Walking is how the theoretical physicist Alexei Kitaev clears his mind after a day of thinking about particles, and on difficult days, he’ll often walk from his workplace at Caltech to nearby Mt. Wilson, a 5,710-foot peak in the San Gabriel Mountains. How appropriate to walk there. Mt. Wilson is the home of the Mt. Wilson Observatory, where Edwin Hubble in the 1920s deduced that the world was expanding. In a New Yorker article on quantum computers, Kitaev said that at a guess, he’s gone to Mt. Wilson a hundred times. But on days spent working on especially difficult problems, he hikes instead on Mt. Baldy, a 10,000-foot peak.
Kitaev made a prediction in 1998 that the world would have quantum computers within 30 years. In 2012, he was awarded the important Breakthrough Prize for his work in the field, in particular for his error-correction scheme, an especially promising approach for developing a quantum computer. So far, however, no one has been able to implement his scheme, and at the time the New Yorker article was published, in December 2022—with five years remaining of the 30—he was no longer so sure his prediction would be met, despite the billions of dollars that have been spent to develop a working quantum computer, despite the labs and whirring brains and long walks. Why not?
Because you must precisely control multiple qubits, short for quantum bits, while keeping them isolated from the environment. You can see the difficulty, explained one scientist, if you try to line up 10 kittens. One runs away, and while you are retrieving it, another two scurry off. Qubits, he said, behave like kittens.
I tried to visualize the 10 kittens, but instead thought of my unhappy black cat. The day before, I had tried to pack him into a carrier. The problem was not multiple animals but one animal with multiple parts, all seemingly independent: I could get my cat in the carrier; I just couldn’t keep him there long enough to close the lid. This was a return visit to the vet for an all-clear after a long illness, and the cat did not want to go. He pushed with his forehead against one side of the box, and while I pushed back, a leg popped out the opposite side. When I shoved that bit back in, his tail slipped out another side. A paw shot out at a corner. While I worked to get the top of the carrier snapped on, the cat scooched backward out the carrier door. It took me a dozen tries to get the carrier closed. Imagine trying to keep 10 cats where you wanted them! Imagine trying to control bigger environments, like the world, like the universe, through taming these quick qubits.
The vet did not give my cat a clean bill of health but prescribed more antibiotics. On arriving home, I gave my cat his new pill. Whether he was already relapsing or whether this new pill, with a different dose, was adversely affecting him I did not know, but he began to seem unwell. The following day, I called the vet, and the day after, I took my cat back for the third time that month. This time he didn’t scramble to get free when I laid him in the carrier. I lifted the plastic case and again bore my cat in my arms the 10 blocks to the vet’s office. The carrier wasn’t terribly heavy at first, but soon it was. My back began to hurt. The cat did not utter a peep.
The first visit to the vet had been two weeks before Christmas, the second the day after the holiday; and the third was two days later, on December 28. That morning, midway between Christmas and New Year’s, I had cleared away half of the Christmas decorations because they seemed to announce a party that had never materialized. I left the rest as a sign that after the first puny wave of holiday fun was past, I was still trying to keep up the spirit for the New Year’s celebration yet to come. Here in Spain, the holiday period extends until the Kings’ Day, Reyes, on January 6. Really, was there so much to celebrate?
While my cat ailed, while my spirits languished, while my back ached, my mother in New Mexico focused her energy on the Friday Peace Vigil, a group of about half a dozen that has met weekly for 20-plus years on the plaza in Socorro—the same stalwart regulars holding signs week after week and the same locals honking their agreement. The message that week was a call for a ceasefire in Gaza. While my mother wrote me of her hopes for the gathering, and I wrote of my cat’s travails, while bombs kept falling not just in Gaza but here, there, and everywhere, while some of those untouched by the suffering of the world failed to appreciate their good luck, while others, filled with the goodwill and good cheer of the season failed to understand the long faces around them—while all this life went on, the universe continued to expand. This is what they say: that the universe is always expanding. But for my cat, it seemed the opposite: his world and universe seemed to be closing in on him. He had turned stiffly away that morning from his food bowl without taking a bite and had slunk into the farthest reaches of the kitchen, under the counter.
I waited in the living room, wishing for my cat to come out and join the party, such as it was. No fire in the fireplace but a cheery glow from the gas heater and lights twinkling on the Christmas tree. More compelling than a fire or the blinking lights, however, was the light in my stairwell, to which I lifted my eyes every so often while I waited. What drew my eye there? In my windowless stairwell, some light falls from above, some rises like the warm air from below. The shadows through the banister make changing patterns on the white walls. The brown of the wooden spindles that is sometimes tawny, the many shades of gray, the white sometimes creamy, sometimes cold: My stairwell is astonishingly beautiful in the changing light. Sitting in the living room, I was hardly aware of the alterations in light around me until I looked toward the stairwell and saw there the record of the change. I watched, waiting, as I know a friend of mine sits at his window and watches his garden, where small birds that he recognizes as individuals come and hop about in small movements.
My black cat had started life homeless, had survived kittenhood on the streets, had come to my house despite the threat of other cats and meowed persistently enough to get taken in, had become sick, had been cured, had relapsed, had suffered, had meowed in pain, had purred in gratitude, had been stuffed into a cat carrier three times. “What’s wrong with him?” I had asked the vet on that third visit. He didn’t know. But he treated the fever, said to continue with the antibiotics, and sent us home again. He surmised it might be leukemia. A lot of cats living in colonies on the streets suffer from this and other sicknesses. Oh, my poor homeless kitten, now a sick and perhaps dying two-year-old, a survivor of a rough infancy, now the welcome inhabitant of a home, and all this struggle and change of fortune for this early end? Life does not honor the words fair and just. “Fair and just” was the phrase Thomas Paine used to describe the struggle of the American colonies to throw off the oppressive rule of England, and because the cause was fair and just, he said, it would prevail. I doubted whether a noble cause in itself was ever enough. Would a quantum computer be able to tell me? A quantum computer might be able to indicate the steps to expand the energy-storing capacity of lithium batteries, or it might help develop biodegradable plastics or carbon-free fuel for airplanes. But would it be able to tell me why my cat finally emerged from the kitchen to sit purring on my lap, leukemia streaming through his veins?
In his first children’s book, James and the Giant Peach, Roald Dahl tells the story of a little boy with a horrible home who, along with some new insect friends, escapes on an enormous peach that rolls out of his garden and into the sea. I was reading the book in a moment of nostalgia. After James saves himself and his friends from a shark attack, the first of many threats, the grasshopper, in celebration, plays some music, to James’s delight. Then the grasshopper explains the different playing styles of the short-horned and long-horned grasshoppers. “How fascinating this all is!” James exclaims. “I had never even wondered how a grasshopper made his sounds.” The grasshopper, who is old, responds gently, “My dear young fellow, there are a whole lot of things in this world of ours that you haven’t started wondering about yet.” To judge from Dahl, and from the many quantum physicists, and surely from cat owners, these things that have not yet fallen into our scope of inquiry are worth pursuing.
Just then, the light changed once more, and the shallow, superficial world was again revealed to be deep, mysterious, and very beautiful, reflected on my wall.
