Abiogenesis is the purported development of life from non-life in the early earth. Also called chemical evolution, the conditions of the early earth supposedly facilitated the formation of organic chemicals in ponds across the earth. Within the primordial soup, the first buildings blocks of life (either RNA or DNA) form. Chemicals then coalesce around the developing RNA strand (in the more plausible RNA-first world), and then the first life emerges. Once life has emerged on the primordial earth, the normal process of biological evolution can happen. Abiogenesis is the only option available for those who deny creation of any kind. Rather, scientific processes must be responsible for the emergence of life on earth.
In 1953, scientists Stanly Miller and Harold Urey conducted an experiment to test the hypothesis of abiogenesis. To this end, they created an experimental setup that seeks to mimic the likely conditions of the primordial earth. The gases ammonia (NH3), hydrogen (H2), methane (CH4) were placed in the reaction chamber, and water vapor was introduced throughout the experiment. Electrical current was passed through the chamber attempting to mimic lightning. At the bottom of the setup, the products of the experiment were collected. After conducting this experiment, behold in the solution at the bottom of the reactor chamber was found organic compounds including crucially amino acids, the building blocks of proteins. The Miley-Urey experiment served to trumpet the growing confidence in the viability of abiogenesis, for it seems to suggest the easy production of key organic compounds like amino acids in the biosphere of the primordial earth.
Once the euphoria died down, the problems with the Miley-Urey experiment emerge. The first main issue is that the production of amino acids is different from production of nucleotide bases, which are much more complex molecules. In contrast, the simplest amino acid, Glycine (G) has a simple molecular formula of H2N-HCH-COOH. Amino acids cannot function as the basis for life, for peptide strands (assuming a linear strand can be produced naturally) cannot encode genetic information or self replicate. Secondly and importantly, the experiment produced a racemic mixture, or a 50:50 mixture of both right (D-) and left (L-) handed amino acids. On earth, amino acids in living creatures are almost all L-amino acids. The two optical isomers, or enantiomers, are not the same molecule, just as your left hand is not the same as your right hand but mirror images of each other. In order for life to emerge naturally, there must exist a mechanism for the sequestering of only L-amino acids from the chemical soup. Since we are on the topic of enantiomers, nucleotides in life are right-handed since the sugar is right-handed (D-ribose). What viable natural mechanism can sequester only one of the enantiomers while not utilizing the other one? Thirdly, as hinted at in the second problem, the molecules need to be sequestered and utilized almost immediately, otherwise they can undergo further reactions like unguided polymerization to create a goey mess, or even reverse the process through hydrolysis. What viable natural mechanism could do that?
Even if such processes were to be found, could they actually proceed? This is where probability comes into the picture. What is the probability that, for example, enough amino acids and nucleotides of the correct optical isomer are formed? What is the probability that a certain surface or substance or catalyst is present which might sequester and utilize the required finished products, and not the unwanted ones. Even after a RNA molecule might form, what is the probability that it would not be destroyed immediately by hydrolysis, or combine with an amino acid that has just been sequestered? The probability that all these things might happen seem infinitesimal, so small that even the 13GYr of the universe is insufficient time for the first RNA life to emerge.
Scientifically, the theory of abiogenesis does not seem viable. The Miley-Urey experiment only proves that simple organic chemical compounds can be produced easily. As an experiment to prove abiogenesis however, it fails.