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Scientists Hunt for Microscopic Black Holes at the LHC · The Quark Side - Quantum Physics Podcast

• 0:01
  Speaker 1: Welcome to the Quarkside Quantum Physics Podcast, an exploration of
• 0:05
  Speaker 1: the fundamental structure of reality, where quantum laws govern matter, energy,
• 0:11
  Speaker 1: and information. Here, uncertainty is a feature, not a flaw,
• 0:16
  Speaker 1: and understanding begins at the smallest scales.
• 0:27
  Speaker 2: You know, usually when, uh, particle physics comes up in conversation,
• 0:33
  Speaker 2: it feels just incredibly abstract.
• 0:35
  Speaker 3: Oh, absolutely.
• 0:36
  Speaker 2: Yeah. Like it's all invisible fields and, you know, subatomic math,
• 0:40
  Speaker 2: theoretical particles that really don't seem to touch our day-to-day
• 0:43
  Speaker 2: lives at all. Right.
• 0:43
  Speaker 3: It feels very detached from reality.
• 0:46
  Speaker 2: Exactly. But then you look at the actual physical experiments
• 0:49
  Speaker 2: happening right now, like at the Large Hadron Collider, and
• 0:54
  Speaker 2: the reality sounds straight out of a Well, a sci-fi blockbuster.
• 0:58
  Speaker 3: It really does.
• 0:58
  Speaker 2: We're talking about scientists intentionally trying to create black holes
• 1:02
  Speaker 2: right here on Earth.
• 1:02
  Speaker 3: Yeah, and phrasing it like that definitely captures people's attention
• 1:06
  Speaker 3: and usually spikes their anxiety pretty significantly.
• 1:10
  Speaker 2: I mean, I can imagine. Which makes it the perfect
• 1:12
  Speaker 2: place to start. So our mission today is to figure
• 1:15
  Speaker 2: out the reality behind that crazy science fiction concept.
• 1:19
  Speaker 3: It's a fun one.
• 1:20
  Speaker 2: We are going to explore exactly how physicists are actively
• 1:24
  Speaker 2: hunting for for these microscopic quantum black holes, why they
• 1:28
  Speaker 2: are so determined to create them in the first place.
• 1:30
  Speaker 2: And here's the real twist for you, how discovering absolutely
• 1:33
  Speaker 2: nothing at all in these experiments is actually a massive
• 1:37
  Speaker 2: scientific breakthrough.
• 1:39
  Speaker 3: Yeah, that's the part that really throws people.
• 1:41
  Speaker 1: Right.
• 1:41
  Speaker 2: So by the time we wrap this up, you're going
• 1:43
  Speaker 2: to have a completely new perspective on how science actually progresses.
• 1:46
  Speaker 2: You'll see how systematically ruling things out is just as
• 1:50
  Speaker 2: powerful as a sudden eureka moment.
• 1:52
  Speaker 3: It's a profound shift in how we think about discovery, really.
• 1:56
  Speaker 3: I mean, in the popular imagination, we always expect the
• 1:59
  Speaker 3: dramatic finding.
• 2:00
  Speaker 2: The big headline.
• 2:01
  Speaker 3: Exactly. The new particle, the literal spark. But the absence
• 2:04
  Speaker 3: of a spark, it can fundamentally rewrite our understanding of reality,
• 2:10
  Speaker 3: forcing us to rethink the universe from the ground up.
• 2:12
  Speaker 2: Well, before we get into the mechanics of how scientists
• 2:14
  Speaker 2: are actually looking for these black holes, we really have
• 2:17
  Speaker 2: to address the giant, terrifying elephant in the room. Yes. Safety.
• 2:21
  Speaker 3: Yeah.
• 2:22
  Speaker 2: Because if I go tell my neighbor, hey, physicists are
• 2:25
  Speaker 2: building a circular track to compress energy and make a
• 2:27
  Speaker 2: black hole. The immediate logical response is, don't we all die? Right.
• 2:34
  Speaker 3: Right.
• 2:34
  Speaker 2: Want to just swallow the earth? Because of a classical
• 2:37
  Speaker 2: black hole is essentially this like cosmic vacuum cleaners, swallowing
• 2:41
  Speaker 2: stars and light and everything around it. What on earth
• 2:44
  Speaker 2: is a quantum black hole?
• 2:46
  Speaker 3: Yeah, it's a bit of a public relations nightmare, honestly.
• 2:48
  Speaker 2: I bet.
• 2:49
  Speaker 3: But it's born out of a fundamental misunderstanding of the
• 2:52
  Speaker 3: physics involved. So physicist Stephen Giddey laid out the framework
• 2:56
  Speaker 3: for this distinction decades ago. He explained that to make
• 2:59
  Speaker 3: a black hole, any black hole, you essentially just need
• 3:02
  Speaker 3: to compress a certain amount of energy into a phenomenally
• 3:05
  Speaker 3: small volume. But the black holes they're theorizing at the
• 3:09
  Speaker 3: Large Hadron Collider, or the LHC, they're quantum black holes.
• 3:13
  Speaker 2: But they're different.
• 3:13
  Speaker 3: Very different. They're born from proton collisions and they are
• 3:16
  Speaker 3: so infinitesimally tiny that they just do not behave like
• 3:20
  Speaker 3: those cosmic vacuum cleaners you find at the center of
• 3:23
  Speaker 3: a galaxy. Right.
• 3:24
  Speaker 2: So I imagine they don't have the gravitational pull to
• 3:26
  Speaker 2: start sucking in the laboratory furniture or anything.
• 3:28
  Speaker 3: Thankfully, no.
• 3:30
  Speaker 2: But infinitesimally tiny doesn't sound entirely harmless either. I mean,
• 3:35
  Speaker 2: a virus is tiny and it could do a whole
• 3:37
  Speaker 2: lot of damage.
• 3:38
  Speaker 3: Sure. But the key difference here is their lifespan. If
• 3:41
  Speaker 3: an accelerator manages to make a quantum black hole, it
• 3:45
  Speaker 3: disintegrates the very instant it's created.
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  Speaker 2: Like instantly, instantly.
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  Speaker 3: Instantly. It evaporates in a flash of particles before it
• 3:52
  Speaker 3: can consume any surrounding matter or grow at all. It's
• 3:55
  Speaker 3: just a fleeting instantaneous blip that's gone before it even
• 3:59
  Speaker 3: truly registers.
• 4:00
  Speaker 2: Okay, so it evaporates instantly. But I can already hear
• 4:02
  Speaker 2: people saying, well, what if the math is wrong?
• 4:05
  Speaker 3: Naturally.
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  Speaker 2: Like what if it doesn't evaporate? We're talking about unprecedented
• 4:08
  Speaker 2: energies here.
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  Speaker 3: Mm-hmm.
• 4:10
  Speaker 2: I would hope physicists didn't just, you know, do some
• 4:12
  Speaker 2: math on a chalkboard and decide to whisk the entire
• 4:15
  Speaker 2: planet out of theory.
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  Speaker 3: They most certainly did not. The safety of the LHC
• 4:19
  Speaker 3: was definitively proven by looking at high energy phenomena that
• 4:22
  Speaker 3: have been happening since the universe began. Every single day,
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  Speaker 3: our upper atmosphere is bombarded by ultra high energy cosmic rays.
• 4:31
  Speaker 3: These are shot out from supernovas and active galaxies.
• 4:34
  Speaker 2: Oh, wow.
• 4:34
  Speaker 3: Yeah. And they hit the Earth's atmosphere with energies far,
• 4:38
  Speaker 3: far greater than anything the LHC could ever dream of producing.
• 4:42
  Speaker 2: So basically nature has been running this exact same high
• 4:45
  Speaker 2: energy collision experiment on our atmosphere for billions of years.
• 4:50
  Speaker 3: Exactly. And the atmosphere hasn't been swallowed by a black
• 4:53
  Speaker 3: hole yet.
• 4:53
  Speaker 2: Fair point.
• 4:54
  Speaker 1: Right.
• 4:55
  Speaker 3: Any quantum black holes created by these natural collisions evaporate
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  Speaker 3: instantly and And the exact same physical laws apply inside
• 5:01
  Speaker 3: the artificial environment of the accelerator.
• 5:04
  Speaker 2: Okay, so the safety check is cleared. The universe itself
• 5:06
  Speaker 2: is basically our proof of concept here.
• 5:08
  Speaker 3: Exactly.
• 5:09
  Speaker 2: But that brings up an even more confusing point, I think.
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  Speaker 2: If these quantum black holes literally blip out of existence
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  Speaker 2: the exact millisecond they're created, and we can't even keep
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  Speaker 2: them in a jar on a desk to study them,
• 5:22
  Speaker 2: what is the point?
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  Speaker 3: Why bother?
• 5:24
  Speaker 2: Yeah. Why are physicists so obsessed with making them?
• 5:27
  Speaker 3: Because creating one could solve one of the most agonizing
• 5:30
  Speaker 3: mysteries in all of physics. It revolves around something called
• 5:34
  Speaker 3: the hierarchy problem.
• 5:35
  Speaker 2: The hierarchy problem. Okay, I've heard physicists complain about this before.
• 5:39
  Speaker 2: Is that basically their frustration over the fact that a
• 5:43
  Speaker 2: tiny fridge magnet can overpower the gravitational pull of the
• 5:47
  Speaker 2: entire Earth.
• 5:48
  Speaker 3: Yes, exactly.
• 5:49
  Speaker 2: Because the Earth is huge, but a little piece of
• 5:51
  Speaker 2: metal on my fridge... easily defies it just to hold
• 5:54
  Speaker 2: up a piece of paper. It seems wrong.
• 5:56
  Speaker 3: That is a brilliant illustration of the core issue. Gravity
• 6:00
  Speaker 3: is unbelievably weak compared to the universe's other fundamental forces,
• 6:05
  Speaker 3: like electromagnetism, which is what the magnet uses. Right. So
• 6:09
  Speaker 3: the hierarchy problem specifically asks why there is such a
• 6:12
  Speaker 3: massive gap between the energy scale of everything we see
• 6:15
  Speaker 3: and interact with and the fundamental energy scale of the universe,
• 6:18
  Speaker 3: which is known as the Planck scale.
• 6:20
  Speaker 2: Let's pause on the Planck scale for a second. If
• 6:22
  Speaker 2: we think about energy scales, a AA battery is low energy,
• 6:26
  Speaker 2: a lightning bolt is high energy. Where does the Planck
• 6:29
  Speaker 2: scale fit into that spectrum?
• 6:31
  Speaker 3: I assume it's at the very top.
• 6:32
  Speaker 2: Yeah, it has to be, right?
• 6:33
  Speaker 1: It is.
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  Speaker 3: Think of the Planck scale as the universe's ultimate maximum limit.
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  Speaker 2: Okay.
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  Speaker 3: It is the point where energy is so densely packed
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  Speaker 3: that the laws of physics, as we currently know them,
• 6:44
  Speaker 3: just completely break down.
• 6:45
  Speaker 2: Wow.
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  Speaker 3: The math literally stops working. So the enduring mystery is
• 6:50
  Speaker 3: why the everyday forces we experience operate at such incredibly
• 6:54
  Speaker 3: low energies compared to that ultimate maximum Planck scale.
• 6:58
  Speaker 2: So going back to my fridge magnet, gravity just seems
• 7:01
  Speaker 2: ridiculously weak. I want to try an analogy here to
• 7:03
  Speaker 2: see if I'm grasping this.
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  Speaker 3: Go for it.
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  Speaker 2: It's like hearing a massive booming rock concert from 10
• 7:08
  Speaker 2: miles away. Okay. To us, standing in our living room,
• 7:12
  Speaker 2: the music sounds really quiet, barely a whisper. But the
• 7:16
  Speaker 2: concert itself is actually deafening. What if gravity isn't actually weak,
• 7:20
  Speaker 2: we just aren't standing in the right dimension to hear
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  Speaker 2: how loud the universe really is?
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  Speaker 3: That captures the theoretical framework beautifully. That's exactly it. The
• 7:28
  Speaker 3: leading idea is that gravity is not weak at all.
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  Speaker 3: It might be incredibly strong, but it's leaking into undiscovered
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  Speaker 3: extraspatial dimensions.
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  Speaker 2: Extra dimensions, like beyond the 3D space we walk around
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  Speaker 2: in plus time.
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  Speaker 1: Yes.
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  Speaker 3: String theory requires these extraspatial dimensions to exist in order
• 7:45
  Speaker 3: for its complex math to balance out.
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  Speaker 2: Right.
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  Speaker 3: Often, string theory assumes a totality of 10 dimensions. Now,
• 7:52
  Speaker 3: it can be hard to visualize, but think of a
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  Speaker 3: telephone wire stretched between two poles.
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  Speaker 2: Okay, I'm picturing.
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  Speaker 3: So from far away, it looks like a one-dimensional line.
• 7:59
  Speaker 3: You can only go left or right. Right. But if
• 8:01
  Speaker 3: you are a microscopic ant walking on that wire, you
• 8:05
  Speaker 3: realize it's actually a cylinder. You can walk forwards, backwards,
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  Speaker 3: and loop entirely around it. The extra dimension is curled
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  Speaker 3: up so tightly that you can only experience it if
• 8:15
  Speaker 3: you are small enough.
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  Speaker 2: Oh, that makes sense. So we don't notice these extra
• 8:18
  Speaker 2: dimensions because we are way too big, just like someone
• 8:21
  Speaker 2: staring at the telephone wire from a mile away. Yeah.
• 8:24
  Speaker 2: But gravity notices them.
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  Speaker 3: Exactly. As you probe shorter and shorter distances, gravity gets stronger.
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  Speaker 3: If gravity is leaking into those curled up extra dimensions,
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  Speaker 3: its effect grows dramatically stronger at those incredibly microscopic scales.
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  Speaker 3: It implies that the massive Planck scale could actually be
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  Speaker 3: much closer to our everyday energy scale than we realize,
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  Speaker 3: just hidden away in the microscopic geometry of the universe.
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  Speaker 2: And this is where the Large Hadron Collider comes back
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  Speaker 2: into the picture. Because the LHC is basically a giant microscope.
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  Speaker 3: Precisely.
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  Speaker 2: If we want to look at those tiny distances, we
• 8:57
  Speaker 2: need to smash things together incredibly hard.
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  Speaker 3: Yeah. Physics professor Joe Incandela, who guides a lot of
• 9:03
  Speaker 3: this research, he points out a fundamental rule of particle physics.
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  Speaker 3: Higher energies means smaller wavelengths.
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  Speaker 2: Okay.
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  Speaker 3: And smaller wavelengths allow you to probe smaller and smaller distances.
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  Speaker 3: The LHC is colliding particles at such extreme energies that
• 9:18
  Speaker 3: they're probing distances down to 10 to the power of
• 9:21
  Speaker 3: negative 20 meters.
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  Speaker 2: 10 to the negative 20. That number is so small
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  Speaker 2: it almost loses all meaning. Is there any way to
• 9:27
  Speaker 2: even visualize a space that incredibly tiny?
• 9:29
  Speaker 3: To put it in perspective, that distance is to a
• 9:32
  Speaker 3: single atom what a single atom is to a human being.
• 9:34
  Speaker 2: Oh man, my brain hurts. But that does put it
• 9:37
  Speaker 2: in perspective. So we're taking an enormous amount of high
• 9:40
  Speaker 2: energy mass and packing it into a space... that makes
• 9:43
  Speaker 2: an atom look like a giant. Yes.
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  Speaker 3: And at that infinitesimally small scale, the extra dimensions wouldn't
• 9:50
  Speaker 3: even need to be that tiny for the proton collisions
• 9:54
  Speaker 3: to be affected by them.
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  Speaker 2: Wow.
• 9:56
  Speaker 3: So you combine that incredibly dense energy with the theoretically
• 10:00
  Speaker 3: super strong concentrated gravity in that tiny environment.
• 10:04
  Speaker 2: And boom, space-time folds in on itself and a quantum
• 10:07
  Speaker 2: black hole is born.
• 10:08
  Speaker 3: Exactly.
• 10:09
  Speaker 2: Which means we would finally find the bridge between classical physics,
• 10:12
  Speaker 2: the heavy stuff governed by gravity and relativity, and the
• 10:15
  Speaker 2: tiny stuff governed by quantum mechanics.
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  Speaker 3: And unifying those two domains has been the ultimate goal
• 10:20
  Speaker 3: of physicists for over a century. Quantum mechanics currently relies
• 10:24
  Speaker 3: on the standard model, which you can think of as
• 10:26
  Speaker 3: the ultimate instruction manual for all known subatomic particles.
• 10:30
  Speaker 2: Right, but the standard model notoriously leaves out gravity entirely.
• 10:34
  Speaker 3: It does. Creating a quantum black hole would finally force
• 10:37
  Speaker 3: gravity and quantum mechanics onto the same stage, proving they
• 10:40
  Speaker 3: can interact.
• 10:41
  Speaker 2: The stakes are unbelievably high. We're talking about unifying the
• 10:45
  Speaker 2: fundamental forces of nature so we know why we want
• 10:47
  Speaker 2: to find them. But here's the logistical nightmare. How do
• 10:51
  Speaker 2: you actually hunt for something invisible that evaporates the exact
• 10:55
  Speaker 2: millisecond it's born?
• 10:56
  Speaker 3: It's very difficult.
• 10:58
  Speaker 2: It's like trying to investigate a massive fireworks display that
• 11:00
  Speaker 2: you didn't actually get to see. And your only option
• 11:03
  Speaker 2: is to try and map out exactly where every single
• 11:06
  Speaker 2: spark landed on the ground afterward to prove the firework
• 11:10
  Speaker 2: ever existed.
• 11:10
  Speaker 3: That's a great way to look at it. Since you
• 11:12
  Speaker 3: cannot see the black hole itself, you have to detect
• 11:15
  Speaker 3: those exact sparks, its decay products. When that quantum black
• 11:18
  Speaker 3: hole disintegrates, it shatters into a burst of particles. Researchers
• 11:23
  Speaker 3: like Tomas Vami and Denny Zhang, working with data from
• 11:26
  Speaker 3: the CMS detector, have been analyzing trillions of collisions recorded
• 11:30
  Speaker 3: between 2016 and 2018 to find that specific burst pattern.
• 11:34
  Speaker 2: I would imagine a black hole's firework burst looks pretty
• 11:37
  Speaker 2: unique compared to a standard particle collision. How do they
• 11:39
  Speaker 2: separate it out from all the noise?
• 11:40
  Speaker 3: Traditionally, physicists look for two specific markers. The first is sphericity.
• 11:45
  Speaker 2: Sphericity. OK. Yeah.
• 11:47
  Speaker 3: When a quantum black hole disintegrates, it creates a highly
• 11:50
  Speaker 3: spherical decay signature. The particles explode outward equally in absolutely
• 11:55
  Speaker 3: all directions rather than spraying in a single cone or
• 11:58
  Speaker 3: a straight line.
• 11:58
  Speaker 2: Which is what standard particle collisions often do, right? They
• 12:01
  Speaker 2: spray in a line. So we're looking for a perfect
• 12:04
  Speaker 2: 3D sphere of debris. And the second marker is... It
• 12:09
  Speaker 2: has to be heat or energy, right?
• 12:10
  Speaker 3: High energy.
• 12:11
  Speaker 1: Yeah.
• 12:11
  Speaker 3: The researchers take all the particles resulting from the collision
• 12:14
  Speaker 3: and sum their energies together.
• 12:15
  Speaker 2: Just add them all up. Right.
• 12:17
  Speaker 3: If the total sum of that energy is extremely large
• 12:21
  Speaker 3: and the physical shape of the debris is highly spherical,
• 12:24
  Speaker 3: you are looking at a region where a black hole
• 12:26
  Speaker 3: signal is very likely.
• 12:28
  Speaker 2: But digging through trillions of proton collisions looking for spherical
• 12:32
  Speaker 2: high energy bursts... That sounds like an impossible computing task.
• 12:36
  Speaker 2: It's way worse than a needle in a haystack.
• 12:38
  Speaker 3: It is a monumental challenge. I mean, the complexity of
• 12:41
  Speaker 3: it led particle theorist Nathaniel Craig and his collaborators to
• 12:45
  Speaker 3: develop a revolutionary new method. They call it the phase-space
• 12:49
  Speaker 3: distance method.
• 12:50
  Speaker 2: Phase-space. It sounds like a sci-fi work drive. What does
• 12:53
  Speaker 2: phase-space actually mean in this context?
• 12:56
  Speaker 3: Phase-space is a mathematical multidimensional map. It doesn't just plot
• 13:00
  Speaker 3: the physical location of a particle in three dimensions.
• 13:03
  Speaker 2: Okay, what else does it include?
• 13:04
  Speaker 3: It incorporates every dimension of space and time, plus the
• 13:07
  Speaker 3: energy and the momentum of an entire system of particles,
• 13:10
  Speaker 3: all into a single, highly complex mathematical point.
• 13:14
  Speaker 2: Wow. So it's not just mapping where the sparks landed
• 13:17
  Speaker 2: on the ground. It's mapping the weight of the sparks,
• 13:20
  Speaker 2: how fast they were falling, the trajectory they took, and
• 13:22
  Speaker 2: exactly when they hit the ground, all combined into one
• 13:25
  Speaker 2: giant equation.
• 13:26
  Speaker 3: Yes. They then take this vast phase space data and
• 13:29
  Speaker 3: feed it into a machine learning tool called a support
• 13:32
  Speaker 3: vector machine or an SVM.
• 13:34
  Speaker 2: I want to guess how this SVM works.
• 13:36
  Speaker 3: Sure, try it.
• 13:37
  Speaker 2: If they have all this complex data, is the vector
• 13:40
  Speaker 2: machine basically drawing a literal line on a graph to
• 13:43
  Speaker 2: separate the normal boring collisions on one side from the
• 13:46
  Speaker 2: weird black hole looking ones on the other?
• 13:48
  Speaker 3: That is a highly accurate way to picture it, actually.
• 13:51
  Speaker 3: In a simple 2D graph, you draw a line. But
• 13:54
  Speaker 3: in face space, which has many dimensions, the SVM calculates
• 13:58
  Speaker 3: a complex multidimensional boundary called a hyperplane.
• 14:01
  Speaker 2: A hyperplane.
• 14:02
  Speaker 3: It analyzes the distances between all these events and converts
• 14:05
  Speaker 3: them into a single variable, an SVM score.
• 14:09
  Speaker 2: So like a grading system.
• 14:10
  Speaker 3: Basically. The larger the score, the further the event is
• 14:14
  Speaker 3: across that boundary line, making it significantly more likely to
• 14:17
  Speaker 3: be a true signal of a black hole rather than
• 14:20
  Speaker 3: just background noise.
• 14:21
  Speaker 2: You know, whenever I hear machine learning or AI, my
• 14:24
  Speaker 2: mind immediately goes to the kind of software where you
• 14:26
  Speaker 2: feed data into a black box. It spits out an
• 14:29
  Speaker 2: answer and nobody, not even the programmers, actually knows how
• 14:33
  Speaker 2: the computer figured it out. Right. Is that what they're
• 14:35
  Speaker 2: doing here?
• 14:36
  Speaker 3: No. And that is a crucial distinction. The support vector
• 14:39
  Speaker 3: machine they use is a supervised machine learning tool. It
• 14:42
  Speaker 3: is not a black box. The researchers can look under
• 14:44
  Speaker 3: the hood at the underlying math and see the exact
• 14:47
  Speaker 3: criteria the algorithm is using to draw that boundary line.
• 14:50
  Speaker 3: It's fully transparent. And honestly, this project was the very
• 14:54
  Speaker 3: first time this specific method was applied to particle physics
• 14:58
  Speaker 3: data analysis.
• 14:59
  Speaker 2: That's awesome. Did this transparent AI beat the old way
• 15:02
  Speaker 2: of just looking for spherical energy?
• 15:04
  Speaker 3: Oh, absolutely. The phase-space distance method heavily outperformed the traditional
• 15:09
  Speaker 3: sphericity variable. It proved to be a highly sensitive, incredibly
• 15:12
  Speaker 3: precise tool for sifting through all that noise.
• 15:15
  Speaker 2: Okay, so the stage is completely set. We have the
• 15:17
  Speaker 2: LHC generating unimaginable energies. We have trillions of collisions. We
• 15:22
  Speaker 2: have extra dimensions theoretically amplifying gravity. And now we have
• 15:26
  Speaker 2: this cutting-edge transparent AI perfectly tuned to spot the exact
• 15:30
  Speaker 2: decay signature of a quantum black hole.
• 15:33
  Speaker 3: So what did they actually find when they read the numbers?
• 15:35
  Speaker 2: They found nothing.
• 15:36
  Speaker 3: Wait, nothing?
• 15:37
  Speaker 2: Nothing. Up to about 12 teraelectron volts, or TV, they
• 15:40
  Speaker 2: found absolutely no telltale signs of quantum black hole production.
• 15:44
  Speaker 3: Let's put 12 TV in perspective for a second. How
• 15:46
  Speaker 3: much energy is that? One TV is roughly the kinetic
• 15:49
  Speaker 3: energy of a single flying mosquito.
• 15:52
  Speaker 2: A mosquito. That does not sound like much energy at all.
• 15:55
  Speaker 3: It doesn't until you remember that they are compressing that
• 15:58
  Speaker 3: mosquito's energy into into a space a trillion times smaller
• 16:01
  Speaker 3: than a single grain of sand.
• 16:03
  Speaker 2: Oh, right.
• 16:04
  Speaker 3: The energy density is mind-boggling. But even up to 12
• 16:08
  Speaker 3: TV of that massively compressed energy, they saw no black holes.
• 16:12
  Speaker 2: I have to ask the exact question you're probably screaming
• 16:15
  Speaker 2: at your device right now. We just went through all
• 16:17
  Speaker 2: this mind-bending theory about dimensions and gravity. We built the
• 16:21
  Speaker 2: ultimate phase-space AI detector just to get a null result.
• 16:25
  Speaker 3: I know. It sounds disappointing.
• 16:26
  Speaker 2: How on earth is finding nothing a win?
• 16:28
  Speaker 3: The frustration is completely valid, but in fundamental physics, null
• 16:32
  Speaker 3: results are the true drivers of progress. Dania Zhang explained
• 16:35
  Speaker 3: that this result is an exclusion limit.
• 16:37
  Speaker 2: An exclusion limit.
• 16:38
  Speaker 3: Yeah. An exclusion limit is a rigorous, publishable statement. It
• 16:42
  Speaker 3: essentially declares, if this phenomenon existed with these specific properties,
• 16:47
  Speaker 3: our tools are so precise, we definitely would have seen it.
• 16:49
  Speaker 3: We didn't, so we can definitively rule it out right here.
• 16:53
  Speaker 2: So it's not a failure, it's genuine knowledge about how
• 16:55
  Speaker 2: the universe actually works.
• 16:57
  Speaker 3: Exactly.
• 16:57
  Speaker 2: It feels a bit like playing a game of cosmic battleship.
• 17:01
  Speaker 2: Every time you call out a coordinate at 12 TV
• 17:04
  Speaker 2: and get a miss, you get to put a white
• 17:06
  Speaker 2: peg on the board. You haven't found the ship yet,
• 17:09
  Speaker 2: but you have fundamentally shrunk the ocean of where it
• 17:11
  Speaker 2: can legally hide.
• 17:12
  Speaker 3: The battleship analogy is spot on. By placing those white pegs,
• 17:16
  Speaker 3: you are aggressively narrowing down the possibilities. This systematic process
• 17:21
  Speaker 3: of elimination is exactly how the Higgs boson was discovered
• 17:25
  Speaker 3: in 2012.
• 17:25
  Speaker 2: Wait, really? It wasn't just a sudden discovery?
• 17:28
  Speaker 3: No, it was not a sudden lucky guess. It was
• 17:30
  Speaker 3: the result of decades of painstakingly excluding one energy region
• 17:34
  Speaker 3: after another until there was only one coordinate left on
• 17:37
  Speaker 3: the board where it could possibly be.
• 17:38
  Speaker 2: So finding nothing here actually corners the remaining possibilities for
• 17:42
  Speaker 2: everything else. Does this null result affect the theories we
• 17:46
  Speaker 2: talked about earlier, like string theory and its 10 dimensions?
• 17:50
  Speaker 3: It puts very concrete limits on them. Because we didn't
• 17:52
  Speaker 3: see black holes at these energies, it means gravity isn't
• 17:55
  Speaker 3: ramping up as fast as some string theory parameters predicted.
• 17:58
  Speaker 2: Okay, so what does that mean for the dimensions?
• 18:01
  Speaker 3: Based on these measurements, you cannot have more than two
• 18:04
  Speaker 3: extra dimensions at these specific scales. The researchers are literally
• 18:08
  Speaker 3: forcing theoretical models of the universe to shrink their footprint.
• 18:13
  Speaker 2: Wow. We didn't find a black hole, but we forced
• 18:17
  Speaker 2: string theory into a tighter box.
• 18:19
  Speaker 3: We did.
• 18:20
  Speaker 2: And they didn't just use this phase space method to
• 18:22
  Speaker 2: look for black holes either, right? They did a sort
• 18:24
  Speaker 2: of bonus hunt while they were sweeping the data.
• 18:27
  Speaker 3: Yeah, they also used these techniques to look for something
• 18:29
  Speaker 3: called sphalerons.
• 18:31
  Speaker 2: Sphalerons. Let me guess, another subatomic particle that refuses to
• 18:34
  Speaker 2: be found.
• 18:35
  Speaker 3: Actually, they are not particles. They're theoretically unstable configurations of
• 18:40
  Speaker 3: particle fields. They are important because they would produce fairly
• 18:44
  Speaker 3: spherical energy signatures, very similar to a quantum black hole.
• 18:48
  Speaker 2: Okay, so the AI could spot them easily. Right.
• 18:50
  Speaker 3: And if they exist, they could explain another massive mystery,
• 18:53
  Speaker 3: the matter-antimatter asymmetry problem.
• 18:56
  Speaker 2: Oh, the question of why we have matter at all.
• 18:59
  Speaker 2: Because the Big Bang should have created equal amounts of
• 19:01
  Speaker 2: matter and antimatter, and they should have, well, completely annihilated
• 19:05
  Speaker 2: each other.
• 19:06
  Speaker 3: Leaving absolutely nothing but pure energy behind. But matter survived,
• 19:10
  Speaker 3: and we are here.
• 19:12
  Speaker 2: Thankfully.
• 19:12
  Speaker 3: Sphaleron transitions might explain why that imbalance happened. However, just
• 19:17
  Speaker 3: like with the black holes, the researchers found a null
• 19:20
  Speaker 3: result for sphalerons in this data, too.
• 19:22
  Speaker 2: So they put white pegs on those coordinates as well.
• 19:25
  Speaker 2: They set strict limits on those theories, relentlessly shrinking the
• 19:29
  Speaker 2: map of the unknown. You know, this whole process, it
• 19:32
  Speaker 2: feels deeply applicable to all of us, well beyond the
• 19:35
  Speaker 2: realm of high-level physics.
• 19:37
  Speaker 3: How so?
• 19:37
  Speaker 2: In our daily lives, you and I are constantly bombarded
• 19:40
  Speaker 2: by information overload, wild theories and endless claims of what
• 19:44
  Speaker 2: is supposedly true.
• 19:45
  Speaker 3: Oh, absolutely.
• 19:46
  Speaker 2: Finding out what isn't true or what doesn't work is
• 19:48
  Speaker 2: just as valuable as finding the truth. right answer. Knowing
• 19:51
  Speaker 2: how to systematically rule things out, that is practically a
• 19:55
  Speaker 2: superpower for critical thinking.
• 19:57
  Speaker 3: Knowing what is false brings you one step closer to
• 20:00
  Speaker 3: what is true. In physics, when you place enough white
• 20:03
  Speaker 3: pegs on the board and exclude enough possibilities, you are
• 20:06
  Speaker 3: eventually forced into a completely new paradigm.
• 20:09
  Speaker 2: Right.
• 20:09
  Speaker 3: I mean, Einstein's theory of relativity was born out of
• 20:12
  Speaker 3: analogous conundrums, where existing physics could not explain the observations,
• 20:16
  Speaker 3: and expected answers kept turning up null. Null results force
• 20:20
  Speaker 3: us to think differently.
• 20:21
  Speaker 2: Where does this leave the hierarchy problem, then? We still
• 20:24
  Speaker 2: don't know why gravity is so weak. We still haven't
• 20:26
  Speaker 2: found the black holes.
• 20:27
  Speaker 3: The mystery remains entirely intact. But Stephen Giddings points out
• 20:31
  Speaker 3: something incredibly provocative.
• 20:33
  Speaker 2: What's that?
• 20:34
  Speaker 3: He estimated that if there are absolutely no extra dimensions,
• 20:38
  Speaker 3: if the universe is just the three plus one dimensions
• 20:41
  Speaker 3: we experience, it would take particle collisions a million billion
• 20:45
  Speaker 3: times the energy currently produced at the LHC to create
• 20:48
  Speaker 3: even the smallest microgram size black hole.
• 20:51
  Speaker 2: A million billion times. Yeah. That is a leap in
• 20:54
  Speaker 2: energy that almost defies imagination.
• 20:57
  Speaker 3: It is an astronomical hurdle. But experimentalists like Vami and
• 21:01
  Speaker 3: Zhang have pushed the standard model to the extreme with
• 21:04
  Speaker 3: the current data, and the search is not stopping. The
• 21:07
  Speaker 3: LHC is currently shut down to undergo an ambitious set
• 21:11
  Speaker 3: of upgrades.
• 21:11
  Speaker 1: Oh.
• 21:12
  Speaker 3: When it reopens, it will be the High Luminosity Large
• 21:15
  Speaker 3: Hadron Collider, or the HL-LHC.
• 21:19
  Speaker 2: High Luminosity. So they are going to be able to
• 21:20
  Speaker 2: see even deeper into the data.
• 21:22
  Speaker 3: Much deeper. The upgrades will allow researchers to study the
• 21:26
  Speaker 3: fundamental components of matter in unprecedented detail, probing even further
• 21:31
  Speaker 3: into those uncharted regions of phase space. The map is
• 21:34
  Speaker 3: going to keep shrinking.
• 21:35
  Speaker 2: Which leaves you with an incredible thought to chew on.
• 21:38
  Speaker 2: We are hunting for the fundamental nature of reality by
• 21:41
  Speaker 2: systematically proving where it isn't. But what happens when the
• 21:44
  Speaker 2: map of where new physics can hide shrinks all the
• 21:47
  Speaker 2: way down to absolute zero? When we have ruled out
• 21:50
  Speaker 2: every single current theory, every dimension... and every particle field
• 21:53
  Speaker 2: we can currently imagine, what completely unimaginable new paradigm will
• 21:57
  Speaker 2: we be forced to invent next?