Haf worked in silence. Roi listened to the clicking of his claws against the stones, and felt herself drifting into sleep.
Afterword
The “weight and motion” of objects in the Splinter follow from Einstein’s theory of general relativity; many of the effects described also occur in Newtonian gravity, but observations within the Splinter are sufficient to discriminate between the two theories. The best general reference on this subject is:
Gravitation by C. W. Misner, K. S. Thorne and J. A. Wheeler, W. H. Freeman, New York, 1970.
The most comprehensive treatment of the particular space-time geometries discovered by the protagonists is:
The Mathematical Theory of Black Holes by S. Chandrasekhar, Oxford University Press, Oxford, 1992.
“Zak’s principle” is essentially Einstein’s equation in a vacuum, that is, the version that applies when the matter in your immediate vicinity has no significant gravitational effect. The general equation, which allows for the presence of matter, is described in terms that are almost as simple in this excellent account:
“The Meaning of Einstein’s Equation” by John C. Baez and Emory F. Bunn.
Some events in this novel depend on the detailed behavior of the plasma accretion disks that are present around black holes, and several aspects of this subject remain uncertain. For example, precisely if and when an accretion disk with given physical characteristics would be forced to lie in the equatorial plane of a rotating black hole (a phenomenon known as the Bardeen-Petterson effect) is a matter of controversy, because determining this theoretically depends on complex computer simulations, and direct observational data is inconclusive. See, for example:
“Spin-Induced Disk Precession in Sagittarius A*” by Gabriel Rockefeller, Christopher L. Fryer, and Fulvio Melia,
A comprehensive discussion of the possible fates that can be suffered by stars that encounter black holes is given in:
“Tidal Disruption of Stars by Black Holes,” by Martin J. Rees, Nature, Vol. 333, 9 June 1988, pp 523–528.
In charting Rakesh and Parantham’s journey, I drew on:
“The Nuclear Bulge of the Galaxy. III. Large-Scale Physical Characteristics of Stars and Interstellar Matter” by R. Launhardt, R. Zylka, and P. G. Mezger,
Panspermia—the spreading of viable biological material from one planet to another—is almost certainly possible between planets in the same system, but the prospects of such material achieving, and surviving, interstellar journeys is far slimmer. Interstellar panspermia is an interesting idea, and I don’t believe it has been shown to be impossible, but I wouldn’t argue with anyone who considers it to be highly unlikely.