Oldskeptic wrote:Given the enormous distance from Earth and the time it would take to get to any planets likely to support human life the proposition that they could be populated by human colonizers seems preposterous if not impossible. But, even though I won't be around to see it happen I do see at least one way that it could happen, and it comes from science fiction. Not cryogenic suspended animation or viable embryos incubated in artificial wombs by caretaker robots after reaching the destination.
It's more like the migration of of Asians to the Americans. Generation after generation was born along the way, and no one that started the journey in Asia finished the journey at Tierra del Fuego or anywhere on the American continents. It was their descendants that did settling.
My idea is along the lines of Larry Niven's ring world. An artificial environment, using centrifugal force for simulated gravity, not adapted to along the way, but an environment that can be manufactured and manipulated, essentially adapted to human needs and requirements. An environment large enough to accommodate large enough populations for varied and successful reproduction.
Laying aside all objections due to current technical feasibility I can also envision multiple man made environments traveling along side each other with brides or husbands leaving one environment for another upon marriage just as many brides and husbands left their own tribe for another in our past. With some environmental units/tribes dropping out or going other directions along the way.
I don't see how, if done in something like this way, journeys of thousands of years through our galaxy could not be possible with science and technology advancing along the way to improve the chances of survival and successful intergalactic colonization.
Something brought up as some sort of objection, I believe by Ven. Kwan Tam Woo, is that it may not be our own species that that is saved in this way but a different species composed of our species' descendants. And while that is entirely possible, dependent on the length of the journey and the isolation of populations, I don't see why it matters. Some of our ancestors were fish, some were amphibians, some where shrew like creatures, some were monkeys, and some were apes that are not recognized as our own species. The species that steps off a transport vehicle may be homo sapien sapien sapien instead of homo sapien sapien and unable to breed successfully with an ancestor that first stepped into the transport vehicle however long ago. Why would that matter? Why would the non-survival of our species be so important if our species' descendants survive to carry on this four billion year long process of evolution that has led up to our existence?
Your proposal is similar to what I posted a couple of pages ago,
here. I think you're too pessimistic in how difficult technologically it would be to do something like this. My proposal is far more low-tech, and doable soon, than anything at all resembling Niven's marvelous creation, Ringworld. Why not use hollowed out asteroids? They're huge, for a ship, and require relatively little assembly. Their massiveness provides for the critical collision protection for high speed travel, and also radiation shielding for external radiation, but also allows for rather large reactors for power if we're still tied to fission. Of course this isn't an idea original to me, it's an old concept, I don't know who first thought of it. What might be original to me is the idea we should be trying to do this already, meaning using asteroids for solar system travel. It's easier to go to an asteroid than to Mars if landing and return are included. We most likely could soon do it with unmanned ships, go grab one and return to earth orbit or a lagrange point, for the mining and/or hollowing out. Long travel times wouldn't be too big an issue, these are long-term projects, ion propulsion likely adequate.
For interstellar travel, possibly the greatest difficulty to anticipate and overcome is what Heinlein wrote about in his
Orphans of the Sky. This is a story of a
generation ship, " or generation starship, is a hypothetical type of interstellar ark starship that travels at sub-light speed. Since such a ship might take centuries to thousands of years to reach even nearby stars, the original occupants of a generation ship would grow old and die, leaving their descendants to continue travelling."[wiki quote] In Heinlein's story, after a mutiny that killed most of the officers long long ago, the inhabitants have forgotten who they are. What should be understood is for a ship to have a high likelihood of maintaining a viable culture for a very long time, you have to have a large enough population to ensure adequate resilience against the contingencies of such travel. This is on top of the genetic diversity requirements you mention. "In 2013 [by] anthropologist Dr. Cameron Smith estimated a minimum viable population, of 14,000 to 44,000, greatly exceeding previous estimates.[8] These numbers take the risk of accidents, disease, etc., into consideration. This had been neglected in previous studies. Dr. Smith's analysis is based on an extensive literature review and modelling of genetic effects in populations over time." [wiki quote]
Of course, advances in genetics/medicine and IT will probably make a lot of this irrelevant/not applicable. What humans are in a century or two can't be anticipated with any confidence. I don't think we'll be all that gung ho to go galumphing across the galaxy, our virtual realities will be more interesting
“When you're born into this world, you're given a ticket to the freak show. If you're born in America you get a front row seat.”
-George Carlin, who died 2008. Ha, now we have human centipedes running the place
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