LW - The Incredible Fentanyl-Detecting Machine by sarahconstantin

The Nonlinear Library: LessWrong

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Welcome to The Nonlinear Library, where we use Text-to-Speech software to convert the best writing from the Rationalist and EA communities into audio. This is: The Incredible Fentanyl-Detecting Machine, published by sarahconstantin on June 29, 2024 on LessWrong. There's bound to be a lot of discussion of the Biden-Trump presidential debates last night, but I want to skip all the political prognostication and talk about the real issue: fentanyl-detecting machines. Joe Biden says: And I wanted to make sure we use the machinery that can detect fentanyl, these big machines that roll over everything that comes across the border, and it costs a lot of money. That was part of this deal we put together, this bipartisan deal. More fentanyl machines, were able to detect drugs, more numbers of agents, more numbers of all the people at the border. And when we had that deal done, he went - he called his Republican colleagues said don't do it. It's going to hurt me politically. He never argued. It's not a good bill. It's a really good bill. We need those machines. We need those machines. And we're coming down very hard in every country in Asia in terms of precursors for fentanyl. And Mexico is working with us to make sure they don't have the technology to be able to put it together. That's what we have to do. We need those machines. Wait, what machines? You can remotely, non-destructively detect that a bag of powder contains fentanyl rather than some other, legal substance? And you can sense it through the body of a car? My god. The LEO community must be holding out on us. If that tech existed, we'd have tricorders by now. What's actually going on here? What's Up With Fentanyl-Detecting Machines? First of all, Biden didn't make them up. This year, the Department of Homeland Security reports that Customs and Border Patrol (CBP) has deployed "Non-Intrusive Inspection" at the US's southwest border: "By installing 123 new large-scale scanners at multiple POEs along the southwest border, CBP will increase its inspection capacity of passenger vehicles from two percent to 40 percent, and of cargo vehicles from 17 percent to 70 percent." In fact, there's something of a scandal about how many of these scanners have been sitting in warehouses but not actually deployed. CBP Commissioner Troy Miller complained to NBC News that the scanners are sitting idle because Congress hasn't allocated the budget for installing them. These are, indeed, big drive-through machines. They X-ray cars, allowing most traffic to keep flowing without interruption. Could an X-ray machine really detect fentanyl inside a car? To answer that, we have to think about what an x-ray machine actually does. An X-ray is a form of high-energy, short-wavelength electromagnetic radiation. X-rays can pass through solid objects, but how easily they pass through depends on the material - higher atomic number materials are more absorbing per unit mass. This is why bones will show up on an X-ray scan. The calcium (element 20) in bones has higher atomic mass than the other most common elements in living things (carbon, hydrogen, oxygen, nitrogen, sulfur), and bones are also denser than soft tissue, so bones absorb X-rays while the rest of the body scatters it. This is also how airport security scans baggage: a cabinet x-ray shows items inside a suitcase, differentiated by density. It's also how industrial CT scans can look inside products nondestructively to see how they're made. To some extent, X-ray scanners can distinguish materials, by their density and atomic number. But fentanyl is an organic compound - made of carbon, hydrogen, nitrogen, and oxygen, just like lots of other things. Its density is a very normal 1.1 g/mL (close to the density of water.) I'm pretty sure it's not going to be possible to tell fentanyl apart from other things by its density and atomic number alone. Indeed, that's not what the scanner vendors are promising to do. Kevin McAleenam, the former DHS secretary who...