> <i>“When you see a transmitted photon, you can’t know which of these occurred,” Steinberg says, adding that because photons are quantum particles in the quantum realm, the two outcomes can be in superposition—both things can happen at the same time. “The measuring device ends up in a superposition of measuring zero and measuring some small positive value.” But correspondingly, Steinberg notes, that also means that sometimes “the measuring device ends up in a state that looks not like ‘zero’ plus ‘something positive’ but like ‘zero’ minus ‘something positive,’ resulting in what looks like the wrong sign, a negative value, for this excitation time.”</i>