CERN Recreates Cosmic Particle Storms Inside the Large Hadron Collider

Welcome to the QuarkSide Quantum Physics Podcast, an exploration of the fundamental structure of reality, where quantum laws govern matter, energy, and information. Here, uncertainty is a feature, not a flaw, and understanding begins at the smallest scales.

I want you to imagine, just for a second, That you're standing outside. Okay.

Picture a perfectly clear day. Right.

There are no clouds. There's no wind. Just, you know, an endless expanse of blue sky.

Sounds pretty ideal.

It does. But what you probably don't realize is that right this very second, an invisible rainstorm is pouring down on you.

And we are definitely not talking about water.

No, we are not.

Yeah.

I mean, we are talking about particles zipping through your body at nearly the speed of light. Relentlessly. Constantly. Constantly. like every single second of your life.

It honestly sounds like something out of a science fiction novel.

It really does.

But it is an absolute physical reality. We're talking about literal cosmic rainstorms.

Right, because high above our heads, you have all this powerful interstellar matter that's constantly striking the very taut of Earth's atmosphere.

Exactly. And when those collisions happen, the incoming matter just shatters.

It breaks apart.

Yeah, it breaks apart into this massive, completely invisible shower of subatomic particles that rains all the way down to the ground.

Passing through buildings, oceans, and.

And yes, even you.

So, okay, if this rainstorm is entirely invisible, and we obviously can't feel it when it hits us, how do we even know it's there?

That is the big question.

Right. Like, how did we first figure out that we were basically being bombarded from space?

Well, to answer that, we have to go all the way back to 1912.

Okay.

To this Austrian physicist named Victor Hess.

Victor Hess.

Yeah. So at the time, scientists had these instruments called electroscopes that measured ambient radiation. Right. And they kept noticing this persistent background radiation everywhere they went.

But didn't they think it was coming from the Earth?

Exactly. The prevailing scientific consensus was entirely Earth-centric. Like, everyone just assumed this radiation was seeping up from the ground.

From, like, radioactive rocks and minerals in the crust.

Right. Which, you know, makes sense logically.

Sure. If the rocks are radioactive... The ground is obviously the source.

Yeah, and based on that logic, if you move further away from the ground, the radiation should steadily decrease.

It should drop off.

Exactly. So Victor Hess decided to actually test this, and he did it by taking his radiation measuring instruments and going up in a hot air balloon.

Which is just.

And get this, he did it during a solar eclipse.

Oh, wait, really? Why an eclipse?

Just to completely rule out the sun as a direct factor.

That is so smart.

Right. So he makes several flights, eventually reaching an altitude of over three miles.

Three miles. That's what, like 17,000 feet?

About that.

Yeah.

Which, by the way, was incredibly dangerous in an open basket balloon without supplemental oxygen.

Yeah, no kidding. So what actually happens to the radiation levels? I'm guessing it didn't drop.

Not only did it not drop, it significantly increased.

Wow.

Up to a certain point, it dipped slightly, but as he kept climbing higher into this freezing sky, the radiation levels rose to several times what they were down at sea level.

It's like hiking up a mountain to escape a flood, only to find out the water is actually getting deeper and deeper the higher you go.

That's a great way to put it.

You'd realize pretty quickly it's not a flood bubbling up from the ground at all. It's a torrential downpour coming from the sky.

And that is exactly what Hess realized. It totally defied all expectations of where the source of background radiation should be. Right. He correctly deduced that this highly penetrating radiation was actually entering our atmosphere from outer space.

Which is just wild to think about for 1912.

Oh, it fundamentally changed our entire understanding of the universe. It eventually earned him the Nobel Prize in physics in 1936.

Okay, so what exactly is raining down on us then? If I hold my hand out in this cosmic storm right now, what is actually passing through it?

Well, the initial particles that hit the top of our atmosphere are incredibly fast-moving nuclei.

Okay.

Mostly we're dealing with protons, which are just the nuclei of hydrogen atoms, right? And they are traveling at blistering speeds.

Like almost light speed.

Exactly. But the really fascinating part happens when they hit our atmosphere.

The shit?

Yes. When a proton slams into, say, a nitrogen or oxygen atom high above the Earth, the sheer violence of that impact converts energy into entirely new mass.

So it's not just breaking pieces off.

No, it creates a cascade. A shower of secondary particles that harbor entirely new fleeting times of exotic matter.

We're talking about antimatter.

Antimatter, yeah. And exotic subatomic particles like muons, pions, and kaons.

Okay, wait. Muons, pions, and kaons. I've heard those terms thrown around in physics before, but what are they actually doing?

Well.

Like, are they just shattered pieces of the original atom?

Not exactly. Like, they aren't just broken pieces. They are newly forged entities. Oh, I see. Think of Einstein's E equals mc squared.

Energy equals mass.

Right. The kinetic energy of the collision is so incredibly high that it literally materializes into these exotic particles.

That is mind-blowing.

Yeah. Pions and kaons, for instance, are made up of quarks and antiquarks.

Okay.

They're incredibly unstable and only exist for a tiny fraction of a second before decaying into other particles.

Just a flash.

Exactly. But their brief existence in these cosmic showers... actually provided physicists with the very first glimpses of these fundamental particles.

Oh, because this was way before we had, you know, particle accelerators on Earth to make them ourselves.

Exactly. The atmosphere was our first particle collider.

OK, so where are the original fast moving protons coming from? Like what kind of engine out in deep space is firing these things at us?

Oh, they originate from some of the most violent, extreme places in the entire universe.

Like what?

We're talking about the aftermath of massive exploding stars. Supernovae.

Oh, wow. Like the Crab Nebula.

Yeah, exactly like the Crab Nebula. The shock waves from those explosions can accelerate protons for thousands of years. And the highest energy cosmic rays. Those are likely ejected from the accretion disks of supermassive black holes.

So the center of distant galaxies.

Right, acting like unimaginably powerful cosmic slingshots.

It's just incredible to think that the debris from a black hole millions of light years away is essentially washing over us right now.

It really connects you to the cosmos.

It does. But, you know, beyond the profound nature of that, why does this matter for the average person? Because you mentioned earlier that we actually use these cosmic rainstorms as practical tools.

We do. Because these particles are raining down at a constant, fairly predictable rate, They interact with our environment in ways that we can measure.

And utilize. Yes.

For example, back in the mid-20th century, we realized we could use the byproducts of these cosmic rays for radiocarbon dating.

Okay, I know radiocarbon dating is how we figure out the age of ancient artifacts, like bones or wooden tools.

Exactly.

But how do cosmic rays actually drive that process?

It all comes down to a very specific interaction high in the atmosphere.

Okay.

So when a cosmic ray hits an atom, it often knocks loose neutrons.

Just stray neutrons floating around.

Right. And those stray neutrons drift around and occasionally bump into a nitrogen-14 atom.

Which is the most abundant gas in our atmosphere.

Exactly. And when that happens, the neutron knocks a proton out of the nitrogen atom, which effectively transforms it into carbon-14.

Which is a radioactive isotope of carbon.

You got it.

Okay. So the space rain is literally manufacturing this Special radioactive carbon high in the sky. Yep. But how does that get into an ancient artifact?

Well, that newly forged carbon-14 mixes with oxygen to become carbon dioxide.

Oh, and plants absorb carbon dioxide.

During photosynthesis, yeah. And then animals eat the plants. Right. So you, me, every living thing on Earth has a very specific, consistent ratio of radioactive carbon-14 in our bodies right now.

And it's constantly replenished while we're alive because we keep eating.

Exactly.

But the exact moment a plant or animal dies, it completely stops taking in new carbon-14.

And because carbon-14 is radioactive, it slowly decays over time.

Precisely. It decays back into nitrogen at a known rate.

So by measuring how much carbon-14 is left in, say, an ancient bone or a piece of charcoal.

Archaeologists can calculate a highly accurate timeline of exactly when that organism died.

That revolutionized archaeology.

It did. And it is entirely powered by this unseen cosmic storm.

That is just brilliant. But you also mentioned muons earlier, those exotic particles created in the shower.

Right, the muons.

I read that geologists and archaeologists are actually using muons to look inside solid structures.

Yes. This is a really cool technique called muography. Muography. Yeah. So out of all the particles created in a cosmic ray shower, muons are the ones most likely to actually reach the ground.

Because they're heavier.

Exactly. You can think of a muon essentially as a heavier cousin of the electron.

Okay.

It has the same negative electrical charge, but it is about 200 times more massive.

So why does being heavy make it useful for looking inside things?

It's all about its sheer momentum. Normal electrons get stopped very easily by solid matter. You know, they bump into the atoms of a wall and just get absorbed or deflected.

They can't get through.

But a muon, because it is 200 times heavier and traveling near the speed of light, it acts like a heavy bowling ball rolling through a field of pins.

It just plows straight through.

It plows straight through. It can penetrate hundreds of meters of solid rock before finally losing its energy.

So it's essentially acting like a giant naturally occurring X-ray.

Exactly. So geologists will place these muon detectors around the base of an active volcano.

Oh, wow.

Yeah. And because the muons are constantly falling from the sky, they pass straight through the mountain.

And then hit the detectors on the other side. Right.

So by measuring how many muons make it through to the detectors, geologists can map the internal density of the volcano.

Because solid rock absorbs more muons, but an empty liquid magma chamber lets more muons pass through.

Exactly.

And archaeologists have done the exact same thing with the Egyptian pyramids.

They have. By placing muon detectors inside the lower known chambers of the Great Pyramid of Giza, they just looked upward.

Just waited for the cosmic rain. Yep.

They mapped the dense stone blocks and a few years ago actually discovered a previously unknown massive hidden void deep inside the pyramid.

Just by analyzing the variations in this cosmic muon rain.

Just from the rain.

That's incredible. But, okay, if these cosmic rays are so useful, right, and we understand enough about them to date, fossils, and x-ray pyramids, why are scientists still so obsessed with studying their origins? I mean, it feels like we have a pretty good handle on them.

Well, we have a good handle on the secondary particles.

The rain that reaches the ground. Exactly.

The real mystery lies in the initial impact. The primary cosmic rays themselves.

The ones hitting the top of the atmosphere.

Right. The highest energy cosmic rays carry more kinetic energy than a baseball thrown by a major league pitcher.

Wait. entirely contained within a single subatomic particle.

Yes, a single particle. And we still don't fully understand the exact mechanics of how the universe accelerates particles to those extremes or exactly what those primary particles are even composed of at the very highest energies.

So how do we even try to answer that?

Traditionally, we look up. We use these enormous observatories like the Telescope Array Project in the high desert of Utah.

Oh, in Utah. Yeah.

Yeah.

It is a massive network of over 500 specialized surface detectors spread across hundreds of square miles of empty land.

That's huge.

It is.

And they are paired with fluorescence detectors, which are essentially specialized cameras that look at the night sky.

What are they looking for? Like a flash of light? Yes.

When a high-energy particle slams into the atmosphere, the resulting shower of particles excites the nitrogen gas in the air.

Okay.

And that causes it to emit this very faint blue ultraviolet glow.

Like a spark in the sky.

Exactly. It's incredibly faint, lasting only a few billionths of a second. But the cameras out in Utah act together as one giant telescope to catch those faint flashes, tracing the path of the shower as it moves through the atmosphere.

I mean, that sounds like an incredible engineering feat, but there has to be a catch.

There is.

If we have hundreds of square miles of sensors looking at the sky, why is there still a mystery?

Because there is a critical, unavoidable flaw in this traditional method. Even with the best cameras in the world, we cannot see the exact moment the initial particle hits the very top of the atmosphere.

Oh, because it's too high up.

The air is simply too thin up there to produce enough light for us to see. We only catch the cascade, the resulting shower of particles, after it has already started spreading out and descending.

So we are seeing the aftermath of the subatomic car crash. But not the crash itself.

Precisely. We only see the debris. So to actually understand the birth of the storm.

To decode what that initial primary particle was.

Exactly. Scientists have to rely on complex computer models. They feed the debris data into a simulation. And the computer works backward to estimate the mass and energy of the original particle.

But wait, if we can't actually see the initial impact and we're completely relying on simulations to tell us what happened. Mm-hmm. Aren't scientists kind of just guessing at this point?

Wow.

Like, why should we trust these computer models?

And that is the exact problem the physics community has been wrestling with for years. You see, the different computer models wildly disagree with each other.

Wildly. But why do they disagree? Shouldn't physics, math just be, you know, universal?

The math is universal, but our understanding of the forces involved at those specific extreme energies is incomplete. When particles collide at near light speed... They interact primarily through the strong nuclear force, which is the force that binds the nucleus of an atom together.

Okay, sure.

Down here on Earth, we understand how the strong force behaves at lower energies. But these cosmic rays hit with energies far beyond what we typically observe.

So the models are basically taking our low energy knowledge and trying to extrapolate it out to high energy extremes.

Exactly. And different physicists make different theoretical assumptions about how particles will behave in those extreme conditions, which leads to divergent models.

So like one model might say a shower was caused by a heavy iron nucleus. And another model looking at the exact same data might say it was caused by a lighter hydrogen proton.

That's exactly what happens. And if you don't know whether you are looking at hydrogen or iron, you can't trace the particle back to its origin.

Because iron suggests one type of cosmic event. And hydrogen suggests another.

Right. It creates this massive bottleneck in high-energy astrophysics.

So what do you do? If the models disagree, and we obviously can't physically strap a microscope to the very edge of Earth's atmosphere to watch the collision happen live, how do we break the tie?

In physics, when observation and simulation hit a wall, you turn to experimentation.

Okay.

If you cannot go up to the edge of the atmosphere to study the cosmic rainstorm up close... you have to figure out a way to build that exact rainstorm down here on Earth.

Which means we need a particle accelerator.

Yes.

And specifically, the Large Hadron Collider at CERN in Switzerland.

Correct. In July of 2025, physicists pulled off a truly groundbreaking experiment at CERN.

Okay, walk me through this.

Researchers like Jesse Liu and Lydia Beresford successfully advocated to take the world's most powerful particle accelerator and temporarily reconfigure it to simulate cosmic rays.

Wait, how does that work? I know the Large Hadron Collider usually smashes protons into other protons to look for things like the Higgs boson.

Right.

How do you reconfigure it to make a sky in a tube?

By changing the ingredients of the collision.

Okay.

To recreate a cosmic ray hitting the atmosphere, you need a proxy for the cosmic ray and a proxy for the atmosphere.

So it's a casting call for the universe. What do they use?

The proton beam plays the role of the cosmic ray shooting in from deep space.

Naturally.

But for the atmosphere, they needed something different. Our atmosphere is largely composed of nitrogen and oxygen. Right. So the Sohn scientists introduced a beam of oxygen atoms into the accelerator.

Hold on. How do you accelerate an oxygen atom to the speed of light? It's a gas. You can't just pump air into a vacuum tube and push it, right?

No, you definitely can't. It requires an incredibly complex pre-acceleration process. All right. You start with oxygen gas, but you have to strip away all of the electrons orbiting the oxygen atoms using intense electric fields.

Leaving just the nucleus. Yes.

Naked, positively charged oxygen nuclei.

Ah, and because they now have a strong electrical charge.

You can use the massive, superconducting magnetic fields of the Large Hadron Collider to grip those nuclei and push them faster and faster around the 27-kilometer underground ring.

That is wild. So you have a beam of protons going one way and a beam of stripped oxygen nuclei going the other way, both approaching the speed of light.

Exactly. And for the very first time in a laboratory setting, scientists steered those two beams to cross and collide.

And what happened?

When the protons smashed into the oxygen nucleus, the immense kinetic energy of the impact instantly converted into a brilliant spray of entirely new particles.

Just like in the atmosphere.

Yes. They flawlessly recreated the exact mechanics of the very first milliseconds of a cosmic rainstorm.

That is just staggering. They literally bottled the violent energy of a black hole inside a tunnel under the Swiss-French border.

It's a profound achievement.

But, okay, even if you successfully smash them together, this microscopic explosion is happening in a fraction of a second. How do you actually record and measure something that fast and that small?

That is where the ATLAS experiment comes in.

ATLAS? Yes.

ATLA is one of the massive particle detectors built around a collision point on the Large Hadron Collider ring. It is an instrument the size of a literal football field, buried roughly 100 meters underground.

Wait, how does something the size of a football field capture a subatomic particle?

It uses layers upon layers of highly specialized technology arranged in concentric cylinders around the collision point.

Like an onion?

Yeah, like a giant high-tech onion. But at its core, closest to where the impact happens... It uses a massive array of silicon pixel sensors.

Silicon sensors. Wait, is that basically the same technology that's in a smartphone camera?

Conceptually, yes.

Really?

Yeah. In your phone's camera, a photon of light hits a silicon pixel, knocks an electron loose, and creates a tiny electrical signal that the phone registers as a piece of the image.

Okay.

The inner tracker of the ATLA's detector works on a very similar principle, just scaled up to an incomprehensible degree of complexity and speed. When the subatomic particles fly outward from the proton-oxygen collision, they pass through these silicon wafers. And as a charged particle pushes through the silicon, it knocks electrons loose, creating a tiny electrical hit.

So as a particle travels outward through the concentric layers, it's basically leaving a connect-the-dots trail of electrical signals.

Precisely. By connecting those dots, scientists can map the exact trajectory of the particle.

That's amazing.

Furthermore, because the entire detector is based in a massive magnetic field, the path of the particle curves.

Oh, because of the charge. Right.

And by measuring exactly how much it curves, scientists can calculate the particle's momentum and precisely identify what kind of particle it is.

And ATLAs isn't just doing this once or twice. I mean, when the collider is running, it's capturing an unbelievable amount of data. I saw that the high-speed camera setup at the heart of ATLAs can take more than 200 million photos or, you know, collision events instantly. In a single day.

Yes. The data generation is so immense that they actually have to use supercomputers to filter out the noise in real time, only saving the most significant collisions.

200 million. That's insane.

But the sheer volume of data is exactly what we needed to solve the mystery.

So that brings us to the ultimate payoff. Yes. We built a football field-sized camera. We spent millions to accelerate naked oxygen atoms to the speed of light. And we took billions of pictures of this tiny artificial sky. What did we actually learn? Like, did it solve the argument between the computer models?

It did something better than just settle an argument. It provided hard empirical truth. The results of this proton oxygen run were recently published in physical review letters, and they represent a massive leap forward for particle physics.

How so?

By analyzing the images, the physicists were able to count exactly how many particles were created in these specific collisions, and they measured the precise energies at which those particles flew outward.

And how did that compare to what the computer models were guessing before?

Well, because they were observing this directly in a controlled lab, rather than trying to infer it from faint flashes in the Utah night sky, they measured the properties of these interactions with more than 10 times the precision of the old computer models.

10 times the precision? Yes. That's not just a minor tweak. That's like taking off a blindfold.

It is entirely transformative. This high precision data from CERN acts as a Rosetta Stone for astrophysicists. We now have a ground truth measurement of exactly how a proton interacts with an oxygen atom at these extreme energies.

So scientists can now take this ground truth math from Switzerland and plug it directly into the computer models they use for the telescope array out in Utah.

Exactly. By updating the models with this empirical data, the disagreements between the simulations will just evaporate.

Wow.

We will finally be able to look at the secondary particle showers hitting the ground and pinpoint with high confidence whether the primary cosmic ray that started it all was a light hydrogen proton or a heavy atomic nucleus.

Which ultimately tells us where they came from.

Yes. It officially bridges a major historical gap.

Between the microscopic and the cosmic.

Exactly. It renews the link between particle physics, the study of the incredibly small and high energy astrophysics, the study of the incredibly massive, Right. By understanding the exact composition of these cosmic rays, we are drawing a new map to track down the most extreme violent events in the universe, tracing the subatomic debris all the way back to the black holes and exploding stars that fired them at us.

It is profound to think that by bringing the cosmos down into a laboratory and smashing it apart, we are quite literally reconstructing the origins of the universe using its fundamental building blocks.

It's human curiosity at its absolute best.

It really is. But as we wrap this up, there is one final thought that keeps lingering in my mind.

What's that?

Well, we established right at the start of our conversation that these particles are passing through your body right now, every single second.

Raining down constantly.

And we know that they carry the chaotic high-speed energy of exploding stars. We know they are heavy and fast enough to be used to map dense, solid rock inside active volcanoes. And we know they can penetrate the heavy stone of ancient pyramids.

Oh, I see where you're going with this.

Knowing all of that, knowing that this relentless cosmic rainstorm is shooting right through our biology, right through our very cells every day of our lives, it makes you wonder.

It does.

What tiny unseen impacts are these relentless cosmic rainstorms having on the human body over the course of a lifetime?

That's a fascinating question.

Right.

Could these subatomic collisions be driving subtle genetic mutations? Are they a hidden variable in the long, slow march of human evolution itself?

It's very possible.

It is definitely something to ponder the next time you step outside, feel the sun on your face, and look up at a seemingly empty sky.

CERN Recreates Cosmic Particle Storms Inside the Large Hadron Collider

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