Twenty feet out he has the feeling of being underwater and, looking back, he can see the surface, but physics is working differently here, light bends in odd ways and he feels unnaturally buoyant, like his own nervousness and expectation could lift him up and he might float down the tunnel.

Thirty feet out is a spacewalk, the light from the platform a thin lifeline already curving away out of view. At this point there is the sound of a train coming, which freezes him for a moment, but then his pinna, millions of years in their evolution, pick out that it’s coming from the other direction and will arrive safely on the opposite side of the platform.

At forty feet out the platform is gone from view and in front of him is only an emergency light glowing a biological red and the long track of metal is a gut, a lair—he’s a mere microbe in an entrail. The train that had come from the other side of the platform thunders past and from his vantage point he sees sparks underneath as it grinds away.