MICROSCOPE tests a pillar of Einstein’s theory

MICROSCOPE tests a pillar of Einstein’s theory

MICROSCOPE tests a pillar of Einstein’s theory

published Wednesday, September 14, 2022 at 6:38 pm

The MICROSCOPE space mission has achieved record accuracy in verifying the “equivalence principle” of physics, which tests Einstein’s general relativity, according to several studies whose results were presented Wednesday.

Launched in 2016, MICROSCOPE was installed in orbit at an altitude of 710 km and provided data for two and a half years.

The microsatellite, built by the CNES (National Center for Space Studies), housed two T-SAGE accelerometers from ONERA, the French center for aerospace research. The latter was also responsible for data processing, thanks to the simulation and data processing tools developed by the Côte d’Azur Observatory.

It all begins with Galileo, in the seventeenth century, who postulated that by simultaneously releasing two bodies of distinct mass and composition, they hit the ground at the same time. Three centuries later, an astronaut on the Apollo XV mission will illustrate this by dropping a feather and a hammer to the surface of the moon, apparently at the same speed.

Meanwhile, Newton postulated the “equivalence principle” between the gravitational force and the force of inertia that a body would have to undergo in an acceleration situation.

This principle is a pillar of Albert Einstein’s theory of relativity, which describes gravitation as a curvature of spacetime distorted by matter.

It was verified on Earth with a degree of relative accuracy up to 13th decimal place in 2007. But space is the ideal environment to go further, freeing oneself from multiple specific disturbances of the Earth’s surface.

The result presented on Wednesday, the subject of publications in the prestigious Physical Review Letters and Classical Quantum Gravity journals, verifies the principle of equivalence with a precise measurement to the fifteenth decimal place.

MICROSCOPE compared, using an accelerometer, the forces necessary to keep two cylinders of different mass and composition immobile, suspended in a small vacuum container and subject to Earth’s gravitation.

Verifying the principle of equivalence meant verifying that the two forces were equal. All with an accuracy whose “equivalent would be to measure the weight of a fly on a 500,000-ton supertanker”, explained Manuel Rodrigues, head of the ONERA experiment, presenting the results at the CNES headquarters.

The execution of the measurement was based both on a satellite control system that allows to obtain an almost perfect stability, and on a data processing that corrects spurious signals, such as “cracks” due to deformations of the coating by isolating the machine underneath. the effect of the Sun.

Future projects, such as MICROSCOPE2, aim to further refine the measurement. With the challenge of further testing one of the pillars of the theory of general relativity. And beyond that, to test models aimed at unifying relativity theory with quantum theory, which for the most part predict violations of the equivalence principle.

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