A research team led by Professor Jiro Murata and Researcher Kazushi Ninomiya of the Faculty of Science, Rikkyo University has found that one of the most basic principles of physics, "uniformity of free fall," is millimeters (thousands of millimeters). ) It was confirmed for the first time that it holds true even with gravity due to a small object of scale.
The uniformity of free fall is that all objects fall at the same acceleration due to gravity, which is famous for the experiment of the Leaning Tower of Pisa in Galileo. Also called the "equivalence principle", it shows that the amount that indicates the difficulty of movement with respect to force (inertial mass) and the amount that feels gravity (gravitational mass) are the same, and Einstein's idea when constructing the general theory of relativity. It became the origin of.
So far, it has been confirmed that the equivalence principle holds with extremely high accuracy in experiments using the gravity of the earth, but it has not been confirmed whether it holds true even with the gravity of small objects on the scale of millimeters in the laboratory.The gravity caused by such a small object is about 1 million times weaker than that of the earth, and it is an extremely difficult experiment to detect gravity.
The research team has developed a unique measuring device that combines a device called a torsion scale and image processing technology to detect gravity between small objects on the scale of millimeters to centimeters and to verify whether there is a difference between the substances.The shortest surface proximity distance is measured to approach 4.5 mm, and it is the first time that the strength of the gravitational field felt by a small tungsten object against different gravitational sources of copper and aluminum matches within an error of about several percent. It became clear.
Currently, we are proceeding with higher sensitivity, higher accuracy, and smaller size, and we are testing the equivalence principle and the law of universal gravitation more rigorously.In the future, there is a possibility that new signs of gravity theory that breaks the equivalence principle at short distances and breaking of the law of universal gravitational force that indicates the existence of surplus dimensions may be discovered.
Paper information:[Classical and Quantum Gravity] Short-range test of the universality of gravitational constant G at the millimeter scale using a digital image sensor
