In DepthPhysics

Relativity survives drop test

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Science  01 Dec 2017:
Vol. 358, Issue 6367, pp. 1117
DOI: 10.1126/science.358.6367.1117

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Summary

A key tenet of Albert Einstein’s general theory of relativity has passed yet another test with flying colors—and for the first time in space. A French satellite experiment has shown that gravity tugs objects of different masses at the same rate, just as relativity dictates. The result is the most precise confirmation yet of the equivalence principle, first explored more than 400 years ago by Galileo Galilei. The MICROSCOPE satellite found no discrepancy in the free fall of two small test masses to about one part in 100 trillion. That’s more than 10 times better than the most sensitive ground-based experiments. Although no discrepancy has been found, physicists continue to look for one, because any violation of the equivalence principle could point to new forces of nature.

  • * Edwin Cartlidge is a journalist in Rome.