Gravity is our most familiar force. Standing on Earth, we feel its pull, and gazing up at the sky, we see its effect on planets and comets. And yet the gravitational constant—affectionately called big G—is one of the hardest fundamental constants to measure precisely. In a replication of an earlier experiment, a group from the National Institute of Standards and Technology (NIST) in Maryland has released a new G value [1]. The results show a disparity between measurements, highlighting how small background effects continue to weigh down precision metrology efforts.
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