In quantum mechanics, the phenomenon of quantum tunneling refers to the ability of a particle to pass through a classically forbidden barrier, even when it does not possess sufficient energy to overcome that barrier according to classical physics. Quantum tunneling is a fundamental aspect of quantum mechanics and has been observed and confirmed experimentally for microscopic particles such as electrons and atoms.
However, when it comes to macroscopic objects like a tennis ball, the situation is different due to the delicate nature of quantum coherence at larger scales and the interaction of the object with its environment. Quantum coherence, which is necessary for tunneling, is easily disrupted by interactions with the surrounding particles and environmental influences. This process, known as decoherence, rapidly suppresses quantum effects and leads to the emergence of classical behavior.
The phenomenon of quantum tunneling relies on wave-particle duality, where particles are described by wavefunctions that can extend and interfere with each other. For macroscopic objects, the wave nature is typically overwhelmed by the particle-like behavior due to their large mass and interaction with the environment. As a result, the probability of observing macroscopic objects tunneling through barriers is effectively negligible.
While it is theoretically possible to construct scenarios where macroscopic objects are described by coherent states that allow for non-zero probabilities of tunneling, these scenarios are highly impractical and unlikely to occur in reality. The decoherence timescales and the fragility of quantum coherence at macroscopic scales make it virtually impossible to maintain the necessary conditions for macroscopic tunneling to occur.
Therefore, in practical terms, it is not meaningful to claim that a macroscopic object like a tennis ball can quantum tunnel with a non-zero probability under normal conditions. The quantum behavior and tunneling phenomena are typically confined to the microscopic realm, where quantum coherence can be preserved and observed.