Exploring a Frontier of Experimental Gravitation

探索实验引力的前沿

• 批准号: 9970987
• 负责人: Eric Adelberger
• 金额: $ 107.84万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-08-01 至 2005-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9970987&HistoricalAwards=false
• 关键词: Exploring; Frontier; Experimental; Gravitation

The Universality of Gravitational Free Fall, the underlying symmetry of general relativity (Einstein's theory of gravity), will be tested with unprecedented precision and generality. There are two strong reasons for testing this symmetry. First, general relativity is not a quantum theory and current ideas about quantum gravity naturally produce violations of the Universality of Free Fall that may be experimentally accessible. Discovery of such fields would have profound consequences for our understanding of gravity and perhaps of cosmology. Second, by searching for violations of a symmetry that general relativity holds to be exact, one can probe for new, ultra-weak, non-gravitational fields. Current ideas in cosmology suggest that much of the energy in the universe may be tied up in such fields. Although such ultra-weak fields would normally be obscured by gravitational forces, they are detectable because they generically violate the Universality of Free Fall. The proposed tests require the continued improvement of instruments for detecting tiny differences in the accelerations of test bodies attracted toward the earth, the sun, large-scale cosmological structures, or toward a massive uranium laboratory source. The test bodies include Be, Al, Ti, Cu, Pb, plus bodies having compositions close to the earth's core and the moon respectively. Three different torsion-balance instruments, initially developed under previous NSF support, will be upgraded and employed in this work. The combination of these instruments will test the Universality of Free Fall for Yukawa length scales from 1 cm to infinity with differential acceleration resolutions down to 10-13 cm/s2. The torsion balance instruments will be adapted to probe for spin-dependent forces by using an electron-spin polarized pendulum and attractor. In addition, the Newtonian constant G will be measured using a new technique that avoids important sources of error in previous measurements. Recent results for G have scattered widely, demonstrating the necessity of several independent measurements of this fundamental constant. The technique should be capable of determining G to a precision of 1 part in 105.

引力自由落体的普遍性，广义相对论（爱因斯坦的引力理论）的基本对称性，将以前所未有的精度和普遍性进行测试。 检验这种对称性有两个强有力的理由。 首先，广义相对论不是一个量子理论，目前关于量子引力的想法自然会产生对自由落体普适性的违反，这可能是实验上可以达到的。 发现这样的场将对我们理解引力，甚至宇宙学产生深远的影响。 第二，通过寻找广义相对论认为精确的对称性的破坏，人们可以探索新的、超弱的、非引力场。 目前宇宙学的观点认为，宇宙中的大部分能量可能都集中在这些领域。 虽然这种超弱场通常会被引力所掩盖，但它们是可以探测到的，因为它们通常违反了自由落体的普遍性。拟议中的试验需要不断改进仪器，以检测被吸引到地球、太阳、大规模宇宙结构或大规模铀实验室源的试验物体加速度的微小差异。 测试体包括Be、Al、Ti、Cu、Pb，以及分别具有接近地核和月球的成分的体。 三种不同的扭转平衡仪器，最初开发的NSF支持下，将升级和采用这项工作。 这些仪器的组合将测试Yukawa长度尺度从1 cm到无穷大的自由落体的普遍性，差分加速度分辨率低至10-13 cm/s2。 扭转平衡仪器将适用于通过使用电子自旋极化摆和吸引子来探测自旋相关力。 此外，牛顿常数G将使用一种新技术来测量，该技术避免了以前测量中的重要误差来源。 最近的结果G分散广泛，证明了几个独立的测量这个基本常数的必要性。 该技术应该能够确定G的精度为1/105。