The Cave That Sings

Reality is like a cave in darkness; we can only explore a small part of it with our faint light.

This thought has lingered in my mind for years. I'm not sure if some writer penned it, but whenever I recall this metaphor, I think of the summer that changed my life.

My name is Makoto Nakajima. I'm an associate professor of geology at Tokyo University, specialising in cave studies for twelve years now. In academic circles, I'm known for my rigorous approach. I never believed in phenomena without scientific evidence. Yet science sometimes fails to explain everything.

In July 2023, I received a special assignment to visit a remote mountain village called "Shadow Valley" in northern Japan. This village had a strange tradition: the villagers believed that a cave system in the northern mountains could sing, and these songs supposedly contained ancient wisdom. University officials thought it was just a simple acoustic phenomenon, worth studying but not worth mystifying.

On my first day in the village, I checked into its only inn. The owner, Yukiko Tanaka, a woman in her sixties with wrinkles as complex as geological maps, handed me the key and warned in a low voice: "Mr. Nakajima, please don't approach the northern caves after sunset."

I smiled politely. As a scientist, I was used to locals having superstitious explanations for natural phenomena.

The next morning, I visited the village head, Kenichi Ono. He was a sprightly old man, reportedly in his eighties but looking only sixty-something.

"Professor Nakajima," he said in a steady voice, "our village's relationship with those caves is more complicated than you might imagine."

"I understand, Mr. Ono. Every place has its traditions and beliefs."

Ono shook his head: "It's not just about belief. Do you know that almost all ancient civilisations considered caves sacred places? From Australian Aboriginals to the Maya, from ancient Greeks to Chinese Taoists, caves were always seen as portals connecting different worlds."

I nodded: "Indeed. Caves played an important role in early human history, both as shelters and sites for religious rituals. But there are scientific explanations..."

"Scientific explanations?" Ono chuckled. "Then tell me, why do civilisations thousands of miles apart, with no contact, have such similar cave worship? Why are the Australian Aboriginals' 'songlines' concept and our village's inherited 'sound path' theory almost identical? This isn't just a coincidence, Professor."

I admitted this question intrigued me. The similarities in cave sacralization worldwide were indeed remarkably similar, a phenomenon that remained a mystery in anthropology.

"Our village history goes back to the Jomon period," Ono continued. "Our ancestors discovered the northern cave system had special acoustic properties. But more importantly, they found that time flows differently there... compared to the outside world."

Over the next few days, I systematically surveyed the caves around the village. Most were typical limestone caverns, varied in form but conforming to geological principles. I recorded temperature, humidity, and acoustic properties, everything was within expected ranges.

Until the evening of the fourth day, when I discovered a cave entrance not marked on any map. It was hidden behind dense bushes on the northern mountain, with an entrance so narrow an adult could barely squeeze through sideways. Curiosity drove me to explore, so I turned on my headlamp and slowly squeezed through the opening.

Unlike the damp forest outside, the air inside was surprisingly dry and warm. The cave walls were smooth as mirrors, without the usual stalactites and stalagmites. When my headlamp shone on the walls, it reflected strange patterns of light that seemed to form symbols I didn't recognise, shifting and changing as I moved.

"The geological structure here is quite unique," I muttered to myself, my voice echoing in the narrow passage with an odd resonance.

As I ventured deeper, my sense of direction gradually blurred. According to my calculations and GPS data, I should have been heading away from the village, yet I could clearly hear village sounds: children laughing, old people talking, even the sizzle of cooking from kitchens.

This defied acoustic principles, I thought. Sound couldn't maintain such clarity through a complex cave system, especially not from the opposite direction. I checked my equipment and found my GPS signal lost, my compass spinning wildly, unable to determine direction.

After walking about twenty more minutes, the cave opened into a nearly perfect circular space illuminated by a faint blue light. In the centre was a small pool of water, its surface as still as a mirror.

I approached the pool and saw my reflection, but not quite me. The "me" in the water was younger, without the scattered grey hairs, without the fatigue in the eyes that comes from years of research. It was me from twelve years ago, when I first began studying caves.

Shocked by this impossible phenomenon, I reached out to touch the water. The surface rippled, and the reflection vanished. When the water became still again, I saw an older version of myself: completely white-haired, face lined with age.

Quantum superposition as a visual presentation? I mumbled, trying to explain this scientifically. Or some kind of psychological projection?

Then I heard footsteps behind me. I turned to see an old man standing there, the same elderly version of me I'd seen in the water.

"You've finally come," he said, his voice and accent identical to mine. "I've been waiting a long time."

I stepped back: "This is impossible. Who are you? Some kind of holographic projection?"

"I'm you, from another timeline," the old man said calmly. "This cave is a node connecting countless parallel worlds."

"Absurd," I said, though my voice lacked conviction. "Quantum mechanics theory might support the existence of parallel universes, but such parallel time travel is impossible. Heisenberg's uncertainty principle and Schrödinger's wave function collapse theory don't support this possibility."

The old man laughed softly: "In Plato's cave, prisoners believed the shadows they saw were the entire world. When someone left the cave and faced the true light, they were considered mad."

"You're like that person now, seeing the structure behind the shadows but reluctant to acknowledge its existence. Science isn't the entirety of truth; it's just one language for understanding the world."

He pointed to the cave walls, saying, "Look at these symbols. They aren't random light patterns but an ancient language recording the laws of spacetime. Cave worship is so similar worldwide because our ancestors all discovered these nodes, just explaining them in different languages."

I carefully observed the flowing symbols on the cave walls, surprised to find they indeed followed patterns, like a combination of mathematical equations and ancient pictographs.

"Why caves?" I asked. "Why not mountaintops or ocean floors?"

"Because caves are wrinkles in Earth's surface," the old man explained, "at certain specific points in the universe, dimensions become thin, and different spacetimes can contact each other. Ancient people called them 'blessed places,' modern physics calls them 'quantum anomaly points.'"

He handed me a notebook. As I flipped through it, I discovered it contained a new theoretical framework merging quantum physics, geological structures, and ancient mythology.

"This is your future research," the old man nodded. "It was my last attempt to explain everything scientifically, a theoretical system built with all my heart. But academia rejected it, media ridiculed it, and my family gradually distanced themselves. I lost too much."

He looked at me with a calm expression: "Later, I returned to the village and found Sachiko Ono, Kenichi's sister, who knew the secrets of the 'sound paths.' She taught me how to use hearing, memory, and rhythm to understand the sound paths left by these caves."

The old man continued explaining that the village's "sound paths" and Australian Aboriginals' "songlines" were both oral maps, recording geographical features and travel routes through songs. But on a deeper level, they were also maps of time, recording creation stories.

"Specific sound frequencies can create resonance in spacetime, allowing information to cross conventional time limits," the old man said. "That's why villagers can hear singing in the caves. Those are information fragments from different points in time."

"If this is true, why has the scientific community never had research reports on this theory?" I questioned.

"Because modern science divides phenomena into different disciplines. Physicists study quantum theory but ignore anthropology; geologists study caves but don't care about acoustic resonance; anthropologists record myths but don't understand the physics principles within them. Only by combining these fields can you see the complete picture."

"Why tell me this?" I asked. "If you're my future self, wouldn't changing my choices make your timeline disappear?"

"Parallel universes aren't linear but web-like," the old man sighed. "When I returned to the village, it was already too late. I hope that at least in some timeline, 'we' can make different choices, find balance, both advancing science and respecting ancient wisdom."

Just then, a distant bell rang. The old man's expression changed: "Time's up. Leave the cave before sunset, or you'll be trapped at this node, becoming the next 'waiter.'"

"Waiting for what?"

"Waiting for the next you, to complete this cycle." The old man's figure began to blur. "Remember, truth is always at the boundary between light and darkness, at the intersection of science and myth."

As he disappeared, a low-frequency resonance sounded from deep in the cave, like distant bells or some kind of countdown pulse. I felt the air compress, and time lost its linear flow.

I ran desperately toward the cave entrance, the innkeeper's warning echoing in my ears: don't approach the northern caves after sunset. Now I finally understood her meaning.

When I burst out of the cave, the sun was setting its final rays. I gasped for breath, uncertain if everything I'd just experienced was real. However, the notebook in my hand proved it wasn't an illusion.

I stared blankly at the empty notebook. Those complex patterns and formulas seemed to have evaporated from my sight, yet remained clearly imprinted in my mind. Only the first page had a line of text:

Caves are not just geological voids but wrinkles in spacetime. Truth is like a Klein bottle, inside and outside indistinguishable.

A Klein bottle is a topological structure with no distinct inside or outside, breaking our intuitive understanding of boundaries. Thinking about it, I suddenly realised that perhaps the boundaries of time and space, like past and future, here and there, aren't as clearly divisible as we think.

The next morning, I went looking for Sachiko Ono in the village. The village head had mentioned that his sister lived in an old house at the northernmost point of the village. I knocked for a long time with no answer. Just as I was about to leave, a passing villager told me Sachiko Ono had died five years ago.

"Impossible," I said. "Mr. Ono mentioned her just yesterday."

The villager gave me a strange look: "Mr. Ono? Our village head Ono died three years ago. Our current village head is Yoshitaro Kiryu."

I suddenly felt a chill. When I stumbled back to the inn, I found the innkeeper, Yukiko Tanaka, looking much older. When she saw me, she didn't seem surprised: "You went to that cave, didn't you?"

I nodded.

"Time flows differently there than outside," she said. "Sometimes an hour might equal a day outside, sometimes a year."

She handed me a yellowed envelope: "This is from Sachiko Ono, left for anyone who would enter the cave. In twelve years, you're the first." The letter contained just a few brief sentences:

The cave is a circle; the entrance is also the exit. The self you see is both past and future. Remember, truth isn't inside or outside but in the moment of crossing.

The letter was dated 1983, earlier than my birth.

Over the next few months, I buried myself in books and data. Those theories heard in the cave repeatedly flashed in my mind like ghostly light. I tried to compare, deconstruct, and reconstruct them with modern physics hypotheses about multiple universes and quantum entanglement.

Finally, I built a new theoretical framework called "Spacetime Node Theory." It hypothesised that certain special "contact points" exist in the universe where different dimensions of spacetime can briefly overlap or penetrate each other. These nodes often appear in places with very special geological structures, especially certain types of cave systems.

If this hypothesis were true, it might provide reasonable explanations for many historical "supernatural phenomena." From legendary prophecies and oracles to the amazing consensus on caves across different cultures. These might not be coincidences but traces of something modern science doesn't yet fully understand.

I derived mathematical models while constantly revisiting anthropological materials from around the world. I knew this theory needed a solid mathematical foundation and must offer truly verifiable predictions. Otherwise, it would just be another elaborate fantasy.

Just as I was preparing to publish this research, I received a warning from a senior professor at Tokyo University: "Nakajima, this is too risky. Mixing science with mythology will destroy your academic reputation."

I remembered the old man in the cave, my future self, who said mainstream academia wasn't ready for this kind of interdisciplinary understanding.

After careful consideration, I finally abandoned the idea of publishing this theory in traditional academic journals. Rather than being constrained by format and thresholds, I wanted it to be an open proposition, inspiring responses and thoughts from different fields.

So I established an interdisciplinary research platform, inviting physicists, anthropologists, geologists, even linguists and religious historians to explore the possibility of "spacetime nodes" together.

I also actively contacted scholars worldwide studying ancient cave cultures, exchanging clues and perspectives. Those narratives long viewed as "myths" by the mainstream began to show some structural significance in the new theoretical framework, as if gradually revealing an unnamed path from chaos.

This unorthodox academic approach generated more attention than I expected. Though mainstream physics still remained reserved, more and more young researchers began to show interest in this intersection of science and ancient wisdom. They were no longer satisfied with explaining the world through a single discipline but yearned to redefine reality within a broader vision.

Three years later, I returned to Shadow Valley. The village had barely changed, except that the inn had a new owner — Yukiko Tanaka's daughter had taken over the business.

I revisited the hidden cave entrance. This time, I brought complete scientific instruments and equipment: quantum field detectors, high-precision recording devices, multispectral cameras, and time synchronisation systems. I activated all equipment, ensuring every piece of data would be recorded. Then I stepped into the cave, this time with a perspective both scientific and beyond scientific.

Inside, the air remained dry and warm, the symbols on the walls still flowing and changing. My equipment captured strange readings: the quantum field detector showed quantum fluctuations hundreds of times higher than normal; recording devices captured multi-layered sounds, from the low pulse of Earth to high-frequency quantum oscillations; multispectral cameras showed the symbols on the walls formed complex mathematical equations in invisible spectra.

When I reached the circular space again, the pool was still there. But this time, no reflection appeared on its surface. Instead, it showed me countless tiny scenes, each featuring a different timeline's "me": some became famous scientists, some became mystical researchers, some lived ordinary lives, and some were completely beyond my imagination.

I understood that this cave wasn't just a simple spacetime node but a quantum observation point: here, all possible timelines could be observed. Ancient people deified this phenomenon as oracles or prophecies, while modern physics might explain it as a physical presentation of the quantum many-worlds theory.

I understood why cave worship worldwide was so similar: because at these special locations, humans could directly experience the multi-layered nature of reality, sensing existence beyond daily experience. Different cultures described this experience using different languages and symbol systems, but the core experience was the same.

I began recording all observations in detail. When I finished my work and prepared to leave, I left my notebook by the pool. On its first page was written:

Caves are not just geological voids but wrinkles in spacetime. Truth is like a Klein bottle, inside and outside indistinguishable.

When I walked out of the cave, the clear night sky was filled with stars. I didn't know how much time had passed outside, nor was I certain what results my research would bring. But I knew that in any timeline, the journey of exploration would never end, and the nature of truth might be just as that unnamed writer said, we can only explore a small part of the world's dark cave with our faint light.

But it's precisely this spirit of exploration, this balance between science and myth, reason and intuition, that constitutes humanity's greatest adventure. And caves, whether physical or metaphorical, will continue to call brave explorers to travel through the river of time, seeking those eternal mysteries.

---

Writer’s Note

The cave you fear to enter holds the treasure you seek.
— Joseph Campbell

This story began with a tweet thread that I composed since 2022, weaving together Buddhism’s cave, Aboriginal songlines, Norse myths of underworld gates, and so many caves’ myths across the cultures.

I wondered: What if a cave could bend time, collapse memory, and let you meet another version of yourself, or another reality?

The striking similarities in cave mythology across human cultures suggested our ancestors might have been describing similar experiences through different cultural lenses. By placing a modern geologist in a situation where physics meets ancient wisdom, I wanted to explore how we might reconcile these seemingly opposed ways of understanding reality.

The cave in this story represents more than a physical space: it's a metaphor for the boundaries of human knowledge and the mysterious places where different worldviews intersect. Like a Klein bottle with no true inside or outside, perhaps the boundaries between science and myth, past and future, are more permeable than we believe.