Three weeks before his death, he was moved to the hospice ward. There he stayed in bed all day, barely awake. On rare occasions he opened his eyes, squinted into the light like a newborn. The nurses put their hands to his forehead kindly.
Liston was there with her when it happened. It was a Sunday. David was breathing, and then he was not: as simply and quietly as the turning of a page. And Liston had said, “David?” One time, just once. A question.
Ada had said nothing.
There was no funeral. David had always been deeply uncomfortable in churches. He was cremated, and for two years his ashes sat on Liston’s mantel, until one day, home from college, Ada realized where he would want them to go. That dark night, she and Liston drove them to the Bit and scattered them all over the campus, and for some reason it was funny, and they laughed. But it was right: the lab was where David had been the happiest, the most at ease, the most himself—whoever he had been.
That was the last year Ada lived with the Listons. She went to college in the fall, attending UMass on scholarship, following in Liston’s footsteps. Over holidays, and in the summers, she visited Dorchester, sat with Liston on her porch for hours, chatting, gossiping about the lab. But mainly she lived on her own. She rented an apartment in Amherst; she shared it with two roommates all year long. She worked in a computer science laboratory headed by a kind professor named Maria Strauss.
It was in her coursework, as an undergraduate, that she discovered the meaning of the Unseen World. Two of the documents she had found among David’s things had been labeled as such: the printed, lengthy source code that she had pulled out of David’s filing cabinet, and the electronic text document on David’s computer that Gregory had found first.
The former, once she had painstakingly, manually entered it into a text document and shown it to Liston, turned out to be an odd virtual tour of their own house: a sort of user-driven navigation of David’s house on Shawmut Street. The user was given choices about where to go and what to see; always, the user was returned, at the end, to the kitchen, where the program began. Ada couldn’t fathom why David would have created such a program, but she was relieved, in a way, that it was nothing more.
The latter, the document that Gregory found, had borne four items: a paragraph—an excerpt from A. S. Eddington’s Science and the Unseen World, which Ada had located easily with the help of Anna Holmes, and which broadly questioned man’s ability to perceive reality using so biased an instrument as his brain—and three phrases, more cryptic. Ivan Sutherland. Sword of Damocles. Elixir’s house.
The work of Ivan Sutherland, a near-contemporary of David’s, came up early in Dr. Strauss’s class on the history of hardware. Sutherland was the primary inventor of the first virtual reality system with a head-mounted display, in 1968. He named it after an object from a myth: the fabled sword that hung on a thread above the head of Damocles, signifying that with power comes the burden of responsibility.
Ivan Sutherland. Sword of Damocles. Elixir’s house.
A series of thoughts occurred to her, one after the next: Was David referring to virtual reality itself as a house for ELIXIR? A virtual world the program could inhabit—long after David himself was gone?
Suddenly the memory of all of David’s masks and goggles returned to her, the row of objects and devices that hung over his workbench in the basement like the helmets of a knight. Head-mounted displays, she thought: they were primitive, basic HMDs. She and Liston had thrown them out as part of the great purging of the house on Shawmut Way; now she wished they hadn’t. Her heart contracted. David had been trying to build a world for them, she thought. For the two of them and ELIXIR. Someplace unreachable and cloistered. Someplace fair.
Virtual reality, she thought, was the unseen world. Or had the capacity to be. In fact, it could be said that all computer systems were such: universes that operated outside the realm of human experience, planets that spun continuously in some unseeable alternate stratosphere, present but undiscovered.
Soon
Boston
“Can I go first?” said Evie.
She was twelve years old. She was standing in the kitchen, holding the apple that would become her breakfast. She was running late for school.
“Go where first?” said Ada.
Evie looked at her, pained. She made a tsk sound and then composed herself. She had been doing this more, recently: trying on adolescent annoyance, rolling her eyes both subtly and unsubtly, depending on the level of the parental offense. Ada caught her sometimes looking guilty in the wake of these moments, or in the wake of an unusually cutting remark that had just burst out of her like a coiled spring. In the pause that followed, she seemed almost shocked by herself, darting a glance at her victim to see if she was hurt, or hastily changing the subject.
“The UW,” said Evie. “Can I try it first?” She lifted her apple into the air, let it hover there in her hand, awaiting her mother’s response.
Ada paused. The answer, of course, was no; there were too many things that could go wrong; there were too many other people in line to try it. But Evie looked so earnest, so hopeful, so brave, that she wanted for a moment to say yes. It was Evie’s project, too, after all; she had come to the lab after school every day. She had stayed late with them every night at work. She had worked out problems with them. Discussed the layout of the UW’s first model city. She had been a trouble-shooter, a mediator, a representative of her demographic. She had given them a yes or no on what would be interesting to people her age, or on what they would find boring or too slow.
“I’ll think about it,” said Ada finally.
“So, no,” said Evie. “I figured it would be no.”
She didn’t look too put out. She bit cheerfully into the apple, waved goodbye.
“See you later,” she said as she went, her mouth full. And she ran out the kitchen door to meet her father, already waiting in the car.
A moment later, Ada received a memo.
, said Evie. Good luck today.
Gregory was dropping Evie off at school that day. At ten-thirty, he would meet the Yang & Cartwright representative at Logan, and then bring him to the Bit, where there was a lab-wide meeting scheduled for 11:00.
That day, they would test the prototype for the first time.