Researchers from ETH Zurich have proposed a new way to measure
The experimental setup consists of twoparallel beams suspended in vacuum chambers. To eliminate sources of interference as much as possible, the researchers installed a measuring device in the former Furggels fortress, located in the Swiss Alps and used as a bunker during World War II.
Experimental setup. Image: Jürg Dual/IMES/ETH Zürich
The researchers made one of the beams vibratewith a frequency of 42 Hz. Under the influence of gravitational forces, the second rod also began to oscillate in the picometer range (a picometer is one trillionth of a meter). The physicists used laser devices to measure the vibrations of each of the beams. The evaluation of this dynamic effect made it possible to draw conclusions about the value of the gravitational constant.
Gravitational constant (Newton's constant, G)is a physical constant that determines gravitational interactions. The law of universal gravitation, which uses this constant, was discovered more than 300 years ago, but its value cannot be calculated mathematically, but can only be measured.
The difficulty in measuring Newton's constant is thatgravity is very weak and difficult to shield. By measuring the interactions between two bodies, you are also measuring the influence of all the other bodies in the world, the researchers say. They believe that the only way to resolve this situation is to determine the gravitational constant using as many different methods as possible.
Researchers say the first preliminarytest results give a high measurement error. The value the researchers determined with their setup is 2.2% higher than the official figure approved by the Committee on Data for Science and Technology (CODATA). But scientists are finalizing their method and are confident that it will help to find a more accurate value of G.
This uncertainty must still be theresignificantly reduced to obtain a reliable value. We are already carrying out measurements with a slightly modified test setup so that the G constant can be determined even more accurately. The first results are available, but not yet published.
Jürg Dual, Professor of Mechanical Engineering and Process Engineering at ETH Zurich, co-author of the paper
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