The two Kith Histories
The Rustum History
Tales Of The Flying Mountains
The Harvest Of Stars Tetralogy
The Boat Of A Million Years
Genesis (only post-organic intelligences fly between stars)
How much inter-species communication is possible at sub-light speeds? If there is a technological civilization twenty thousand light years away, then it cannot detect our present civilization because it can see Sol only as it was twenty thousand years ago. At that distance, would it be able to detect a Solar planet, then oxygen in the atmosphere, vegetation on the surface and artificial light on the night side? (Not that there would have been artificial light back then.) If there is going to be a technological civilization at that distance twenty thousand years hence, then it might with difficulty detect our present civilization. Our brief burst of radio signals - now being replaced by fibre-optic cables? - would be weak and swamped by other cosmic noise. But, if such a civilization were to launch an expedition towards Earth, then, at sub-light speeds, that expedition would arrive here well over forty thousand years in our future. Would such an expedition even be launched?
I am summarizing from memory arguments presented by Brian Cox.
Starfarers is Poul Anderson's approach to the concept of detecting an extra-solar civilization and launching a slower than light expedition to it.
4 comments:
Kaor, Paul!
In STARFARERS Anderson did not have humans discovering signs of a high tech non-human civilization from a truly implausible distance of 20,000 light years away. He scaled that down to a more doable 10,000 light years.
Ad astra! Sean
Correction, in STARFARERS Anderson had humans discovering signs of a high tech non-human civilization 5,000 light years from Earth, not 10,000 light years.
The STL expedition to investigate those signs was expected to take at least 10,000 years to return to Earth. Because of relativistic time effects the journey for the crew of "Envoy" would take only about 15 years for them.
Ad astra! Sean
A species that develops STL interstellar travel might settle *many* solar systems, maintain *very* loose contact between settled systems and in the course of expansion eventually contact other technological species hundreds or thousands of light-years from its starting point.
The backstory to Vernor Vinge's "A Deepness In The Sky" involves humans expanding in such a way.
Kaor, Jim!
And we see Anderson examining that kind of scenario in the Kith stories/STARFARERS. One very interesting possibility he examined is that the effort needed to sustain such STL interstellar contact will start flagging, waning, failing, after thousands of years. Mostly because the colonized planets will have less and less need to maintain such slow and intermittent trade and communication over so many years. And that meant more and more Kith ships could no longer afford the costs of such STL trade/traveling. As we see in STARFARERS, before the "Envoy" returned, Kith ships were increasingly disbanding.
Fortunately, the discoveries made by Capt. Nansen and his surviving crew helped to jump start and rejuvenate and revive interstellar travel.
Ad astra! Sean
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