George Musser is a writer on physics who loves to seek new metaphors to better understand Einstein’s general theory of relativity. While working on his last book, which was titled “Spooky Action at A Distance”, Musser thought to compare the warping of space-time to the motion of Earth’s tectonic plates.
Einstein explained gravity as the bending of spacetime. A well-hit baseball arcs through the air to an outfielder’s glove because it is following the contours of spacetime, which the planet’s mass has resculpted. The mutability of spacetime also means that nothing in the universe has a fixed position, since the framework by which position is defined is fluid. And something like that is also true of Earth’s surface. Nothing on the ground has fixed coordinates because the landscape is ever-shifting.
This intrigued Musser.
If nothing has fixed coordinates, then how do Google Maps, car nav systems, and all the other mapping services get you where you’re going? Presumably they must keep updating the coordinates of places, but how?
He figured that he can just Google the answer quickly and get back immediately to Einstein. Unfortunately, what he thought to be just a 30-second Q&A turned out to be a several days’ search for answers.
I discovered a sizable infrastructure of geographers, geologists, and geodesists dedicated to ensuring that maps are accurate. But they are always a step behind the restless landscape. Geologic activity can create significant errors in the maps on your screens.
… The image above shows my position in Google Maps while I was standing on my back deck—a discrepancy of about 10 meters, much larger than the stated error circle. When I go to Google Earth and compare images taken on different dates, I find that my house jumps around by as much as 20 meters.
More details over at Nautilus.
(Image Credit: George Musser/ Nautilus)