Probing Fundamental Physics with Gravitational Experiments

在现代物理学中，自然由两种理论描述。一种是“标准模型”，它用量子粒子描述了所有材料的特性；另一个是爱因斯坦描述万有引力的“广义相对论”。大多数物理学家认为这两种理论之间一定存在某种联系，但到目前为止，还没有实验证明这种联系。此外，暗物质和暗能量的发现表明，引力现象存在于广义相对论之外。华盛顿大学的研究小组专门测量超微弱的力，以寻找与广义相对论所描述的引力之间前所未有的微小偏差。虽然观测到任何与广义相对论的偏差都将是一项革命性的科学发现，但它也可能对GPS或下一代精密时钟的未来技术应用产生影响。此外，利用为重力测量而开发的仪器，该小组将寻找暗物质的特征。该小组开发的技术和专业知识的应用范围从工业计量到地震预测，再到为该国的STEM劳动力做好准备。统一引力和粒子物理学的现代思想，以及对暗能量和暗物质的观察，表明引力的某些方面仍未被发现。华盛顿大学重力实验室（Eöt-Wash组）的桌面实验提供了一个独特的机会，可以在广义相对论，宇宙学和粒子物理学的交叉点上寻找新的物理学。该小组是超弱力探测领域的领导者，通过技术专长和创新，并通过响应最相关的及时和永恒的物理问题。具体来说，该小组将：1)测试等效原理（EP）：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。该小组的扭力天平提供了最精确的实验室ep测试。通过熔融硅扭转纤维、新型重力梯度测量、改进的钟摆和更好的仪器控制，灵敏度将大大提高，新的EP测量将比该小组之前在约束B-L耦合方面的测量灵敏度提高15倍。此外，通过探测包含富氢测试质量的EP，将增强EP测试的普遍性和与宇宙学的相关性。2)在短距离上测试牛顿平方反比定律（ISL）：该小组将利用其在短距离测量重力方面的专业知识，建立一个新的仪器，并在短至20微米的距离上进行测量。3)使用扭转天平搜索超轻暗物质。4)推进低频超小力技术前沿：创新和具有挑战性的技术开发使集团取得了成功。该小组将进一步改进角度测量，并开发干涉测量和电容测距仪。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。

In modern physics nature is described by two theories. One is the “Standard Model,” which describes all material properties with quantum particles; the other is “General Relativity”, Einstein’s theory that describes gravitation. Most physicists think that there must be a connection between these two theories, but to date there is no experimental signature for such a connection. Furthermore, the discoveries of dark matter and dark energy suggest that gravitational phenomena exist that lie outside of General Relativity. The group at the University of Washington specializes in measuring ultra-feeble forces to search for unprecedentedly small deviations from gravity as described by General Relativity. While observing any deviations from General Relativity would be a revolutionary scientific discovery, it may also have consequences for future technical applications of GPS or next-generation precision clocks. Furthermore, using instruments developed for gravity measurement, the group will look for signatures of dark matter. Technology and technical expertise developed by this group has applications ranging from industrial metrology to earthquake prediction to preparing the country’s STEM workforce.Modern ideas for unifying gravity and particle physics, as well as the observation of dark energy and dark matter, suggest that some aspects of gravity remain undiscovered. The table-top experiments of the University of Washington gravity laboratory (Eöt-Wash Group) provide a unique opportunity to search for new physics at the intersection of General Relativity, cosmology, and particle physics. The group is a leader in the field of ultra-weak force detection through technical expertise and innovation and by responding to the most relevant timely and timeless physics questions. Specifically, the group will: 1) Test the equivalence principle (EP): It is almost certain that any connection between General Relativity and the Standard Model violates the EP. The group’s torsion balances provided the most precise laboratory EP-tests. With highly increased sensitivity through fused silica torsion fibers, a novel gravity gradient measurement, an improved pendulum and better instrument control, new EP measurements will be carried out that will be up to 15 times more sensitive than the group’s previous measurements in constraining B-L couplings. Furthermore, the EP-test’s generality and relevance to cosmology will be enhanced by probing the EP involving hydrogen-rich test masses. 2) Test Newton's Inverse-Square Law (ISL) at short distances: The group will use its expertise in measuring gravity at short distances to build a new instrument and carry out measurements to test gravity at distances as short as 20 µm. 3) Search for ultra-light dark matter using torsion balances. 4) Advance the frontier of low-frequency ultra-small-force technology: Innovative and challenging technology development has enabled the group’s success. The group will further improve angle measurement and develop interferometric and capacitive distance gauges.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.