NSF Ideas Laboratory at NIST: Measuring "Big G" Challenge

牛顿常数G是决定质量之间相互吸引的引力的基本常数。它是迄今为止最不为人所知的自然基本常数。令人不安的是，近几十年来世界各地实验室对G的测量所得到的数值彼此之间的差异远远超过其指定的不确定度。针对这种情况，NIST（美国国家科学技术研究所）将开展为期一周的“创意实验室”，汇集来自广泛科学学科的科学家，探索如何对这一基本常数进行新的明确而准确的测量。这样发展出来的最好的想法将被纳入国家科学基金会预期资助的提案中。随着我们对理论物理的理解的进步，很可能会有一个时刻，一个精确已知的G值将检验那些试图将引力与量子理论统一起来的理论。同时，理解精确和绝对测量微小力的微妙之处对物理学和计量学的许多领域都很重要。事实上，最近测量的G值的不一致表明，从根本上误解用于测量它们的仪器的特性的可能性很小，对这些特性的理解可能对物理理论产生重要影响。2016年7月18日至22日，美国国家科学基金会（NSF）的“创意实验室”——测量“Big G”挑战，将在美国国家标准与技术研究院的盖瑟斯堡设施举行。来自各个科学学科的参与者将共同努力，探索对牛顿基本常数g进行新的明确测量的方法。最有希望的想法将导致向国家科学基金会提出合作建议，以获得资助。最初的NSF资助将涵盖约20名实验室参与者（15名受邀参与者加上5名主任和导师）的注册、旅行和住宿以及注册。这些费用将由加州大学欧文分校管理。

Newton's constant, G, is the fundamental constant which determines the attractive gravitational force between masses. It is by far the least well known of the fundamental constants of nature. Disturbingly, measurements of G in recent decades by laboratories world-wide have yielded numerical values which differ among themselves by far more than their assigned uncertainties. In response to this situation a week-long "Ideas Lab" is to be conducted at NIST (National Institute of Science and Technology) to bring together scientists from a wide range of scientific disciplines to explore ways to make a new definitive and accurate measurement of this fundamental constant. The best ideas so developed will be incorporated in proposals for anticipated NSF funding. As our understanding of theoretical physics advances it is likely that there will come a time when an accurately known value of G will test theories that attempt to unify gravitation with quantum theory. In the meantime, understanding the subtleties involved in precisely and absolutely measuring a small force is important for many fields of physics and metrology. Indeed, the disagreement of recently measured G values suggests the remote possibility of fundamentally misunderstood properties of the instruments used to measure them, whose understanding could have important consequences for physical theories.An NSF "Ideas Lab", Measuring "Big G" Challenge, is to be held July 18-22, 2016 at NIST's Gaithersburg facility. Participants drawn from a wide range of scientific disciplines will work together to explore ways to make new definitive measurements of Newton's fundamental constant G. The most promising ideas will lead to collaborative proposals to NSF for funding. The initial NSF grant will cover registration, travel and lodging for about 20 Lab participants (15 invited participants plus 5 Director(s) and Mentors) and registration. These expenditures will be administered by the University of California, Irvine.