When testing gravity, no news is good news

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Looking for nothing to test gravity

When they look for violations of Einstein’s general relativity, physicists deliberately plan experiments to find nothing at all.

For Symmetry Magazine:

In 1887, physicists Albert Michelson and Edward Morley performed one of physics’ most famous experiments (at Case Western Reserve University, coincidentally, across the street from where this article was written). Unlike other important experiments, they didn’t find what they were looking for, but unexpectedly their “null” result prepared the way for the theory of relativity.

Sometimes researchers deliberately set out to generate null results—while on the lookout for something new. One type of experiment is looking for deviations from Einstein’s general theory of relativity.

“General relativity has been the staple of gravitational understanding for 100 years,” says Katie Chamberlain, a physics student at Montana State University. “We have to rule out the potential for other existing theories to come in and replace [it].”

[Read the rest at Symmetry Magazine]

Looking for the fifth dimension with wrinkles in spacetime

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Are We Closer to Finding a Fifth Dimension?

For The Daily Beast:

In Madeleine L’Engle’s classic novel A Wrinkle in Time, the characters travel from one place to another in space using a hidden fifth dimension, which they use to “wrinkle” the fabric of space and time. In the book and upcoming movie, this travel is more mystical than it is science. However, some scientists think there might be extra dimensions beyond the four (three space plus one time) that we’re familiar with—and those dimensions might affect the way gravity works.

But how can we know for sure? One way to check uses the collision of two neutron stars, as detected by the gravitational wave observatories LIGO and Virgo in 2017.

While they found no sign of a fifth (or sixth or seventh or…) dimension, researchers—who recently posted their work on the website arXiv—were excited.

That’s because looking for extra dimensions is difficult. We only see three dimensions in space (length, width, and depth) and one in time on the scale of the everyday; if a fifth dimension exists, it has to be hiding from us. That pushes any detectable consequence into the realm of the very small—the regime of particle physics and string theory—or the very large, where LIGO and other astronomical measurements come in.

[Read the rest at The Daily Beast]