When he unveiled his general theory of relativity, Albert Einstein wasn’t exactly met with applause. Almost no one else could do the math necessary to understand his abstract ideas, and at the time he didn’t have any evidence to back it up. But in the century since it was proposed, Einstein’s theory has continued to pass ever more stringent tests.
It remains our best explanation of the phenomenon of gravity. The theory bears out all sorts of wild predictions, the bulk of which boil down to this: Gravitation behaves the same for all observers, resulting from curving “space-time,” the fabric of the universe.
Einstein’s concepts have been verified — just as he reckoned they would — on scales from a foot-long sub sandwich to galaxy clusters millions of light-years wide. In between, general relativity has made its mark on the Global Positioning System, while explaining anomalous planetary orbits and the ...
