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The rise and fall of star faring civilizations in our own galaxy

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Our place in the Milky Way galaxy, small version

The approximate location of Earth is at the center of the cross-hairs in the pic.

Rise and fall table of contents

Introduction and summary

The Fermi Paradox which contrasts the 100% probability of life and intelligence developing on Earth against the thunderous silence from the heavens so far (no alien signals) may be resolved by four things: One, gamma ray bursters of all types, from faraway 'longs' through nearby 'shorts', which may have effectively prohibited the development (or devastated the longevity) of sentient races throughout all galactic history; Two, the lengthy gestation period required for the emergence of intelligence (which almost requires the entire useful lifespan of a given planet, based on our own biography); Three, the need for an unusually high measure of stability in terms of climate over hundreds of millions of years (the 'Goldilocks' scenario, enabled by a huge natural satellite like our Moon moderating the tilt of a planet's axis, as well as gas giants parked in proper orbits to mop up excess comets and asteroids to reduce impact frequencies for a living world); and Four, an extremely dangerous 600 year or so 'gauntlet' of challenges and risks most any technological society must survive to become a viable long term resident of the galaxy (i.e. getting a critical mass of population and technology off their home world, among other things). That 600 year period may be equivalent to our own span between 1900 AD and 2500 AD, wherein we'll have to somehow dodge the bullets of cosmic impacts, nuclear, biological, and nanotechnological war, terrorism, mistakes, and accidents, as well as food or energy starvation, economic collapse, and many other threats, both natural and unnatural. So far it appears (according to SETI results and other scientific discoveries) extremely few races likely survive all these. So why haven't we heard from those which have? What are they like? And how far away might they be? Details of all the above and more (along with references) may be found on this and succeeding pages.

What are the most probable elements involved in the emergence of an intelligent race capable of interstellar signals and/or mobility?

These factors consist in part of stages of development virtually any race resembling us in our basic motives and behavior would likely go through; they also include general 'logic gates' which filter out those peoples and worlds which would be unlikely to qualify for relevance in our search for extraterrestrial intelligence (for reasons explained later).

Assumptions and intentions:

A. We will focus here only on the likelihood of intelligent, interstellar capable civilizations within our own galaxy.

One, because the distances between galaxies represent an almost infinitely greater obstacle to star farers compared to interstellar travel.

Two, because each galaxy is essentially an island universe in its own right, with possibly hundreds of billions of stars in each-- it would be almost an unimaginable feat for one civilization (or even several) to explore a sufficiently large fraction of a single galaxy so that they would then feel compelled to turn their attention to a whole other island universe in the void, possibly thousands to hundreds of thousands of lifetimes of maximum speed travel distant.

B. The stages suggested below are by no means intended to be distinct phases of development with clear beginnings and endings, with no overlap between them. Rather, they represent likely-to-be important trends or characteristics of a civilization along the developmental path. For example, humanity itself could be argued to have ranged in development across several different stages as described on this site, circa 1996-2002. Specifically, we were clearly not entirely free of the conceptual competition among politico-economic and religious systems described in stage Seven; obviously still at risk from our own wastes in stage Eight; we had yet to fully realize our vulnerability as spoken of in stage Nine; and the challenge of balancing opposing concerns of stage Ten remains far from won. Too, though we faced a real danger of the cataclysmic accidents or war suggested in stages Seven, Ten, and Eleven, we didn't yet possess any off-world colonies which could survive our doom to become orphan vestiges of our civilization.

C: The Fermi paradox essentially asks the question "where are all the aliens?", if life itself is as common throughout the galaxy as many think. It would appear from much of what we know that we should find ourselves surrounded by alien folk.

However, ways to resolve the paradox are now becoming apparent. For instance, in recent years a wholly new and unexpected discovery was made, which makes a good case for our own present generation being among the first and/or earliest of star farers in the Milky Way.

The discovery? Gamma ray bursters, both great and distant, and near and small. The faraway worst ones being massive explosions of radiation rivaling the Big Bang itself in some ways, possibly serving to virtually sterilize significant swathes of entire galaxies on a fairly frequent basis, universe-wide.

But the narrow death beam of those large bursters, coupled with their typical distance, and especially their declining frequency of occurance in the last few hundred million years, may have effectively removed them as an important player in galactic evolution today-- if indeed they ever were in the first place.

However, the much more frequently occurring and closer 'short' (but much less powerful) gamma ray bursters could well have played a bigger role in the intelligence lottery of our galaxy, than their more spectacular brethren. And continue to do so today.

[For more on this particular topic please refer to The gamma ray burster threat]

Now that the Fermi Paradox may have been dealt a reasonably devastating first blow (with more to follow), let us closely examine the numbers and types of alien star faring civilizations we are most likely to contact or encounter during the present or near future, and why-- in From the first spark of life to the first starships...

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