A history of dark matter

Enlarge / The Bullet Cluster, which has been viewed as a demonstration of dark matter. (credit: APOD)

Across decades, the hunt for a dark matter particle has looked at many possible solutions—but so far, humanity hasn’t produced a clear answer. Is dark matter a neutrino? An axion? A figment of our imagination? Scientists don’t agree, though experiments from XENON to ADMX continue to strive towards giving us an answer.

“We have to be extremely open-minded about what it might be,” James Bullock, a professor of physics and astronomy at UC Irvine, told Ars. “Dark matter could be even more interesting than we were thinking it was going to be 20 or 30 years ago.”

The built-up confusion surrounding dark matter today can be extremely hard to parse. Recent headlines declared dark matter may not even exist, and even dedicated followers could be forgiven for asking how scientists came up with the idea in the first place. So to better understand dark matter’s place in the Universe, it may be helpful to take a look back at how our ideas about this mysterious material started and evolved over time—it's time to traverse a condensed history of dark matter.