It was important to Walsh that a human being, not a rover or a probe, first saw the bottom of the Pacific. “You can’t surprise a machine,” he said to me. And it is this capacity to appreciate the unknown, to be surprised by it, he believes, that will always set the human explorer apart from the machine. The moment of surprise informs you emphatically that the way you once imagined the world is not the way it is. “To explore,” he says, “is to travel without a hypothesis.”
