Relativity comes down to Earth

Albert Einstein's theories of relativity, which predict that relative speed and gravity affect the passing of time, have never been easy to bring home to the general public. In the early 1970s, scientists demonstrated relativity by putting synchronized atomic clocks on jumbo jets that flew eastwards and westwards around Earth. The westbound plane — the one flying against Earth's rotation — gained time compared with a fixed reference clock on the ground. But this wasn't exactly an everyday scenario. via Relativity comes down to Earth : Nature News.