Most of us use GPS—the Global Positioning System—on a daily basis: to find our location when we’re driving, running, shopping, dating, and so much more. But GPS is even more important, and more vulnerable, than you think.

In the last few years, GPS interference has been reported all over the world, from war zones to shipping routes to public squares. What was once the fanciful plot of a Bond movie—bad guy manipulates GPS to start World War III—is increasingly plausible. How did the world come to rely so heavily on such an unreliable system?

In this episode of Decoder Ring, host Willa Paskin talks to journalist Katherine Dunn, author of the new book Little Blue Dot: How GPS Shaped the Modern World. You’ll learn how GPS works, why it was created, how it became so ubiquitous, and why it’s now under attack. You’ll also hear from Dr. Todd Humphreys, an aerospace engineer who manipulated GPS to trick an $85 million superyacht into following his direction—for science, of course.

This episode was written and produced by Max Freedman. It was edited by Willa Paskin and Evan Chung, our supervising producer. Merritt Jacob is Senior Technical Director. Our intern is Phoebe Mulder.

If you have any cultural mysteries you want us to decode, email us at DecoderRing@slate.com or leave a message on our hotline at (347) 460-7281.

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Sources for This Episode

Burgess, Matt. “When a tanker vanishes, all the evidence points to Russia,” WIRED, Sep. 21, 2017.

Dunn, Katherine. Little Blue Dot: How GPS Shaped the Modern World, Bloomsbury Publishing, 2026.

Dunn, Katherine. “How to Hack a Superyacht,” The Walrus, Jun. 13, 2026.

Hopper, Nate. “The Thorny Problem of Keeping the Internet’s Time,” The New Yorker, Sep. 30, 2022.

Hopper, Nate. “The Timekeeper of Ukraine,” The Atlantic, Sep. 21, 2024.

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