Original sentence: According to Bohr's complementarity principle, light and matter are neither a wave nor a stream of particles.During an observation, the system must interact with a laboratory device.Nothing can be said about a single detection, but the statistical probabilities for the detection of large numbers of processes is quantifiable and defined by the wavefunctions.The Born rule: the wave function of a system yields probabilities for the outcomes of measurements for that system.The electron or photon wave is initially coherent at the two slits, but If the electron or photon is detected at one or other slit, the coherence is lost so there is no interference.There are several ways to interpret the dual-slit experiment in terms of the Copenhagen interpretation, which differ slightly in terms of their philosophical implications but follow the same mathematics:.When that device makes a measurement, the wave function of the system collapses
Edited sentence: The particles are discrete and identical; many are needed to build up the full interference pattern.The results from the most basic double slit experiment, the observation of an interference pattern, is explained by wave interference from the two paths to the screen from each of the two slits.The results from the which-way experiments are described as observations of complementarity: modifying the experiment to monitor the slit suppresses the interference pattern.The single-particle results show that the waves are probability amplitudes which square to produce a probability distribution