To solve a long-standing puzzle about how long a neutron can “live” outside an atomic nucleus, physicists entertained a wild but testable theory positing the existence of a right-handed version of our left-handed universe. They designed a mind-bending experiment at the Department of Energy’s Oak Ridge National Laboratory to try to detect a particle that has been speculated but not spotted. If found, the theorized “mirror neutron” — a dark-matter twin to the neutron — could explain a discrepancy between answers from two types of neutron lifetime experiments and provide the first observation of dark matter.

Nine seconds. An eternity in some scientific experiments; an unimaginably small amount in the grand scheme of the universe. And just long enough to confound nuclear physicists studying the lifetime of the neutron.

At Oak Ridge National Laboratory in eastern Tennessee, physicist Leah Broussard is trying to open a portal to a parallel universe.

Leah Broussard, a physicist at the Department of Energy’s Oak Ridge National Laboratory, has so much fun exploring the neutron that she alternates between calling it her “laboratory” and “playground” for understanding the universe.