Search for Deviations from Newtonian Gravity at Micron Scale (A Continuation Proposal)

寻找微米尺度上牛顿引力的偏差（延续提案）

• 批准号: 1205236
• 负责人: Aharon Kapitulnik
• 金额: $ 66万
• 依托单位: Stanford University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-15 至 2015-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1205236&HistoricalAwards=false
• 关键词: Search; Deviations; Newtonian; Gravity; Micron

Modern theories attempt to bridge the gap between the scale of the accepted model for particle physics (the 'Standard Model'), and the scale at which the force of gravity becomes as strong as all other forces in nature (about 23 orders of magnitudes smaller than the size of an atom), predicting modifications to Newton's law at much longer length scales, up to 1mm. Recently, there have been several experiments designed to detect or constrain deviations from Newton's law at this macroscopic length scale. At Stanford we have built such an experiment based on a low temperature probe to measure forces as low as attoNewton between masses separated by distances on the order of 20 micrometers. In our experiment a cryogenic helium gas bearing is used to rotate a disc containing a drive mass pattern of alternating density under a small test mass mounted on a micromachined cantilever. Any mass-dependent force between the two will produce a time-varying force on the test mass, and consequently a time-varying displacement of the cantilever. The holy grail of theoretical physics is to provide a compact and elegant theory that unifies all forces of nature. While the Electromagnetic (force between charged particles), Strong (force that holds the nucleus together), and Weak (force associated with certain decays of nuclei) forces are well understood, the force of gravity, the first force that human beings probably experienced, is poorly understood, and unifying it with the other forces poses an enormous intellectual challenge. The new theoretical insight in this field gave researchers an opportunity to try and contribute to this field of research through precision, 'table-top' experiments. At Stanford University we utilized advanced techniques used in physics, chemistry, materials science, and engineering to build an apparatus that can measure forces that are more than twenty orders of magnitudes smaller than the force measured by a normal scale. The challenge to design, to construct, to test, and to use in a real experiment such an apparatus forced us to come up with many elegant solutions to engineering problems. This benefitted not only the students working on the project, but also other researchers working in different fields. For example, the miniature cantilevers that we developed for the project are now being used as torque magnetometers for measuring magnetic properties of nano-samples. In another example, a solution we found for controlling the speed of a spinning rotor in our experiment bears on a fundamental physics law of pressure exerted by radiation.

现代理论试图弥合公认的粒子物理模型（“标准模型”）的规模与重力变得与自然界中所有其他力一样强的规模（大约小 23 个数量级）之间的差距。比原子的大小），预测在更长的长度尺度（高达 1 毫米）下牛顿定律的修改。 最近，已经有一些实验旨在检测或限制在这种宏观长度尺度上对牛顿定律的偏差。在斯坦福大学，我们建立了这样一个基于低温探针的实验，用于测量相距 20 微米量级的质量之间低至阿托牛顿的力。在我们的实验中，低温氦气轴承用于在安装在微机械悬臂上的小测试质量下旋转包含交替密度驱动质量图案的圆盘。两者之间任何与质量相关的力都会在测试质量上产生随时间变化的力，从而产生悬臂随时间变化的位移。理论物理学的圣杯是提供一个紧凑而优雅的理论来统一所有自然力。虽然电磁力（带电粒子之间的力）、强力（将原子核结合在一起的力）和弱力（与原子核的某些衰变相关的力）已被很好地理解，但重力是人类可能经历的第一种力，人们对其知之甚少，将其与其他力量统一起来构成了巨大的智力挑战。 该领域的新理论见解为研究人员提供了通过精确的“桌面”实验尝试并为该研究领域做出贡献的机会。在斯坦福大学，我们利用物理、化学、材料科学和工程学领域的先进技术建造了一种设备，可以测量比正常规模测量的力小二十多个数量级的力。设计、建造、测试和在实际实验中使用这样的设备所面临的挑战迫使我们针对工程问题提出许多优雅的解决方案。这不仅使从事该项目的学生受益，也使不同领域的其他研究人员受益。例如，我们为该项目开发的微型悬臂梁现在被用作扭矩磁力计，用于测量纳米样品的磁性。在另一个例子中，我们在实验中发现了一种控制旋转转子速度的解决方案，该解决方案与辐射施加压力的基本物理定律有关。