Involves

Moment

A microscope tests a statistical prediction

Paris, 1908; Jean Perrin investigates suspended particles

Perrin studied particles suspended in liquids and tested relationships associated with the molecular account of their behavior. His experiments supported the theory developed by Einstein and Marian Smoluchowski. Motion that had looked irregular became quantitative evidence about matter's microscopic structure.

Researcher
Jean Perrin
Year
1908
Target
Brownian motion

The caveat

The experiments tested several predictions, including how suspended particles were distributed. Their combined results supported the theory.

The achievement did not require making each particle move along a predicted line. Statistical regularities across observations were the evidence. Perrin later received the Nobel Prize for work on the discontinuous structure of matter: evidence that matter consists of discrete particles.

How it connects

Perrin used population-level regularities to investigate molecular structure.

This moment appeared in Predictable patterns without predictable paths, the Involves connection for October 20, 2026, which asked: Can randomness produce something we can reliably calculate?

Check yourself

What made irregular particle motion useful to Perrin?

Statistical relationships could be compared with molecular theory. Exactly. Regularities across observations can test a theory without predicting each path.

What the sources establish

  • Perrin's 1908 experiments supported the molecular interpretation of suspended-particle behavior.

Sources