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Welcome to Science Talk, the weekly podcast of Scientific American. For the seven days starting December 20th, I'm Steve Murski. This week on the podcast, a discussion of the cloak and

dagger world of radioactive spy dust with historian of science Christy McCrackus. That conversation

includes some discussion of the recent polonium poisoning case

involving Russian secret policeman Alexander Litvinenko.

We'll have a Christmas poem dedicated to those working late in the labs,

and we'll test your knowledge about some recent science in the news.

First up, Christy McCrackus, she's a science historian at Michigan State University, who specializes in 20th century German science.

She's just completed a book called Seduced by Secrets Inside the Stasi's SpyTech World.

One chapter of the book is called Radioactive Spy Dust. I called her at her office in East Lansing.

Professor McCrackis, great to talk to you today.

Thanks for calling, Steve.

My pleasure. What is spy dust, and how did you get so interested in it?

Spy dust is actually the vernacular name for a police technique used to track people.

And it was called spy dust in 1986 by the CIA because they discovered that the KGB

had used a chemical marking material to track their officers, and they dubbed it spy dust.

So it's not really dust, but it's used on spies,

...