In the context of quantum mechanics, macroscopic objects, such as everyday objects or volumes, are typically treated as classical systems rather than quantum systems. This is because macroscopic objects generally consist of an extremely large number of particles (atoms or molecules) that interact with each other and their environment in complex ways. As a result, the quantum mechanical behavior of individual particles becomes negligible on macroscopic scales, and classical mechanics provides an accurate description of their behavior.
Quantum mechanics is primarily relevant and noticeable at the microscopic scale, where individual particles or systems composed of a few particles exhibit quantum phenomena like superposition and entanglement. In such cases, the wave-like nature of particles becomes significant, and their behavior is described by quantum mechanical principles.
While it is theoretically possible to construct quantum models of macroscopic objects, the computational complexity involved in simulating and manipulating such systems quickly becomes impractical. The interactions and entanglement of a large number of particles make it challenging to maintain and control quantum coherence, which is necessary for quantum effects to manifest.
However, there are some exceptions where macroscopic systems can exhibit quantum behavior under carefully controlled conditions. These are known as macroscopic quantum phenomena. Examples include superconductivity, where large numbers of electrons can flow coherently without resistance, and Bose-Einstein condensates, where a large number of atoms occupy the same quantum state. In these cases, quantum effects emerge on a macroscopic scale due to specific collective behaviors of particles.
In summary, while macroscopic objects are typically treated classically due to the overwhelming number of particles involved and the dominance of classical interactions, there are rare cases where macroscopic quantum phenomena can be observed under specific conditions.