The double-slit experiment is indeed a fascinating phenomenon that illustrates the wave-particle duality of particles. The act of observation does have an impact on the experiment, but it is not the act of observation itself that collapses the wave function. The collapse of the wave function occurs when there is interaction or measurement performed on the system.
In the case of the double-slit experiment, when particles (such as electrons or photons) are sent through the double slits, they exhibit wave-like behavior and interfere with each other. This interference pattern can be observed by allowing the particles to pass through the slits and strike a screen or detector placed behind them. The pattern that emerges on the screen is a result of the constructive and destructive interference of the waves associated with the particles.
However, when we introduce an observer or a measurement apparatus to determine which path the particle takes (i.e., which slit it passes through), the situation changes. The measurement process involves interactions between the particles and the measurement apparatus, which disrupts the interference pattern. The act of measurement effectively collapses the wave function of the particles, causing them to behave more like particles rather than waves.
This phenomenon is known as the "observer effect" or "quantum measurement problem." It highlights the intrinsic connection between the act of observation and the wave-particle duality of quantum systems. The observer's involvement disrupts the interference pattern because the particles' wave-like behavior is disturbed by the measurement process itself.
To observe the interference pattern, it is crucial to ensure that the measurement apparatus does not disturb the particles in a way that destroys the interference. Techniques such as weak measurement or delayed choice experiments have been devised to extract information about the path of the particles without fully collapsing the interference pattern. These techniques allow for the observation of both particle-like and wave-like behaviors in the same experiment.
In summary, the observation or measurement in the double-slit experiment disrupts the interference pattern due to the interaction between the particles and the measurement apparatus. However, through specialized techniques, it is possible to extract partial information without completely destroying the interference pattern, allowing us to observe the wave-particle duality in action.