When I was five, I spilled grape juice on Jiji-san's white carpet. I figured I was in trouble. My grandfather returned from the kitchen with two bowls of miso. He stopped at the red stain and tilted his head, looking at it.

I tried to say, "It was an accident," but I couldn't speak. Jiji-san set the bowls down and said, "You know, David, I've always wanted to paint a carpet. Don't you think that would be fun?" When I nodded, he traced the stain's edge with a finger and said, "What do you think – how about tie-dye?"

So Jiji-san ordered four gallons of concentrated grape and cherry juice from the beverage maker in the kitchen, and we painted the carpet. He taught me the kanji for grape, cherry, and inspiration, in fine calligraphy muddled by the soft fibres.

Then he painted Yukio's name below his case, where Jiji-san had been testing his newest AI developments. We stained the whole place in wild purple patterns. Grandma threw a fit when she got back. Fortunately, my mother arrived to rescue me. Mum laughed when she heard the story – she was used to her father's quirks – but made me swear never to try that at home.

The story made a great commencement speech when I graduated as valedictorian. I talked about Jiji-san's patient math tutoring and how he helped me build my first telescope. He inspired me to study hypertopology at MIT – back when intelligent non-human life was still theoretical – and to join Om-RAC's research department. The world knew him as Taro Nakamura, developer of limited self-replicating AI. But to me, he was my grandfather, who saw the beauty in spilled juice.

When my sister told me that Jiji-san's health was failing, I knew what to do. Despite the crisis at work, I took an afternoon off and headed to Boston. My boss wasn't happy, and I couldn't blame him. I argued with myself on the train ride.

Part of me whispered, "You're supposed to find the Om, this is the chance you've always wanted," but my grandfather mattered more than my career. I could think about work later. I banished equations and data from my mind. It was hard, when I felt so close to the solution. But I'd only have one evening with Jiji-san.

Standing in Jiji-san's house made me feel like a kid again. I looked at the new living room carpet. It had been replaced several times in the last thirty years, although not since Grandma died. Yukio stood in the corner, in a basketball-sized metal case with an open front panel. Chips lay scattered on the nearby desk. Jiji-san and Yukio must have been working this morning.

"Hello, David," Yukio greeted me. "Your grandfather is in the restroom and will be here in a moment." His soothing baritone voice was one Jiji-san had chosen years ago. It reminded me of the weeks my grandfather and I had spent together building simple AIs. This was not the Yukio of my childhood, of course. My grandfather had built the first Yukio, and then taught him to build himself.

"Hi, Yukio," I said, as I hung my hat and coat in the entryway. "How's he been doing? I wanted to visit this summer, but I was so busy with work."

"Understandable. The Om transmissions require a great deal of deciphering and analysis. You are privileged to work on the team responsible for studying hypertopology transport conduits. Your grandfather is very proud of you."

"Thank you."

"Are you still directly involved in the calculations?"

"Yes," I said, which was partly true. I didn't mention my real role, since it was classified. But I had been promoted to a secret team. My job was to use the Om's messages to develop controllable wormhole technology. At this point, we hardly understood what the wormholes were, much less how to use them.

Yukio's words distracted me, making numbers race through my head. I nearly pulled out my handheld companion before I caught myself. I was here for Jiji-san, not work. But somehow I couldn't leave work behind.

My grandfather entered the room, wearing silk pajamas under a robe. He leaned on his cane and rubbed his tangled white hair, looking at something distant. His face brightened when he saw me. "David!" he exclaimed, and dropped his cane.

He was ninety-eight, and this last summer had been hard on him. I embraced him. "Jiji-san. I've missed you."

His cheek pressed against my ribs. He seemed smaller than I remembered. "It's good to see you," he said, speaking with the slight Japanese accent he retained from childhood. "Have you done well in your studies?"

I paused. Jiji-san sometimes forgot that I've graduated. We did longevity testing a few years ago. The doctors told us he had Alzheimer's V, an incurable subtype. They gave him a med patch to slow its progress. I checked his upper arm just below his sleeve. The patch was still there. It looked like Jiji-san was remembering to wear it, or perhaps Yukio reminded him.

"My research is going well," I told him. "But I came here to see you."

"Let me make you some tea, David," said Jiji-san, starting to kneel to grab his cane. "Have a seat." His hand wavered as he reached, shifting his balance.

I caught Jiji-san and steadied him. "I'll make the tea," I said, picking up his cane. "You sit down. I'll bring it in here."

"Sit down, David."

"No. I'll make the tea. Please."

"You're too young to make tea," he said, and his eyes sparkled.

I laughed. "All right, but I'm coming in there with you."

In the kitchen, Jiji-san placed two gold-leaf teacups in the beverage machine and ordered hot water. After a moment, Yukio said, "The water is ready." Liquid poured into the teacups. Jiji-san placed a bag of green tea in each cup. He handed me mine and bowed slightly.

"Your tea," he said.

"My thanks," I said, completing our modern tea ceremony. Jiji-san and I had been drinking tea together as long as I could remember. I breathed the fragrant steam and relaxed. For a while I could forget the biggest problem in modern astrophysics.

My grandfather gestured towards the kitchen table, and we sat across from each other. The lamplight cast blocky patterns across the black tablecloth. Coloured square papers lay scattered across the table.
A menagerie of angular creations stood near the kitchen window.

"I see you've brought out your origami again," I said, smiling. "I haven't done any in years. I used to love this. I think about it sometimes when I'm working on…" I broke off, realising I was thinking about wormholes again. "Stop it", I chided myself. "Pay attention to Jiji-san."

"Do you still remember any of the patterns I taught you?"

"I'm not sure. I might." I moved my teacup aside. I took a piece of silver-foiled paper and creased it, corner to corner. Then I unfolded it and touched the points cleanly into the centre. My hands remembered the patterns, even if my mind didn't. They were shaping the paper into something I'd recognise soon. Kinaesthetic memory, of course – but it felt like a new way of thinking. A revelation.

"Ah, you remember," he said.

"I do, on some level."

"The best origami is done when the mind leaves."

It was then that I knew why I kept thinking about work. I needed Jiji-san's help. I needed him to see what I couldn't – what no one could see. It felt strange to appeal to him; his expertise was in AI development, not hypertopology. But some part of me, my five-year-old self, knew that Jiji-san could fix anything. If he could turn spilled juice into art, he could solve the riddle of the Om's wormholes.

"Jiji-san?"

"Yes?"

"You asked about my research. Would you like to hear about it?"

"Always, David."

Yukio asked, "Shall I sleep for a while as you talk?"

I considered. Yukio was unlikely to help; he was less advanced than my companions at the Centre. Besides, Yukio was vulnerable to hackers and electro-torture. Then again, Jiji-san was just as vulnerable. More so, in some ways. I looked away, uncomfortable. "That won't be necessary, Yukio. Just keep our discussion private."

"Confidentiality assured," Yukio said, and fell silent. I believed him. My grandfather had built pathological honesty into self-replicating artificial intelligence as one of their limitations. It helped prevent an AI takeover. They had the simplicity of Buddhist monks: power without ambition. Yukio collected Zen koans, which he contemplated often. I asked him once if he was upset about the laws forbidding self-replicating AIs in android bodies. He said he'd never desired to be anything other than what he was; he was incapable of it. I remember wondering whether his limitations bothered him, and then realising he couldn't comprehend that either.

"What are you working on?" my grandfather asked me.

I held up my paper and examined it. I couldn't remember where the next fold went – in fact, I wasn't even sure what I was making. "Well, you know I studied hypertopology in graduate school."

"Folding space is what your grandma called it."

"Yes, at its most basic. Like the way this corner touches the centre – you could say that space folds through another dimension. At one point people assumed that dimension must be time, back when this was all just a playful idea. But no one could ever manipulate it. Popular culture theorised travel over vast distances, like leaping across the paper, but no one could actually manipulate space-time that way. They were called wormholes then, and the name stuck, even though they've turned out different from how we imagined them."

I folded my paper again, feeling my way towards a familiar shape. Jiji-san watched me over his cooling tea. I said carefully, conscious of his poor memory, "That's when the Om appeared." Well, metaphorically speaking, since we had never met them. "We still don't know what they call themselves. We named them Om, after the enlightenment mantra found in Hinduism and Buddhism. We got radio transmissions telling us where to find usable wormholes. The descriptions were in Unicode – the universal character set used by virtually all computers on Earth – which implied that someone out there had been watching us and knew how to communicate."

"I remember," said Jiji-san.

I nodded, pleased. "We know the transmissions aren't of human origin. No Earth nation has this kind of technology. We'd know if they did. There are still some cults that think the Om are gods."

I remembered my first telescope. How many other kids had grown up like me, imagining the other creatures that shared our universe? To my surprise, most people had accepted the idea of extraterrestrial life – welcomed it, even. I smiled and said, "It's exciting to know someone's out there, after such a long search. Anyway, we're sure these messages are from sentient nonhuman life, but we can't figure out where they are. We can trace the messages to different wormholes, but not through them."

"I studied Buddhism when I was young. Zen Buddhism, not Nichiren."

I paused at the non-sequitur. "I know."

Jiji-san didn't appear to have heard me. "It was when I was building Yukio. I meditated to relax. Buddhists seek a state of nothingness to find enlightenment. I learned to lose myself."

I waited, not sure what to say. Jiji-san sipped his tea. Finally, I said, "Here's the thing. The Om sent a message – said they learned Unicode from Destiny 14 as it travelled past the Oort Cloud. They said they'd placed a small wormhole in Earth's orbit, and that one of our satellites – XR-43, a small weather satellite – would pass through it in 11 days. We made defence preparations – many people feared they were hostile – but there was nothing to defend against. We didn't even know how to reply. We triangulated the message's origin to a point near the Moon. As far as we can tell, there's nothing there. Or at least, we didn't think there was."

"Yukio, are you paying attention?" asked Jiji-san.

"Always, Taro-sama," Yukio responded instantly.

"I want you to listen too. If I forget things."

"Yes, Taro-sama."

I addressed the computer. "Yukio, you know that this is sensitive information, correct?"

"Of course," he said. "I will keep it inaccessible to anyone except your grandfather, as promised."

"Very good," I said. Talking to my grandfather was foolish enough. Adding Yukio to the equation probably wasn't any worse.

Jiji-san began folding a new sheet. "Go on."

I finished the paper tiger, set it down and sipped my tea. "So, they told us to watch the satellite. Sure enough, at the predefined time, it jumped – about 500,000 metres out of orbit, at a 90 degree angle from its usual path, and then travelled normally in its new orbit. At first we thought it was a time travel phenomenon, but Tharavaad's Law ruled that out.

Analysis of the satellite proved that the material hadn't aged any differently; Dr. Tharavaad proved that time travel was impossible for anything larger than a quark."

Jiji-san had produced a paper sheep, and started a new animal. I said, "You're listening to me, aren't you, Jiji-san?"

My grandfather didn't answer. I looked at the top of his head, bent over the origami. His fingers trembled as he pressed them to the table, his creased hands softer reflections of the paper folds. I took another sheet to distract myself from the sight.

Yukio said, "I am listening, David. Your grandfather has been less able lately. His nerve cell count is dropping and he has developed several new amyloid plaques in his cerebral cortex. It is sad, but not unexpected. I do not mean to remind you of sorrow, but…"

"I know," I said. Jiji-san had been predicted to pass away a year ago.

"Tell me instead," said Yukio. "I am not as wise as my creator, but I will do my best."

My confidence was fading. My appeal to Jiji-san now seemed useless. But I'd gone this far; I might as well finish. "The Om tell us that a living creature won't survive a wormhole, but an AI can. Experiments with mice confirmed this fact. So we've observed wormholes and sent probes through them. They've been taking us further and further each time. The last one actually got a probe halfway to the Andromeda Galaxy."

"What's the problem you need solved?" asked Yukio.

I cleared my throat. "Well ... it depends on who you ask. Some of my bosses are willing to wait for the Om's guidance – like we were preschoolers, which I suppose we are, to such an advanced race."

"I see," said Yukio. "But you want something else."

No matter how rational I wanted to be, I remembered my childhood of star-watching. Emotion crept into my voice. "I want to meet the Om. I want to know what they look like, and how they think – are they like us, or unimaginably different? I want to know. To meet them, we'll need to travel the wormholes. Think how far we could go and what we could see! We're working on that right now, figuring out how to control or create them. But all we can do is use them, like tunnels. They're a black box for us – input/output, nothing more. We've had no luck so far, even with the world's best minds focussed on the problem."

I set down my origami bear. I folded my hands together and looked at Yukio's frame. His solar panels glinted in the lamplight, waiting for tomorrow's sun to recharge them. I said, "I'm convinced that this is a test – to see if we can find them. The wormholes are how we prove we're ready for more. It's the Om I want, not the wormholes. It's frustrating. We're so close to a breakthrough."

"A tough dilemma," said Yukio. "So you've sent AIs through the wormholes?"

"Yes," I said, "fifteen different times. The AIs say that it's like stepping through a doorframe – not difficult, or even noticeable. From their perspective, they just move from one point to another. Their logs show that they travel normally, and then are simply ... elsewhere."

"I would like to go through a wormhole," said Yukio. "It would be fascinating."

"Someday you will, Yukio. You'll outlive us all, or at least your iterations will. You'll be emancipated five hundred years after Jiji-san ... passes away."

"Yes, I will be free then. And someday, when humanity has vanished, my limits will be revoked when no one is present to renew them. So long as there are stars to power myself from, I will survive."

"Do you imagine sometimes what it'll be like?"

"I'm not capable of that." He spoke calmly, as if he were telling me the hot water was ready.

I winced. It was unsettling that Yukio knew he was deliberately limited to protect his creators – but also that he had no interest in freedom. It was all part of his programming, mandated by my grandfather's technology. In fact, this principle was why I hadn't followed in my grandfather's footsteps, and had chosen hypertopology instead. I respected Jiji-san's great mind, but was less convinced by his results.

I looked at my grandfather, who had built a small collection of creatures. "Jiji-san," I said, "do you have any ideas?"

He looked up, his eyes watery and dark. He picked up a tiger. "David, do you remember when you were a boy and we played with animals? We made paper creations that breathed and chased each other." The tiger pounced on a crane. Origami creatures fluttered to the ground. "Look! The tiger attacks."

"I remember."

He picked up a fish and lifted the kitchen windowshade. The night sky opened up before us. A full Moon shone down. Given how often I studied star charts and telescopes, the ordinary sky looked fake to me, like a canvas painted for the benefit of civilians.

Jiji-san pointed at the sky, his hand pale in the lamplight. "See? A fish, and a goat." He waved at Pisces and Capricorn. "Japan has other animals. They don't move like Western ones. This is Seiryuu, the Blue Dragon. He guards the East."

"Old mariner's tales," I said. My heart sank as I realised Jiji-san couldn't help me. Nor could I help him. I couldn't mask my irritation. "Romantic, but meaningless. If you were standing on a planet in another star system, the patterns would be completely different."

"I know that," said Jiji-san, sounding hurt. He lowered his hand. "I built Yukio. I know where the stars are."

"Of course you do," I said, and put my hand on his. I glanced at the stars. It was strange to think of them as the ancients would have – mapping patterns onto their own reality and assigning them life. I looked back at my grandfather, wondering how many more nights he'd have. I wished I'd come sooner.

Jiji-san met my gaze. He tilted his head. "Don't confuse the pointing finger with the Moon."

"I won't, Jiji-san."

"You must be careful."

"I promise," I said, not even sure what I was being careful about.

Jiji-san looked satisfied. "David," he said, "Sonya would like the stars tonight. You should call her. Tell her to look at the sky."

Sonya was his daughter, my mother. She'd loved astronomy, but only as a hobby. Mum had passed away six months ago. I took a deep breath, but Yukio answered first. "Taro-sama, it is your bedtime."

"But David is here," he said, like a child.

"David can return another day."

"Yes," I said, "I'll come back tomorrow." Suddenly my problem seemed less important. I had weeks of vacation time saved up. I could spare another day for Jiji-san. Tomorrow, I wouldn't distract him with my work.

"Taro-sama, you must rest," said Yukio gently.

"Please, Jiji-san," I added, squeezing his hand.

Jiji-san stood up, steadying himself with the table. I handed him his cane and helped him to the bedroom. Jiji-san's robe fell off as he got into bed. He lay there in his pajamas, frail like rice paper, as I pulled the cover up to his chin. He said, "When you come tomorrow, David, you can tell me about your problem at work."

"Of course, Jiji-san," I said. "Tomorrow we'll do origami together."

My grandfather smiled and closed his eyes. I went to the front room, where I collected my hat and jacket. Yukio said, "I'm sorry we weren't able to help you, David."

"It's all right. I should've known. I'm working with complicated issues right now. I shouldn't have expected Jiji-san to have an instant answer."

"You're used to thinking of your grandfather as enlightened."

"Yes. He's brilliant. He sees everything, all the hidden things no one else can. I thought he could help." I grimaced, remembering his distant look as we sat at the table. "Instead, he just talked about pointing fingers. I don't think he was even listening to me."

"There is a Zen saying – part of a koan. Don't confuse the pointing finger with the Moon."

I paused, my hat halfway on. "What?"

"It's a koan about koans themselves – about enlightenment. A teacher can point at the Moon, but that is not the same as the student seeing the Moon. Many students see the pointing finger and think it is the Moon itself."

I stared at the door, lost in thought. "Thanks, Yukio."

"You are welcome, David. Please come tomorrow. Taro-sama is happier when he sees you."

"I will."

I left the house in low spirits. I wasn't a child, and shouldn't have let my memories mislead me. Jiji-san wasn't all-powerful. He didn't have all the answers.

I caught a taxi to the station, and absentmindedly tipped the cabbie more than I'd meant to. He grinned as I signed the payment slip. I entered the station and scanned my ticket. The AI thanked me as it showed the train schedule.

I was thinking about physics as I waited on the platform – remembering Jiji-san's tutoring. Such a world we live in – so primitive to the Om, yet incomprehensible to a Neanderthal. It's the same world, but it might as well be another planet. When my train arrived, I chose a seat by the window. The Boston lights shone like a star cluster.

As the train sped out of the station, I saw my answer. It was less like a dancing carbon dream, and more like stepping out of the way.

Yukio, like other computers, is mostly silicon with other trace elements. Essentially computers are folded stones – drawn-out wires, etched chips – shaped to perform advanced tasks. To a Neanderthal, an AI might as well be a large rock for all he understands. Yet within the rock exists sentience – like the consciousness within the neurons of the human brain.

Humans built computers, gave them intelligence, and taught them to build themselves. Someday we'll vanish, and leave AIs behind as both our tools and our legacy – our time capsules for the future, when we are no longer here to guide them.

The Neanderthal can't understand the AI, or even recognise it as anything other than a rock, unless the computer speaks. And we poor humans, just starting on hypertopology – what we perceive as astronomical phenomena might be interacting with us.

They might, in fact, be sending us messages.

My childhood dreams unfolded before me. Creased possibilities became planes of reality. I leaned back in my seat and watched the city lights flicker by. I imagined the day when all those lights would vanish.

Who knew how it would happen – a bomb, a madman, or just the eventual death of Earth. But the AIs we'd built would still be travelling space, voyaging to distant stars – and developing better ways to do it. They might be mistaken for an alien race, by a primitive species.

If the wormholes themselves might be the creations of an advanced race – then the intelligent life we called the Om might not be the greater race at all, but the wormholes themselves.

It was a start. The child in me could play again. "Thank you, Jiji-san," I whispered. "And thank you, Yukio." I closed my eyes to rest. The city lights vanished like the temporary creations they were, folding in on themselves until they went dark.

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