Probing Fundamental Physics with Gravitational Experiments

在现代物理学中，用两种理论来描述自然。一种是“标准模型”，用量子粒子描述所有物质的性质；另一种是“广义相对论”，爱因斯坦用来描述引力的理论。大多数物理学家认为这两个理论之间肯定有联系，但到目前为止，还没有实验签名来证明这种联系。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，以寻找广义相对论所描述的前所未有的微小重力偏差。尽管观测到与广义相对论的任何偏离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。该小组开发的技术和技术专长的应用范围从工业计量到地震预测。统一引力和粒子物理的现代思想，以及对暗能量和暗物质的观测表明，广义相对论并不是一个完整的理论，新的超微弱的自然力可能仍未被发现。华盛顿大学重力实验室(EOT-Wash Group)的桌面实验为探索广义相对论、宇宙学和粒子物理学的新物理提供了一个独特的机会。该小组通过技术专长、创新和对最相关、及时和永恒的物理问题的回应，在超弱力探测领域处于领先地位。具体地说，该小组将：1)继续测试等效原理：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。该组织的扭转平衡实验提供了范围从微米到100公里的最精确的EP测试。该集团已将旗舰旋转扭转平衡仪升级为熔融石英扭转纤维，并将进行新的EP测量。2)暗物质唯一已知的相互作用似乎是引力。根据最近的理论建议，暗物质可能是玻色子，粒子质量低至10exp(-22)eV/c2，该小组将通过重新分析档案数据集和收集新的基于超灵敏硅纤维的测量来寻找暗物质证据。3)短距离测试牛顿平方反比定律：EOT-Wash小组在50微米以下的距离测量和测试了重力。该集团将开始另一个测量周期，升级其现有仪器。4)推进低频超小力技术前沿：创新和具有挑战性的技术发展使集团取得了成功。展望未来，该组织将继续致力于低温仪器、光学读取器和二氧化硅光纤的开发。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。

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 gravitation 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. Technology and technical expertise developed by this group has applications ranging from industrial metrology to earthquake prediction. Modern ideas for unifying gravity and particle physics, as well as the observations of dark energy and dark matter, suggest that General Relativity is not a complete theory and that new ultra-feeble forces of nature may remain undiscovered. The table-top experiments of the University of Washington gravity laboratory (Eot-Wash Group) provide a unique opportunity to probe for new physics at the intersection of general relativity, cosmology, and particle physics. The group leads the field of ultra-weak force detection through technical expertise, innovation, and by responding to the most relevant timely and timeless physics questions.Specifically, the group will: 1) Continue to 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 balance experiments provide the most precise EP-tests over ranges between microns and 100 km. The group has upgraded the flagship rotating torsion-balance instrument with a fused silica torsion fiber and will carry out a new EP measurement. 2) Dark matter's only known interaction appears to be gravitational. Following recent theoretical suggestions that dark matter may be bosonic with particle masses as low as 10exp(-22) eV/c2, the group will search dark matter evidence by re-analyzing archival datasets and by collecting new ultra-sensitive silica-fiber-based measurements. 3) Test Newton's Inverse-Square Law at short distances: The Eot-Wash group has measured and tested gravity at distances below 50 microns. The group will begin another measurement cycle with upgrades to its existing instrument. 4) Advance the frontier of low-frequency ultra-small-force technology: Innovative and challenging technology development has enabled the group's success. With a vision towards the future, the group will continue pursuing development of cryogenic instruments, optical readout, and silica fibers.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.