"Oh, Drake. Yeah, but you're missing the colonisation parameters, here --" Anthony said, withdrawing his own pen, and he scribbled another series of three equations, and the numbers seemed to purr for him, like he was petting a particularly affectionate housecat. "You've got to take into consideration the way societies expand, how they change over time, and the distances they can travel. That's a far more complete picture."
And then, more equations, more variables, things he'd been gnawing on, things he'd been thinking about came out, an elegant sprawl of Greek letters and Hebrew and some recognisable English characters, too. These were like magic on the page, and where the colonisation factors purred, these nearly shimmered, thrumming with some unseen energy, but that was maths for you, he thought. It scarcely blipped on Anthony's radar any more.
"What I'm interested in, the thing that I'm struggling with, is how to calculate the degree of difference between universes as they present -- what does it take to get a female version of you, for example, or the version of my world where Professor Snape remembers me staying in England for the rest of my schooling, what degree of separation is there, does it depend on when in the timeline the separating incident occurs, what other factors impact that separation or are derived from it, and how are we managing to interact with closely-related universes without causing paradoxes, and -- the big and -- is the disruption of our timelines by removing individuals enough to cause singularities. Those are my big questions, and these are the best approximations of the factors that I can come to," he explained, then paused, nearly contrite. "Just stop me when I don't make sense any more."