"I know, it doesn't make sense," Sam says. She imagines his head is about to explode from the math. "The thing is, people can disappear from here just as randomly as they arrive, and the other Jack O'Neill disappeared about a year ago. Not quite a year. A little less than a year. There have been a lot of Stargate personnel here over the years--you, me, Jonas, Daniel, Vala, John Sheppard, Ronon, Dr. Keller, Rodney, Cam...I think Teal'c was here too, before I came along. And some people from the Destiny, which you don't know about yet, do you? No, of course you don't. I didn't learn about that till later. They're all gone now, except for Jonas. Never any two of the same person at once, which is good, because of the whole entropic cascade failure thing. But... just trust me. It happens."