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

洪堡州立大学(HSU)是联邦承认的西班牙裔服务机构，位于加利福尼亚州北部以农村为主的地区，引力物理实验室(GPL)是物理和天文学系唯一专门的动手物理研究实验室。该奖项支持在人类头发宽度的极小范围内进行引力研究。对平方反比定律(ISL)的测试是通过桌面实验进行的，以寻找可能指示新物理的偏差。这一奖项确保了华中大学物理学研究的继续，并确保该校的本科生--其中许多是第一代大学生，以及STEM领域中代表性不足的群体的成员--获得了追求研究生学习或工业职业生涯所需的宝贵研究技能。本科生还将被派往华盛顿大学进行研究，与那里的一个引力研究小组建立了合作关系。最后，引力测试对从天体物理和宇宙学到粒子物理和精密测量科学等不同领域的研究都非常有兴趣。该奖项支持高精度实验，这些实验将在前所未有的水平上测试广义相对论的弱等价原理和引力ISL。WEP将在毫米级进行测试，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。这两种测试都使用了一种新颖的平行板扭转摆和吸引器质量设计。近年来，短距离(亚毫米)引力相互作用的研究得到了广泛的关注，这在很大程度上是由于弦或M理论中出现的统一场景，这些场景需要三个以上的空间维度，其中一些可能是宏观的。重力和WEP的短程测试也调查了可能提出的机制，试图解释宇宙的加速膨胀，通常被归因于暗能量。最后，这样的测试提供了寻找由于外来粒子或其他现象而产生的假设的新相互作用的可能性。许多有关这些影响的情景预测在短距离内会违反WEP和/或ISL。自1999年以来，实验极限得到了极大的改进，因此ISL已被证明在大约55微米的距离内是有效的。然而，WEP的专用测试尚未在毫米级以下进行。该项目的资金将允许完成正在进行的WEP和ISL的初始测试，测试质量分离在亚毫米级(ISL测试的测试质量分离接近100微米)。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.