When Colin Hill found himself bored on winter break from Princeton University in late 2013, he decided to search through old cosmology papers. (Grad students are fun like that.) He saw one that sparked an idea: Now that telescopes are so sensitive, could we learn anything new about missing matter by comparing the latest maps of galaxies with traditional records of the universe’s oldest light?
Over the next few days, Hill worked through a quick analysis. It looked like he might be on to something. He returned to campus in January and sat down with his thesis adviser, David Spergel, and others to dig deeper on this map comparison. After finishing up — and triple-checking every step — they could do something no one had done before: reliably account for all of the normal matter in the universe.
