We live in a universe we know surprisingly little about. The normal matter we can see—like people, planets, stars, and even peanut butter—accounts for an estimated 20 percent of all the matter in the universe. The remaining approximately 80 percent is called dark matter. We can’t see it and we don’t know what is, yet this ubiquitous substance whizzes through the universe—and us—all the time. So how do we know dark matter exists?
Dark Matter Day, an international event founded in 2017 by Glenn Roberts of Lawrence Berkeley National Lab, aims to shed some light on that mystery. Between October 25 and November 4, a series of Dark Matter Day events in countries around the world will highlight the global search for dark matter, the many fascinating ways scientists search for it, and the importance of devoting scientific resources to unraveling this cosmic riddle. This year’s Dark Matter Day is dedicated to the memory of Glenn Roberts, who passed away earlier this year.
Although scientists haven’t seen dark matter, indirect evidence tells us it exists—in the gravitational pull it has on galaxies and the way light bends around unseen objects in space. Understanding the nature of dark matter could help us better understand the universe in which we live. And if scientists do find the answer, it will raise yet another question: Will the discovery require a complete re-write of our understanding of physics?
A host of innovative experiments are searching for the source of dark matter using different types of tools, such as detectors built deep underground, powerful particle beams, and telescopes located on Earth and in space. For more on the global hunt for dark matter, visit the Interactions Collaboration’s Dark Matter Hub.
Sponsored by the Interactions Collaboration, an international community of particle physics communication specialists, Dark Matter Day celebrates the work being done in laboratories and institutions around the world, and shares what we do know about this cosmic puzzle with audiences worldwide.
To find resources or to register your event, go to the Dark Matter Day website.