It's always dark outside the windows when we leave the city. I sit in my window-seat and stare out into the apparent nothingness that the train races through, straining my eyes periodically to try and see something, anything that might be out there. I never see anything back, though now and then it seems like there might be a darker shadow keeping pace with the train, something that would become clear if only it came closer. But I rub my eyes and the shadow disappears and I know that it was just a tired mind longing for something new to look at.
The cities were all built inside pressurised domes back when the sun was still visible, but the light now comes from all around, from many sources. Luminescent moss coats most flat surfaces, firefly genes have been inserted into almost all the birds, insects and small mammals so that they constantly give off additional light. Some people have gone so far as to be fireflied too, but they're a minority still, and the doctors are just as busy turning fireflies off as they are turning them on. It's just too odd. There are street-lights everywhere, and in the richer parts of the cities there are huge aerial balloons that provide light as well. Because outside the domes it's just dark.
It was an accident, no-one intended to put the sun out. They, whoever they are, were testing a nuclear weapon and something went wrong, something caught fire in the atmosphere, and the resulting ash and dust filled the sky and blocked the sun out. Or sometimes people say that it was accident, a plane carrying a nuclear bomb crashed into a volcano and the bomb exploded, throwing millions of tonnes of ash and dust into the atmosphere, blocking the sun out. Or perhaps the bomb was just a coincidence, and it was a tidal wave that crashed into the Harwell crater that was the largest active volcano on the planet, and the resulting conflict between seawater and boiling rock thrust millions of tonnes of ash and dust... you get the picture.
It was no accident, and there is no ash or dust in the atmosphere. The planet has been shifted from its orbit and is going to a new home, all by itself. Though there's only a few of us who know this, and we all expect to be dead by the time we arrive.
The train is quiet, there are never many people who want to travel between cities these days, and the restrictions are getting harsher anyway. But tonight my carriage is actually empty apart from me, and it feels a little lonely. When the ticket-inspector finally tramps to my seat, I turn, almost pleased to see him.
But it isn't him, it's a young girl with ratty brown hair down to her shoulders and a grubby notebook in her hand. She sits down opposite me without introduction, and I find myself a little annoyed.
"That seat's taken," I say, and she smiles and shakes her head.
"There's only us on the train," she replies. "It's been arranged."