-Hard science, artistic license and obsolete data-
The son of an engineer and with an education in physics himself, Poul Anderson was not shy about including hard science in his fiction. While future tech was often handwaved off with a minimum of techno-babble, when it comes to strange stars and planets, we get a veritable catalogue of facts from spectral type of the star, the axial tilt of the planet, even in some cases including the geology of his worlds! And while he did create a lot of fictional stars, he also made use of real ones when building his future histories. This is very apparent in his Technic civilization stories, where some actual stars are recurring “characters” together with some fictional ones. It is notable that in that series of stories, most of the action takes place either in the Sol system or in rather distant star systems. Hardly any Technic story takes place within 20 light years of Sol (excepting Sol itself). Staple stars of science fiction like Epsilon Eridani, Sigma Draconis or Tau Ceti are seldom mentioned. In a rare exception, the future first Emperor of Terra, Manuel Argos, is captured by the Gorzuni on Alpha Centauri. Another relatively close system mentioned is Chee Lan’s home planet Cynthia which orbits Omicron 2 Eridani A, 16,3 LY from Sol.
The position of the real star systems used, just as the fictional ones, are often described at least relative to the Sol system – and it is here that the advancement of science has made a disservice to Anderson’s work. During, and especially after the period during which he worked on the technic civilization saga, the data we have on the distance from Sol of many of the stars mentioned in the stories have improved considerably.
Because we do not know with certainty the absolute luminosity of a distant star – we cannot really tell at a glance if it is a shining giant at an enormous distance we are seeing or a modest dwarf closer to Sol – we can measure distance from us by using the parallax method. It is how our depth vision work. Just as our brains can calculate the distance to an object through (among other means) the slight difference in angle between the picture of either eye, astronomers can measure the angle to a star at two points in time. Using the difference in angle between the two observations, trigonometric calculus can give an estimate of the distance to a star. However, the more distant the star, the smaller the angle is and the harder it is to accurately calculate the distance. And in this, the state of the art has advanced considerably since the 1950s. For example, in the 1990s, close to the end of Poul Anderson’s career, the Hipparcos mission obtained parallaxes for over a hundred thousand stars with a precision of about a milliarcsecond, providing useful distances for the first time for stars out to a few hundred parsecs (a parsec is equal to about 3.26 light years). With the Hubble telescope we can today reliably determine distances out to 5 000 parsecs. None of this was possible in the 50s, 60s or even 70s.
This coupled with the fact that the Technic stories involve mainly distant stars has caused the distances mentioned by Poul Anderson to become very dated. I shall name a few examples.
In A SUN INVISIBLE, the distance from Sol to Beta Centauri is given as 190 LY. Currently, it is believed to be 397 LY. In SATAN’S WORLD, the Serendipity supercomputer tells David Falkayn that Beta Crucis is 204 LY from Sol. Currently it is believed to be 287 LY. Note that this also means that the author thought of these two stars as being be much closer to each other than what we now believe.
The obsolete data for distance to real stars have consequences also for the locations of fictional ones, since their position is often described as relative to real stars.
In WINGS OF VICTORY, in which an Earth star ship of The Great Survey visits the Home world of the avian Ythrians, their star is said to be “beyond the great stars Alpha and Beta Crucis”, “in the constellation Lupus” and “278 light years from Sol”. As mentioned earlier, this is inconsistent with modern data, since the closer of the two stars, Beta Crucis is about 287 LY from Sol, and Alpha Crucis is 326 LY. To be considered “beyond” both these stars in any sense of the word, Ythri must be no closer than 326 LY to Sol. Add to this that Ythri is to be found in Constellation Lupus, not Crux as Alpha and Beta Crucis, that is to say a considerable distance to one side of Crux. If we are truly to consider us to be “beyond” and not “beside” Alpha Crucis, we would have to increase the distance further – exactly how long is impossible to determine, but one could safely assume another 100 LY at the least, to place A .Crucis “behind” rather than beside us.
But we have more clues in other stories. In THE PEOPLE OF THE WIND, the Terran Empire initiates a war of conquest against the Ythrians. Among the reasons are to secure for Terra the system of Beta Centauri, around which orbited several Krakoan- and one human-inhabited worlds before Ythri might beat them to it, as they already had with the Dathyna-system (from SATAN’S WORLD). Beta Centauri is, also as mentioned, 397 LY from Sol, and while it is not inconceivable that Terra and Ythri would dispute a system beyond Ythri from Sol, intuitively we would assume that the disputed systems are between the two. Beta Centauri is not mentioned as a close neighbour to Ythri in “wings of victory”, which makes sense since we know that the author believed B. Centauri to be only 190 LY from Sol, we can conclude that he also thought of Ythri as being no closer to B. Centauri than 88 LY (which would any way require it to be behind Beta Centauri and in Constellation Centaurus, not Lupus). These considerations would lead us to the conclusion that Ythri is near to 500 LY from Sol.
Another problematic set of data appears in Anderson’s Dominc Flandry stories set in the decadent Terran Empire of the early 31st century. The Empire is said to control a rough sphere with a radius of two hundred light years including around 4 million stars – but within that sphere are Beta Centauri (397 LY away), Alpha Crucis (326 LY from Sol), Beta Crucis (287 LY) and Antares (609 LY from Sol). Betelgeuse (642 LY from Sol) is not within the Empire, but a buffer state between Terra and Merseia (which is said to be located in “the wilderness between Betelgeuse and Rigel” in THE DAY OF BURNING). To make matters worse, Antares and Betelgeuse are almost exactly opposite each other from Sol. The Empire thus claims space up to more than 600 LY in both these directions.
Another problem is that within a sphere with even a 250 LY radius from Sol, there are in the proximity of 260 000 stars, so nowhere near the 4 million stars mentioned. That amounts to about 0,0038 stars per cubic light year. Using this star density, it would require a sphere with a radius of almost 630 LY to include 4 million stars.
On the other hand, in THE REBEL WORLDS, Polaris and Deneb are said to be “unutterably far beyond the Empire and its enemies”. This is doubtlessly true about Deneb (1 547 LY from Sol) but Polaris is “only” 431 LY from Sol, that is to say closer than both Antares and Betelgeuse and also notable for being on one end of the sphere controlled by the Polesotechnic League in the era of Van Rijn and Falkayn, which held sway “from Polaris to Canopus” (Canopus is 313 LY from Sol, by the way). While it is mentioned by Flandry that the Polesotechnic League explored far beyond the Empire’s reach, it is odd that Polaris should be considered “unutterably” beyond the Terran sphere, when being closer to Sol than some of the Empire’s more notable border systems.
None of the this would really be problematic unless for the oft-repeated statement that the Empire controls a “rough sphere” 400 LY across, or with a radius of 200 LY. An Empire that controls Antares, Alpha and Beta Crucis, Beta Centauri and which borders Betelgeuse but otherwise only holds sway out to a radius of 200 LY from Sol is not a sphere – rather it is shaped like a three-dimensional starfish!
Now, how to reconcile these inconsistencies with Poul Anderson’s texts? One way is to decide that the entire universe is fictional, and that in the universe of the technic civilization, Beta Crucis really is only 200 LY from Earth. Another approach is that of “minimum rewrite”, i.e. to ignore those measure of distance given by the author that are inconsistent with modern data but accept all other facts – in other words, accept that Antares is an Imperial system, and Betelgeuse is a buffer state, and thus conclude that the Empire is over 1 200 LY across between those systems. That would also mean accepting that the Empire, as stated, is a rough sphere rather than a starfish, but that it is a sphere with a diameter of roughly 400 parsec (rather than light years). Interestingly, the earlier mentioned radius of a sphere required to englobe 4 million stars, 630 LY, corresponds to 193,1 parsecs. A sphere with a 200 parsec radius would hold, on average, 4,4 million stars. Close enough!
Not all astronomic inconsistencies in Anderson’s work stem from obsolete data however. Above all, he was a writer of fiction, and as such he would engage, from time to time, in artistic license. In WE CLAIM THESE STARS, the dastardly Merseians are trying a land grab (or star grab perhaps?) in the fictional Syrax star cluster, which, if held by the Merseians would “bypass Antares” (presumably an imperial bastion) and thus hasten the demise of the Terran Empire by a century or more. The only problem is that, as mentioned before, Antares in constellation Scorpio is on the exact opposite side of Sol from constellation Orion where Merseia orbits the star Korych between Betelgeuse and Rigel (according to THE DAY OF BURNING). Thus, if we are to take this at face value, the Merseians have completely surrounded the Terran Empire at least on one side and can threaten it from the exact opposite direction of their home world, more than 1 250 LY away, in a straight line and more than 2 000 LY away if they have to fly around the circumference of the Terran sphere. Assuming speeds similar to those given in SATAN’S WORLD (Sol to Beta Crucis in two weeks), such a journey would take close to 100 days. It could be less, if the state of the art of hyperlight travel has improved in the centuries since SATAN’S WORLD, or it could be more, given that the estimated travel time in that story was for a small, swift ship for a few passengers. A heavy battlefleet might be considerably slower. The Merseian fleet at Syrax could well have made a journey comparable in length to that of the ill-fated Russian Baltic Fleet sailing to Tshushima in 1904-1905 (which took around six months).
On the other hand, we are told the Merseia threatens the Empire on its “Betelgeusan flank, and the barbarians everywhere else” – the Empire does not have Merseia around half of its periphery. This leaves a distant Merseian base the only possible explanation, perhaps similar to Cuba becoming a Soviet base during the Cuban missile crisis. That analogy makes clear the problem with that assumption obvious – while the US would have very much deplored and opposed a Soviet attempt to take over, say Haiti from its Cuban base in 1961, the really big beef was having Soviet missiles on Cuba in the first place.
By the same token, if the Merseians were threatening Syrax from a distant exclave in Constellation Scorpius, then surely it would be worth at least a passing mention by Flandry or his superiors? Such a base would constitute a major strategic conundrum for Terra, far more important in itself than the fate of the Syrax cluster and one it could scarcely leave unaddressed, even in it morose decadence. Nonetheless, this is what the reader will have to assume, if we are not to dismiss the premises of the story out of hand!
In this case, obsolete data are not to blame – the directions of Antares and Betelgeuse where as well known in 1969 when that particular story was written as they are today. But Antares had been used in several prior stories and connects the reader with the Technic universe through familiarity of places and names. It will be noted though that never in the story does Anderson say that Antares is anywhere near Betelgeuse or Korych. The inconsistency is not in astronomy but rather in somewhat implausible geo- or rather astropolitics.
