How did Perrin prove the reality of molecules?
The reality of molecules, for me, was not a matter of mere speculation but of rigorous, repeatable observation. My approach, as outlined in 'La Réalité des Molécules,' was to employ diverse experimental methods, each independently probing the atomic and molecular realm. The study of Brownian motion was crucial, showing how the incessant, irregular dance of visible particles could only be explained by the bombardment of far smaller, unseen entities – the molecules. Furthermore, by measuring quantities like Avogadro's number through various means, such as the study of light scattering and the properties of solutions, I found a remarkable convergence of results. When different paths of investigation lead to the same quantitative conclusion, the underlying reality they describe becomes undeniable.
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