GPS alternative taps cosmic rays for underground or underwater navigation

GPS is a powerful navigation technology, but it doesn’t work as well inside buildings, underground or underwater. Now engineers in Japan have developed and tested an alternative technology that uses cosmic rays to track movement beneath a building with precision of a few meters.

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I ought to look at that link. Cosmic rays have previously been used for looking through Mayan pyramids and also (if I remember correctly) the pyramids of Egypt. But this is the first time I’ve heard of them being used to track movement.