Research press release



これまで測定されてきた重力場の中で最も小さな重力場が測定されたことを報告する論文が、今週、Nature に掲載される。この重力測定は、金でできた半径1ミリメートルの球体を2個使って達成されたものであり、暗黒物質の探索、量子物理学と重力の関わりなどの基礎物理学の新しい領域を探求する実験への道が開かれた。


今回、Markus Aspelmeyerたちの研究チームは、質量が約90ミリグラムの金でできた球体(2個)の間の結合力としての重力を分離するための実験を計画した。この実験では、外部摂動の影響を最小化するために厳密に制御された装置が用いられた。例えば、ファラデーシールドを用いて、静電力を遮断し、1個の金の球体を真空チャンバーに接続することによって、地震と音の効果を最小限に抑えた。もう1個の金の球体は、接地した微小球に周期的に接近させて、重力結合を分離できるようにした。この重力結合は、回転信号に生じる変化によって検出された。


The smallest known gravitational field measured so far is reported in Nature this week. This measurement, achieved using two 1-mm-radius gold spheres, could pave the way towards experiments to explore new areas of fundamental physics, such as probing dark matter or the interplay between quantum physics and gravity.

Gravity is a fundamental force, but our understanding of this force remains incomplete; it does not fit into the standard model of physics and seems to be disconnected from quantum theory. Testing the coupling force of gravity in very small objects may shed some light on some of the mysteries of this force, such as deviations from the predictions of Newtonian gravity theory. However, such tests are challenging and require a tightly controlled environment to minimize perturbations from other sources and gravity itself.

Markus Aspelmeyer and colleagues design an experiment to isolate gravity as a coupling force between two tiny gold spheres with masses of about 90 mg. Their tightly controlled set-up minimizes the influences of external perturbations; for example, a Faraday shield is used to block electrostatic forces, and seismic and acoustic effects are minimized by connecting one of the gold spheres to a vacuum chamber. The other sphere is periodically moved closer to the grounded sphere, allowing the isolation of gravitational coupling, which can be detected in a change in the rotational signal./p>

The experiments confirm what is already expected from classical Newtownian physics, in which the gravitational force between the two spheres depends on their masses and their distance. The authors suggest that the sensitivity of their experiment has potential to be further improved, which could enable the measurement of gravitational forces for even smaller objects. Such experiments may allow tests of fundamental physics that have so far remained elusive, including gravitational effects of dark matter and gravitational coupling between quantum systems. However, incorporating quantum physics in such tests still remains challenging, the authors conclude.

After the embargo ends, the full paper will be available at:

doi: 10.1038/s41586-021-03250-7

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