Accelerators of even greater energy can break up a proton or other nuclear particles. By measuring position and momentum of the ejected proton and deflected electron, physicists can gain a better understanding of the way the protons are positioned within the nucleus. This description of particle position, the wavefunction of the proton, is currently much better understood outside of the nucleus than within. Teleology aside, the experiment essentially consists of measuring ejected particles. But, we are forced to say that any particle which entered the detector was ejected at exactly 15 .
Life is just full of hard choices.