If Extra Dimensions Do Exist, They Must Be Really, Really Small

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Probably not on large scales, according to new research published July 23 in the Journal of Cosmology and Astroparticle Physics. The study found that across vast distances in space, the universe likely operates in just the dimensions we experience on Earth. The results are also helping scientists better understand the puzzling nature of dark energy, the mysterious phenomenon behind the accelerating expansion of the universe.

By Mara Johnson-Groh | SPACE.com

In October 2017, scientists used the Laser Interferometer Gravitational-Wave Observatory (LIGO) to detect a gravitational wave produced in the collision of two neutron stars. Dubbed GW170817, the event was also seen with traditional telescopes, allowing the scientists to simultaneously study the occurrence via gravitational waves and light waves. The dual measurements are allowing scientists to learn all sorts of things about our universe, including how many dimensions it might hold. The new results also offer additional evidence for Albert Einstein’s general relativity. [8 Ways You Can See Einstein’s Theory of Relativity in Real Life]

„General relativity says gravity should be working in three dimensions, and [the results] show that that’s what we see,“ said Kris Pardo, lead author on the study and a doctoral student at Princeton University.

While general relativity has proven so far to be spot-on in describing our universe, there’s one thing it can’t explain very well: why our universe’s expansion is accelerating. Scientists nicknamed the cause for this acceleration „dark energy,“ but no one knows what it is. Some theories modify gravity to explain the expansion, suggesting gravity works differently on large scales. Many of these ideas predict that other dimensions exist, and these could be probed by gravitational waves.

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