In the context of the double-slit experiment, the term "observer" can be somewhat confusing. In quantum mechanics, the act of observation generally refers to any interaction or measurement that causes the quantum system to collapse into a specific state. This collapse is often associated with the detection or measurement of a particle.
In the traditional double-slit experiment, light or particles are passed through two closely spaced slits, creating an interference pattern on a screen. When particles are used, such as electrons or photons, they can exhibit wave-particle duality, meaning they can behave as both particles and waves. When they pass through the slits, they create an interference pattern suggestive of wave-like behavior.
Now, in the context of your question, the human eye itself does not play a direct role as an observer in the double-slit experiment. Rather, the observer typically refers to the measuring or detecting apparatus that records the outcome or presence of the particles.
However, it is worth noting that the detection process, whether it involves the human eye or any other measurement device, can collapse the wave function of the particles. This collapse determines whether the particle is detected at one particular slit or shows an interference pattern. In other words, the act of observation, by any means, influences the behavior of the particles.
It's important to distinguish between the role of the observer in this context and the act of human observation in everyday life. The interpretation and implications of quantum mechanics can be quite complex and are still a subject of ongoing debate among physicists and philosophers.