(OSA.open.org)Pphysicists have been trying for decades to develop a full-fledged theory of quantum gravity that preserves quantum mechanics while modifying Einstein’s general theory of relativity. Until now, they have been unsuccessful.
A team of researchers in China has carried out a satellite-based experiment that goes some way toward ruling out an alternative kind of theory—one that assumes it is quantum mechanics, rather than relativity, which needs an overhaul
A group led by OSA Fellow Jian-Wei Pan of the University of Science and Technology of China in Shanghai exploited the gravitational gradient experienced by any object moving away from the surface of the Earth.
The researchers generated and then split a series of entangled pairs of photons at a ground station in Tibet, before detecting one half of each pair on the ground and sending the other to a satellite known as Micius. Launched into a 500-km-high sun-synchronous orbit by the Chinese Academy of Sciences in 2016, Micius has also been used to perform tests of entanglement, cryptography and teleportation.
Performing measurements over the course of a handful of orbits, Pan and his colleagues found that the data collected onboard the satellite and on the ground contained no surprises. “Our measurement results are consistent with the standard quantum theory,” the researchers wrote in their paper, “and hence do not support the prediction of event formalism.”

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