Tests of Gravity Below the 50-micron Distance Scale
Tests of Gravity Below the 50-micron Distance Scale
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50 微米距离尺度以下的重力测试
DOI：
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
H. Leopardi
中科院分区：
文献类型：
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作者：
D. Smith;C. Hoyle;H. Leopardi
300多年前，引力是第一个被数学描述的力；然而，它仍然是目前唯一不被很好地理解的基本力。另外三个已知的基本相互作用在量子力学的标准模型中得到了成功的描述。然而，爱因斯坦成功的引力理论--广义相对论--与这个模型根本不一致。在微小但可测量的距离研究引力的动机源于探索新理论的愿望，这些理论试图将重力纳入一个包括所有四个基本相互作用的一致框架中。这样的模型，包括弦理论的版本，表明我们的宇宙包含了超出观察到的三个空间维度的“额外维度”。在亚毫米的距离内，这些额外的维度可能会改变引力平方反比定律。与暗能量有关的理论也表明，在亚毫米距离观察时，引力的行为可能会从根本上不同。暗能量是一种未知的现象，有助于加速我们的宇宙膨胀。此外，对弱等价原理(WEP)的违反，这是广义相对论的一个中心特征，可能表明弦理论预测的未发现的奇异粒子。与其他基本力相比，重力非常弱，这使得实验室测试平方反比定律和WEP变得困难。这样的测试需要高精度的技术。在洪堡州立大学，我们正在探索低于50微米距离的前所未有的重力性质。利用一种新型的平行板扭转摆，当吸引子质量在附近振荡时，我们测量了摆的扭转度，为摆提供了一个可测量的、时变的扭矩。这种扭矩幅度的大小和距离依赖性提供了在未经测试的距离尺度上搜索偏离广义相对论的方法。本报告将重点介绍该实验室的现状和最新成果，包括设计一种新的钟摆，专门用于世界领先的WEP短程测试。
The force of gravity was the first to be mathematically described over 300 years ago; however, it remains the only fundamental force that is not currently well understood. Three other known fundamental interactions are successfully described within the Standard Model of quantum mechanics. Einstein’s successful theory of gravitation, General Relativity, however, is fundamentally inconsistent with this model. The motivation to study gravity at small but measurable distances arises from the desire to probe new theories that are attempting to include gravity in a consistent framework that includes all four fundamental interactions. Such models, including versions of String Theory, suggest that our universe contains “extra dimensions,” beyond the three observed spatial dimensions. At sub-millimeter distances these extra dimensions may alter the gravitational inverse-square force law. Theories involving Dark Energy, an unknown phenomenon contributing to the acceleration of our universe’s expansion, also indicate that gravity may behave fundamentally differently when observed at sub-millimeter distances. Furthermore, a violation of the Weak Equivalence Principle (WEP), a central feature of General Relativity, may indicate undiscovered exotic particles predicted by String Theory. Gravity is incredibly weak compared to the other fundamental forces, making laboratory tests of the inverse-square law and WEP difficult. Such tests require highprecision techniques. At Humboldt State University, we are exploring the nature of gravity at unprecedented levels below the 50-micron distance scale. Using a novel parallel-plate torsion pendulum, we measure the pendulum’s twist while an attractor mass is oscillated nearby, providing a measurable, time-varying torque on the pendulum. The size and distance dependence of this torque amplitude provide means to search for deviations from General Relativity on untested distance scales. This presentation will focus on the current status and recent results from the laboratory, including the design of a new pendulum devoted to world-leading, short-range tests of the WEP.