Scientists have demonstrated that Einstein’s theory of general relativity is correct to a remarkable degree of accuracy, despite having been around for more than a century. The team behind the research wanted to test a component of Einstein’s theory of general relativity called the weak equivalence principle, which states that all objects, regardless of their mass or composition, should free-fall the same way in a particular gravitational field when interference from factors like air pressure is eliminated.
One of the most famous tests of the weak equivalence principe occurred during an Apollo 15 moonwalk, when astronaut David Scott dropped a feather and a geological hammer at the same time; without air resistance, both objects accelerated toward the moon’s surface at the same rate.
To do so, the scientists measured the acceleration of free-falling objects in a French satellite called MICROSCOPE, which launched in 2016. The team’s results, which are the culmination of 20 years of research, revealed that acceleration in pairs of objects in free fall differed by no more than 1 part in 10^15, or 0.000000000000001, meaning they found no violations in the weak equivalence principle larger than that.
— source scientificamerican.com | Sep 15, 2022
