Omega, by Jack McDevitt

This is the fourth book in this author's Academy series, the earlier ones reviewed here being The Engines of God (TEoG), Deepsix and Chindi. A linking element between all of them is starship captain Priscilla Hutchins (Hutch), although in this story – set years after Chindi – she is now desk-bound on Earth as the Academy's Director of Operations and has a relatively minor role.

The plot of this story returns to the vast interstellar clouds which were the main plot device of TeoG, and the author's most memorable invention. The Omega clouds travel at speed and can change their direction of travel. Most notably, they appear to be drawn to any straight lines or angular structures, and cause civilisation-ending destruction when they arrive. In Omega, one of these clouds is heading for a planet dubbed Lookout which, almost uniquely, has a thriving civilisation of humanoid aliens at the technological level of ancient Greece, and the Academy doesn't know what to do about it. They have tried various means of destroying the clouds without success; can they be decoyed away from the planet? Or failing that, can the citizens be warned to leave the cities and travel to high ground, without breaking the important principle that alien cultures must be allowed to develop by themselves without outside interference?

The story focuses on the various attempts to solve this problem being made by teams working surreptitiously on Lookout and in the vicinity of the approaching cloud, with occasional switches to Hutch's headaches as she tries to aid her staff at long distance while deciding what to do.  There is much detail about the amusing aliens and their engaging lifestyle, which of course just makes the problem of what to do more acute, especially when public opinion back on Earth becomes involved. The author puts forward an interesting explanation for the lack of expansion of the natives' population or of any aggression between the different, independent, cities – natural population control – as well as taking a few digs at current social issues:

"Somewhere we taught ourselves that our opinions are more significant than the facts. And somehow we get our egos and our opinions and Truth all mixed up in a single package, so that when someone does challenge one of the notions to which we subscribe, we react as if it challenges us."

Compared with the early books, the author's writing style has improved and the characterisation is now less clunky. The story rattles along at a good pace, and is easy to follow. One issue of writing style of which I have become increasingly aware is that with modern, very long stories (Omega runs to 580 pages) including lots of characters and switching between multiple viewpoints, there is quite an art to keeping the reader up to speed with who's who – and authors vary considerably in how well they do this. It is necessary first to spend enough time with each character to establish them firmly in the reader's mind, then subtly prompt the memory on each appearance to enable the reader to recall who they are and what they are like. Some authors do this apparently effortlessly (but I am sure that is deceptive), others do it badly, some give up and just put a list of characters in an appendix. In Chindi, McDevitt manages this pretty well; not quite up there with the best, but not far off them.

Finally, the traditional nit-picking section! As I have mentioned before, with SF books it is sometimes not the most mind-stretching ideas which test the credibility of a story. Faster-than-light travel? Routine. Alien races? Yawn. Vast, apparently intelligent and highly destructive clouds moving through the galaxy? OK. But it can be something quite mundane that trips up the author. In this case, it's a humble helicopter. An antique one of these is brought along to Lookout, for the sole purpose of being stationed underneath vast lightweight atmospheric chimneys and running the rotor to blow air up them, thereby starting an air circulation pattern. In the story, the helicopter is manoeuvred into place underneath each chimney and then its rotor is run as fast as it can without the helicopter actually taking off. One minor quibble is that the degree of lift generated by a rotor is not adjusted by varying rotor speed, but by altering the blade angle through changing the collective pitch. However, the really big problem is this: as a rotor develops lift, it pushes air downwards, not upwards. To blow air upwards would require the rotor's collective pitch to be negative, effectively pushing the aircraft down onto the ground and therefore in no danger of taking off. Some naval helicopters can do this to keep them on a ship's deck in rough weather, but it is clear from the text that the author misunderstood this rather basic fact concerning how a rotor works.

Fortunately, this minor point doesn't spoil the enjoyment. Chindi is well worth reading; an exciting space adventure on the grand scale.