Cosmology: The strength of gravity is an open question
|June 20, 2014||Posted by News under Cosmology, News, Physics|
Says Ars Technica :
You might expect that, all these years after Newton, we might have a good measure of his gravitational constant, G. As the authors of a new paper on the topic note, there are plenty of reasons to want a good measure of G “given the relevance of the gravitational constant in several fields ranging from cosmology to particle physics, and in the absence of a complete theory linking gravity to other forces.”
Yet most of our measurements of G come from an updated version of a device designed by Henry Cavendish back in the 1700s. And rather annoyingly, these measurements don’t agree with each other—they’re all close to a single value, but their error bars don’t consistently overlap. Now, researchers have made a new measurement of G using a method that certainly wasn’t available in the 1700s: interference between clouds of ultracold atoms. And the value that they have come up with doesn’t agree with many of the other measurements, either. …
A new measuring system may help by providing a different set of experimental errors—facts established slowly by degrees.
Interesting to contrast this with the popular simile: “sure as the law of gravity”
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