Cryptids

[Anomalocaris]

Freeman Dyson (and others) noted in the 1960s the proposed Orion nuclear impulse technology could be stretched sufficiently to someday enable interstellar flight. And not just a sightseeing trip to a nearby star, a colonizing effort carrying 50,000 people, no less.

And once 'we' have a viable colony on a world orbiting a nearby star, realize earth can still send other colonizing ships towards other stars, and the colony will be able to also.

And then you have colonies sending out colonizing ships, etc, etc.

It turns out, that is an exponentiating system, and in less than 10 million years, you have a galaxy colonized from ene to end (so to speak).

So for those positing 'thousands' or 'tens of thousands' of advanced civilizations in our galaxy, it must be realized it only takes a SINGLE instance of a civilization to develop and refine technology humans had in the 1960s to colonize our entire galaxy in less than 1/10 of 1% of the age of the galaxy.

That there is not an outpost, colony, or an entire planet full of 'aliens' in our solar system is very significant.

Idon't find that line of extrapolation compelling because it implicitly assume behavioral paradigms are somehow fundamental and fixed, and technologies merely facilitates ever more grandiose implementations of the basically the same paradigm, regardless of whether technological progress would in fact nullify other driving forces behind the behavior. I think behavioral paradigms are actually nothing more than somewhat consistent responses to remediable, but as yet consistently unremediated, limitations in capability. I think echnological remediation of these limitations will happen long before our ability to travel interstallerly reaches economic porportions, and this would alter the landscape of our capability and make our past behavioral paragdimes completely invalid within just a thousand years at most.

Look at the colonization paradigm. The petri dish extrapolation above assumes that as humans have colonized frequently in the past, so we would like to think we would have a glorious future that is nothing but a higher flying, and ever lasting, version of the romantic interlude in the past. Therefore we would go on making heavy impact colonization of ever more stars indefinitely into the future in much the same way we made heavy impact colonization of all parts touching America. The Fermi paradox implicitly assumes that because we think this is what we would like to do in our future, based on our own past, then this must be what at least some other alien civilization have done if they are already ahead of us.

I think that assumption and the line of extrapolation is shaky and does not stand up to close scrutiny. Humans are not inexorably driven to colonial expansion by irresistible instincts (as an aside even if we were there is no reason to assume other intelligent civilizations would have the same instincts). Rather colonization and expansion is fundamentally driven by 4 more fundamental factors:

1. Overpopulation,
2. Natural resources,
3. Markets and trade routes,
4. Military and political advantages.

Each of these four factors are reflective of and responses to severe deficiencies in technological capabilities which we have not yet overcome. It seems to me that so long as we presume technological civilization will continue, then a technological path to overcome these deficiencies can be envisioned with at least as much confidence as the Petri dish extrapolation which implies they would not be overcome.

1. Overpopulation - There are two fundamental drivers for overpopulation. The first is there is short term advantage to having a bigger population in a sedantary society. Because even now, overall productivity remains closely tied to input of human capital in the short term. A society with larger population is capable of higher overall (not necessarily per capita) productivity, and higher overall productivity means higher surplus productivity that can be devoted to discretionary projects. Greater ability to embark on discretionary projects gives the fast breeding society a powerful short term competitive advantage. See China. They key here is overall productivity show short term positive correlation with population. I think the Correlation has been diminishing since development of increasingly mechanized manufacturing, see inability of highly productive societies like that of the US to provide full employment. But the trend is by no means cancelled, again see China. But I think the trend is clear. In the long run, short term total productivity will be increasingly divorced from population size. The competitive advantage of a larger population will diminish. This removes economic incentive for overpopulation.
The second driver for overpopulation is the biological urge to breed. I think this is a weak driver, easily modified by social convention and economic incentive, to say nothing of what we can do with another 2-3 centuries of research into neuroscience. People like to wax sentimental about what makes us human, and biological need for family and offspring being high on the list. I think this is hog wash. The only thing that makes us human is the desire to call ourselves human. Everything else about human is susceptible to change. If the short term drive for population increase loses its power, the need to colonize to deal with overpopulation will diminish.

2. Natural resources - Ultimately all natural resources are equivalent. Whether they are mineral, energy, or whatever, they are all nothing but energy by E=MC^2, only packaged slightly differently. The amount of energy potentially available to us in the solar system alone vastly exceed, by many orders of magnitude, our most vainglorious conception of our needs in the foreseeable future. The reason why we are resource constrained is we lack the technological ability to freely change the package the energy comes in to suit our needs. We can only utilize energies packaged in the right form, whether that is the right ore, right oil deposit, or the right wind direction and velocity. As a result we are slaves of where the right packaging of fundamentally the same underlying energy can be found. Hence we need to go out to colonize to get to where the right packages are. But here you can see technological progress is already expanding out ability to use more types of energy package to suite the same need. We are currently doing this mostly thorugh using chemical processes to change some energy package into other packages. We also have some technology to use nuclear processes to change energy packages at atomic level. I think it is not unreasonable to suppose our capacity to change package of energy will grow exponentially, eventually to the point where we can economically disassemble any substance to the nuclear level and reorganize them from nuclear upwards. So any matter can substitute for any other matter for any purpose. True, It will probably always be cheaper to mine locally raw material if they are already of the right type than to transmutate substances to get what one needs. But with interstellar travel the case is altered. Interstellar travel is immensely energy expensive. It is by no means clear that the right substance can be mined and transporter across interstellar distances cheaper than the substance can be manufactured from subatomic level upwards in the home system. So I think resource acquisition as motivation for extensive interstellar colonization is questionable at most. Dyson sphere is one example of how one might go about utilizing billions of times more energy than we can now. But even the total output of the sun over the life of the dyson sphere is but a tiny fraction of the total energy the sun would emit in its life time, which in turn is a tiny fraction of the total energy available from all matter in the sun, even adjusting for negative gravitational potential energy. I can envision we can go on for many thousands, if not millions, of years subsisting only on energy available in the solar system if we develope the technology to tranmutate matter as well as to extract all energy from matter for other use. A civilzation that can consume the entire mass of a star for energy in a million years would be consuming power at about 1 million times the normal output of that star. So a civilization could potentially be well on the way to being Kardashev Type III (the level of development where its power usage is equal to the total power output of an entire galaxy) without leaving its home solar system. Again arguing for the limited need for interstellar colonization in civilzational development.

3. Market and trade routes - If moving things across interstellar distances are more expensive in the ultimate fundamental unit of exchange - energy - than making the stuff up in situ, Colonizing for the sake of markets and trade routes will make no sense, at least not until one has exhausted all energy in systems one already occupy.

4. Political and military advantage - Given that the Universe is 13 billion years old, and any two civilization that do come in contact is likely to be separated by millions to billions of years in level of technological development, I don't think positional advantage gained through colonization would be material at all in any political or military struggle. I think in overwhelming majority of hostile encounters between two civilizations, the encounter would end in the utter subjugation if not annihilation of the less developed civilization before it knew what had hit it. Colonization would be irrelevant to the outcome. If anything, it makes it more likely for the civilization to run afoul of one more advanced.

So I think a heavy colonization foot print is both unnecessary, and unlikely, for technological advanced civilization because there is only a narrow window in which any such civilzation would have reasonable ability for interstellar travel, as lack the degree of technological progress in automation, artificial intelligence, energy collection and material transmutation that would nullify the advantages of colonization.

Fermi envision the future of technological civilization to be one where the species spread like a mold, superficially, over the skins of as many planets as it can get to, and without the economic ability to freely transmutate matter and energy, with population behavior still largely conditioned by evolutionary survival needs from before the age of technology. I think a more likely future of technological civilization would be one where matter and energy transmutation would be economically, population behavior is wholly artificially conditioned, and the civilization operate not through wide but superficial exploitation of many worlds, but extremely intensive exploitation of just a few. Each system would be totally exploited to the point where virtually nothing of it would be left, and then it would move onto another. Most interstellar travel it would take in between would be for scientific purposes, and these need not leave much of a foot print in the visited world.

Let's say the typical advanced culture occupies just one or a few solar systems at any one time, exploits that system to the max over a million years by literally consuming all planets and asteriods, and even the central star, until nothing is left but but a thin and diffuse debris cloud, before moving to the next. Say there is 10,000 such advanced cultures. Assuming the first advanced civilization appeared 4 billion years after the formation of first Population I star, then the oldest civilization would roughly be 6 billion years old. Let's say the 10,000 civilization appeared at a uniform rate, then they've on average have existed for 3 billion years. Let's say on average they would totally consume all the matter and energy in a solar system in 1 million years. Then each of them would have on average gone through and totally consumed 3,000 stars and their planetary systems. They together would have consumed 30,000,000 planetary systems. Milkyway has been variously estimated to contain from 1,000,000,000 to 10,000,000,000 planetary systems. If these advanced civilizations are evenly distributed according to star density in the Milky way, then there would seem to be anywhere from 97% to 99.7% chance that our solar system would not yet have crossed paths with a alien civilization setting up shop to consume another planetary system.

So the fact that there are no glaring evidence of alien bases or colonies in our solar systems doesn't mean much in my estimate of how many intelligent aliens there can be in the Milky way.

As to the trail of 3,000 destroyed stars and planetary system that on average each civilization leaves behind, we don't really have the ability to detect that, or to recognize it even if our instruments see them.

So I think our absense of evidence of aliens does not really put any significant constraints on how many advanced aliens there might be, unlike what is implied by fermi's paradox. Even if there are 10,000, or even 1,000,000 civilizations roughly following the developmental path I hypothesized, there would still be only a low chance that they have left any major foot print in our solar system for us to discover.