"'Think of the requirements. Mass, temperature, irradiation, atmosphere, hydrosphere, biosphere...the best estimate is that 1 per cent of the stars may have planets which are any approximation to Earth." (p. 120)
1%?
May have?
Approximations?
How approximate does it have to be? My intuitive guess is that no planets will be suitable for human beings to colonize in the way that they colonized new continents on Earth.
We evolved in this single environment and are adapted only to it. No other planet will exactly reproduce all the flora and fauna of Earth. At best, Terrestrial crops will have to be planted in soil that will have to be chemically persuaded to accept them. But surely one ecological change would require others until a whole terraforming job became necessary? Within the Solar System, Mars or even the Moon might eventually be terraformed but that is a very different proposition from finding a habitable planet in the first place.
I think that there is a big problem here. However, anyone who crosses an interstellar distance will have to carry their environment with them and therefore will not be dependent on finding a habitable environment on a planetary surface in a new system.
8 comments:
Kaor, Paul!
One answer to the admitted likelihood of there not being many, if any, very terrestroid planets would be to build O'Neill habitats in solar systems of interest. That way large numbers of people could live there in reasonable comfort while a planet was being terraformed. Or many people might say to heck with using planets to live on and prefer O'Neill habitats.
Or asteroids could be terraformed, as we see in both the FLYING MOUNTAINS or HARVEST OF STARS stories. Or there might actually be some terrestroid planets humans could live on. We simply don't know!
I see you had Anderston's story "Strange Bedfellows" in mind when you mentioned the possibility of terraforming the Moon! I rather like that idea. Or we could still try terraforming Venus.
There ares so many possibilities in space, some of which I admit might not work, if ONLY we got out there to TRY developing them!
Sean
Humans are extremely adaptable. We're an intrusive weed species like rats, generalists capable of flourishing in a broad range of environments.
The environment we evolved in was a tropical refugium in a glacial period; but in the last 80,000 years or so we spread to every ecological niche on the planet, even before evolving a sophisticated technology, many of them radically different from the one in which we developed -- glacial tundras, high mountains with thin atmosphere, etc. We're far and away the most widespread large mammal.
The biosphere on an extrasolar planet would have to be roughly similar to try at all -- it would have to have planets that produced oxygen, for example.
Some plants would be inedible or poisonous; but then, many plants right here on earth are, or are until processed -- raw grain isn't consumable as is, many plants have to be cooked to break down their fibers and complex chemical compounds into simpler forms so that our guts can assimilate them, and so on.
On the upside, it's very unlikely that local bacteria could survive in our bodies, and vanishingly unlikely that viruses or their equivalent could hijack our genetic systems.
We could probably get -some- use out of some local plants or animals, unless there were bad allergic reactions (as in WAR OF THE WING-MEN/THE MAN WHO COUNTS.)
Earth plants would need coaxing at first, but any basically similar biosphere would have the basic constituent elements they need, like nitrogen and various minerals.
If there are many planets -- and we now know that most stars have planets -- then the number is so large than some will be doable. You try and fail until you succeed, as the saying goes.
Kaor, Mr. Stirling!
I absolutely agree with your comments here! As you said, many Earth plants would very well need "coaxing" on some terrestroid planets. I also add that Poul Anderson speculated in some of his stories that some planets might have PRIMITIVE life forms easily pushed aside by more highly evolved species introduced from Earth. Which is what happened on Nike, in "A Tragedy of Errors."
Anderson speculated as well that humans could adapt to higher gravity planets as well, such as Rustum in ORBIT UNLIMITED, or Imhotep in THE GAME OF EMPIRE.
Yes, it's reasonable to think that even one percent of millions of stars will have terrestroid planets that humans could colonize. The tricky part is GETTING there. Preferably by FTL means.
Sean
Human adaptability is the other side of the coin.
https://en.wikipedia.org/wiki/List_of_potentially_habitable_exoplanets
Sean, from my understanding, most types of FTL violate causality.
http://www.projectrho.com/public_html/rocket/fasterlight.php
Cheers,
-kh
Kaor, Keith!
Yes, I was aware of the difficulty you raise, about FTL violating CURRENTLY knonw theories of physics/causality. But, allow me to hope some end run around these difficulties will be found! (Smiles)
Sean
We most certainly do not have a "theory of everything". In the 19th century, the best available physics made it impossible for the Earth to be old enough to account for the evolution of life. The problem wasn't that either the physics (Newtonian synthesis at the time) or the biology (pre-genetic evolutionary theory) were -wrong-, it was that they contradicted each other because they were -incomplete-.
When two testable theories both have experimental validation and -also- contradict each other, you're getting a strong signal that your knowledge is incomplete. Not wrong, just covering 'special cases' rather than 'everything'.
We're in precisely that position currently with our physics.
Indeed, Mr. Stirling. Our theories are far from complete; I posit that some of them may be theoretically completable, but practically: not so. Consider if our knowledge of some subject were a fuzzy image we view at some distance, and it increased in clarity as we walked toward it. Now imagine this fuzzy image were not a few-dozen feet away, but hundreds or thousands of miles, and we can only walk (and the path gets more diffuiult the farther we proceed)...
-Keith
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