Summertide

“No. Definitely not.” She felt relief at being able to give an honest answer. “I never thought about the Conjunction until Commander Perry mentioned it.”

“I believe you.” Rebka smiled, and she was suddenly convinced that he did. But she recalled Legate Pereira’s words: “Don’t trust anyone from the Phemus Circle. They practice survival skills that we in the Alliance have never been forced to learn.”

“People’s reasons for coming here are not too relevant, of course,” he went on. “They don’t make Quake any safer.” He turned to Perry. “And I feel sure you are right about the dangers of Quake at Summertide. On the other hand, I have a responsibility to maximize the revenues of Dobelle. That’s my job. We have no responsibility to protect visitors, beyond a duty to warn them. If they choose to proceed, knowing the risks, that is their option. They are not children.”

“They have no notion of what Quake is like at Summertide.” Perry’s face had turned blotchy white and red. He was overwhelmed by strong emotion. “You have no idea.”

“Not yet. But I will have.” Rebka’s ma

He turned to Darya. “And when we return… well, then, Professor Lang, I will make my decision.”

ARTIFACT: SENTINEL

UAC#: 863

Galactic Coordinates: 27,712.863/16,311.031/761.157

Name: Sentinel Star/planet association: Ryders-M/Sentinel Gate

Bose Access Node: G-232 Estimated age: 5.64 ± 0.07 Megayears

Exploration History: Sentinel was discovered in Expansion Year 2649 by human colonists of the trans-Orionic region. First entry attempt, E. 2674, by Bernardo Gullemas and the crew of exploration vessel D-33 of Cyclops class. No survivors. Subsequent approaches attempted E. 2682, E. 2695, E. 2755, E. 2803, E. 2991. No survivors.

Sentinel warning beacon set in place, E.2739; monitoring station established on nearest planet (Sentinel Gate), E. 2762.

Physical Description: Sentinel is a near-spherical inaccessible region, a little less than one million kilometers across. No visible internal energey sources, but Sentinel glows faintly with its own light (absolute magnitude +25) and is visible from every point of the Ryders-M system. The impassable surface of Sentinel readily permits two-way passage of light and radiation of any wavelength, but it reflects all material objects including atomic and subatomic particles. There is photon flux only from the interior, with no particle emission. Laser illumination of the interior is possible, and reveals a variety of structures at the center of the sphere. The most prominent such feature is “The Pyramid,” a regular tetrahedral structure which absorbs all light falling onto it. If interior distances within Sentinel have meaning (there is evidence that they do not — see below) then the Pyramid would be approximately ninety kilometers on a side. No increase in temperature of the Pyramid is detectible, even when incident absorbed radiation is at the gigawatt level.

Path length measurements using lasers show that rhe interior of Sentinel is not simply-co

Sentinel holds a precise distance of 22.34a.u. from the Ryders-M primary star, but is not in orbit about it. Gravitational forces and radiation pressure forces either are exactly compensated by some unknown mechanism in Sentinel, or do not act on the structure at all.

Physical Nature of Sentinel: According to Wollaski’i and Drews, Sentinel takes advantage of and is built around a natural anomaly of space-time and possesses only weak physical coupling to the rest of the universe. If so, this is one of only thirty-two Builder artifacts that were created with the use of preexisting and natural features.

Sentinel topology appears to be that of a Ricci-Cartan-Penrose knot in 7-space.

Intended Purpose: Unknown. However, it is conjectured (by analogy with other Builder artifacts, see Entry 311, 465, and 1223) that the Pyramid may possess near-infinite information storage capacity and lifetime. It has therefore been suggested (Lang, E. 4130) that the Pyramid and possibly the whole of Sentinel form a Builder library.

CHAPTER 4

Summertide minus thirty-one

The first part of the flight to Quake was conducted in total silence. Once it was clear that Hans Rebka was insistent on going and could not be dissuaded, all Perry’s energy had vanished. He sank into a strange lethargy, sitting at Rebka’s side in the aircar and staring straight ahead. He roused briefly when they came to the foot of the Umbilical, but only long enough to lead the way to a passenger capsule and initiate the command sequence for ascent.

Seen from sea level the Umbilical was impressive but not overwhelming. It appeared to Rebka as a tall slender tower of uniform thickness, maybe forty meters across, stretching from the surface of Opal’s ocean at the lower end up into the thick and uniform cloud layer. The main trunk of the structure was a silvery alloy, up and down which passengers and cargo could move in huge cars. The attachments were electromagnetic, held and driven by linear synchronous motors. The detailed design might be unfamiliar, but Rebka had seen the concept used on a dozen worlds, carrying people and materials up and down multikilometer buildings, or high into orbit. The knowledge that there were over two kilometers more of the Umbilical below sea level, reaching down to a tether on the ocean floor, was more surprising, but the mind could accept it.

What the mind — or Rebka’s mind at least — could not so readily accept was the twelve thousand kilometers of the Umbilical above the clouds, reaching all the way from Opal to Quake’s parched and turbulent surface. The observer who climbed into a capsule was seeing less than one ten-thousandth of the whole structure. With a maximum free-space car speed of a thousand kilometers an hour, travelers would expect to see two sunrises on Quake before they got there.

And now they were on their way.

The capsule was as tall and broad as Opal’s biggest buildings. As the Builders had left it, the inside was one large empty space. Humans had added interior floors, from a massive cargo hold at the bottom to the control-and-observation chamber at the top.

The car’s motors were silent. All that could be heard as they rose smoothly through the cloud layer was a whistle of air and the mutter of atmospheric turbulence. Five seconds more, and Hans Rebka had his first view of Quake as seen from Opal. He heard Max Perry grunt at his side.

Maybe Rebka grunted, too. For Opal’s permanent cloud layer suddenly seemed like a blessing. He was glad that the other planet had been hidden when he had been down on Opal’s surface.