Protons spin. It’s an intrinsic property that can affect experiments at accelerators that use beams of protons. Yet flipping proton spins could offer insights into nuclear physics experiments that study the first moments of the universe in a laboratory setting. A new “spin flipper” magnet assembly efficiently reverses the spin direction of protons circulating in the Relativistic Heavy Ion Collider (RHIC). These flips change the particle’s spin with 97 percent efficiency without changing other beam characteristics. This flipping is essential to eliminate systematic errors that might be caused by protons having one spin direction throughout an experiment.