In quantum mechanics, the term "observer" refers to any physical system or apparatus that interacts with a quantum system and causes its wavefunction to collapse. The act of observation or measurement in quantum mechanics is the process by which a quantum system's properties are determined or become definite.
It is important to note that in the context of quantum mechanics, the term "observer" does not necessarily imply a conscious being or a human observer. The observer can be any physical entity capable of interacting with the quantum system and obtaining information about its properties.
The concept of observation in quantum mechanics is often associated with the measurement process, where the observer interacts with the quantum system, causing its wavefunction to collapse into a specific state. The exact mechanism by which wavefunction collapse occurs is still a topic of debate and interpretation within the field of quantum mechanics.
The role of consciousness in the collapse of the wavefunction is a subject of philosophical and interpretational discussions rather than a settled scientific question. Various interpretations of quantum mechanics, such as the Copenhagen interpretation, propose that the act of measurement or observation by a conscious observer is necessary for wavefunction collapse. However, other interpretations, such as the Many-Worlds interpretation or the decoherence theory, argue that wavefunction collapse occurs due to interactions between the quantum system and its environment, independent of consciousness.
In the mainstream scientific community, the consensus is that quantum mechanics applies universally to all physical systems, regardless of the presence or absence of conscious observers. According to this viewpoint, the behavior of quantum systems can be described and predicted mathematically without invoking consciousness as a fundamental requirement.
In summary, in the context of quantum mechanics, an observer refers to any physical system that interacts with a quantum system and causes wavefunction collapse. While the role of consciousness in wavefunction collapse is a subject of philosophical debate, it is not a necessary condition for the existence of objects or things in the physical world according to our current understanding of quantum mechanics.