Melvyn Bragg and guests discuss how scientists sought to understand the properties of gases and the relationship between pressure and volume, and what that search unlocked. Newton theorised that there were static particles in gases that pushed against each other all the harder when volume decreased, hence the increase in pressure. Those who argued that molecules moved, and hit each other, were discredited until James Maxwell and Ludwig Boltzmann used statistics to support this kinetic theory. Ideas about atoms developed in tandem with this, and it came as a surprise to scientists in C20th that the molecules underpinning the theory actually existed and were not simply thought experiments.

The image above is of Ludwig Boltzmann from a lithograph by Rudolf Fenzl, 1898

With

Steven BramwellProfessor of Physics at University College London

Isobel FalconerReader in History of Mathematics at the University of St Andrews

and

Ted ForganEmeritus Professor of Physics at the University of Birmingham

Producer: Simon Tillotson