The Gravitational Constant: Theory and Experiment 200 Years After Cavendish

摘要: Conference on The Gravitational Constant: Theory and Experiment 200 Years After Cavendish (23-24 November 1998, Institute of Physics, Portland Place, London, UK) This conference was held to mark the bicentenary publication Cavendish's determination Newton's constant gravitation. aims were to: (i) assemble key workers in field, give them an opportunity present their latest results for G discuss planned experiments (ii) current status physical theory (iii) celebrate torsion balance as a detector gravitational recent innovations weak-force detection (iv) achievement Right Honourable Henry Cavendish, who founded this field research years ago. attended by some forty-five people, three-quarters whom from outside UK. participants came eleven countries around globe, representing practically whole international community now engaged upon measurements G. As far we know, first that has ever been dedicated measurement constant. We, organizers, delighted all researchers supported event most cases made substantial effort attend. We believe that, thanks efforts, these proceedings represent accurate complete picture work research. must add, however, reported here are nearly still progress; given preliminary likely be much improved over next year or two. Indeed, at end it agreed another similar meeting would useful two three years' time. programme comprised 14 invited papers seven contributed papers. appear first, followed papers, specially section issue Measurement Science Technology. modern interpretation mean density Earth is precise gravitation, uncertainty achieved his experiment about 5%. Today, hundred after pioneering work, CODATA Task Group Fundamental Constants envisaging 0.15% its 1999 evaluation accuracy our knowledge thus advanced rate less than one order magnitude per century, which painfully slow comparison with progress determining other constants. Table 1. Values entries table included illustrate disparity results. All described proceedings. Figure At conference, six groups announced new These values 1 illustrated figure 1, together 1986 value. provoked flurry activity inclusion result Physikalische-Technische Bundesanstalt (PTB), Germany, (Michaelis et al 1995), original Standards Laboratory (MSL), New Zealand, (Fitzgerald Armstrong 1995). Gillies presents excellent review prior conference. unweighted presented 6.6772 × 10-11 m3 kg-1 s-2, 840 parts million (ppm). ensemble therefore agrees value within uncertainty, diversity methods employed, provides reassurance remains robust estimate PTB intriguing mystery. It worth noting determinations Gundlach, Newman Ni, leads us expect uncertainties level few ppm years. A highlight Damour's presentation theorists' view role fascinating exposition attempts construct theories welcome gravitation into fold quantum theories. One left tantalising hope rest physics will finally appreciate relevance not-too-distant future. balance, developed popular choice physicists. However, interesting note even years, promising being made. For example, Luther development bifilar suspension G, Richman made, time, using torsion-strip balance. aimed eliminating anelastic effects traditional fibre. Our understanding phenomenon progressed significantly past decade so. Speake gave overview topic, also Kuroda's talk absence. Isobel Falconer offered spellbinding insight both psyche formidable scientific achievements Cavendish. organisers, conference's efforts concerned culminated occasion worthy commemoration remarkable man measurement. References [1] Michaelis W, Haars H Augustin R 1996 Metrologia 32 267-76 [2] Fitzgerald 1995 Bull. Am. Phys. Soc. 40 975