I worked out a model of the situation, supposing that the giant molecular clouds orbiting at high velocities there provided the energy for the electrical discharges. They would provoke huge, multicolored arcs playing across the night sky, like permanent twisted neon lights. The ancient Asian Indian name for the Milky Way, Great Sky River, would be spectacularly true at the center. In my mind’s eye I saw these pyrotechnics as backdrop for my puny humans…

Those hunches became the kernel of several papers on the center, the first published in The Astrophysical Journal in 1988. They work out an electrodynamic model that has become generally accepted—for now, pending more data. About half a dozen competing views surfaced and sank in the storm of incoming observations. More filaments turned up. Arguments waxed over how big a black hole at the center of it all might be.

While I was mulling over maps and jotting equations, I kept on writing. Over years, the writing fed the physics, and vice versa.

Intriguing setting is essential in a series of novels, or else a sense of sameness creeps in. I used all the gaudy color and striking effects I could muster in #3 of what came to be called The Galactic Series, Great Sky River.

I focused on the innermost few light-years, for dramatic effects, even though I knew the sheer energy flux there made humans quite vulnerable. To protect them I made them huge and armored. The central figure was a man named Killeen, who flees across a ruined landscape dominated by the black hole, which his people call the Eater of All Things—though they don’t quite know why.

This ravaged panorama seemed an ample stage to act out my main theme, the superiority of machines in much of the galaxy. We need a moist envelope of air and mild temperatures. They can take just about anything, including vacuum. I also got to spring their size as a twist at the very end of the series, when they meet Walmsley, whom they take to be a dwarf.

By then, measures of the very high orbital velocities of stars very close to the true galactic center, called Sagittarius A, suggested that some enormous mass was tugging at them. The data implied a compact mass of several million stellar masses lurks there, and—big clue—giving off very little light. A black hole.

I opted for a million-mass black hole, because then a ship could fly through the ergosphere, the very rim of the black hole, and not be crushed by the tidal forces. Contrary to intuition, the bigger the hole mass, the larger the comfy zone at its “edge” where the stresses can be small. Big enough, and a ship could skim through. This fact would be crucial to the last volume, Furious Gulf. I thought I would have a band of fleeing humans dodge into this warped region of space-time, only to discover a surprise… which I won’t reveal here.

The huge energetics of the center would draw machines, I felt. There they could live heartily, while their vermin enemies (us) struggled. The black hole would intrigue any inquisitive life-form, their struggles surging across a virulent territory. Humans would be part of it all, but certainly not the major players.

So I began envisioning what it might be like at stage center, where the diet of particles and photons is rich and varied. Only hard, tough machines could survive for long there—and evolve into forms I could imagine.

In the fourth novel, Tides of Light, I drew out these contrasts. Hard work, but fun. I devised “photovores” and “metallovores” as adaptations to special evolutionary niches. After all, machines that can reproduce themselves would, inevitably, fall under the laws of natural selection and specialize to use local resources. The entire panoply of biology would recapitulate: parasites, predators, prey.

How to envision this? I prepare for novels by writing descriptive passages of places and characters. In spare moments I began working up snapshots of possible life-forms and their survival styles.

Years before I had found a technique to deal with “obstructions”—a better word than the fearsome “block.” To me it meant something rather more subtle. At times I simply couldn’t get my subconscious to flower forth with free material along the lines of the novel. So I pretended that I was working on another story entirely and wrote that. At times I found that I was right—it really didn’t connect with the novel. Most times, with some tuning, it did. I made a policy of following through, publishing the work independently if possible, out of an almost superstitious belief that my subconscious would catch on. So far it hasn’t.

That’s why occasionally pieces of my novels appear first as short stories. I often don’t know whether they fit the novel, sometimes until years later. This trick I had to use again and again, because my subconscious proved lazy and headstrong. I’d planned to rap out three novels and be done by 1989, but #3 appeared in 1987, #4 in 1989. Then I got interested in another novel, wrote it in three tough years… and ground to a halt.

The pesky subconscious just wouldn’t cooperate with my game plans. This cost me considerably, for the series’ momentum broke, and undoubtedly some readers lost the thread.

In 1992 I had to start from scratch again, thinking through the overarching logic of the series. Slowly it dawned that some part of me had shied away from doing the “last” novel because I couldn’t reconcile the many forces within the narrative. I realized with a sinking feeling that one more book wouldn’t be enough.

Intelligent machines would build atop the galactic center ferment a society we could scarcely fathom—but we would try. Much of #5, Furious Gulf was about that—the gulf around a black hole, and the gulf between intelligences born of different realms.

For years I had enjoyed long conversations with a friend, noted artificial intelligence theorist Marvin Minsky, about the possible lines of evolution of purely machine intelligence. Marvin views our concern with mortality and individualism as a feature of biological creatures, unnecessary among intelligences that never had to pass through our Darwinnowing filter.

If we could copy ourselves indefinitely, why worry about a particular copy? What kind of society would emerge from such origins? What would it think of us— we Naturals, still hobbled by biological destiny?

Through Books #3, #4, and #5, I had used the viewpoint of humans hammered down by superior machines. This got around the Walmsley lifetime problem, but demanded that I portray people enormously different from us. They had to seem strange, yet understandable—a classic sf quandary.

A slowly emerging theme in the novels, then, was how intelligence depended on the “substrate,” whether in evolved humans or adaptive machines—both embodying intelligence, but with wildly different styles.

By the time I reached the last volume, in 1993, I had spent over twenty years slowly building up my ideas about machine intelligence, guided by friends like Marvin. I had also published several papers on the galactic center and eagerly read each issue of The Astrophysical Journal for further clues.

I finished the last novel, #6, Sailing Bright Eternity, in the summer of 1994. It had been twenty-five years since I started on In the Ocean of Night, and our view of the galactic center had changed enormously. Some parts of the first two books, especially, are not representative of current thinking. Error goes with the territory.

When the series was finished, I was happy with the response. All along readers had nominated the books for awards, written in with ideas (and urgings to hurry up), asked for references to the scientific background. I realized that my readership was sophisticated and liked a challenge. The books sold well and got listed regularly in best-of-year summaries. Quite enough to keep me going, but part-time writers do not have the momentum of the full-time pros.