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.

现代理论试图弥合所接受粒子物理模型的规模（“标准模型”）的差距，以及重力力变得与自然界中所有其他力一样强的尺度（大约23个尺寸的大小比原子的大小小），预测了牛顿定律在较长长度尺度上对牛顿定律的修改，最高为1mm。 最近，已经设计了几项实验，以在此宏观长度尺度上检测或约束牛顿定律的偏差。在斯坦福大学，我们基于低温探针建立了这样的实验，以测量与20微米阶距离距离分开的质量之间的adtonewton的力。在我们的实验中，低温氦气轴承用于旋转一个圆盘，该圆盘在安装在微机械悬臂上的小测试质量下的驱动质量模式。两者之间的任何质量依赖力都会在测试质量上产生时间变化的力，因此悬臂的时变位移。理论物理学的圣杯是提供一种统一自然力量的紧凑而优雅的理论。尽管充分了解了电磁（电荷颗粒之间的力），强（将核凝聚在一起的力）和弱（与某些核的某些衰减相关的力），但重力的力量，人类可能所经历的第一力，是人类可能经历的第一力，并与其他力统一的力量构成了巨大的知识挑战。 该领域的新理论见解使研究人员有机会通过精确的“桌面”实验来尝试为这一研究领域做出贡献。在斯坦福大学，我们利用了用于物理，化学，材料科学和工程学的先进技术来建立一种可以测量比正常尺度测得的力小的幅度的力量的仪器。设计，构造，测试和使用的挑战是这样的设备，迫使我们提出了许多优雅的工程解决方案。这不仅使从事该项目的学生受益，而且使其他在不同领域工作的研究人员受益。例如，我们为该项目开发的微型悬臂现在被用作测量纳米示例的磁性特性的扭矩磁力仪。在另一个示例中，我们发现在实验中控制旋转转子的速度的解决方案对辐射施加的基本压力定律承担。