While quantum tunneling allows for the possibility of particles, including atoms, to pass through potential barriers, the probability of observing such events is extremely low for macroscopic objects like rocks. The reason why physicists have not observed or documented atoms tunneling out of solid objects on a macroscopic scale can be attributed to several factors:
Magnitude of the probability: While the probability of quantum tunneling can be non-zero, it is typically extremely small for macroscopic objects. The likelihood of an atom tunneling out of a solid material is many orders of magnitude lower than the probability of it remaining bound within the material. The vast number of atoms in a solid, combined with their relatively low tunneling probabilities, makes the likelihood of observing a macroscopic tunneling event minuscule.
Experimental limitations: Detecting and observing individual atoms or their tunneling events within a solid material is technically challenging. The resolution and sensitivity of current experimental techniques are not sufficient to directly observe or track individual atoms within a solid on a macroscopic scale. The ability to precisely control and manipulate individual atoms within a solid material is also a significant experimental hurdle.
Time scales: The time scale for macroscopic tunneling events can be exceedingly long. While individual particles can tunnel through potential barriers, the timescales involved can be extremely large for macroscopic objects. The time required for an atom to tunnel out of a solid material can be on the order of many lifetimes of the universe, rendering direct observation impractical.
It's important to note that while the probability of macroscopic tunneling events is infinitesimal, quantum tunneling has been experimentally observed and documented in various systems at the microscopic and nanoscale levels, where the effects are more pronounced and measurable. These observations have contributed to our understanding of quantum mechanics and have practical applications in fields like electronics and microscopy.