Here are a few random thoughts on the interpretations of the quantum double slit experiment, the Mach Zehnder experiment, the delayed-choice experiment and the measurement problem.
In the 17th century, there existed two theories of light, namely, the wave theory of Huygens and the corpuscular theory of Newton. At the beginning of 19th century Thomas Young demonstrated the wave character of light using diffraction experiments. James Clerk Maxwell developed his electromagnetic wave equation and showed that light is an electromagnetic wave. This chapter considers a Mach–Zehnder interferometer experiment, an equivalent experiment of the double slit experiment. To test whether light priorily get the information about the experimental set up in the double slit experiment John Archibald Wheeler proposed a gedanken delayed-choice experiment with the Mach–Zehnder interferometer. This thought experiment was then realized experimentally using various systems. An experiment was proposed to observe simultaneously both particle and wave character of the quantum through quantum entanglement. In quantum mechanics the relative temporal order of measurement of events is not relevant.