Gravity is one of the fundamental forces of the universe, keeping us attached to the planet and governing many of the interactions between celestial bodies. With such an important role in the universe, you’d think we’d know everything there is to know about it by now, but you’d be wrong. However, new research has allowed us to get closer to that goal than ever before.
Science News reports on research conducted by physicists at the Huazhong University of Science and Technology in Wuhan, China that has given us new information as to the exact value of the force of gravity. Led by Professor Shan-Qing Yang, these experiments were conducted in a controlled lab setting using a device called a torsion pendulum.
These pendulums are silica plates covered in metal and held in the air by a thin wire. Steel spheres are then positioned around the plates, the minute gravitational force exerted by the spheres causing the plates to spin in a certain direction. By measuring the degree of rotation, the team could then find out just how much force was being exerted on the pendulum, doing the necessary math to solve for the force of gravity.
Two pendulums were used in this experiment, each with a slightly different setup. One pendulum allowed the team to measure the amount the wire suspending it was twisted by gravity while the other was attached to a turntable which spun as the pendulum moved without twisting the suspension wire. Both the amount of twisting the first wire underwent and the amount of rotation experienced by the second turntable were used as two means of measuring gravity.
To be on the safe side, the team had to account for any number of tiny, almost imperceptible variations that could skew the results, like variations in the materials used to make the pendulums that were out of their control.
For the last 40 years, the accepted measure of the G force has been 6.67408 × 10−11 meters cubed per kilogram per square second with an uncertainty (basically a “give or take” percentage) of 0.0047%. Notably, this is one of the least precise measurements of a fundamental universal force that was have. Much of this came down to simply not having the means to find a more precise measurement for the time, but this all seems about to change.
After making their calculations, the two pendulums came up with a G value equaling 6.674184 × 10−11 meters cubed per kilogram per square second in the first experiment and 6.674484 × 10−11 meters cubed per kilogram per square second in the second. Both of these measurements had the same uncertainty value of 0.00116%, making it the most precise measure of gravity to date.
While this precision is astounding, with the likes of University of Birmingham physicist Clive Speake going so far as to call it “a fantastic accomplishment,” it is still far from the definitive answer to the question of gravity’s true power. Many more tests will be required over many more years, but results like these bring us closer and closer to better understanding our universe and unlocking the secrets of reality.
