that the carbon-dioxide greenhouse warmup of the Earth came to a halt, and the pollution of Earth's air stopped overnight. Small vehicles burned hydrogen or ran by flywheel kinetic-energy storage. Everything else took its power off the grids.
Things were really getting to be very nice on Earth, because human technology hadn't stopped, either.
For not everything in mankind's flowering of science and technology was a gift from the Heechee. There were computers, for instance.
Human computers were intrinsically better and more advanced than those of the Heechee, because the Heechee had never gone the adding-machine-to-mainframe route. Their methods of dealing with data handling were quite different, and in some ways not as good. Once the human scientists had begun to figure ways of adding Heechee refinements to the already powerful human machines, there was an explosion of knowledge that sparked new technologies in every part of human life.
Quantum-effect devices had long since replaced the clumsy doped silicon microchips, and so computers had become orders of magnitude faster and better. No one had to tap out a program on a keypad any more. He told the computer what he wanted done, and the computer did it. If the instructions were inadequate, the computer asked the right questions to clear it up-it was face-to-face communication, a machine-generated hologram speaking to its flesh-and-blood master.
Heechee food and Heechee power ... human computers Heechee biochemistry allied to human medicine
The human world at last allowed true humanity to every persoh who lived on it. And if, even so, any human wanted more, there was a whole galaxy waiting for him that was now within his reach.
There remained the burning and never-forgotten question of the Heechee themselves.
They were elusive. Their works were everywhere, but no one had ever seen a living Heechee, though every last Gateway explorer had wanted to look, and almost every human on Earth dreamed (or had nightmares) of what they would be like when found.
Arguments raged. Answers were scarce. The prevailing theory was that somehow, in some tragic way, the Heechee had died off. Perhaps they had killed themselves in a catastrophic war. Perhaps they had, for reasons not known, emigrated to a distant galaxy.
Perhaps they had suffered a universal plague-or reverted to barbarism-or simply decided that they no longer wanted to bother with traveling through interstellar space.
What everyone agreed on, at last, was that the Heechee were gone.
And that was just where everyone was very wrong.
It was not true that the Heechee had died. Certainly not as a race, and, funnily enough, in an astonishing number of cases they hadn't even died as individuals.
The Heechees were very much alive and well. The reason they were not found was simply that they didn't want to be. For good and sufficient reasons of their own, they had decided to conceal themselves from any unwelcome attention for a few hundred thousand years.
The place where the Heechee hid was in-the core of the galaxy, within an immense black hole-a black hole so enormous that it contained thousands of stars and planets and satellites and asteroids, all orbiting together in a space so small that their combined mass had pulled space in around them. The Heechee were all there-several billion of them, living on some 350 roofed-over planets inside their Core.
To create their immense hidey-hole, the Heechee had tugged together 9,733 individual stars, together with their appurtenant planets and other orbiting objects. That gave them, among other things,
some really spectacular nighttime skies. From the surface of the Earth, human beings can see at most maybe four thousand stars with the naked eye, ranging from fiery blue-white Sirius all the way down to the sixth- magnitude ones that lie on the squinting border of visibility. The Heechee had more than twice that many to look at, and they were easier to see because they were a whole hell of a lot closer-blue ones far brighter than that familiar Sirius, ruby ones almost as bright as Earth's Moon, asterisms of a hundred stars in a bunch and all wondrously bright.
Of course, that same stellar population density kept the Heechee from having much in the way of nights. Except when the clouds were thick they just weren't used to much darkness. On their planets inside the Core there was seldom a time when the collective stellar effulgence didn't give them light enough at least to read by.
With all those stars, they had plenty of planets to live on. The Heechee only occupied a fraction of the available planets, but they had made the ones they chose to live on very homey. Naturally, a
very high proportion of those planets were temperately warm, benign in atmosphere, and right-sized for the kind of surface gravity the Heechee enjoyed (not all that different from Earth's, as it happened). That wasn't any accident. They had naturally chosen the cream of the crop to shift into their Core colony so they could inhabit them. There they built their cities and their factories, and laid out their farms and cultivated their oceanic fish ponds-none of those things looked exactly like the human equivalents, but they all worked just as well. Generally they worked a lot better. All of this building and making and growing was so thriftily done that the Heechee avoided pollution and everything unsightly. They were as snug as bugs in a rug.
It wasn't quite perfect. But then, nothing is. Jamaica has hurricanes, Southern California has its Santa Ana winds, even Tahiti has its rainy seasons. The most nearly ideal of climates generally has a few unpleasant kinds of weather. The Heechee had their own weather problems in their Core hideaway. For them, it wasn't rain or wind, it was the built-in nastiness of any black hole. Black holes pull whatever happens to be nearby into themselves. They do
