The new experimental observations, published in November, 2022 in Nature, joined related surprising results from 2021 in deepening a 35-year-old mystery about the internal structure of the proton. Protons, neutrons and electrons are the basic constituents of all matter. Scientists have known from observations since the 1930's that protons have some sort of internal structure, but have long struggled to understand what that structure is. The widely-accepted current model, first formulated in 1964, describes protons as each made up of three "quarks"?"hypothetical point-particles that only exist inside protons. While popular in the field, the model has not been able to predict key properties of protons, especially their ability, together with neutrons, to hold the nuclei of atoms together through the nuclear force. It is this nuclear force that gives rise to fusion reactions and fusion energy.