RUI: Continuation of Support for Short-range Tests of Gravity at Humboldt State University

洪堡州立大学（HSU）是联邦政府认可的西班牙裔服务机构，位于北加州的一个主要农村地区，重力物理实验室（GPL）是物理和天文学系唯一专门的动手物理研究实验室。该奖项支持的引力研究范围非常小，只有一根头发的宽度。对平方反比定律（ISL）的测试是通过桌面实验进行的，寻找可能表明新物理的偏差。该奖项确保了HSU物理研究的延续，并确保其本科生（其中许多是第一代大学生和STEM领域代表性不足的群体的成员）获得追求研究生学习或行业职业所需的宝贵研究技能。本科生还将通过与华盛顿大学重力研究小组的合作，被派往那里进行研究。最后，从天体物理学和宇宙学到粒子物理学和精密测量科学等各个领域的研究都对重力测试非常感兴趣。该奖项支持高精度实验，将在前所未有的水平上测试广义相对论的弱等效原理（WEP）和引力ISL。WEP将在毫米尺度上进行测试，ISL将在亚毫米距离上进行探测，其无与伦比的灵敏度可低至约25微米。两个试验都采用了一种新颖的平行板扭摆和吸引子质量设计。近年来，在短（亚毫米）距离尺度上对引力相互作用的研究受到了广泛关注，这在很大程度上是由于弦理论或M理论中出现的需要三维以上空间维度的统一场景，其中一些可能是宏观的。引力的短程测试和WEP也研究了可能提出的机制，试图解释宇宙的加速膨胀，通常归因于暗能量。最后，这样的测试提供了寻找由外来粒子或其他现象引起的假设的新相互作用的可能性。关于这些影响的许多情景都预测在短距离上会出现WEP和/或ISL的破坏。自1999年以来，实验限制得到了极大的改善，因此ISL已被证明在距离低至约55微米的范围内有效。然而，WEP的专用测试尚未在毫米尺度以下进行。该项目的资金将允许完成正在进行的WEP和ISL的初步测试，测试质量分离在亚毫米尺度（ISL测试的测试质量分离接近100微米）。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Humboldt State University (HSU) is a federally-recognized Hispanic Serving Institution in a predominantly rural area of Northern California, and the Gravitational Physics Laboratory (GPL) is the only dedicated hands-on physics research laboratory in the Department of Physics and Astronomy. This award supports research in gravitation at very small ranges of the scale of the width of a human hair. Tests on the Inverse-Square Law (ISL) are conducted with tabletop experiments, looking for deviations that may indicate new physics. This award ensures the continuation of physics research at HSU and that its undergraduates, many of whom are first-generation college students and members of underrepresented groups in STEM fields, gain valuable research skills necessary for the pursuit of graduate studies or careers in industry. Undergraduates will also be sent to perform research at the University of Washington through a collaboration formed with a gravity research group there. Finally, tests of gravity are of great interest to research in diverse fields ranging from astrophysics and cosmology to particle physics and precision measurement science.This award supports high-precision experiments that will test the Weak Equivalence Principle (WEP) of General Relativity and the gravitational ISL at unprecedented levels. The WEP will be tested at the millimeter scale and the ISL will be probed over sub-millimeter distances with unmatched sensitivity down to approximately 25 microns. Both tests use a novel parallel-plate torsion pendulum and attractor mass design. In recent years the study of the gravitational interaction at short (sub-millimeter) distance scales has gained much attention due in a large part to unification scenarios arising in string or M theory that require more than three spatial dimensions, some of which could be macroscopic. Short-range tests of gravity and the WEP also investigate possible proposed mechanisms that attempt to explain the accelerated expansion of the universe, generally attributed to Dark Energy. Finally, such tests present the possibility to search for hypothetical new interactions due to exotic particles or other phenomena. Many scenarios concerning these effects predict a violation of the WEP and/or ISL at short distances. Since 1999, experimental limits have improved dramatically so that the ISL has proven valid over distances down to approximately 55 microns. A dedicated test of the WEP, however, has not been performed below the millimeter scale. The funding of this project will allow the completion of the ongoing initial tests of the WEP and ISL with test mass separations at the sub-millimeter scale (with test mass separation approaching 100 microns for the ISL test).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.