Story 2 begins — proton radius puzzle (precision frontier)

1:03:02super high accuracy. >> Yes, extremely high accuracy. >> This is from the Max Plank Institute uh for quantum optics and it was published in Nature. I'm excited for this one. Let's dig in. >> Yeah, we'll start with the standard model. Yes, the standard model of particle physics is the most successful model that we have to date about our universe. Okay. It's the model that the working constituents are the fundamental particles or I should really say the fundamental quantum fields. >> The Higs Bzon comes out of it. The electron, the proton is actually not in the standard model. You have up and down quirks. Those are the constituents of the protons and the neutrons.

1:03:43>> And it's incredible. [snorts] >> It is incredible, but it is incomplete. There's no dark matter. There's [clears throat] no dark energy >> and there's no gravity. >> Mhm. So we've always been in the search for new physics. How do we break the standard model so we can find out what is missing and what is the path forward to find out what is missing? >> This is the idea of like unification a grand unified theory. >> Yeah. Yeah. Not just reunification but also these new particles like is dark matter a particle? >> Oh understood. Understood. >> That's like not even has anything to do with unifying with gravity. It's like there's just a whole set of other particles that we don't know anything about. >> Most of the universe we have no idea what it is. >> Yeah. Yeah. Yeah. Exactly. [laughter] So there's got to be a way for us to find

1:04:24out, right? And usually when we think about >> probing that frontier of particle physics, we think about particle accelerators, >> right? >> The most famous one is the one at CERN. The Large Hydron Collider is, you know, tens of kilometers long. They want to build like a giant future collider that's hundreds of kilometers long. They want a lot of money because they want to build these large large colliders. >> Higher energy means we can probe the depths of these particles in these fields. But there's another frontier that physicists talk about when they're

1:05:05looking to test the standard model and that is the precision frontier. >> Okay? >> And it might offer an equally vital search for new physics. What you can do is instead of building giant particle colliders, you build extremely precise experiments in your lab, in a room, in a physics department. And you're able to now measure stuff so precisely that perhaps you can discern between what is known physics and what is new. This particular um photograph is from the Maxplank Institute and I saw this actually um on LinkedIn

1:05:48>> from the author of the study that we're going to talk about Loar Misenbacher. >> Okay. >> He posted this photo of his lab that actually made this measurement of the size of the proton. And what it reminds me of is um a colloquium that I had attended at UCLA when I was a PhD student there. It was a colloquium given by Dave Deile who's now at University of Chicago. He used to be at Yale. >> He was one of these precision physicists um atomic molecular optical physicists. Yep. >> And he was showing you know the lab setup and he was trying to he was trying to measure the dipole moment of the electron effectively how round is the electron. We think the electron is the

1:06:28roundest object in the universe. Okay? But there's a possibility that it's like got a tiny bump on the north pole. >> Okay? >> Right? And the and a not tiny bump on the south pole. So there there might be a little bit of not roundedness >> in the electron. And he wanted to measure that. And what he was showing was um he he showed a photo of his lab and he would >> you know the lab the path of the laser light is you know a few meters things like that. But he would put that as 0.0001 kilometers and he would do a dig at the particle accelerator guys and be like I'm going to put this um in a unit of length that you know these particle

1:07:09accelerator guys can understand. So this is about [laughter] 0.001 km. Um the size of my lens is about 0. And it was just so funny dude because you know it's just like >> he's just like pulling their leg. >> That's quite nice. >> I think I it was so funny. Look, it's okay to take the piss every once in a while. >> Yeah. Yeah. Yeah. He's he was a really funny funny guy. Really great speaker as well. So, what these guys are trying to do at the Maxplank Institute >> when they came out with this landmark nature paper in the February 2026, so just this this month, is try to solve the proton radius puzzle. Okay. There's been a decadel long discrepancy in how

1:07:51big the proton is. >> Right. >> Okay. Right. And this particular paper in nature is trying to put that to rest. Yes. >> Okay. >> Subp part per trillion test >> of the standard model with atomic hydrogen. What a great name. [laughter] >> You know they're testing the standard model. >> Yes. >> With just a normal hydrogen atom. >> Okay. >> Okay. This is out of the Maxplank Institute for Quantum Optics. Yes. >> And the precision is 0.7 parts per trillion. >> That's that's that's pretty that's pretty small. >> Yeah, that's pretty small. And I want to give you a sense of just how small that is and why that's like ridiculous. >> Okay. >> Okay. Um we're going to start with the