The Kepler space telescope continues to collect data on planets around distant stars. The Kepler telescope detects small decreases in light from stars that happen when an orbiting planet passes between its star and the Kepler observatory (in heliocentric orbit). This method is biased towards large planets that are in short-duration orbits near to their star.
Kepler has found several planets that might be suitable for life. Unfortunately, it is hard for the Kepler telescope to detect planets that are the same size as Earth and that are likely to have liquid water. However, it can be estimated from the data collected so far that more than 3% of stars have a planet that is the correct distance from its star to have liquid water and, possibly, life. Most of the candidate potentially-habitable planets are larger than Earth, as shown in the image, above.
Gravitational microlensing can detect planets that are not bound to stars. It has been suggested that there are more such planets without stars than there are stars. The planet Re^Ens is a fictional world that is not in orbit around a star, but which provides a home base for artificial life forms.
I’ve previously discussed the fact that it is difficult for science fiction authors to avoid including in their stories imagined technologies that make possible faster-than-light space travel or time travel. However, it seems likely that the Fermi Paradox involves the fact that faster-than-light space travel is apparently impossible. It might be significantly easier for artificial life forms to travel between the stars than for biologicals like humans. In the novel Assignment Nor’Dyren, Sydney Van Scyoc made faster-than-light space travel a technological element of Civilized Unity, but I’m imagining that Nor’Dyren was a coloney world of an interstellar empire that did not have faster-than-light space travel.
The Fermi Paradox is often stated in terms of human-like organisms: why don’t we see evidence for human-like organisms from other planets? It might be that only artificial life forms are capable of traveling between the stars. Human-like species might produce artificial life forms that go out and colonize distant worlds, and those worlds might mostly be planets that are not in the “habitable zone” near stars. Artificial life forms might actually avoid the deep gravity wells of stars. If our galaxy was swarming with artificial life forms, would they bother to visit a world like Earth?
What do I mean by “artificial life forms”? Ever since Alan Turing recognized the power of digital computing, there have been many optimists who anticipate that it will “soon” be possible to make machines with human-like brains. A popular plot element in science fiction stories is the “mind upload”, the transfer of a person’s mind into an artificial brain. Asimov also imagined going the other way, moving the mind of the robot Daneel into the brain of a human in his story “Foundation and Earth”.
At our level of technological development and (lack of)understanding of how a brain makes a mind, “mind uploading” is just as impossible as time travel or faster-than-light space travel. I doubt if it will ever be easy to make a copy of a human mind and transfer the copy into the brain of an artificial life form or robot. In The Start of Eternity I imagine that with the help of advanced technology from the Huaoshy it might be possible to make an artificial life form that has a human mind inside a robotic body.
If humans can eventually make artificial life forms with human-like minds, might we humans become little more than pets for our A.L. creations? I’m imagining that the artificial life forms of Re^Ens had biological “pets”. Maybe when the artificial life forms make the long journey from their home star to the distant world Re^Ens they packed away some frozen embryos of their favorite “pet” species. These “pets” were biologically related to the inhabitants of the world Nor’Dyren. At some point, those “pets” revolted and claimed the right to leave Re^Ens and go find a world of their own, a planet in the habitable zone of a nearby star.
Note: This (above) is the second of a three part series of blog posts about my proposed fan fiction sequel to Assignment Nor’Dyren. The other two posts are Departure from Nor’Dyren and Stellar Engineering.