"Tell me you have good news, Pete."

Pete scowled, but didn't correct me, which is how I knew we were in deep trouble. His real name was Pietro Paolo, after the humanist, and he was terribly particular about it; I only got away with calling him Pete when he was stuck on a puzzle, too caught up in it to really pay attention to what I was saying. "We have a model," he told me, "technically. A dozen free parameters, and no compelling physical interpretation."

"In other words," I said, "you have nothing." I was no statistician, but enough degrees of freedom and even I could recognize signs of overfitting. Pete's team must have been desperate, if they were even bothering to consider a model that bad.

He nodded. "The trouble is that the phenomenon should be impossible, which means our normal theories of physics must have some hidden flaw, and until we know what it is, we can't meaningfully rule out any hypotheses at all."

'The phenomenon' was Pete's term for it, understated and maximally vague. The rest of us tended to use terms like calamity, disaster, or, as one too-clever-for-its-own-good news channel had done, the aphorism. We all meant the same thing: over night, about three months ago, every human in the city had discovered we were trapped. You could walk right out the city gates, and nothing would seem amiss, but within a half hour's walk you would find yourself right back where you began. Signals went out just fine, and even most birds could fly away freely, but anything weighing more than about ten kilograms was stuck.  

I bit back my irritation. Pete's research team was the best we could put together; it wasn't their fault the problem was intractable. "Alright," I said. "What do you recommend, then? Doesn't have to be perfect; I'll take your best guess."

He shrugged. "The thing about knowing nothing is that one response is as good as another, here. We can collect more data, try to pin down the mass threshold, see if that narrows things down at all. But we could just as reasonably go out to the streets and start giving gifts to as many beggars as we can, on the off chance we've found ourselves in a fairy tale, or go knock on the Vatican doors and ask the Pope to intercede for us."

He smiled bleakly. "Really, all roads lead to Rome."