Casey reached down and grabbed the microphone back before Wallace could continue, and I heard a titter from someone in the audience.

‘Right,’ said Casey. ‘However the hell it happened, the results are startlingly clear. We stitched together all that orbital stuff with some ground-based surveillance footage to give you a pretty accurate depiction of just how things went down in the final hours.’

Wallace had returned his attention to his console. The image juddered and changed so that we all saw the Earth from low orbit. Clouds cast shadows over Asia Minor, far below. The moon, far larger than it should have been, hung huge above the curving horizon. I could tell from the exaggerated pace of the clouds that the footage had been sped up so that hours passed in minutes. I could have walked all the way around the projection if I had wanted, and Oskar in fact began to do precisely this, peering first at the Antarctic continent and then back at the approaching moon.

I could see what was coming, with dreadful inevitability.

‘They knew they were going to die,’ Casey continued, ‘but someone down there still wanted to witness the whole damn thing for as long as they could.’ He shrugged. ‘Maybe the people in charge of their communications networks were crazy enough to think they could somehow survive. If not for them, we wouldn’t have hardly any of this.’

A number of separate, two-dimensional moving images appeared, arranged in a ring around the Earth about level with the Antarctic. They showed what looked like ground-based views of the approaching moon. One in particular caught my attention. It appeared to have been filmed on a hand-held camera, its owner directing its lens towards the distorted face of the falling moon. Luna’s craters and hills were entirely visible with the naked eye; indeed, the ancient satellite blocked out much of the sky as it rose over a savannah plain. As I watched, deep cracks appeared in its crust, growing wider and deeper with every passing second, like something out of a nightmare.

‘How could they get this footage, if the guy was down on the ground while all this was happening?’ I whispered to Nadia, but she just shook her head.

‘Wallace’s a wizard at this stuff,’ she whispered back. ‘That’s all you need to know.’

I tore my gaze from the awful sight and moved my attention to another of the accompanying videos. This one showed a different view from orbit, and I watched an enormous shadow crawl across the face of the Earth.

I put one hand to my belly, feeling my insides twist. The things I had lived through back on my own alternate, as terrible as they were, barely compared to what I was witnessing. If some other version of me had lived on that world, he would have been under no illusions about his chances of survival.