A careful analysis of 10 years of data collected from the Collider Detector at Fermilab (CDF) reveals the most precise mass measurement yet of the W boson, a force-carrying particle related to the weak nuclear force. The CDF team measures the W boson to be much more massive than what physicists predict based on the Standard Model — physicists’ current understanding of subatomic particles and their interactions. If confirmed, the discrepancy could indicate the presence of a new particle or interaction currently unknown to physicists. In this special session, a leader of the CDF collaboration will present the new results.