In the macroscopic world, quantum tunneling of macroscopic objects through a barrier is highly improbable due to a phenomenon known as decoherence. Decoherence refers to the interaction of a quantum system with its environment, which leads to the loss of coherence and the suppression of quantum effects on macroscopic scales.
When a macroscopic object, such as an atom or a subatomic particle, interacts with its surroundings, the quantum superposition of its wavefunction is disrupted. This interaction with the environment causes the quantum state to rapidly decohere and collapse into a classical state, following the principles of classical physics.
The environmental interactions that contribute to decoherence can include interactions with photons, other particles, or even thermal effects. These interactions introduce random and uncontrollable phases and perturbations to the system, making it highly unlikely for the entire object to tunnel through a macroscopic barrier simultaneously.
As a result, the probability of macroscopic objects quantum tunneling through a barrier is essentially negligible in everyday circumstances. The wave-like behavior and quantum tunneling effects are typically observable only on microscopic scales or in carefully controlled experimental setups, where decoherence effects can be minimized or isolated.
However, it is worth noting that quantum tunneling can still occur for individual particles within macroscopic objects, and there can be non-zero probabilities associated with their tunneling through a barrier. The key distinction is that for the entire macroscopic object to tunnel coherently, overcoming the decoherence effects becomes highly improbable due to the large number of interacting particles involved.