According to our current understanding of quantum mechanics, it is extremely unlikely for a macroscopic object, such as a tennis ball, to spontaneously exhibit quantum coherence on a macroscopic scale at ordinary room temperature. Quantum coherence refers to a state where all the constituent particles of a system are in a superposition, meaning they exist in multiple states simultaneously.
The phenomenon of quantum coherence is typically observed at the microscopic scale, where individual particles like electrons or photons can exhibit wave-like behavior and be in superposition states. However, as the number of particles in a system increases, the delicate quantum states become more susceptible to environmental interactions and decoherence. Decoherence occurs when the system interacts with its surrounding environment, leading to the loss of quantum coherence and the emergence of classical behavior.
Macroscopic objects, such as tennis balls, are composed of an incredibly large number of particles and are subject to a wide range of environmental interactions and thermal effects. These interactions cause rapid decoherence, effectively destroying any quantum superpositions and leading to classical behavior.
While it is theoretically possible to engineer systems in highly controlled environments, such as ultra-cold temperatures or isolated from external influences, where macroscopic objects may exhibit coherent behavior for short periods, achieving and maintaining coherence on a macroscopic scale in typical room-temperature conditions is extremely challenging and has not been observed in practice.