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Dark Energy

The mysterious, repulsive force known as dark energy is one of the newest yet most important scientific challenges in modern science. It makes up roughly 70 percent of the universe’s content, and discovering its nature is a sizable pursuit at CCAPP.

Based on Einstein’s so-far reliable general theory of relativity—which predicted gravity would eventually slow the expansion of the universe that began with the Big Bang—astronomers in the 1990s looked at supernovae to compare the universe’s current and past rates of expansion. To the world’s surprise, however, they discovered that not only was the expansion not slowing down, it was actually accelerating.

Some unknown force in the universe, it would seem, has been countering gravity’s attractive pull for the last five billion years or so and forcing the universe’s expansion to speed up.

Ohio State astronomers and physicists have been at the forefront of research to figure out what that unknown force is, and through an unprecedented joint approach became key participants together in the Dark Energy Survey. Since then, CCAPP’s scientists have played a leadership role in every aspect of dark energy research—serving as project scientist for the Sloan Digital Sky Survey; writing DES theory white papers; building instruments for BOSS, DES and DESI; publishing the first paper using DES data and more.

In addition to partnering with scientists from other elite institutions on DES, SDSS and other international mapping projects, CCAPP faculty, postdoctoral fellows and graduate students have made discoveries about dark energy with other resources as well. Using the NASA-ESA Hubble Space Telescope and Ohio State’s share in the Large Binocular Telescope, for example, they have used measured lensing signals from galaxy clusters to determine their properties and better understand the history of the universe and its increasing pace of expansion.

The search for dark energy has proven useful to other types of research, too. DES has discovered new supernovae and quasars, and its colored views have helped confirm ASAS-SN observations.

While no one knows yet what dark energy is or is caused by, all evidence and data suggest it is a real phenomenon. Much like scientists predicted the existence of the Higgs boson, Ohio State researchers expect that dark energy research will reveal a new particle or symmetry, a new energy component or the breakdown of general relativity, even a new kind of physics.

Whatever it is, the discovery will be big.