What was the purpose of Miller and Urey's experiment?

The purpose of the Miller and Urey experiment was to see if organic compounds that could sustain life be created spontaneously in Earth's early atmosphere. They wanted to see if complex molecules of life (eg. Amino acids, etc.) could be created using natural chemical reactions when Earth had harsh conditions.

Answer: it was to test the whole iddea of the complex molecules in life basically amino acids.