Polystom (43 page)

Take a point
x,
at a geostationary orbital position above the Earth. Imagine a column of air reaching from ground level to
x;
such a quantity of air would indeed be very much heavier than that found in our world, and would weigh horribly upon the person standing underneath it. But imagine the same column extended, as it would be in the Polystom cosmos, as far out again, to 2
x
(and, indeed, further still, but let us simplify the model). As with the hypothesised Clarke space-elevator cable, the weight of the quantity of air from
x
to 2
x,
moving away from the world under centrifugal orbital effects, would in practice
counteract
the weight of the quantity of air from ground to
x,
and the net air pressure at sea level would in fact be less than is the case on Earth. In fact, and because we are not dealing with a rigid structure like a space-elevator cable, we cannot think of a vertical column of air over every person. Instead we must imagine very long, spiral trailing areas of air, in which the cumulative weight of all the individual molecules of air does not press directly downwards, but instead acts via a complex pattern of shearing forces and diagonal partial-pressures. Calculations suggest that air pressure under these circumstances, at sea level on any rotating body with gravity
g,
would be slightly
less than one bar.
To suggest otherwise, as some slapdash scholars have done – scholars of whom one must say, in certain cases, that they really ought to have known better – is to be guilty of solecisms that would embarrass a schoolchild
.

Interested readers may consult the extensive bibliography on the subject to be found at
www.polystom.com
.

I’d like to thank the following people for help and support during the writing of this novel: Simon Spanton for the economical excellence of his editorial work, as well as for his friendship; Malcolm Edwards; Malcolm Dixon, who read the manuscript; Steve Calcutt; Roger Levy; James Lovegrove; Bob Eaglestone, who disagreed with the physics of the Polystom world. Most of all, I would like to thank my wife Rachel, who read the manuscript and made many helpful suggestions.

I would also like to acknowledge one very particular debt. Gillian Allnutt’s exquisite collection of poetry
Lintel
(Blood-axe, 2001) provided me with general inspiration for this novel, as well as specific quotation. Polystom’s own readings of Phanicles’ poetry are taken from three of Allnut’s poems: ‘turf’, the opening of ‘Tabitha and Lintel’ and ‘Annunciation’. These lines are quoted by kind permission of the author, and remain copyright to her.

This book is for Lily.