\n These constants are \u201cbaked into the fabric of the universe,\u201d Schlamminger said. \u201cIt\u2019s quite beautiful, because they are the same over generations. If you ever talked to an extraterrestrial, they would have the same concept.\u201d\n <\/p>\n
\n For more than 225 years, scientists have tried to measure the gravitational constant, nicknamed Big G. British scientist Henry Cavendish performed the first experiment to measure it in <\/strong>1798, more than <\/strong>a 100 years after Isaac Newton first discovered the force of gravity.\n <\/p>\n \n Scientists have not, however, been able to converge on a measurement with a level of precision comparable to that of constants such as the speed of light (299,792,458 meters per second) or Planck\u2019s constant, which is known to eight decimal places.\n <\/p>\n \n The Committee on Data of the International Science Council, or CODATA, issues recommended values of fundamental physical constants<\/a>. Its recommended numerical value for Big G is a four digit number with a measurement uncertainty of 22 points per million.\n <\/p>\n \n Given that other constants in nature are known to six or more significant digits and are considered exact, this value, he said, is an \u201cembarrassment for the active metrologist,\u201d a scientist who specializes in measurements.\n <\/p>\n \n \u201cIf you had a watch that runs 22 ppm late, you would measure the year 12 minutes too long,\u201d he added.\n <\/p>\n \n The field of metrology \u2014 the science of measurement \u2014 is important, he noted, because it creates trust in science, the economy and trade. \u201cIt is the kind of the science that undergirds a lot of our society, and nobody notices,\u201d he said.\n <\/p>\n \n \u201cWhen you pay your electricity bill, you want to make sure that you pay the right amount, right? There are people who know how to measure voltages and how to measure currents and how to measure power.\u201d\n <\/p>\n \n Gravity is notoriously difficult to measure accurately for three reasons, said Christian Rothleitner, a physicist at Physikalisch-Technische Bundesanstalt, Germany\u2019s National Metrology Institute, who was not involved in the research. First, it is a relatively weak force.\n <\/p>\n \n \u201cWe perceive the force of gravity as a very strong force, as we have to exert a lot of force to lift something up on the earth,\u201d he said via email.\n <\/p>\n \n In reality, he said, it is much weaker than the other three fundamental forces \u2014 electromagnetic, weak nuclear and strong nuclear forces \u2014 which hold atoms and nuclei together.\n <\/p>\n \n \u201cYou can easily see this if you look at a magnet, which is relatively small, but nevertheless exerts a very strong force on magnetic objects.\u201d\n <\/p>\n \n The other reason it\u2019s hard to determine the gravitational constant is that in a laboratory, the masses used in the experiment must fit inside a relatively small, constrained space: \u201cAnd small masses in turn only generate small gravitational forces.\u201d\n <\/p>\n \n What\u2019s more, because the gravitational force is generated by every object, it\u2019s \u201cextremely challenging\u201d to make sure the force you measure in the laboratory really comes from the intended mass.\n <\/p>\n \n \u201cThe problem with the Big G measurements is that the values are all very scattered, so the results of the measurements are not consistent with each other,\u201d Rothleitner said. \u201cThis leaves a lot of room for speculation about the origin of the inconsistency.\u201d\n <\/p>\n \n In more four decades, there have been at least 16 other attempts to measure Big G. Rather than add a new measurement to an already inconsistent dataset, Schlamminger and his colleagues sought to replicate an experiment conducted by the International Bureau of Weights and Measures in S\u00e8vres, France.\n <\/p>\n \n If he could independently produce the same results, the mystery surrounding Big G\u2019s exact value might be solved. \n The experiment relied on a sensitive piece of equipment known as a torsion balance, a device that senses minute forces by measuring the twisting angle, or torsion, of metal masses suspended on a thin fiber, which must be operated in a vacuum. The twist can\u2019t be perceived with the naked eye but can be detected with sensors, allowing the gravitational force to be inferred.\n <\/p>\n \n Over the course of the experiment, Schlamminger spent years calibrating the equipment and troubleshooting the physical effects of characteristics such as temperature and pressure that could confound the measurements to prove these factors weren\u2019t affecting the results.\n <\/p>\n \n Given that the team was replicating a previous experiment, he also took another precaution to avoid any personal bias, conscious or unconscious, that might creep in toward the answer he thought the experiment ought to get, and to prevent him stopping the study too soon.\n <\/p>\n \n A colleague, who wasn\u2019t involved in the work, added a random offset number to the masses to blind Schlamminger to the actual measurement he was taking. This number was kept in a secret envelope hidden from Schlamminger until the work was complete.\n <\/p>\n \n After a honeymoon research period, Schlamminger at times found the work dispiriting. \u201cIt felt to me like it was like a random number generator,\u201d he said. \u201cI felt like I was going to a casino every day to work.\u201d\n <\/p>\n \n The envelope with the secret number was unsealed on a conference stage in July 2024, and Schlamminger and his team finally found out the real results of their work. His initial joy \u2014 the final numerical value for Big G was in the right ballpark \u2014 subsequently soured, and he said he felt a \u201clittle bit unhappy.\u201d\n <\/p>\n \n The team\u2019s measured value of Big G was 6.67387×10-11 cubic meters per kilogram per second squared. The unit reflects distance, mass and motion: how gravity works. It is 0.0235% lower than the result that the researchers had attempted to replicate and at odds with the CODATA figure.\n <\/p>\n \n Schlamminger said that\u2019s a notable difference \u2014 such as measuring the height of a human and being a millimeter or two off. \u201cIt\u2019s small in the grand scheme of things, but it\u2019s pretty embarrassing when it comes to these fundamental concepts,\u201d he said. A scientific paper detailing the work was published April 16 in the journal Metrologia<\/a>.\n <\/p>\n \n Schlamminger\u2019s endeavors may provide scientists with the tools to make precise measurements in other areas involving extremely small forces, said Ian Robinson, a fellow at the National Physical Laboratory in the United Kingdom. Robinson wasn\u2019t involved in the research, although he attended the meeting in which Schlamminger\u2019s data was revealed.\n <\/p>\n \n \u201cSome extremely obscure problems were found, addressed and a new result was produced,\u201d Robinson said\n <\/p>\n \n What might explain the inconsistency in the measurements of Big G?\n <\/p>\n \n It\u2019s possible that there\u2019s something unknown about the universe that could be preventing an accurate value. But while that unknown was an exciting possibility, Schlamminger, Robinson and Rothleitner all said that hypothesis was a stretch.\n <\/p>\n \n \u201cIt is highly unlikely some fundamental physics that we do not understand is causing the discrepancy in the results,\u201d Robinson said. \u201cIt is much more likely that an undiscovered, extremely small and obscure effect, or effects, biased some results.\u201d\n <\/p>\n \n Schlamminger suggested that better engineered equipment could improve the situation or perhaps there was some human error at play. \n \u201c<\/strong>Precision metrology is not merely about converging on a number, it is about the rigorous exposure of unknowns,\u201d his study concluded.\n <\/p>\n \n Schlamminger\u2019s passion for the field remains undiminished. His forearm is tattooed with the numbers in Planck\u2019s constant, which was fixed in 2019 in work that he was involved in.\n <\/p>\n \n Schlamminger said he hoped that young researchers interested in Big G would not be discouraged from taking up the quest. But even if an exact numerical value is found, he would never tattoo Big G: \u201cIt\u2019s too finicky of a number.\u201d\n <\/p>\n![\"Schlamminger](\"https:\/\/www.europesays.com\/uk\/wp-content\/uploads\/2026\/05\/stephan-headshot-final-edit-3.jpg\")
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Nonetheless, he said he did not consider the past 10 years wasted.\n <\/p>\n