Stanley Miller and Harold Urey conducted an experiment, simulating the atmosphere as it was before, to explain how compuds would form in those atmospheric conditions (the atmosphere changes over time).
The hypothesis was used as a way of demostrating the origin of life, since in this experiment, organic materials were formed from inorganic materials.
To get the results, they simulated the earth's eraly atmosphere with different gases (the ones found in the atmosphere millions of years ago), water (simulating the ocean) and electrodes (simulating lightnings).
Hope it helped,
BioTeacher101