According to quantum theory, particles act as waves rather than point masses on very small scales. (scientificamerican.com)
In 1727 he modelled a violin string as a large number of closely spaced point masses, linked together by springs. (newscientist.com)
Cogley (1999) pointed out that with a measurement network spaced at 50 - 100 m apart the largest source of uncertainty is the error in actual point mass balance measurement (> 0.05 m), and sampling error is negligible. (nichols.edu)