RUI: Search for Non-Newtonian Gravity Using A High-Sensitivity Torsion Balance, A Continuation

引力是自然界中四种基本相互作用之一。但与其他三种相互作用（电磁力、弱力和强力）不同，它的理论描述基于牛顿对万有引力的描述，后来被爱因斯坦的广义相对论扩展，与标准模型不兼容，标准模型是一个统一了所有其他三种相互作用的量子力学框架。面对这种二分法，理论物理学中的一些现代提议提出，牛顿开创的平方反比定律（ISL）可能在实验上可达到的亚毫米间隔上被打破，从而为统一引力与量子理论提供了诱人的前景。拟议的研究将利用最灵敏的台式仪器之一，扭转天平，直接探测50微米以下的ISL。因此，与SU学生合作从这项研究中获得的具体成果将增加基础研究的基础知识，并对从天体物理学到基本粒子和核物理学的广泛物理领域产生深远的影响。 该项目旨在通过直接量化非引力相互作用的贡献来测试平行平面配置中的平方反比引力定律。所提出的策略允许进行低于70微米的高精度实验，其中界面表面的粗糙度和平面度是唯一的限制性物理障碍。因此，该方法将大大改善目前对汤川空间强度α参数的限制，至少在10 μm范围内提高四倍。拟议研究的另一个新奇是在汤川空间探测1厘米以上的重力，这是一个以前未探索过的范围。从技术的角度来看，在测试物体之间插入静电屏，在这种尺度上探测重力将大大减少近场效应，如电贴片效应和卡西米尔力。完成的扭秤实验将为学生获得关键的实验技能提供一个很好的实验平台，并为SU物理系的教学和科研一体化做出重大贡献。这项研究将极大地受益于华盛顿大学（UW）Eöt-Wash小组提供的技术资源和专业知识，该小组是一个以数十年来对ISL的精确研究而闻名的先驱小组。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

Gravity represents one of the four fundamental interactions in nature. But unlike the other three interactions (electromagnetism, weak, and strong forces), its theoretical descriptions, based on Newton’s description of universal gravitation, later expanded by Einstein’s General Relativity, are incompatible with the Standard Model, a quantum-mechanical framework that unifies all of the other three interactions. Faced with this dichotomy, some modern proposals in theoretical physics have suggested a possible breakdown of the inverse-square-law (ISL) pioneered by Newton at experimentally-accessible sub-millimeter separations, thereby providing a tantalizing prospect for unifying gravity with quantum theory. The proposed research will utilize one of the most sensitive table-top instruments, a torsional balance, to directly probe the ISL below 50 micron. Specific results obtained from this research in collaboration with SU students will thus increase basic knowledge in fundamental research and have profound impacts across broad areas of physics ranging from astrophysics to elementary particle and nuclear physics. This project aims to test the inverse-square law of gravity in the parallel-plane configuration by directly quantifying the contributions from non-gravitational interactions. The proposed strategy allows for conducting a high-precision experiment below 70 micron for which the roughness and planarity of the interfacing surfaces are the only limiting physical barriers. The approach will thus substantially improve the current limits on the strength α-parameter of the Yukawa space at least by a factor of four at the 10-μm range. Another novelty of the proposed research is to probe gravity above 1 cm in the Yukawa space, a previously unexplored range. From a technical perspective, with an electrostatic screen inserted between the test bodies, probing gravity at this scale would significantly reduce the near-field effects, such as the electric patch effect and the Casimir force. The completed torsion balance experiment will provide an excellent experimental platform for students to gain critical laboratory skills and make significant contributions to the integration of teaching and research in the SU physics department. The research will greatly benefit from technical resources and expertise provided by the Eöt-Wash group at the University of Washington (UW), a pioneering group renowned for their precise studies of the ISL for many decades.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.