The phenomenon of quantum tunneling is a fundamental concept in quantum mechanics, and it has been experimentally observed and confirmed in various systems, including microscopic particles and even some macroscopic objects. However, it is important to note that quantum tunneling becomes increasingly improbable for larger and more massive objects due to the suppression of quantum effects at larger scales.
While there are no mainstream versions of quantum mechanics that completely forbid quantum tunneling of macroscopic objects, there have been attempts to propose alternative theories or modifications of quantum mechanics that could potentially provide different predictions at macroscopic scales. However, these alternative theories often face significant challenges and are not widely accepted by the scientific community.
One example of such alternative theories is the "decoherence" approach, which suggests that macroscopic objects can undergo rapid and effective decoherence, leading to the suppression of quantum behavior on large scales. According to this view, the wave function of a macroscopic object becomes entangled with its environment, leading to the appearance of classical behavior and the absence of macroscopic quantum tunneling. However, decoherence does not completely forbid quantum tunneling; it simply explains why quantum effects are not commonly observed on macroscopic scales due to the interaction with the surrounding environment.
It is worth noting that the suppression of quantum effects at macroscopic scales is a well-established empirical observation. Macroscopic objects, such as everyday objects, do not typically exhibit quantum behavior in our daily experience. However, this does not imply that quantum tunneling is completely forbidden for all macroscopic objects in all circumstances. There may still be extreme or highly controlled experimental conditions where macroscopic quantum tunneling could be observed, although such cases are currently beyond the scope of our technological capabilities.
In summary, while there are alternative proposals and interpretations that attempt to explain the absence of macroscopic quantum tunneling, there is no widely accepted version of quantum mechanics that completely forbids it. The prevailing understanding is that quantum tunneling becomes increasingly unlikely and suppressed as the size and complexity of the object increase.