Krypton-tagging velocimetry — ionizing atoms as tracers

31:22to be my tracer >> because it's it is closer in size to the thing we are trying to trace >> track yeah >> than the other aluminina dust and other things and so the we can the point is if we do it this way we can start to rule out the lag problem as the source of the issue >> because the crypton is just going to be going with it >> yes it's going to be moving at the same level and paste and all these things as the actual >> and this is the part that was like a little bit non-trivial to me right it's like with dust it's really easy to set up a 2D laser field and like image the dust because the laser remember from first principles how do we image something we got to capture light

32:02>> yes so what do we do for the dust for the um particle image velocry we set up a 2D laser field the dust is moving moving around the laser bounces. The light from the laser bounces off the particle and then it goes to our detector and we take an image. >> Mhm. >> With a single krypton atom. What? How are you going to do that? Here's what they did. And it's I I thought this was very cool. So, they got a laser and they use the laser to ionize krypton. Okay, they have this two photon procedure where they focus all the laser beam into a tiny spot where the where the krypton is getting seated.

32:43>> Okay, and if two photons interact with a single krypton atom, it's going to bump up in energy level and ionize itself. >> And then you're going to be able to >> and now this krypton is an ionized thing. And when it goes back to its normal state, it's going to release a photon. the the krypton itself is going to create the photon that we're going to use to track it with. So there's like a read. So there's a write mechanism, right? We're writing the krypton. We're tagging it. >> We're tagging it. Yeah. Yeah. >> And then and then we're reading it later when the photon's released. >> Yeah. >> And it's we're basically created readwrite level permissions on >> on like on an atom. >> On an atom >> and we're tracking it as it goes through

33:25this Mach Mach 5 Mach 6. I hope people who are watching and listening to this understand how outrageous what he said. >> That's so like and it took him 10 years to like figure this out obviously like like >> credit to them dude that that's so that's such a cool idea. That is a really that's actually really right cuz you got to think like that's really that's clever. Yeah, it is clever because because I want to trace how the gas is moving around, but I want to image the gas itself. >> Right. >> Right. How do I image the gas? I can't image atoms. >> Right. >> Right. I can image dust particles cuz they'll scatter light. >> Yes.

34:05>> But if I make the atoms themselves like this like weird like light bulb. >> Yes. This this reminds me of the story we talked about in episode 16 last week about how we were use the the the camouflage story about how we're manipulating biology in order to generate an outcome based on its existing evolutionary processes and building into that infrastructure >> uh in order to get the outcome we're looking for. Just conceptually it's like using the fundamentals of physics. It's like we're eliciting >> the reaction >> that then enables us to do the thing we want to do based on the fundamental principles. >> Uh we're not just like we can't just

34:45force the answer. We kind of have to like work with the universe a little