Everyone loves them some aliens. But …if the encounter is to work out to the satisfaction of all concerned, it is best if the aliens not be too advanced (because they could brush us aside like ants) or too primitive (we might brush them aside like ants). No, there’s a Goldilocks zone for aliens, in which they are close to the same tech level as humans … and can interact peaceably with us.
Which leads me to wonder: just how likely is it that two unconnected civilizations could reach the same technological level (roughly) at the same time?
Time for some large, round numbers.
The universe is about 13.8 billion years old. The boundaries of the era in which rocky planets could form are a bit fuzzy, but Kepler-444 seems to point to them. Say the boundaries are 11 billion years old, plus or minus a billion years. OK, the era of rocky worlds starts about ten billion years ago. Humans are perhaps 300,000 years old as a species. Most of our advanced technology is less than a century old. To put that in cosmic terms, humans are about 3/100,000 times as old as rocky planets, while our whiz-bang tech is 1/100,000,000th as old as rocky planets.
To put it another way: if we imagine that ten billion years as one day, humans have been around for a bit over 2 1/2 seconds. High tech has been around for about a thousandth of a second.
For a second species from an unrelated world to have evolved into intelligence and invented tech—specifically tech that hit human levels at just that thousandth of a second…it’s extremely unlikely. Even the possibility that we’d show up in someone’s sky while they were still playing with stone axes seems unlikely .
But alien races are fun! So how can authors deal with the grim numbers? The usual way: denial, anger, bargaining, depression, and acceptance.
The easiest way is to ignore the implausibility. It helps not to be aware of it, so for all the authors choosing this path, sorry about everything above between “The universe…” and “unlikely.” And also footnote 1. Try not to think about it. No, I’m not going to give examples of authors in denial.
Don’t deal with the issue within your story but do shout angrily at people who point out the problem. The extreme example of this tactic is what I once called the SFnal Lysenkoist Tendency: when actual, tested science contradicts some detail in an SF story, attack the science. Again, no examples will be pointed out.
Offer the reader a semi-plausible explanation—in exchange for which, it is hoped that everyone will pretend it all makes sense.
Semi-plausible explanation 1: Assume that every tool-using species save for humans is a knucklehead. The poor aliens have been slowly puttering along at their own, very slow pace, and suddenly humans pop up among them, so young that their first vacuum tube radios are in museums and not ancient fossil beds. The classic example is Arthur C. Clarke’s Rescue Party but there are others. So many others.
Semi-plausible explanation 2: Postulate a cap on technological advancement. Perhaps there is hard limit to progress, one we will encounter in the near future. If we’re lucky, the cap is that the law of diminishing returns limits the effectiveness of science at a point not too much more advanced than the one we’ve reached. R&D looks easy to humans because we’re still collecting low-hanging fruit. Shane Dix and Sean Williams’ Evergence books are one example of this ploy.
It’s also possible that high tech species will develop tech up to the point where they can destroy themselves (as we can), at which point they destroy themselves (as we might.) Envision On the Beach, repeated across time and space until habitable planets cease to exist.
Semi-plausible explanation 3: Perhaps there’s a causal link between the various civilizations. The humans in Brian Stableford’s Optiman suspect that the reason they and their bitter enemies appeared on the galactic stage at the same time is that they are pieces in a game played by superior beings. Similarly, the various species in the Lensman Saga have been subject to Arisian tinkering since time immemorial.
The worlds of Ursula K. Le Guin’s Ekumen all have humanoid species operating at roughly the same tech level (somewhere between stone axes and starships) because they were seeded on their respective worlds by the Hain in ages past. Time, natural selection, and some genetic engineering did the rest. It’s not clear if the Shing (who show up in City of Illusions) are Hainish in origin, but the non-technological aliens in “Vaster Than Empires, And More Slow” suggest that the Shing may be Hainish foundlings, because the true aliens are very alien indeed.
If not descended from the same ancestors, perhaps alien species can be descended from animals shaped by humans. Neal Barrett, Jr.’s Aldair series is set on an Earth populated by genetically engineered animals that were carefully redesigned to look humanoid. Why long-absent humans would have done this is unclear to the series’ porcine protagonist. Answering this question could fill a series—in fact, it did.
On a similar note, Lawrence M. Schoen’s Barsk books are set in a distant future populated by intelligent animals created by humans. The various species come in a variety of shapes, but they share tech that they inherited from humans.
Perhaps it’s humanity that has been alienified. John Varley’s Eight Worlds and Charles Sheffield’s Proteus books provide examples, as do Tanith Lee’s unfortunately incomplete Four-BEE series. When one can edit genes, adding and subtracting, the results can be wonderfully diverse.
Another method that works is to postulate a synchronizing event. In Niven’s Known Space setting, for example, a galaxy-wide war killed off everything with a brain a billion or two years ago. There still seem to be a lot of high tech species showing up in the same part of the Milky Way in a very short period, but the event at least reduces the scale of the problem, particularly given the presence of the tech-spreading Outsiders.
This is not recommended because too much time spent on the implausible aspects of one’s setting may preclude writing any further books in it. While the issue wasn’t quite the one I am discussing here, Charles Stross’s Eschaton series fell prey to its own author’s successful “disbelieve” roll.
Accept that either we’re the top dogs in the observable universe because everyone else is still working on multicellularity, or that we’re not and we’re sharing the universe with beings more powerful and more insightful than we are: Gods, if you’re an optimist like James Alan Garner (as seen in his League of Peoples novels), or demons, if you’re a paranoid xenophobe from Providence.
1: In fact, Earth has had complex life only for about one twentieth of the time rocky worlds have been around; even finding life on the order of salamanders or fish might be long odds.
In the words of Wikipedia editor TexasAndroid, prolific book reviewer and perennial Darwin Award nomineeJames Davis Nicoll is of “questionable notability.” His work has appeared in Publishers Weekly and Romantic Times as well as on his own websites, James Nicoll Reviews and Young People Read Old SFF (where he is assisted by editor Karen Lofstrom and web person Adrienne L. Travis). He is surprisingly flammable.