Tapping an iron piece with a finger over millions of years could eventually create a dent, as each tap displaces iron atoms. However, this process would need to occur in a water and oxygen-free environment to prevent rusting, which would hinder the effect. While rocks in streams smooth out due to flowing water, iron can resist deformation under small forces for extended periods, approaching an infinite cycle of deformation. Over extremely long timescales, iron may sublimate atom by atom if not otherwise damaged. The discussion highlights the slow but possible erosion of metal under consistent, minimal force.
