Why the US Is Emptying a Mountain 1,500 Meters Underground

Added: 2026-05-11

[00:00:01]Deep beneath South Dakota, inside the Sanford Underground Research Facility, workers are digging caverns nearly 4,800 ft below [music] the surface. They drill, blast, and carve their way through solid rock. [music] More than 800,000 tons of ground have been removed. They're not opening a mine, and they're definitely not looking for gold.

[00:00:22]They're digging for answers to some of the biggest questions humanity has ever asked.

[00:00:28]How does our world actually work at the deepest level? Why does matter exist at all? How are stars born? And how do black holes come into existence? The answers aren't hidden in some underground vault or buried [music] treasure. Instead, these caverns are part of one of the most ambitious physics experiments ever attempted, [music] the deep underground nutrino experiment, better known as Dune.

[00:00:53]Down here, far below the noise of the surface world, scientists are installing enormous detectors designed to study some of the strangest and most elusive particles in existence, nutrinos. What are these particles? Why do we need to go nearly a mile underground to study them? And what could they possibly tell us about the universe and about us?

[00:01:15]Let's find out. By the end of this story, you'll feel a little more like a scientist.

[00:01:21]So, why are nutrinos such a big deal?

[00:01:24]Because they're everywhere. They're among the most abundant particles in the entire universe. And yet, at the same time, they're almost completely invisible. These tiny subatomic particles pass through matter as if it barely exists. Right now, this very second, around 100 trillion nutrinos are passing straight through your body, but you don't feel a thing. Nutrinos are incredibly light. For a long time, scientists weren't even sure they had mass at all. That's why they're often called ghost particles. They're everywhere, constantly streaming through space, planets, and people, but almost never leaving a trace. Nutrinos are created whenever atomic nuclei collide or decay. They're born in nuclear reactions, radioactive processes, and energetic cosmic events. They even come from something as ordinary as a banana.

[00:02:16]Bananas contain potassium which is slightly radioactive. That means every banana quietly produces nutrinos. Don't worry, the amount is completely harmless. You can eat bananas without fear. But the biggest nutrino factory anywhere near us is the sun. Deep in its core, nuclear fusion is happening nonstop, and nutrinos pour out in staggering numbers. The sun floods our solar system with them every second. And beyond the sun, even more powerful sources exist. Exploding stars, supernovas, [music] and possibly even black holes. Nutrinos may also be connected to one of the greatest mysteries in modern physics, the disappearance of antimatter.

[00:03:00]According to our best theories, the big bang should have created equal amounts of matter and antimatter. Antimatter is made of particles with opposite electric charge. When matter and antimatter meet, they annihilate, [music] turning into pure energy. And yet, here we are living in a universe made almost entirely of matter. The antimatter is gone. But why?

[00:03:24]Scientists don't know. One leading idea is that nutrinos played a [music] role tipping the balance. Somehow, early in the universe's history, nutrinos and antiutrinos may have behaved slightly differently. That tiny imbalance could explain why matter survived and why galaxies, stars, [music] planets, and people exist at all. So, nutrinos might hold answers to how the universe works, [music] how it began, and why it didn't erase itself. But there's a problem. To study nutrinos, you have to catch them. You have to observe their interactions, measure their properties, and see how they change. And that's incredibly difficult.

[00:04:03]That's why scientists are digging giant caverns in South Dakota. Why underground? Why not study nutrinos out in the open, in a [music] field, on a mountain, or on a sunny beach? Because nutrino detectors need silence. Not silence from sound, but silence from radiation. Nutrino detectors are massive, extremely sensitive machines.

[00:04:26]They're built to notice incredibly rare events. But Earth is constantly bombarded by cosmic [music] rays and background radiation. At the surface, those signals would completely overwhelm the data. [music] Going deep underground solves that problem. Thick layers of rock act [music] like a natural shield, blocking unwanted radiation and creating a quiet environment where nutrinos have a chance to reveal themselves. That's why Dune's detectors sit underground.

[00:04:55]In total, DUNE will use four gigantic detectors, [music] each about the size of a sevenstory building. Together, they form a single [music] experiment. But the heart of the project is actually far away at Fermy Lab near Chicago, about 800 m from these caverns. [music] From here, a team of scientists will release nutrinos that will travel through the underground, and giant detectors will collect information about them and transmit [music] the data. But how do they catch the information?

[00:05:26]The detectors will be filled with liquid argon. It's a cryogenic, colorless, odorless, and tasteless substance extracted from the air by liquefaction.

[00:05:36]Liquid argon creates an [music] inert environment that greatly helps scientists in their experiments. Imagine that our world is a huge canvas with millions of drawings and colors. So liquid argon is such a white piece, a [music] perfect place for studying tiny particles. When nutrinos collide with this liquid, they create other [music] particles. Detectors read those particles and send the information to the lab. [music] Then scientists from all over the world begin to carefully study these data. They hope to create a clearer picture of the universe to understand why matter [music] rather than antimatter dominates here. But what do we care about this information? Why is knowledge about matter important to us? Because we're part of this matter, too. By manipulating particles, scientists will be able to find out what happens to nutrinos during the explosion of a star [music] and the birth of a black hole.

[00:06:32]So, scientists collect invisible nutrino particles which are associated with the birth of the [music] universe, star explosions, and black holes. They release them into a single beam and launch them through detectors. [music] Everything seems clear, but where did they get the nutrino beam from? And how do they get them? It starts with hydrogen gas. [music] Scientists take hydrogen atoms and strip away their electrons, leaving behind pure protons.

[00:06:59]These protons are then fed into a massive particle accelerator where electric fields push them harder and harder, faster, and [music] faster until they're moving at nearly the speed of light. Then they're smashed into a solid target made of graphite or burillium.

[00:07:15]The impact is so hard that the atomic nucleus breaks into a spray of new unstable particles and [music] explodes outward. Among those particles are pions. Pions are extremely short-lived.

[00:07:28]Almost instantly they decay into other particles, nutrinos [music] and antiutrinos.

[00:07:33]Powerful magnetic devices force the pons to fly in the same direction. Chaos becomes order.

[00:07:40]A wide spray of particles turns into a tight [music] focused beam. That beam then slams into thick blocks of aluminum, steel, and concrete. These blocks act like a filter. Muons and other leftover particles [music] can't go through it. But nutrinos are different. They barely interact with matter at all and pass through the filter. What emerges on the other side is [music] a clean beam of nutrinos.

[00:08:06]Right now, the caverns are complete. The first DUNE detector is expected to [music] turn on before the end of 2028.

[00:08:13]Around 1500 scientists from [music] 36 countries are waiting for the experiment to begin. All of this might look familiar. Giant caverns, tiny particles.

[00:08:23][music] Scientists are chasing the deepest structure of reality. It sounds a lot like the Large Hydron Collider, but Dune and the [music] LHC have different goals. At the Large Hadron Collider, scientists [music] accelerate particles, mostly protons, to near light speed and smash them together. The goal is to recreate [music] conditions similar to those just after the Big Bang. The LHC has already confirmed the existence of the Higs Bzon particles that help us to understand why some elementary particles have mass.

[00:08:57]The collider may also help uncover dark [music] matter, an invisible form of matter that makes up about 27% of the [music] universe. Stars, planets, galaxies, and everything we can see [music] are about 5%. The rest is dark energy, a mysterious [music] force expanding the universe. Dark matter, dark energy, invisible ingredients shaping reality itself. None of it is easy to understand. But experiments like [music] DUNE and the LHC help us to make sense of it.

[00:09:32]That's it for today. So hey, if you pacified your curiosity, then give the video a like and share it with your friends. Or if you want more, just click on these videos and stay on the bright