Probing Fundamental Physics with Gravitational Experiments

在《现代物理学》中，有两个被广泛接受的描述整个自然的理论。一个是“标准模型”，它描述了所有材料属性。标准模型包含了所有的量子粒子。另一种理论是“广义相对论”，爱因斯坦描述万有引力的理论。尽管有一些相似之处，但这两种理论非常不同，没有经过验证的理论或实验证据将两者联系起来，尽管大多数物理学家认为肯定存在联系。这个小组专门测量非常小的力，以进行超精密的重力测试。在团队进行的所有测试中，他们都试图发现与正常重力的微小偏差。如果发现这样的偏差，这将意味着广义相对论还有更多的东西，或者这是第三个基本理论的暗示，或者这是关于如何统一标准模型和广义相对论的暗示。具体地说，该小组专门开发和使用扭转平衡仪器来测试等价原理：几乎可以肯定，广义相对论和标准模型之间的任何联系都违反了等效原理。该集团使用的扭力天平提供了迄今为止最精确的EP测试。通过技术创新，该测量的灵敏度将提高一倍或更多：引入熔融石英光纤，并应用两种新方法来跟踪环境重力梯度。通过用含氢测试质量探测EP，实验的一般性和与宇宙学的相关性将得到增强。2)寻找自旋耦合力和洛伦兹破坏的迹象：本征自旋是标准模型相互作用的基础，但显然不是广义相对论的基础。利用该小组的自旋极化实验结果，将对一类新兴的超轻暗物质候选者施加限制。3)短距离测试牛顿平方反比(ISL)：该小组的实验保持着观测到引力的最短距离的记录，将引力强度ISL偏差约束在小于42微米的距离内。该集团将委托对其120倍对称的ISL设备进行现有升级，并继续推进更小的距离。4)推进低频小兵力技术的前沿：创新和具有挑战性的技术发展支撑了该集团的成功。展望该领域的未来，该集团将继续改进超低噪声低温扭转平衡和高灵敏度、但用户友好的光学角度传感仪器。在低频下测量引力强度所需的创造性技术进步已经并将对相关领域产生影响，包括引力波探测。在NSF的投资下，该集团建立了一支强大的世界领先的实验室，拥有独特的专业知识和基础设施，能够高效而严谨地应对这些实验挑战。

In Modern Physics there are two very well accepted theories that describe all of nature. One is the 'Standard Model' which describes all material properties. The Standard Model contains all the quantum particles. The other theory is 'General Relativity', Einstein's theory that describes gravitation. Despite some similarities, these two theories are very different and there is no verified theory or experimental evidence connecting the two, even though most physicists think that there must be a connection. This group specializes on measuring very small forces to conduct ultra-precise tests of gravity. In all the tests carried out by the team, they try to find ever so small deviations from ordinary gravity. If such deviations are found, it would mean that there is more to general relativity, or that this is hint of a third fundamental theory, or that this is a hint of how to unify the Standard Model and General Relativity.Specifically the group is specialized in developing and using torsion balance instruments to1) Test the equivalence principle (EP): It is almost certain that any connection between General Relativity and the Standard Model violates the EP. The torsion balances utilized by the group provide the most precise EP tests to date. The measurement's sensitivity will be doubled, or more, through technical innovation: introducing fused silica fibers and by applying two new methods to track ambient gravity gradients. The experiment's generality and relevance to cosmology will be enhanced by probing the EP with hydrogen-bearing test masses.2) Search for spin-coupled forces and hints of Lorentz violation: Intrinsic spin is fundamental to the standard model interactions but apparently not to general relativity. Leveraging the group's spin-polarized experimental results, constraints will be placed on an emerging class of ultra-light dark matter candidates.3) Test Newton's Inverse-Square (ISL) at short distances: The group's experiments hold the record for the shortest distance at which gravity has been observed, constraining gravity-strength ISL deviation to act over distances less than 42 microns. The group will commission existing upgrades to their 120-fold-symmetric ISL apparatus and press onward to yet smaller distances.4) Advance the frontier of low-frequency small-force technology: Innovative and challenging technology development has underpinned the group's success. Looking to the future of the field, the group will continue to refine both an ultra-low noise cryogenic torsion balance and highly-sensitive, but user-friendly, optical angle-sensing instruments. The creative technical advances required for gravitational strength force measurement at low frequency have had and will have impact on related fields, including gravitational-wave detection. With NSF investment, the group has built up a strong world-leading laboratory with unique expertise and infrastructure in position to address these experimental challenges with efficiency and rigor.