What Cannot Be Taken Back

"Entropy is the cost of a choice that cannot be taken back."Three years after the accident that took his wife, John Reed has made himself very rich and very careful. He has trained his eyes never to drift toward a window, and his days never to drift toward the afternoon he lost. Then a physicist offers him the one thing he has taught himself never to want: a door - narrow, sealed, thirty stories beneath the Atlantic - through which a single irreversible loss might be reached, and undone.
But the gate keeps its own arithmetic. The price of taking a thing back is not paid in money. It is measured in everyone who would, in exchange, cease ever to have been - the lives that branched from the loss, the people who exist only because the world did not turn back. And the promise that first sent John toward the door was made on a bright afternoon, by a woman he can no longer ask whether she meant it.
What Cannot Be Taken Back is a luminous, devastating novel about grief, physics, and the conversations that do not end so much as change who we have them with. It asks what we owe to the self that survived, and whether love is the wish to undo a loss - or the willingness, finally, to carry it.