Gravity is often considered the stable, fundamental constant in the universe. It keeps us on the Earth, the Earth around the Sun and everything held together in a tidy package. Or, so Einstein’s Theory of Gravitation says. There are alternative theories out there, and some speculate that gravity might, in fact, vary with the expansion of the universe, or as objects of different densities move around. This idea could fundamentally change our understanding of how the Universe operates.
Astronomers have tested for changes in gravitational forces using an accumulated 21 years of data from a pulsar. The pulsar is known as PSR J1713+0747, and it has a tiny white dwarf. The two objects orbit each other with exceptional predictability, meaning scientists can account for most factors that have altered their orbits for the 21 years of data. This has led astronomers to rule out any changes in the gravitational constant.
Astronomers have used laser ranging studies – bouncing a laser beam between Earth and the Moon, to prove gravity’s consistency locally for years. If gravity was changing, such a dramatic, dense and distance event like a pulsar system would show the effect in a more pronounced manner. In August, the team published the research, combined with the local lunar laser data, in the most definitive proof yet than gravity is truly a constant everywhere.
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