In an infinitely large universe with all of time and space to choose from, even Jack isn't arrogant enough to assume that he actually knows everything. But in his time and place, from Torchwood and the Time Agency and not least travelling with the Doctor, he knows a lot, and this Lieutenant Commander T'Karr sounds like his Federation is big news.

To Jack, it means nothing.

What does mean something, though, is the way the guy talks about times and dimensions.

"Times and dimensions?" he says, eyes narrowing. He glances around, eyes scanning the room like people from other dimensions would be obvious to him, instead of looking just like anyone else.

Which he knows they do.

"That shouldn't be possible."