In the context of the double-slit experiment, the act of observation or measurement by a human being does not fundamentally alter the behavior of the particles or the outcome of the experiment.
The crucial aspect to understand is that in quantum mechanics, the act of observation or measurement disturbs the system being observed, leading to wavefunction collapse and the particle behaving like a classical object with definite properties. This collapse occurs regardless of whether the observer is a human or a measuring device.
If a human being were to observe the double-slit experiment, they would interact with the particles in some way, such as detecting or measuring their positions or detecting which slit the particle went through. This interaction causes the wavefunction of the particles to collapse, and the interference pattern on the screen would no longer be observed.
The key point is that the act of observation disturbs the system, leading to the collapse of the wavefunction, regardless of the nature of the observer. Whether it is a human or a measuring device, the outcome of the experiment is determined by the interaction between the observer and the quantum system.
It's worth noting that human observation in the double-slit experiment typically involves macroscopic objects and a large number of particles. Quantum effects are more pronounced at the microscopic level, such as with individual electrons or photons. Nevertheless, the fundamental principle of wavefunction collapse and the disturbance caused by observation apply to any interaction between a quantum system and an observer, regardless of scale.