First results of the MICROSCOPE satellite confirm the validity of the equivalence principle at an unprecedented precision
First results of the MICROSCOPE satellite of CNES, equipped with ONERA accelerometers, show with an improved precision that bodies fall in a universal way in vacuum. This is a new confirmation of general relativity, the theory proposed one century ago by Albert Einstein which has been verified recently by the first direct detection of gravitational waves. However, the other grand theory of 20th century, quantum field theory, which describes in an accurate way the microscopic world seems irreconcilable with general relativity. The search for a universal and quantum theory of gravitation leads in most known cases to a violation of the founding principle of general relativity, the equivalence between gravitation and acceleration.
MICROSCOPE (MICROSatellite à trainée Compensée pour l’Observation du Principe d’Équivalence) was launched on April 25th, 2016. The first scientific measurements were collected from december 2016 to spring 2017 during 1.900 orbits suited to equivalence principle test. Their analysis improve the precision of the test to the unprecedented level of 2.10-14. The result published in the review PRL pushes a possible violation of the principle down by a factor 10 and leads to new constraints for the theories extending general relativity. Other data already collected or to be collected before the end of the mission in spring 2018 will improve the precision further to approach the objective of 10-15.
Serge Reynaud, physicist in the team « Quantum fluctuations and relativity » at LKB, is a member of the « Science Working Group » of the MICROSCOPE mission and a co-author of the publication.
Contact LKB : Serge Reynaud
 See the press release of CNES, ONERA and CNRS [lien] https://presse.cnes.fr
 See the letter « The MICROSCOPE mission: first results of a space test of the Equivalence Principle » published in the Physical Review Letters [lien] https://journals.aps.org/