Jack keyed 'Torchwood' into the hand held device and laughed to himself.

"Recreational mathematics? Seriously? Oh Doctor what do I see in you?" he teased him as the door unlocked ready for them to head through the corridor and along to the next.

"I always thought it was the magnets," he offered. "Central magnetic core these things have, these outposts. And that's all well and good until something comes and knocks off the polarisation and them bam. But even that wouldn't be enough to rip a hole like that. No that's something specific. Some sort of time technology."