This experiment was designed to test the hypothesis of Oparin/Haldane.
The hypothesis remained untested until 1953, when University of Chicago graduate student Stanley Miller reported an experiment in which methane, ammonia, hydrogen and water (thought to be the components of the ‘primitive’ atmosphere) were mixed in a closed glass apparatus. The water was heated and the gases circulated past a high-voltage electric spark to simulate lightning. This provided the energy to break the chemical bonds of the compounds present, and the resulting free radicals combined to form a mixture of simple organic compounds, including trace quantities of some amino acids.
Crucial to the success of the experiment was Miller’s water trap in which the amino acids generated could dissolve and thus be protected from subsequent destructive contact with the spark. But on the hypothesized primordial Earth with no oxygen (and therefore no ozone), the products would have been exposed to destructive ultraviolet rays. This is so even if they reached the oceans, because UV radiation can penetrate tens of metres of water.
Per se, this experiment does not pose difficulties to the creationist. With the most astute intelligent guidance, such an experimental set-up, which generates a multitude of interfering organic acids and bases (plus racemic and biologically useless amino acids) cannot produce a single biologically relevant protein strand. To claim this experiment as evidence for evolution would be akin to allowing water to flow over a bed of coal, and upon identifying a little ink-like substance, claiming the Encyclopaedia Britannica was produced by natural, random processes.
Oxygen, deliberately removed from Miller’s apparatus, destroys amino acids. But geological evidence indicates oxygen was always present on earth. It is produced by photolysis of water vapour in the atmosphere, where hydrogen escapes gravitation and oxygen thereby increases in concentration.
Currently, the most probable early atmosphere is deemed by evolutionists to have consisted of water, carbon dioxide, nitrogen and hydrogen, a very different composition than used by Miller. Hydrogen would have been present in small concentrations at most, because it could escape Earth’s gravity; ammonia and methane would have been destroyed by ultraviolet light. In 1983, Miller reported that if carbon monoxide is added to the more realistic mixture, plus a large proportion of free hydrogen, then only glycine, the simplest amino acid, could be produced, and in trace amounts only.
The experts know the experiments provide no support for an abiogenesis model. But nevertheless, biology textbooks and popular magazines like National Geographic continue to mislead the public into thinking that the Miller-Urey experiment is evidence for evolution.