Physics has a bit of a messy problem: There's matter missing in our universe. Something is there that we can't see but can detect! What could this mysterious substance be? A lot of astronomers are searching for the answer. And some, like theoretical particle physicist Chanda Prescod-Weinstein, think a hypothetical particle called the axion may make this problem a little ... tidier. That's right: hypothetical. Scientists have never seen one, and don't know if they exist. So today, we point our cosmic magnifying glasses towards the axion and ask how scientists could find one — and if it could be the neat solution physicists have been searching for. Help shape the future of Short Wave by taking our survey: npr.org/shortwavesurveyListen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave.Learn more about sponsor message choices: podcastchoices.com/adchoicesNPR Privacy Policy