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Physicists Measure Gravity With Record Precision (gizmodo.com)
An anonymous reader quotes a report from Gizmodo: A team of scientists in China are reporting that they have now performed the most precise measurement of gravity's strength yet by measuring G, the Newtonian or universal gravitational constant. G relates the gravitational attraction between two objects to their masses and the distance between them. The new measurement is important both for high-powered atomic clocks as well as the study of the universe, earth science, or any kind of science that relies on gravity in some way. The values measured by the team "have the smallest uncertainties reported until now," according to the paper published in Nature.
In the new study, scientists performed two independent calculations of G using a pair of pendulums in a vacuum, one pendulum setup for each test. Each pendulum swings back and forth between a pair of massive objects whose positions can be adjusted. The pendulums measure the force of gravity in two ways. First, they measure the difference between how quickly the pendulum swings to the "near," or parallel position, versus the "far," or horizontal position. They also measure how the direction of the pendulum's swing changes based on the pull of the test masses. The researchers ended up measuring 6.674184 and 6.674484 hundred billionths (10-11) for the time-of-swinging and angular acceleration methods, respectively. These measures were both very precise, but are still different from one another for unknown reasons. This might have had something to do with the string used for the pendulum. The paper's reviewer, Stephan Schlamminger from the National Institute of Standards and Technology, wrote in a commentary: "Li et al. carried out their experiments with great care and gave a detailed description of their work. The study is an example of excellent craftsmanship in precision measurements. However, the true value of G remains unclear. Various determinations of G that have been made over the past 40 years have a wide spread of values. Although some of the individual relative uncertainties are of the order of 10 parts per million, the difference between the smallest and largest values is about 500 parts per million."
In the new study, scientists performed two independent calculations of G using a pair of pendulums in a vacuum, one pendulum setup for each test. Each pendulum swings back and forth between a pair of massive objects whose positions can be adjusted. The pendulums measure the force of gravity in two ways. First, they measure the difference between how quickly the pendulum swings to the "near," or parallel position, versus the "far," or horizontal position. They also measure how the direction of the pendulum's swing changes based on the pull of the test masses. The researchers ended up measuring 6.674184 and 6.674484 hundred billionths (10-11) for the time-of-swinging and angular acceleration methods, respectively. These measures were both very precise, but are still different from one another for unknown reasons. This might have had something to do with the string used for the pendulum. The paper's reviewer, Stephan Schlamminger from the National Institute of Standards and Technology, wrote in a commentary: "Li et al. carried out their experiments with great care and gave a detailed description of their work. The study is an example of excellent craftsmanship in precision measurements. However, the true value of G remains unclear. Various determinations of G that have been made over the past 40 years have a wide spread of values. Although some of the individual relative uncertainties are of the order of 10 parts per million, the difference between the smallest and largest values is about 500 parts per million."
Your mama's so fat, she emits Hawking radiation.
Correct, in the same sense that an object's desire to release phlogiston causes it to catch fire.
Thanks for this... my daughter has officially added this to her arsenal of mamma jokes that only a handful of people understand.
I will admit though, she already had :
"Your mamma's so fat that her spiritual guide refers to her aura as an event horizon"
How do you explain a helium balloon's desire to move upward?
Well, it's got Helium inside instead of gravity. Duh.
6.674184×10^-11 and 6.674484×10^-11
This kind of cryptic number stuff isn't suitable for a mainstream news site like this.
CLI paste? paste.pr0.tips!
Tea is from China and Tea is the drink of the gods, second only to mead.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
So Newton managed to get his name used for the unit of force, Joule for energy, etc. They at most one unit each. Until Planck comes along and somehow gets his name stamped on units for length, mass, time and according wikipedia pretty much all the others too. The man's a branding genius!
Electrons exist. So do positions. So do all other leptons.
Remember a world without autocorrect? Peppermint Farm remembers.