A Japanese team of researchers has shown that time at Tokyo Skytree's observatory — around 450 meters above sea level — passes four nanoseconds faster per day than at near ground level.
The finding, based on extremely precise "optical lattice clocks" that only go out of synch by one second every 16 billion years, proves Albert Einstein's general theory of relativity, which predicts that clocks in a strong gravitational field will tick slower than those in a field with weaker gravity.
The outcome of the research led by Hidetoshi Katori, of the government-backed Riken research institute's Quantum Metrology Laboratory and the University of Tokyo, was conducted from October 2018 and was released April 6 in the online scientific journal Nature Photonics.