Noun
a fundamental principle of classical physics that matter cannot be created or destroyed in an isolated system
Source: WordNetThe law of causality is no longer applied in quantum theory and the law of conservation of matter is no longer true for the elementary particles. Werner Heisenberg
The extension of Black's method by the physicist Lavoisier led to the downfall of the purely qualitative theory of phlogiston, and gave to chemistry the true methods of investigation, and its first great quantitative law-the law of conservation of matter. J. R. Partington
The extension of Black's method by the physicist Lavoisier led to the downfall of the purely qualitative theory of phlogiston, and gave to chemistry the true methods of investigation, and its first great quantitative law-the law of conservation of matter. Antoine Lavoisier