three-dimensional projections of rotating four-dimensional objects. In other words, they were how objects in four-dimensional space would look in our three-dimensional universe. On condition, that is, that such objects did exist in reality, not only in theory.
Clive put each of the figures in turn in the centre and magnified it. After several rotations, not finding any similarity to the visualisation of the gravity anomaly, he turned the figure back.
"That one's something like it," said Steve, when Clive reached the fourth figure.
Clive looked at it intently, but then shook his head.
"No, hardly," he said, and went on to the next projection.
"Not that one, either," said Steve and Clive at the same time.
Eventually it came to the turn of the tesseract. With a vivid enough imagination, the similarity looked quite good. This time Steve did not say anything, but only turned to look at Clive. Not hurrying to change the figure, Clive gave a barely perceptible nod.
"What do you think?" he asked Steve.
"Could be."
"Shall we try it then?"
"Let's do it."
Clive made a gesture as if grabbing something floating in the air and then throwing it towards the display, on which the visualisation of the data from their gravity scans was rotating in an endless cycle. The visualisation froze at once. The computer waited for the next task.
"Simulate a visualisation of the portal as a three-dimensional projection of a four-dimensional hypercube," he ordered the computer.
The electronic brain of the AI paused briefly, then produced the solution. Clive combined the two images on the screen. The external resemblance was quite strong.
"There is a certain similarity," said Steve, without taking his eyes off the screen.
"Yes, they are visually similar," said Clive, echoing this opinion.
"Now we have to check it analytically. If they coincide... you could easily write a hundred doctorate theses on the subject," said Steve slowly.
"And theses for a dozen Nobel Prizes," added Clive. Inspired by scientific curiosity, he had completely forgotten about his lack of sleep. His disordered hair and eyes, running from lack of sleep but burning with fire, made him look crazy. Now he looked exactly like the mad scientists in the comics, though much younger.
"You know what bothers me a little?" said Steve. "The fact that the portal is rotating."
"If they are connected rigidly to each other, there is nothing surprising in that. After all, its other side comes out in some other star system, which could have angular momentum relative to the Solar System. If in one such system it is at rest, it must rotate in the other."
Steve thought about it carefully.
"Then the axis of rotation must coincide with the direction towards the other end," he said eventually.
"Sounds logical."
"Let's see where it's pointing."
Clive turned back to the console again. On the screen there appeared an image of the Milky Way, viewed from above and to the side.
Steve knew the position of the Solar System in it by heart. He found it with a quick look. A few seconds later, a winking yellow spot appeared at that point.
"The pulsating marker is our Sun," Clive told Steve.
Steve rolled his eyes heavenwards. Clive thought that without his prompting, no-one was capable of finding his own star himself! Too clever by half!
A white arrow extended out from the yellow spot.
"The straight white line is the direction of the axis of rotation of the portal," added Clive.
The white line extended in the plane of the galaxy, barely touching its centre, towards the other side of the disc.
"Damn, that sector is covered in dust," said Steve disappointedly.
"Perhaps deliberately, to prevent us finding out where the tunnel ends?"
"Looks like it."
"All right, we must send the data to Shelby. They can feel out that sector, maybe they will be able to see where the tunnel leads in the gravity band," said Clive.
"Go get some sleep, I'll check the calculations and prepare a report."
"OK. If anything happens, wake me up," said Clive, rising with difficulty from his chair.
"Yes, of course, of course. Go and sleep."
The first thing Steve did when he was left on his own in the compartment was to brew himself some green tea. He didn't like drinking coffee while he was working, as the others did. It lay too heavily on the stomach. Tea was another matter. It had a calming effect, both on the body and on the spirit.
A few hours later, the latest report was ready. Steve had a last-minute look through the whole document. He didn't appear to have forgotten anything, it could be sent.
"Send," he commanded.
The document on the screen closed and disappeared. He reckoned he could take a break now. He gestured to switch off the desktop displays, then got up and turned to the central one to do the same. Up to now, it had been visualising information from the gravity scanners on the anomaly. But now the axis of rotation of the tunnel was pointing not to the other side of the galaxy, but somewhere upward. Steve caught his breath.
"When did the portal change its axis of rotation?" he asked the computer.
"Twenty minutes and thirty-four seconds ago," the computer replied calmly.
"Why didn't you warn me before?"
"I had not received any instruction to do so, sir."
Steve waved at it in disgust. Electronic idiot...
"Compare with scanning data from the very beginning of the expedition. Has it done this before?"
"No, sir."
"Extend the axis of rotation to the edge of our galaxy. Look only at the star systems of the Milky Way. Does it intersect any planetary systems where the planar inclination of the orbits coincides with the angle of rotation?"
"Yes, sir."
"Which star is it?"
"83 Leonis."
With a shiver, Steve ordered the computer to create a new report.
"Report for Shelby. Twenty minutes ago, the portal changed configuration. Possible activation with view to transfer. Input point believed to be in star system 83 Leonis. Message ends."
9
Lost in thought, Steve and Clive looked at the visualisation of the portal in silence. Kimble, in his chair as always, was reading a book, and only glanced at the two of them when they were talking about something he understood.
The latest report from Shelby had come in today. In it, he had included an actualised version of the theory describing the portal. Steve and Clive were to go into the physico-mathematical model and check it as far as they could experimentally, using the scientific apparatus on board the ship.
It was not an easy job. The original research work was really more art than science. The study of a new hitherto unknown phenomenon is always like an attempt to open the door of a massive safe with bare hands. Every millimetre of its surface has to be carefully studied to find even a microscopic clue. At first it is not always known which way the door with the new knowledge behind it opens. And sometimes it isn't even known where the door is.
Steve got up from his seat and stretched himself. His muscles were beginning to ache from hours of sitting still, and it was as if someone had filled his brain with a thick grease that was slowing down his thought processes.
"Can I get you anything?" he asked Clive as he set off for the drinks machine.
"No thanks."
Steve went up to the machine, poured himself some sparkling water and drank it slowly. The cold feeling ran down his throat, dissipating his sleepiness to some extent.
"Let's take model number two as a basis," proposed Steve, leaning on the wall. "The one in which the portals are bonded by two points in space-time, rather than serving as a way out into hyperspace through which travel time can be shortened. Then we can theoretically direct a telescope onto the portal and look into that part of space, as if we had put a telescope at the location of the other portal."
"That
doesn't happen. It does not appear in the electromagnetic spectrum, unless you count the light gravity ripple which slightly diverts the light beam."
"That's because the portal is closed. It hasn't been activated yet. But at the moment when ships pass through it we shall see exactly what I said: the star pattern of that sector of space from which the ships come. Just imagine, if their central star or planet comes within the field of vision of our telescope, it will be the first time we have been able to study another system from such a short distance."
Clive considered this.
"Not a bad idea. We can try. Only it will have to be placed as close as possible to the portal so that its angle of vision on the other side is as great as it can be."
"And we'll have to mount another telescope on the rear of the portal."
"That's also true."
Suddenly the compartment was filled with a soft signal. The computer always produced this sound when it wanted to attract attention, and Steve and Clive simultaneously turned their heads towards the screens. The background of one of the graphics they were displaying, of which there were well over a hundred, was winking red. Steve pushed himself off from the wall and went right up to the monitors. Even on the miniature image, it was apparent that its graph was creeping upwards.
"OK, magnify it," he asked Clive, who was sitting at the console.
In the magnified view, it could be seen that the graph depicted the measurement results of the alpha radiation around the portal.
"What new trick is this?" muttered Clive.
"What processes in nature generate alpha radiation?" asked Steve, thinking aloud.
"Well, the Sun, for instance... And then there's..."
"No, that's it. The Sun."
"So what?"
"So we are