As of mid-2000, all but one of the stars found to possess planets were dissimilar to our own Sun in type and behavior-- but that one seems to possess at least three large planets (present technologies may only detect Jupiter-sized and larger worlds at this time).

Of all the stars determined to possess at least one planet already, roughly 50% of those under long term observation show signs of still more planets (or other significant masses) interacting with them.

Unfortunately (for the chance of higher life forms), the single planet already found in all these same systems consisted of a gas giant closely orbiting its home star-- forming a recipe for regular superflare disasters for any potentially living worlds of these systems.

The technology available for planet detection at this time seems biased only towards the discovery of planets in systems which may be especially hostile towards the evolution of higher life forms, such as gas giants either in close superflare producing orbits about their stars, or gas giants in eccentric comet-like orbits which tend to be inhospitable to any living worlds which might exist within the inner regions of their systems. I say this because the latest three finds are all gas giants in eccentric orbits, all the finds describe roughly Jupiter-sized or larger planets, all the finds but one list stars unlike our own Sun, and in general some scientists have estimated that at least one element of these discoveries (the eccentrically orbiting gas giants) may only be present in some 5% of star systems overall.

-- 3 new extrasolar planets, hints of more [""] by David Watanabe, September 16th, 2000 (published August 7th, 2000)

The total mass of a proto-solar system's dust disk determines the speed by which planets will form. Less mass delivers much slower formation times, such as 10 million years or thereabouts, while more mass leads to more rapidity and violence in formation-- perhaps in as short a time as one million years. By implication, mass would also determine to a great extent the general composition of the resulting planetary system.

It appears logical to assume that the more rapid and violent the planetary formation process is, the more unbalanced the resulting system-- with the consquences possibly being inimical to higher lifeforms. So perhaps those systems which tend to form fastest are also those which end up with the Jupiter-like worlds in planet-killing cometary style orbits. And perhaps these conditions only extend to some 5% or so of star systems, as described elsewhere.

-- Early planet formation triggers planet offspring ,8 DECEMBER 1999, EurekAlert! Contact: Janet Wong 416-978-6974 University of Toronto

There's also the possibly mitigating circumstances even for systems suffering superflares that the majority of the star systems involved (binaries and trinaries) will offer their living planets some protection from such things by virtue of more distant orbits, without starving them of light and heat (because they have two or three suns rather than merely one). However, for this edition of Contact I will ignore this long shot chance of higher life forms arising in such systems despite local superflares.

So what's the final numbers here? How likely is it that a given system will possess a couple of 'Goldilocks'-style gas giant planets, or else one truly immense body that can maybe do the job of two, in the proper orbit(s), and too far from the central star to spawn superflares?

The number may be as high as 95%-- the same value given before, above-- a value which we've already factored into our projections once, but for other reasons. It's now neccesary to use it again.

Future findings of course may reduce this number, but for the present it seems solid enough. So 0.95 is the likelihood that higher life forms will dodge the gas giant bullet in their own systems, so-to-speak.

Now, how likely is a given planet to possess a single large moon, or several smaller ones in a suitable orbit to achieve similar effects to Earth's actual companion?

The odds here get a bit antsy. If our solar system is average so far as inner system worlds go, then the probability might be as high as 20-25% that such an inner system world which is otherwise suitable for life formation, might also get a single large moon, or its equivalents in several smaller bodies.

YIKES! Folks, this is a major bottleneck on the numbers. Splitting the difference to get 0.225 as the factor to multiply by, then combining it with 0.95, gives us 0.214.

A couple of different estimates from experts in the field for Moon-like companion probability are 0.000001 and 0.083. Combining these respectively with the 0.95 factor gives us 0.00000095 and 0.07885.

So we've got varying probability estimates here of 0.00000095, 0.07885, and 0.214. Ouch!

Well, what say we average these out and consider the leniency provided by that process to account not only for those Earth-like worlds which enjoy their own single large Moon or several significant moons capable of similar protection (plus the gas giant(s) mentioned before), but also all those worlds which manage to squeeze by without such a Moon anyway, for various reasons (see citations below).

This leaves us with an averaged factor of 0.098. And 0.098 times 23,940,000,000 gives us 2,346,120,000

Without the Moon, the Earth's axis tilt could randomly change over a range of 85 degrees during the course of millions of years, due to gravity effects from other bodies in the solar system. Such chaotic changes would wreak havoc with the seasons and any long term consistency of climate for a given region of the planet, thereby making it much more difficult for complex lifeforms to evolve, and perhaps altogether impossible for intelligence to do so (but maybe among sealife-- for the sea might moderate these climate changes, if it was sufficiently deep and distributed worldwide). There's a good chance that an unstable world like this would end up with a destiny similar to that of Venus or Mars.

The article cited below offers odds on the creation of a large moon like ours for an Earth-like planet to occur around once out of a million cases.

-- Aliens: Are We Alone in the Univers? by ROBERT NAEYE; Astronomy Magazine (July 1996); found on or about 10-2-2000, and other sources

Some place the odds of an Earth-Moon-like combination taking place at around 0.083-- and also point out that an Earth denied a Moon might keep its original fast spin, and alternatively enjoy some axial stability from that. There's also indications that some stresses actually cause bursts of new species from the evolutionary process-- so a chaotic Moonless Earth might well flourish-- at least in some ways (but develop intelligence? Maybe-- if the climatic changes weren't too much, and didn't happen too often).

-- The Chance of Finding Aliens: Reevaluating the Drake Equation By Govert Schilling and Alan M. MacRobert (based on an original piece in Sky & Telescope; last updated July 2000; Sky Publishing Corp

Thus it appears that life will develop beyond the microbe stage on at least one of the worlds in 2,346,120,000 systems across the galaxy within four billion years or more of those worlds beginning to offer conditions conducive to such events (note that our own Sol system seems to have developed maybe more than half a dozen potential life-bearing worlds during its history so far)

Here, 2,346,120,000 living worlds seem to have squeaked through the cosmic pinball game over the history of our galaxy.

3-6-99 Newz&Viewz: Over its lifetime, our solar system may have possessed as many as FIVE different worlds where life could develop?

The five locations include Earth, Mars, Venus, Jupiter's moon Europa, and the asteroid/planetoid Chiron near Pluto.

-- "Search For Space Life Starts Right Here On Earth" By Maggie Fox, Health and Science Correspondent, Yahoo/Reuters, 1-26-99

The moons Europa, Ganymede, and Callisto of Jupiter all show hints of possessing oceans. Pluto, Triton, and Titan may also sport oceans. Even Neptune and Uranus could conceivably possess oceans of some sort.

-- Oceans Could Be Common In Our Solar System And Others; 20-Dec-2001; UniSci Daily (; (citing PHYSICS NEWS UPDATE, the American Institute of Physics Bulletin of Physics News Number 569, December 14, 2001, by Phillip F. Schewe, Ben Stein and James Riordon.)

-- Alien ocean by Jonathan Knight; 18 December 2000; New Scientist Online News

One other point here: It seems that our solar system's orbit around and rotation speed through our galaxy are just about perfect to minimize our system's exposure to dangerous supernovae which tend to be encountered nearer the galactic core (for systems with more eccentric and/or inclined orbits), as well as during the crossing of galactic arms (for systems which move significantly slower or faster than ours around the galactic disk). The slight inclination also reduces the likelihood that comets will be knocked loose from our Oort Cloud to threaten Earth, whenever our system bobs up or down through the galactic plane on its travels.

(The reason supernovae are bad for us of course is the life-threatening radiation baths to which they can subject us.)

One estimate is that less than 5% of the systems in our galaxy may enjoy such good fortune. So far as I can determine however, a large proportion of the stars near our own also possess these 'lucky' orbital aspects, and so these factors may well apply to most or all the stars in the life-friendly region of our galaxy, as defined elsewhere in this work. For that reason, in this edition of Contact, I am NOT applying this particular value as a filter, but assuming that its effect has already been accounted for elsewhere.

Even rocky worlds similar to Earth may develop harsh atmospheres more like gas giants if they are too large.

-- Stars and Habitable Planets; Sol Company; found on or about 10-4-2000

First Spark of Life to the First Starships Contents

5. The rise of intelligence in a suitable system

LOCAL TIMING NOTE BASED UPON THE SINGLE SCIENTIFIC DATA POINT AT OUR DISPOSAL CIRCA 2002: Modern human intelligence capacities seem to have evolved on Earth within around 4.5 billion years of the planet's formation.

The current Earth (version two) is 4.5 billion years old; modern human brain complexity and capabilities appear to have first emerged sometime between two million and 100,000 BC.

-- Moon Probably Split From Earth In Collision - NASA, Reuters;; March 16 1998

-- Firebirth By Jeff Hecht, New Scientist [""], 7 August 1999

-- If We Had No Moon, 12-18-99, The Discovery Channel,

-- page 789, "Stone Age", The Concise Columbia Encyclopedia, Second Edition, 1989, Columbia University Press

-- Milestones in Technology, February 26, 1999, The Knoxville News-Sentinel [""]

-- lamp; Encyclopedia Britannica [",5722,46974,00.html"], found on or about 2-16-2000, and fire; Encyclopedia Britannica [",5716,34938+1,00.html"], found on or about 2-16-2000

-- "Light My Fire: Cooking As Key To Modern Human Evolution, ScienceDaily Magazine,, 8/10/99, Source: University Of Minnesota

-- "Dogs Really Man's Best Friend, Book Claims" ("Evolving Brains,'' biologist John Allman of the California Institute of Technology);; Reuters Limited, 12-16-98

-- "U.S. News: Archaelogists study dogs to learn about humans (7/5/99), The secret life of animals" BY JONAH BLANK , Science & Ideas 7/5/99, U.S. News Online [""]

-- Stalking the Ancient Dog By CHRISTINE MLOT, June 28, 1997, Science News Online,

-- The secret life of animals BY JONAH BLANK, Science and Ideas, US News and World Report, 7-5-99,

-- Paleoanthropology (revised 16 December 1999) by Francis F. Steen, Department of English, University of California at Santa Barbara,

-- THE ANCIENT HORSEMEN From Science Frontiers Digest of Scientific Anomalies [""] #29, SEP-OCT 1983 by William R. Corliss, citing Timothy Perrin; "Prehistoric Horsemen," Omni, 5:37, August 1983

-- "Was The Lack Of Language The Force Of Driving Stone Age Art?", 12-9-98, New Scientist [""]


Assuming humanity required some 15 million years to transform itself from an animal form hardly distinguishable from other large species to one capable of radio transmissions and space flight, we could reasonably say that 15 million years could be considered a realistic intelligence emergence cycle from a platform of lifeforms already consisting of complex, large animal species.

Earth seems to have possessed lifeforms at least as large as smallish human beings (and potentially offering the size and shape capacities conducive to intelligence development) for at least 250 million years. So dividing the 15 million year cycle into that gives us at least 16 distinct periods in which intelligence could realistically have evolved among the animals available at the time.

But so far as we know intelligence only developed once among all those chances (I'm assuming the late hominid variants such as Neanderthal and Homo sapiens to have been so closely related as to count all as a single instance of emergence). Based on this admittedly rough concept, the probability of high intelligence developing from large, complex lifeforms may only be 0.0625.

We will therefore assume that intelligence comparable to our own arises in a minimum of one species on a living planet which manages to get beyond the microbe stage, with a probability of 0.0625.

This particular variable offered up a raging debate between scientists in the late 20th and early 21st centuries, as on the one hand there seems everything to suggest a 1.0 probability (as the survival advantages of intelligence seem obvious to we intelligent folks)-- but then again we may be blinded by bias and too little attention to life's history on Earth. Though it does seem now that life on Earth was predisposed towards developing intelligence, it would not necessarily have seemed so to observers monitoring much of the events leading up to today. For example, there is no evidence that dinosaurs would have developed intelligence any time soon had their extinction not taken place. And even before their extinction they'd possessed plentiful time for such development to occur, based on our own origins. And yet it did not. It's not at all clear that intelligence is an inevitable consequence of evolution. Indeed, it's not necessarily even probable. Throw in the amount of time required for intelligence to develop (where it does appear) based again on our own origins, and the appearance of intelligence looks easily thwarted altogether by mass extinctions from various sources 're-setting' the clock too frequently, and finally time itself running out as a particular solar system enters its death thros.

All that being said, I'm still alloting a sizeable probability to the emergence of intelligence (0.0625). How do I justify this? The development of intelligence will skew probabilities in favor of that life possessing it, over that of life lacking the attribute. Intelligence will also aid in many instances of overcoming non-living enemies, such as climate and terrain. Once multiple species develop even low levels of intelligence this will create an evolutionary 'arms-war' where intelligence is an adaptive weapon, resulting in an upward spiral for those species which survive. Species caught in this spiral will rise naturally (if they survive the increasing competition), at least up to the point that they form a civilization, and take control of their own development, as humanity appears to have begun doing in past millennia. Then, increasingly artificial influences may be applied to a specie's genetic development (leaving the ultimate consequences uncertain, as such artificial means do not tend to seek the same goals as natural evolutionary forces, and also are often tested in different ways; we will not pursue that idea at this point).

As for the cosmic time constraints on development and survival, once intelligence reaches a certain point it'll be able to advance further and robustly respond to environmental changes at dizzying speeds, allowing it to effectively squeeze millions of years worth of natural evolutionary developments into mere months of technological advances, thereby likely overcoming most cosmic threats to their lifespan beyond that point. For example, around 2002 humanity is rapidly developing the means to detect Earth-threatening comets and asteroids years to decades before they strike, as well as practical weapons with which to deflect or destroy them.

There is evidence to suggest that intelligence may offer substantial survival value-- and therefore will be more likely to evolve than not on a given world-- assuming there are suitable conditions for higher life forms to develop in general.

-- Could We Be Wrong? [""] By Seth Shostak, Special to, March 6 2000

-- Evolution is deterministic, not random, biologists conclude from multi-species study [""] 19-Nov-2007 Contact: James Devitt 212-998-6808 New York University

Simple lifeforms appear to be virtually an inevitable development anywhere in the Universe where conditions mimic those of the Earth of 4 billion BC.

Would it not then be logical to assume that intelligence may also be almost this certain to appear? Especially where and if we add in a reasonable amount of extra time for intelligent forms to emerge after the initial microbes of life are well established in a given environment?

Earth's own evolutionary history suggests that while single celled lifeforms might exist nearly everywhere throughout the Universe, multi-celled lifeforms might be considerably more rare.

The failure of dinosaurs over 140 million years to develop sentience and a civilization indicates that even among higher and more complex lifeforms, intelligence development is not necessarily inevitable, or may sometimes take much longer than it did with our own primate family and circumstances.

-- Scientific American: Feature Article: Where Are They?: July 2000 [""] by Ian Crawford

Quite a few evolutionary biologists circa 1996 considered the chances of human level intelligence developing (even on Earth-like worlds) was roughly one in a billion. A big reason for this opinion is that evolution doesn't appear to assemble high intelligence in any particular hurry. Or necessarily at all. The dinosaurs continued to change and evolve for many more millions of years than mankind's own lineage can presently claim, yet apparently came nowhere near humanity in smarts. If evolution dawdles too long, it risks being set back millions or even billions of years by cosmic impacts or other threats. If the delay goes on long enough, even the planet and its hosting star system itself may fall prey to the dying central star engulfing the inner worlds and drastically changing the location of the system's habitable zone.

Thus, there are significant time limits on the development of intelligent life, as well as other possibly prohibitive circumstances, such as the probability of large cosmic impacts or climate changes due to other reasons. Too high a frequency of impacts/large climate changes will 'reset the clock' for development of intelligence on a given world so many times as to prevent it altogether before that world is burnt to death by its own sun.

-- Aliens: Are We Alone in the Univers? by ROBERT NAEYE; Astronomy Magazine (July 1996); found on or about 10-2-2000

-- The Chance of Finding Aliens: Reevaluating the Drake Equation By Govert Schilling and Alan M. MacRobert (based on an original piece in Sky & Telescope; last updated July 2000; Sky Publishing Corp

Circa 1997, our technology was evolving at "...10 million times the speed of [natural] evolution".

Above quote and a bit more from W. Brian Arthur, Scientific American, Feb 97 issue

-- A c| interview with Paul Saffo, futurist, on or about 6-23-97

-- "The Internet Economy: the World's Next Growth Engine" By MICHAEL J. MANDEL With Irene M. Kunii in Tokyo, BUSINESSWEEK ONLINE : OCTOBER 4, 1999

But perhaps the most important factor encouraging the development of star farer intelligence from life is an environment composed of a suitably 'open' system. That is, a home world blessed with a far greater input of energy and other critical resources than is necessary for sustenance alone. Such a world makes significant profit possible in certain endeavors, and profit leads to higher, more complex forms of surplus in the system, which in turn may make more sophistocated organizations of life and intelligence possible. Wealth builds upon wealth, allowing ever greater investment, experimentation, and competition, leading to higher efficiencies, bigger surpluses, greater reserves, further investment, and additional security against adversity, in an ideally unending upward spiral, much faster and easier than such could occur amidst lesser resources. An open system such as the Earth encourages a form of evolutionary capitalism, where resources naturally flow to that part of life best able to expand upon such largess in a manner useful to its survival. As some forms of intelligence may contribute greatly to maximizing available resources, such intelligence is likely rewarded and nourished by natural forces.

Unfortunately, there may be a minimum of 40 percent of all living worlds which endure a much harsher environment than our own, with little or no surplus energy and other resources to allow reasonably rapid development. This 40% of worlds probably reach a certain plateau of development (say animals as smart as average chimpanzees at most, but usually nothing smarter than a dog or cat on most of these energy-poor worlds), and never rise beyond this in any significant way. Another factor can be such a high frequency of global impact and climate catastrophes that intelligence gets knocked back everytime it raises its figurative head.

So 0.0625 times 0.6 gives us a total factor here of 0.0375. 2,346,120,000 times 0.0375 yields 87,979,500 living worlds developing intelligent beings over the course of each world's lifespan, according to this filter.

However, at the speed civilizations appear they will evolve or change once they reach a certain level of technological sophistocation, it could well be that there's a limited window of opportunity for any meaningful interaction between us and an alien civilization, before they transform into something incomprehensible to us, or travel far beyond the universe we know, or become extinct for various reasons.

Therefore, we'll limit our calculations here to just that number of probable civilizations that falls within a certain window in time.

But here again we encounter a tantalyzing challenge, in the form of a single question:

Just how long does the average civilization last, once it reaches a technological level approximating that of 1900 AD humanity?

Unfortunately, any seemingly realistic answer to this question would seem dismal indeed from someone who spent most of their life in the last half of the 20th century on Earth, rife as it was with war, mass murder, and state oppression. From such a base of observation, an answer of only 50 to 100 years beyond 2000 (or 150 to 200 beyond 1900) would seem itself optimistic.

"This century may be a defining moment for the cosmos. If humans do not destroy themselves they may spread beyond the earth into a universe that could last almost forever."

-- The science of eternity by Martin Rees;; January 2002

-- Is Humanity Destined to Self-Destruct? [""]

-- Extinction expert fears for humans (link#1) [""] and link#2 [""]

From such a vantage point we often seem bent upon destroying ourselves, and advances in our technology look to make this goal easier and quicker to achieve with each passing day.

It could be argued that humanity has only barely been tested in regards to avoiding wholesale suicide, as of 2002 AD, since it's only possessed one means (nuclear war) to actually make a decent attempt at achieving self-extinction for around 30 years now-- or about a single human generation. In terms of biological and nanotechnological war-making, well, as of 2002 we've only just begun building practical versions of those weapons and related delivery systems.

AUTHOR'S NOTE: Yeah, I know the US developed the first nuclear weapons at the end of WWII-- but it took some years after that for the US and a plausible opponent (the Soviet Union) to actually manufacture large numbers of the devices and create a practical means of delivery for them, thereby making global nuclear war a real possibility. The concept of a 'Doomsday Clock' was first created in 1947 by scientists concerned about the implications of nuclear weapons becoming available to a war-like mankind. That virtual clock made its debut marking seven minutes 'til midnight, but was sometimes changed to offer a bigger buffer between the present and Armageddon, as prospects for peaceful co-existence brightened. In February 2002 however, the hands were moved back to where they started. In other words, the world in 2002 appeared just as much at risk as that of 1947. END NOTE.

-- Doomsday Clock Creeps Forward By Robert E. Pierre Washington Post; February 27, 2002

But let's be much more optimistic, and assume I'm considerably underestimating humanity's capacity here to overcome its shortcomings and adapt to changing circumstances and technologies. That humanity's future might well follow a course much like that laid out in my future timeline. As of the summer of 2002, I've been able to envision a more or less prospering humanity making it at least as far as 4000 AD without destroying itself. So that offers us a minimum of 2000 years for a possible technologically advanced civilization's lifespan.

Of course, to truly justify such optimism we must account for the typically short average lifespan of human civilizations in general, as indicated by known history. Apparently human civilizations usually last only some 420 years or so, from beginning to end. And as increasingly sophistocated technology has become a part of the mix, that span has been shrinking, to only around 305 years.

Michael Shermer points out the average lifespan of a given human civilization throughout known history has only been 421 years. But where technology has become more advanced (such as in more modern nations as opposed to ancient states), the average has declined to 305 years.

Such low numbers for the average span of a potential star faring civilization does not look promising-- but plugged into the Drake equation it does seem to help explain why the skies have been so silent.

-- Scientific American August 2002 issue: Why ET Hasn't Called By Michael Shermer

But luckily Earth currently houses a considerable diversity of different human 'subsets' of civilizations, economies, and technological bases. So when one particular subculture fails, it can be more or less readily replaced with another, or else helped back 'onto its feet' by the other societies, if they're willing to pitch in on the matter.

So long as Earth possesses such a diversity of cultures, economies, and techno-platforms, and can minimize the possible disasters stemming from excessive concentrations of wealth, power, and influence, or from excessive secrecy, censorship, intellectual property rights seizures by big business, proliferation of weapons of mass destruction, armed conflict, and industrial accidents, then this natural 'bootstrapping' of individual societies by the larger global community should serve to keep things going well for quite some time, even when various societies on the planet do fail catastrophically.

However, many forces tend to quash diversity as technology, organization, and complexity all ramp up-- especially under economic systems like capitalism, or political systems where religion, wealth, or corruption are allowed excessive sway.

The more homogenized an entire world becomes, in language, technology, economic systems, products, and services, the more efficient it may well become-- but also the more risk of doom such a world will face. For any world inadequately 'compartmentalized' in its functions and diverse in its methods and perspectives is vulnerable to an overwhelming cascade failure at some point in its history.

Respected author Vernor Vinge has pointed out similar ideas in his works of fiction, only there depicting an entire galaxy of worlds being available to help individual planetary societies to recover from periodic collapses due to excesses in local socio-economic complexity and other liabilities.

Unfortunately for Earth, there appears to be no nearby benevolent aliens to help us pick up the pieces if we fail. And the 'safety net' of diversity humanity presently possesses in social, economic, and technological systems appears to be rapidly shrinking in size and capacity with each passing decade-- thereby making human civilization on Earth at more risk for wholesale collapse, rather than less.

[For more on this topic please refer to Risky behavior: Reductions in the overall diversity and redundancy of human civilization and its home planet which may raise the risk of extinction or collapse over the next few centuries.]

But we can do better than this in our estimations; if a civilization only reaches a technological level equivalent to, say, 2500 AD humanity (as described in the timeline), then it may well live on in some fashion for much, much longer, as it'll be able to spread itself throughout the galaxy, making total annihilation by any means much less likely than before-- at least from any secular or cosmic threats an early 21st century human like myself can imagine.

-- Humans Doomed Without Space Colonies, Says Hawking; Yahoo! Science Headlines; October 15, 2001

So we may well have an important divergence here-- between advanced technological civilizations which last less than 600 years, and those which live much, much longer.

Thus, the question becomes what percentage of technological civilizations live less than 600 years, and what live for much longer spans?

Although there's still lots more issues to be considered, and filters to be applied, we'll go ahead and make some preliminary estimates based on what we already know and/or have assumed.

OK. Here is a grand opportunity to exercise my 20th century-based pessimism, and say 84% last less than 600 years, while 16% survive.

Furthermore, I will venture to say that of the 16% surviving, only the top 2% survive intact to become truly glorious and awesomely advanced civilizations, while the bottom 14% suffer mightily, scraping by as it were in the cosmos, having been badly mangled by many of the challenges listed elsewhere in this paper.

This gives us (0.14) times 87,979,500 for 12,317,130 relatively impoverished scavenging civilizations, and (0.02) times 87,979,500 for 1,759,590 'rich' civilizations both ending up being around not just for 600 years on average, but up to 10,000 or more, in some form or fashion recognizable to us as intelligent beings.

This will also leave us with as many as 73,902,780 'dead' civilizations, the majority of which will have exterminated themselves in some fashion with technological or economic or social errors or some combination thereof, when the civilization itself possessed technology equivalent to that estimated for humanity between 1900 AD and 2500 AD.

My choice of percentages here is not entirely arbitrary. Much is based upon the various star farer filters described later in this work-- and especially the 600 year long 'gauntlet' of challenges/obstacles I propose to serve as the primary gateway separating people like us from races which may be more fittingly described as long-lived, and technologically advanced star faring civilizations.

My estimates also relate somewhat to the significant percentage values found in the normal distribution phenomena of probability and statistics, which appears to apply to an astonishingly wide variety of events in our universe (significant values therein roughly include 68%, 14% and 2%). Again, I attempt to describe much of my reasoning for these elements in detail, later in this work.

Note that for the purposes of useful living contact, it's unlikely that any of the short-lived technological civilizations will be around long enough to matter. To be significant to our purposes here, such a civilization would have to be almost our next-door neighbor-- very close in galactic terms. Plus, they must have developed in a timeline so eerily parallel to our own as to be quite improbable.

There is the matter of their technological relics left behind possibly being of use to us. Except that by the time we ourselves possess the means to reach and find such relics, we'll likely already possess an equivalent or better techno-expertise as that embodied in said artifacts. But some minor or incremental techno-profit or scientific knowledge might be gained.

Now the discussion turns to the ten thousand year lifespans themselves. Beyond 10,000 years we'll assume a given civilization has usually changed so much they'll be unrecognizable as living intelligent beings, and/or have utterly no interest in biologicals like ourselves, and/or have declined in an evaporative or precipitous way. In many cases the technology of a long-lived civilization may outlive them, remaining behind ready to serve whomsoever comes along, or ready to defend a now non-existent civilization against intruders. Or, the techno-servants may even have established their own and radically different civilization atop the ashes of their long dead masters.

In any case, any technological civilization we meet which is 10,000+ years old is likely to be inorganic, no matter whether they began as biologicals like ourselves, or as the mechanical servants of biologicals. And it's highly unlikely we could purposely locate them, as they and their artifacts might appear identical to natural forces-- and even if we could discover them, any interaction with them or their devices could be terribly dangerous for us.

So what's the possible number of 10,000+ year old civilizations in the galaxy?

Well, assuming these stem pretty much exclusively from those systems which came into being between 6.6 billion BC and 5 billion BC, we get these numbers:

6.4 billion times 0.8 times 0.15 times 0.95 times 0.098 times 0.0375 times 0.02 = 53,625

[RECAP: There were likely 6.4 billion star systems created between 6.6 billion BC and 5 billion BC (around four per year over 1.6 billion years). Eighty percent were estimated to possess planets, 15% of these systems were estimated to be within the life-friendly band of the galaxy, metals-wise, 95% of systems were expected to possess at least one world of suitable composition and distance from its star to host life, 0.098 probability that complex life develops on a suitable planet, 0.0375 probability of intelligent beings emerging from complex lifeforms, and 0.02 probability of a given race evolving into a highly advanced and long lived technological society. END RECAP]

Or 53,625 almost surely totally inorganic, and super advanced technological civilizations, which have been around for longer than 10,000 years. These folks are very unlikely to be interested in us, except under some sort of very extraordinary circumstances.

1,759,590 minus 53,625 gives us 1,705,965 advanced technological civilizations younger than 10,000 years, possibly still somewhat organic in composition, perhaps still recognizable to us as living beings, and still able to relate to us in some coherent fashion. In theory we could communicate with or locate such races by various means. Interaction with these beings would be completely unpredictable in consequence.

12,317,130 long-lived but struggling civilizations, younger than 10,000 years, likely mostly organic. These peoples would possess superior technologies to our own, and resemble humanity in perhaps too many ways, motivation and behavior-wise, making them likely more dangerous to us than beneficial. In theory we could communicate with or locate such races by various means.

I'm assuming here that all long-lived 'scavenging' civilizations simply die or peter out after 10,000 years (along with their inorganic servants). Or perhaps become subsumed somehow into either younger and more energetic civilizations, or one of the advanced and more resourceful long-lived cultures.

There could exist possible ruins and artifacts distributed about space from as many as 73,902,780 'dead' civilizations, which possessed technological capacities equivalent to somewhere between 1900 AD and 2500 AD humanity's when they collapsed. These relics are pretty much insignificant technology-wise to anyone who already has the means to reach and find them. But there may be some interesting biological, social, and historical aspects to them for scholars. In some cases biological survivors of these races may still exist, but living in primitive conditions equivalent technology-wise to humanity's past, somewhere between one million BC and 1900 AD.

Note folks that the above tallys are totals for the whole galaxy, over its lifetime so far. The limited lifespan of civilizations means that many of those in the numbers above would not be around today, having collapsed or otherwise went away a long time ago.

So how do we narrow down the numbers to find out who's likely around and kicking today?

Many or all of the 53,625 super-advanced civilizations could still be kicking-- but it'd be pretty much impossible for us to tell, as they might be indistinguishable from the forces of nature in the cosmos. As some of these fade out of existence, they might be replaced by new, younger races reaching this pinnacle from the lower technology classes. The bottomline here is that it'd be darn difficult to prove that any of the folks at this level are dead or alive-- unless they themselves decided to let us know.

For the remainder of technological civilizations, the 10,000 year life cycle could be a meat-grinder on the cosmological scale.

Over the whole span of life developments leading to technical civilizations in the galaxy, from around 6.6 billion BC to 4 billion BC, new civilizations looked to have emerged at the 1900 AD level of technology at a rate of around 338 every 10,000 years-- based on the numbers provided before. Note that fully 284 of these go extinct or regress catastrophically technology-wise within only 600 years or less of reaching this point (maybe much less than 600). This leaves only 54 surviving civilizations per every 10,000 year generation of same actually being around in a meaningful way throughout the period. And of these, roughly 47 may be struggling so badly much of the time as to be oblivious to much of what's going on outside their own society. This leaves something like seven wealthy and well-adjusted cultures distributed across the galaxy during any particular 10,000 year period which would not only be recognizable to us in some fashion (with physical spacecraft, roughly human-sized physical bodies and human scale architecture, etc.) but also capable of communicating with us in a coherent fashion if contact could be made.

So how close to us might the nearest such folks be?

There's one hundred 10,000 year periods in a million year span. So over a million years there'll appear the wreckage of some 28,400 doomed civilizations across the galaxy. Much of this wreckage will be recognizable and salvagable in some way by anyone who happens across it.

The life-bearing space of the galaxy may be some 84 billion cubic lightyears in total. These 28,400 worlds would be spread across that, so each would possess its own region of space of some 2,957,746.5 cubic lightyears.

This results in the nearest such world being around 178 lightyears from our own.

There should be around 47 chronically struggling technological civilizations present throughout our galaxy at this time (the present 10,000 year cycle). The majority of these are likely millennia ahead of us in certain ways, although they will still suffer many problems similar to those we face today. A handful of the most prosperous may command a half dozen solar systems, but most will have achieved little outside their own system, even having possessed advanced technologies for millennia.

Each of the homeworlds of these will be surrounded by 1.79 billion cubic lightyears of space. This means that the nearest such world is likely some 1,506 lightyears from our own.

Of the seven robust and wealthy civilizations in existence during this 10,000 year cycle, the nearest one should be around 2,840 lightyears away. These civilizations are typically thousands of years ahead of us in virtually every measure. They almost certainly possess craft (or other transport means) capable of a high measure of lightspeed-- maybe even faster than light. Several of them may well have commandeered dozens of neighboring solar systems for their own use.

AUTHOR'S NOTE: In calculating distances I always consider ourselves to be a potential peer for various types of civilizations. If this assumption turns out to be false (i.e., humanity is doomed to fall short of such status) then the intervening distances could become much larger where the more advanced technological civilizations are concerned. END NOTE.

[For more on this topic please see Civilization's best defensive measures against war, terrorism, technological stagnation, and economic ruin]

For the purpose of this project we'll ignore the possibility of newly emerging civilizations in the galaxy currently at technological levels commensurate with humanity between 100,000 BC and 1900 AD. However, such primitives could still be of interest for various scientific reasons. Thus, I encourage anyone interested in estimating the distance to the nearest such primitives to modify and use my various estimates and procedures as required to do so.

I mentioned gamma ray bursters near the beginning of this paper. But we haven't really applied their potentially devastating effect to the calculations up to this point. Let us do so now.

The gamma ray burster funnel may have served to heavily prime the galaxy for a sudden explosion in intelligent life to occur in only the most recent couple of hundred million years. Practically every living planet described here has suffered quite a few mass extinctions which especially included higher life forms which had not yet managed to position themselves to survive the gamma ray bursters, as well as other cosmic dangers. Time after time entire living worlds are stripped of virtually all complex lifeforms, and forced to start from near scratch once more.

Any given world in the galaxy today appears at risk for being caught in the terrible death ray of a gamma ray burster about once every 100 million years. Earth may indeed be overdue by a 100 million years for such a fate, but there remains much uncertainty about the frequency of such events in the galaxy. It appears the frequency may have been much higher in the distant past than it is today.

We'll assume here that our galaxy has only in the last 200 million years become relatively 'safe' for intelligent star farers to evolve and prosper-- at least long enough to establish some limited presence in interstellar space-- before being eliminated again (because the bursters continue to appear, albeit at a much slower rate).

-- "Cataclysmic Explosions May Have Held Up Alien Visitors", Author: Robert Matthews, New Scientist magazine issue 23rd Jan 99

-- Sorry, we'll be late by Robert Matthews; New Scientist, 23 January 1999

-- Extinction is eons overdue by Michael Brooks; Weekly Mail & Guardian; August 07, 1998, and other sources

-- Tango between black hole and star remnant may explain cosmic explosion, MIT team reports; 21-Feb-2002; Contact: Denise Brehm brehm@MIT.EDU 617-253-2704 Massachusetts Institute of Technology

-- Cosmic catastrophe 'a certainty' By Dr David Whitehouse; BBC News Online; 8 May, 2002

-- Gamma ray bursts tied to supernovae by Eugenie Samuel; 17 May 02; news service

There's precious little info available on the subject of burster frequency previous to 200 million BC. For that and other reasons (plus our focus here on currently existing civilizations), I'm just going to axe out of the estimates entirely all potential civilizations which might have formed prior to 200 million BC.

This filter really has a much smaller effect on the numbers than you'd expect, however, since we've already culled the numbers down to just those civilizations likely to be in existence during the current 10,000 year cycle.

Indeed, only the numbers of the 10,000+ year old civilizations are impacted.

So how many of the potential 53,625 ancient and super-advanced civilizations could have actually formed just in the last 200 million years (minus 10,000)?

200 million minus 10,000 gives us 199,990,000 years in which the survivors would have arisen.

If 53,625 could theoretically have developed over 2.6 billion years if no bursters afflicted them, then how many could actually have done so during 199,990,000? Utilizing the equal ratio method gives us the number of 4,125.

So in actuality there may at most be only 4,125 super-advanced, extremely ancient alien races or entities out there circa 2002.

Note that we never did calculate the probable distance to the nearest such entity, for several reasons, among them being that it might be impossible for us to even discern such beings as different from natural cosmic phenomena. Plus, any calculation could only give us the distance to their original home system, and not to the race itself, which may have left their home system a long time ago.

We'll ignore at this stage the Brin style 'uplifting' of species by other, more advanced beings. This will allow us to assume a fairly random distribution of (more-or-less) 'naturally evolved' civilizations about the moderately metal enriched band of the galaxy.

So we're basically talking 54 civilizations we could interact with in a secular manner (assuming contact could be initiated), sharing a band of our galaxy with us at this time.

But there's still more filters we must apply...filters which account for the risks inherent to intelligence and civilization in themselves, as well as filters for types of intelligent beings which may be too far removed from our own history and experience to be aware of, or to exploit, space itself. I believe such filters would support the idea that there's a brief period of extreme danger for any fledgling technological civilization like our own, near the beginning of their potential star faring career. Something I here refer to as a '600 year gauntlet', during which most races either go extinct or suffer such a collapse of society that they usually never rise to star farer status again.

First Spark of Life to the First Starships Contents

Wait! There's more!

The establishment of the first space colonies and the likelihood of contact between alien cultures

All text above not explicitly authored by others copyright © 1993-2009 by J.R. Mooneyham. All rights reserved.