Extensive tests with a levitating force sensor fail to find evidence of a fifth force

Extended tests with levitated force sensor fail to find evidence of fifth force Diagram of the experiment. a, The “fifth force” of the chameleon field is generated by eight thin films (source masses) of polyimide with a thickness of 75 μm, spaced equally on a rotating plate. The force sensor consists of a piece of pyrolytic graphite, in diamagnetic levitation in a magneto-gravitational trap and a 12.5 μm thick film (test mass) of the same material as the source masses at the top supported by a glass rod. The magneto-gravitational trap is placed in a vacuum chamber with seismic sound insulation. The distance between the test mass and the source masses is 390 μm. The rotation of the source masses and the movement of the force sensor are controlled by optical systems, the optical signals being detected by photodiode 1 and photodiode 2 respectively. strength. b, The rotating source masses generate a periodic “fifth force” Fcham acting on the test mass. A thin window of electrical shielding with a thickness of 0.5 μm and magnetic shielding are used to filter out background electrostatic and magnetic forces. c, The field ϕ along the central axis z at two different rotation phases. The red and blue curves indicate the cases with and without source mass film above the test mass, respectively. The diagram is not to scale but for visibility. Credit: Natural Physics (2022). DOI: 10.1038/s41567-022-01706-9

A team of researchers from Nanjing University, together with two colleagues from the University of Science and Technology of China, conducted new tests of the chameleon theory and report a failure to find any evidence for it. a fifth force. They published their article in the journal Natural Physics.

Previous research has suggested that there is a mysterious force acting on the universe – dubbed by theoretical physicists dark energy, it has been theorized as a way to explain why the universe is expanding at such an accelerating rate. Despite many efforts, no one has been able to prove that dark energy exists. A theory called the Chameleon Theory suggests that objects affected by gravity can behave in fluctuating ways depending on factors in their environment. The theory includes the idea of ​​a chameleon field as a fifth force. The theory has been hotly debated because it directly contradicts the theory of general relativity, which states that gravitational forces must be constant.

In this new effort, the researchers sought to prove or disprove the theory using a levitating force sensor – a wheel-like device with plastic fins that spin in front of a thin film resting on a piece of graphite in magnetic levitation. The base under the graphite is held by springs. The goal is to test the idea that gravity exerts different amounts of force depending on the density of nearby objects. In a broad context, the chameleon field would exert less force in a dense environment such as on an individual planet than it would on a large swath of less dense space. If a fifth force exists, then the spinning films should exert a periodic force on the levitating film.

After running the experiment several times, the researchers found no evidence for the impact of the spinning fins on the levitating film, which they say rules out the chameleon theory as a candidate explanatory of the dark energy. They also suggest that their methodology highlights the need for robust laboratory testing as a way to verify or discredit theoretical research. They suggest their methodology could also be used in other efforts.

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More information:
Peiran Yin et al, Experiments with Levitating Force Sensors Challenge Dark Energy Theories, Natural Physics (2022). DOI: 10.1038/s41567-022-01706-9

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Quote: Extensive tests with levitated force sensor fail to find evidence of fifth force (2022, Aug 26) Retrieved August 27, 2022 from https://phys.org/news/2022-08-levitated-sensor- evidence.html

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