If you go to the world known as Far Passage and ask its inhabitants about the arch, they’ll tell you to look for the man known as Lehman. He still lives near the arch, out in the Great Desert where he makes a marginal living as a silicate supplier for fabricators.

He lives in a small dome, left over from the original expedition, where he can stay protected from the desert’s thousand-plus degree temperatures. He’ll tell you how his team found the arch, and why he used it only once and never again, and why it’s forbidden now, except for the dead or terminally-ill who don’t want extension treatments or a post-organic existence.

There are words written on the arch in a language that was dead when humans were still carving pictures on rocks. Lehman knows what the words mean, their significance and why they’re both a greeting and a warning.

If you’re smart, you’ll listen, and not try to use the arch yourself while you’re still alive and healthy.

The system that was home to Far Passage wasn’t important in the grand scheme of things. Few outsiders went there, and human deep space telescopes had found it by accident. Those ships that did perform flybys did so mostly because their navigational systems were using Far Passage’s parent star as a reference point while on their way somewhere else. But Far Passage did have its small share of human colonists, who lived in those hemispheres that had climates that were technically tolerable for them, with the aid of pressure domes and suits. They’d made contact with the natives, who had first told them of the arch. Lehman had been one of those who wanted to see it for themselves.

Lehman and his team had crossed the equatorial desert seas, the desert stretched around their small train of rovers. The others often commented on the emptiness, but Lehman didn’t mind; he was solitary by nature. He’d heard the stories about the arch often enough to be motivated by his curiosity.

“Who found it first? Humans, I mean.”

“One of your surveyors was the first to sight it after studying our historical records,” his companion, a native archaeologist, replied. Like most of his species, he was shorter than humans, but strong and hefty, his body having been bred for Far Passage’s hot climate. A thin outer shell protected his skin from the heat, making him resemble an upright armadillo. “We translated the writing for him, but he didn’t believe it was meant to be taken literally. But it is. That’s why it was used only once by my own people, before being abandoned.”

“But not shut down entirely,” Lehman pointed out. “It still has an active field—it’s been noticed from orbit.”

“Yes,” the native replied. Pausing, he added, “Some will always be curious, even when they shouldn’t be.”

“We have a saying:” Lehman said, “Knowing is better than not knowing.”

“We say something similar,” the native replied. “Curiosity is, after all, part of what motivates intelligent species. But I believe you also have another saying: curiosity killed the cat.”

Lehman climbed down from the rover’s cab as they stopped a few hundred feet from the arch. It was horseshoe-shaped, with a smooth, burnished surface that didn’t look like it was tens of thousands of years old. The writing was inscribed on its surface, precisely cut. Lehman told the rover to wait in standby mode as he and the others approached the rest of the way on foot, his native companion staying behind, watching as they went.

Lehman felt the desert wind against his suit. This was the first time he’d actually seen the arch up close, although there was a life-size replica in the native science museum. It was giving off an electromagnetic field, which the other members of the team were measuring with their instruments. The arch seemed to react when they got close, as if it had scanned their bodies’ natural electric impulses.

“It’s definitely giving off a Casimir effect,” one of the team members said. “There are vacuum fluctuations, and I’m getting indications of zero-point energy readings…”

“Like from a wormhole?” Lehman asked. He wasn’t a scientist, but he’d taken enough space jumps during his days as a trader to know how they were grown and stabilized in deep space. “Then it ought to have a dark matter source, right?”

The team member nodded. She was half his age, young and enthusiastic. “That’s right. But I can’t see how. Without a particle accelerator—and I don’t see any sign that the arch is or was ever connected to one directly—I can’t see how that’s possible.”

“Maybe extra dimensions?” one of her companions asked. “Even on Earth, we can do that. Scan for them, I mean.”

The young scientist nodded. “Set up our field transmitter,” she suggested. “The arch might not have been set up for matter, but if we can send a message through, maybe we can see where it went on the other side.”

“What about the warning?” Lehman asked. “I’m not a superstitious man, but the natives take it seriously.” He thought about their companion, still standing back with the rover.

“Where none may pass?” The woman looked at the writing. “I’m sure that was just symbolic. After all, why keep it turned on if it wasn’t meant to be used?”

“Maybe they couldn’t turn it off,” her companion suggested. “It may be connected to a singularity, in which case they couldn’t shut it down. Maybe that’s where none may pass.”

“I’m not picking up any sign of an event horizon. If there is one, it may be so weak that light can escape.” She nodded, having made up her mind. “Get the transmitter.”

The transmitter was a beacon that used a miniaturized array for sending off-world messages. The messages were normally sent as a series of signals, using quantum tunneling. The scientist angled the transmitter at the arch as she entered a basic first contact message, a series of numbers and simple equations.

“Mathematics is a universal language,” she explained, “still used for interspecies communication when vocal translation software isn’t compatible. Ok2ay, done. Now we’ll just wait…”

The message went through. Lehman waited expectantly with the others while they waited for a reply. When it came—in the form of numbers in the native language—the scientist was, of course, at first excited. But the atmosphere of celebration quickly died down as she translated the numbers into their alphabetic equivalent. She stared at them for several minutes, in a panic telling the others to stay back when they tried to crowd around to get a look. Then she asked Lehman to signal for the native guide to come over.

He looked at the translation, his face expressionless while the woman expressed a mixture of consternation and fear. They spoke to each other in quiet tones before the native came over to Lehman.

“She will heed the warning,” he said simply.

Lehman nodded. “Does she know what it means?”

The native looked back. “The message was…personal. She knows. Only the dead or dying pass through, after all. And they do not return.”

The scientist didn’t say anything about the message as they drove away from the arch. Lehman later heard that she’d gone back to Earth, to tell her family what the message had said. The native was right; it had been personal, and Lehman made it his business not to get involved in personal matters. She never came back to Far Passage, but others came and got similar messages. They, too left; some not wanting to accept what they’d read, others seeming to find some measure of closure or comfort in them.

Lehman stays away from the arch. He’s never sent his own message through. He’ll tell you where it is, but you’ll have to go on your own, with or without native assistance; mostly without. When you go, you may or may not send a message of your own. If you get a reply, heed it.

After all, there are some regions through which some may pass, never again to return.