Decoherence is a process in which quantum systems interact with their environment, leading to the suppression of quantum interference effects and the emergence of classical-like behavior. In the presence of strong decoherence, the quantum properties of subatomic particles can indeed become difficult to observe or manifest at macroscopic scales. However, it does not mean that particles always behave strictly classically in the real world.
While decoherence can dampen quantum effects, it doesn't completely eliminate them. Even in the presence of decoherence, quantum properties can still influence the behavior of particles and systems, especially in specific circumstances or under controlled conditions. Moreover, there are experimental setups and systems where quantum coherence and quantum behavior can be maintained or effectively isolated from the environment, allowing for the observation of quantum phenomena.
It's important to note that the boundary between classical and quantum behavior is not always well-defined. The transition from quantum to classical behavior is a complex and fascinating area of research known as quantum-classical correspondence. In certain macroscopic systems, classical behavior emerges as a result of the collective behavior of a large number of quantum particles, even though the individual constituents are fundamentally quantum.
While the influence of decoherence can make quantum effects less apparent in everyday macroscopic objects, at the microscopic level, such as with individual atoms, molecules, or subatomic particles, quantum behavior and the superposition principle remain crucial and are experimentally observed.