Carter scrubbed at her eyes, willing them to focus on the screen. The mug of coffee at her elbow had once again grown cold, and she was no nearer a solution to the question that had plagued her for the past thirty-six hours than she’d been… well, thirty-six hours ago. She knew she could use some rest, but she doubted her ability to sleep. She was lucky to have slept as much as she had the previous night. Once her brain was wrapped around a problem, she felt herself driven to push through and solve it. That trait had gotten her through the Academy, through all her subsequent Air Force training, and through grad school. It had served her well over two years spent analyzing the Stargate and its capabilities, before Daniel had shown up and solved the problem of dialing another world. It had helped her come up with a way to decouple the wormhole from the gate on P3W-451, a world doomed to spiral to its eventual death as it was sucked into a black hole, taking SG-10 with it. If it weren’t for her pushing through a problem until she reached a solution, none of them would be here right now, and she knew it.

Of course, that solution had very nearly lost them Jack O’Neill… and might still result in the loss of Colonel Cromwell, if they didn’t manage to find him on P2A-870.

That was the damnable thing about it. She shuddered again to think how very easily it could have been SG-1’s CO whose rope parted, and who fell into the wormhole. Or who might have been crushed by G-forces as he fell against the iris, had those same forces not already ripped it away. At least Cromwell had been spared that fate. It was hard enough, feeling responsible for whatever had happened to him.

And she did feel responsible. It was her idea that had sent both men rappelling into the gravity well to rig the explosive. Hell, it might even be her fault that the gate here had locked to the gate on P3W-451, unable to disengage. What if I hadn’t been so eager to study that black hole, via the MALP? she asked herself for what had to be the twentieth time. If we’d tried to disengage just a minute earlier, would the gravitational field have already been strong enough to prevent us from doing so, or would we have been able to avoid the whole thing? She knew intellectually that one minute’s difference probably wouldn’t have been enough, that the two gates might well have been locked upon contact, but the fact remained that there was no way to be sure. This entire event was so far outside anything predicted by current theory that she was at a loss to make any hypothesis she felt certain about.

Except one. When she and Siler had arrived in the Control Room, several windows had already given way to the gravity and shattered. If I’d really been thinking, I’d have insisted we knock out the rest ourselves before sending anyone into the Gate Room. After the wormhole had disengaged, Jack had been given first aid and then carted off to the infirmary, and clean-up had commenced amid the return of teams who’d been stranded off-world for nearly two weeks, she’d helped the sergeant reel in the remainder of the line that had been attached to Cromwell’s harness. The broken end had been “above” the shaped charge when it went off, thus escaping the blast energies, which had been almost entirely directed into the Stargate. Once they’d retrieved the length that was left, Carter had held it in her hand and simply stared, unwilling to accept what she was seeing, already cursing her own stupidity. The line ended with a break too clean to have been caused by the stress of the gravitational field alone. It gave every indication of having been at least partially cut by something sharp. As she stared at it, she kept seeing over and over in her mind’s eye the shattering windows and the flying shards of glass raining down upon the two men. She was struck by a single, cold realization: whether by the idea she’d had or the one she’d failed to have until it was far too late, she was responsible for Cromwell’s fate.

Not only that, but she’d been so sure that anything falling into the wormhole prior to the detonation would simply exit on P3W-451 and be lost to the black hole or its gravity that it hadn’t even occurred to her to suggest sending a team to search for him on the world to whose gate the wormhole had connected before being shut down from the SGC. Not until Daniel asked the question, and she’d opened her mouth to answer that it was pointless, only for it to dawn on her that she really didn’t know that for certain. So much of what she’d done regarding the situation had relied on guesswork that she couldn’t in good conscience bet a man’s life on it. She’d simply stared at Daniel for a moment, before stammering, “No, not yet.”

It had been late at night, and even General Hammond had gone home. No one was on-base who could authorize a search and rescue mission. Not only that, but before he’d left for the night, the General had instructed Siler to have a tech team begin checking every bit of equipment connected to the gate. The sergeant had put his techs on it immediately, and the gate was out of commission until Hammond gave his okay. At least she had time to refine her calculations before he was scheduled to return in the morning. Urging Daniel to go and get some rest, Carter had hurried to her lab and spent the next seven hours figuring out that in fact, it was entirely possible that Colonel Cromwell had remained in transit at the time the wormhole skipped to its new destination and had survived his journey.

What wasn’t possible was for that journey to have taken him to P2A-870, although clearly it had. She’d run the modeling program with virtually every variable she could think of, and still it insisted that the world to which the wormhole had skipped lay just outside the realm of possibility. P2A-870 was closer to Earth than to P3W-451.

Many stargates occupied worlds whose stars hadn’t even been named by Earthbound astronomers. Some were lucky to even have numbers, while others had no designation at all beyond the address of their stargate. The gate network appeared to cover the bulk of the Milky Way galaxy, and even allowed for travel to stars beyond the local galaxy, based on what had occurred not long ago when that alien database had been downloaded into Colonel O’Neill’s mind. But not all planets with stargates were vast distances from Earth, astronomically speaking. Abydos was only a bit over twenty lightyears distant, for example. And while it wasn’t exactly next door, P2A-870 wasn’t terribly distant either. She’d been able to identify its parent star as Gliese 651, a very sunlike star less than sixty lightyears away. She’d shared that information with O’Neill, sensing that he might want to know. He’d accepted the knowledge gratefully.

What she hadn’t told him was that she had no idea how the wormhole had connected to that world. And she wasn’t about to tell him, either. Not when he was already worried about his friend. Besides, they already knew that Cromwell had been there; the unit coin found in the streambed was proof.

Sighing, she studied the computer screen again, through bleary eyes. Two days they’d spent waiting for the weather to clear, and she really should get some sleep. But something kept niggling at the back of her brain, try as she might to push it aside. The thought was ludicrous, really.

Or was it?

Spacetime included, of necessity, a dimension of time as well as the familiar spatial dimensions. And there was one mathematical model that brought Gliese 651 to just within possible range of a gate skip from P3W-451. That model required allowing for travel in reverse along an imaginary temporal axis included as a subset of the coordinates. Put another way, stars changed position relative to one another over time. There was an analogue of this positioning inherent in the system of coordinates that made up Gate addresses, and even slight alterations over time could alter one or more coordinates in the set. Alter the orientation of the temporal axis relative to a set of coordinates, and what passed for “close” could change as well. On this last set of simulations, desperate to find anything that might explain what had happened, no matter how bizarre that explanation might be, she’d allowed temporal adjustments — normally locked out of the modeling program — into her calculations. Once the model allowed for relocation along the temporal axis as well as the spatial axes, Gliese 651 and the corresponding gate on P2A-870 suddenly edged into the realm of possible destinations for the wormhole as it decoupled from the gate on P3W-451.

She wasn’t about to tell O’Neill that, either. For one thing, the range of allowable temporal dislocation was somewhat wide, ranging anywhere from 10 years to approximately five hundred, possibly more. For another, the fact that they’d found that coin in the sort of condition they had indicated it could have been dropped as recently as yesterday. It certainly hadn’t looked any older to her than similar coins she’d seen that she knew to be of recent vintage. Allowing for its being carried around over a twenty-year career, it didn’t appear to be much older. So even if Cromwell had traveled into the past, he hadn’t gone five hundred years. That much she was sure of.

Beyond the uncertainties, however, lay one thing of which Carter was certain. She’d never seen Colonel O’Neill this stressed, this worried about anyone, with the possible exception of Major Kawalsky. Kawalsky had clearly been another good friend of his, a friendship of long standing, and her heart had gone out to her CO as she’d watched him struggle with his fear and concern for his friend’s well-being. She was seeing the same thing again now, and until she was positive she had a very good reason to suggest that Colonel Cromwell had not indeed arrived on that other planet just four days ago — and she couldn’t be sure yet, given that she was still working in the scientific equivalent of uncharted territory — she was not going to give him anything more to worry about.

Behind her, a familiar voice said, “Hey.”

The captain turned to see her CO in the doorway. He shrugged as well as the two steaming cups in his hands would allow. “Screw-up in the commissary. Want one of these?” Without waiting for an answer, he moved to the desk, setting a coffee next to her computer before lowering himself into a vacant chair.

“Thank you, sir.” Carter studied his face. He looked haggard; shadows beneath his eyes echoing the deeper shadows within them. She nearly asked how he was, then thought better of it. Picking up the cup, she removed the lid and took a sip, still watching him.

O’Neill sipped from his own cup. “So, what’cha working on?” he asked.

Carter noticed a forced lightness in his tone that only added to the incongruity of the question. The colonel didn’t often ask her to explain the science behind things, although he’d done precisely that just before the SGC’s encounter with the black hole at P3W-451…

She suppressed a shudder. “Just some models of wormhole behavior, based on data we were able to collect recently,” she replied, keeping her own voice as light as possible under the circumstances. O’Neill gave every impression of a man at loose ends who was looking for whatever he could find to occupy his mind and his time while he waited to be able to do what it was he really wanted to be doing. “The fact that the gate was able to transmit gravitational energy from one world to another opens up a whole new area that no one’s even thought of exploring.”

The captain was tempted to kick herself as soon as she heard the words leave her mouth. Sure, because he needed yet another reminder of what just happened, she reflected.

O’Neill merely nodded, however. “So this wasn’t something predicted by theory?”

“No, sir. I was as surprised as anyone.”

“Ah.” The colonel sipped at his coffee in silence, staring off into space at something only he could see.

Carter watched his face for a moment before turning back to her monitor. She’d been working on her models ever since she’d arrived that morning, breaking away only when the gate was dialed to query the MALP left on P2A-870, and once for lunch. The dinner hour had come and gone, marked only by the arrival of Teal’c in her lab, bearing a sandwich and keeping her company for the twenty minutes it took her to eat it. She darted a glance at the time display on the lower corner of the screen, noting that it was 2218 hours. Each check of conditions near P2A-870’s stargate since that morning had revealed either current or incipient storm activity, keeping them from returning to the planet. At local sunset, General Hammond had once again suspended the queries, promising to resume them at dawn. He’d stopped short of ordering SG-1 off-base, however, clearly trusting them to use their own judgment in seeking their rest. The captain knew she’d have to either go home or spend the night in her quarters within the mountain, and she should make the decision soon. She wondered what her CO was going to do. From the look of him, he hadn’t gotten much sleep in the past twenty-four hours, and now he sat drinking coffee in her lab. “Sir?”

He blinked, the brown eyes refocusing on the room. “I know, Carter. ‘Get some rest.’ Right?”

She smiled despite her concerns. “Yes, sir. We can’t do anything more tonight, and the storms almost have to be over by sometime tomorrow. We’ll all want to be at our best when we go back.”

“I know.” O’Neill stood and stretched, craning his neck to glance at the computer monitor. “Uh, captain…”

She bit her lip, turning her face away, although she was sure that a brief glance wouldn’t tell him anything he didn’t need to know right now. Not unless he’d been paying attention to the modeling program all day. All he can see are abstract graphics and some numbers. Nothing to worry about.

“Yes, sir?” she asked.

There was the slightest hesitation, and she looked at him, noting the puzzled expression as he attempted to decipher the display. He shook his head abruptly. “Nothing.” He stifled a yawn; she caught it, but said nothing, the look in his eyes telling her he was aware that she’d noticed. “I’m going to go crash in my quarters on base, if anyone needs me,” he told her, picking up his empty Styrofoam cup and crushing it before dropping it into the wastebasket.

She smiled again. “Yes sir.” A pause. “I could explain what the model is about if you really want me to, but — ”

He shook his head. “No, that’s all right. You just… do your thing, Carter. Or better yet, get some sleep yourself. When the storms end, I’ll need you at your best, too.” O’Neill moved toward the door.

“Good night, sir.”

“Good night, Carter.”