At one point in a former life, I was one of the trainers for the incoming helpdesk technicians. One of the practical exams we put them through involved us doing creative things to fuck with their computers before they came to class, and then having them figure out what was wrong and how to fix it. Plugging the mouse from one computer into its neighbor’s USB port and vice versa was one of my favorite tricks. For whatever reason, it had a 100% success rate in effectively fucking with them.
TL;DR: quantum mechanics is freaky. In the double-slit experiment, it was shown that un-observed photons behaved like a wave, interfering with itself (top pic), while observed photons acted like particles (bottom pic). The phenomenon is known as wave function collapse.