He mused over the spectacle, puzzled as to why he had been brought here. The energy for all that weather must come from the planet's interior and its rotation, rather than the wizened star. This monster world was self-contained and complete in itself: it didn't need the rest of the Universe. In fact, Paul reflected wryly, this world should be safe even from the depredations of the photino birds. While the dark matter foe turned stars to dust this world and billions like it would spin on, a container of massive but purposeless motion, until the energy dissipated by its huge weather systems caused its core to cool, its rotation to grind slowly down. Then at last it would come to rest, its only function being to serve as a gravitational seedbed for a photino bird Ghost world. The planet was harmless, dull and old; even that cloud spot might be older than mankind, he realized--

Again he was being watched.

A vast speculation thrilled through him. The huge Qax he had detected earlier, with thoughts like hours...

It was here. In the spot system. The whole self-organizing complex contained the awareness of a Qax, and it was studying him.

He opened himself. New data trickled into his awareness.

The Xeelee ship was semisentient. The function of the ship was to optimize the chances of survival of its human occupants.

It studied the machines working at the heart of the ancient Jovian, and considered how this might be achieved.

Once this System had been the home of a race who had waged war for hundreds of millennia. The Jovian had been reworked to serve as the hub of an industrial-military conurbation which had launched wave after wave of strikes out at the humans' perceived foe, the Xeelee. The ship saw how even the moons had been moved to their present altitudes, their orbits regularized, to serve as weapons shops. Power for the shops, and for the great fleets which had poured out of this system, had come from the substance of the Jovian itself.

Now, of course, the war was history, the human fleets brushed aside; the shops were deserted and the Jovian was largely spent -- but still, the ship perceived, entities remained brooding at its core, vast machine-minds waiting to fulfill their final purpose--

The last defense of the Solar System.

They saw the Xeelee ship, with its cargo of two primitive humans, as a threat. And they had attacked.

The ship methodically studied the weak tractor beam which was drawing it steadily towards the Jovian.

Gravity wave technology -- called by the humans "starbreaker beams" -- had been one of the many Xeelee mysteries never solved by man, even after generations of study. The ship now recognized this tractor as a pale imitation of a starbreaker; and it made out, somewhere near the core of the Jovian, the generator which served as the core of the tractor. A group of point-singularities were being impelled, by strong electrical fields, to collide and coalesce. As pairs of the ultradense singularities impacted a new, more massive, hole would form; for some seconds the new hole's event horizon would vibrate like a soap bubble, emitting intense gravitational waves. By controlling the pattern of such collisions the modes of vibration of the horizons could be controlled -- and thus, indirectly, the tractor beam of gravity waves was generated.