The claim that macroscopic objects, such as tennis balls, do not exhibit quantum phenomena like quantum tunneling is based on several factors and arguments. While it is challenging to provide an absolute certainty in such claims, physicists generally make these assertions based on the following considerations:
Decoherence: Macroscopic objects are subject to interactions with their environment, which can lead to the phenomenon of decoherence. Decoherence refers to the rapid and irreversible loss of quantum coherence in a system due to its interactions with the surrounding environment. The interaction with the environment causes superpositions to "collapse" into classical states, effectively suppressing quantum behavior. As a result, macroscopic objects are believed to undergo rapid decoherence, making quantum tunneling effects highly unlikely.
Interaction with Many Degrees of Freedom: Macroscopic objects consist of an enormous number of particles and degrees of freedom, making their behavior highly complex and difficult to describe in terms of quantum mechanics. The sheer number of particles involved and their interactions with each other and the environment make it impractical for quantum effects to manifest on a macroscopic scale.
Experimental Observations: Quantum tunneling has been extensively studied and experimentally observed in systems involving particles with much smaller masses, such as electrons and atoms. On the other hand, direct experimental evidence of quantum tunneling in macroscopic objects is lacking. The absence of empirical observations supporting macroscopic quantum tunneling suggests that the phenomenon is highly unlikely in such objects.
It is important to note that these arguments are based on our current understanding of quantum mechanics and the behavior of macroscopic objects. However, research in this area is ongoing, and future discoveries may challenge or refine these assertions. As of now, the consensus among physicists is that macroscopic objects do not exhibit quantum tunneling due to the factors mentioned above.