Changes

===Re-analysis of samples and other discharge experiments===  

===Re-analysis of samples and other discharge experiments===  

Miller had performed other experiments between 1952-1954 using two other apparatuses. A few vials of the samples he made were found in the 2000s and analyzed using modern techniques that have more sensitivity.<ref name="Bada2016">Bada, J. L. (2016). One of the foremost experiments of the 20th century: Stanley Miller and the origin of prebiotic chemistry. Metode Science Studies Journal, (6), 183–189. https://doi.org/10.7203/metode.6.4994</ref><ref>Bada JL. [https://web.archive.org/web/20190225141103id_/http://pdfs.semanticscholar.org/6f46/3e8a3611fa7f25c143991dfddac49c396b73.pdf New insights into prebiotic chemistry from Stanley Miller's spark discharge experiments]. Chem Soc Rev. 2013 Mar 7;42(5):2186-96. doi: 10.1039/c3cs35433d</ref> After modern analysis of his 1950s samples (including the 1953 experiment and volcano experiment), 31 amino acids, 6 amines, and 12 dipeptides/cyclodipeptides formed in very small amounts.<ref name="Bada2016" />

Miller had performed other experiments between 1952-1954 using two other apparatuses. A few vials of the samples he made were found in the 2000s and analyzed using modern techniques that have more sensitivity.<ref name="Bada2016">Bada, J. L. (2016). One of the foremost experiments of the 20th century: Stanley Miller and the origin of prebiotic chemistry. Metode Science Studies Journal, (6), 183–189. https://doi.org/10.7203/metode.6.4994</ref><ref name="Bada2013">Bada JL. [https://web.archive.org/web/20190225141103id_/http://pdfs.semanticscholar.org/6f46/3e8a3611fa7f25c143991dfddac49c396b73.pdf New insights into prebiotic chemistry from Stanley Miller's spark discharge experiments]. Chem Soc Rev. 2013 Mar 7;42(5):2186-96. doi: 10.1039/c3cs35433d</ref> After modern analysis of his 1950s samples (including the 1953 experiment and volcano experiment), 31 amino acids, 6 amines, and 12 dipeptides/cyclodipeptides formed in very small amounts.<ref name="Bada2016" />

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==Modern Interpretations==

==Modern Interpretations==

===Early earth atmosphere===

===Early earth atmosphere===

The Miller-Urey experiment assumed an a primitive atmosphere was composed of ''reducing'' (oxygen poor)  gases [e.g. methane (CH₄), ammonia (NH₃), hydrogen (H₂), and water vapor (H₂O)], but by the 1980s geochemists believed that early earth atmospheres probably had ''neutral'' gases like those emitted by volcanoes [e.g. water vapor (H₂O), carbon dioxide (CO₂), and nitrogen (N₂)] and perhaps some ''reducing'' gases like carbon monoxide (CO). Since hydrogen was a light element, there probably would not have been any in early earth.<ref name="wells" /> Some scientists believe that early earth atmosphere was similar to earth today.<ref>[https://astrobiology.nasa.gov/news/earths-early-atmosphere-an-update/ Earth's Early Atmosphere: An Update] - NASA</ref>

There is significant uncertainty to what the primitive atmosphere was composed of.<ref name="Bada2013" /> The Miller-Urey experiment assumed an a primitive atmosphere was composed of ''reducing'' (oxygen poor)  gases [e.g. methane (CH₄), ammonia (NH₃), hydrogen (H₂), and water vapor (H₂O)], but by the 1980s geochemists believed that early earth atmospheres probably had ''neutral'' gases like those emitted by volcanoes [e.g. water vapor (H₂O), carbon dioxide (CO₂), and nitrogen (N₂)] and perhaps some ''reducing'' gases like carbon monoxide (CO). Since hydrogen was a light element, there probably would not have been any in early earth.<ref name="wells" /><ref name="Bada2013" />

 

Some scientists believe that early earth atmosphere was similar to earth today.<ref>[https://astrobiology.nasa.gov/news/earths-early-atmosphere-an-update/ Earth's Early Atmosphere: An Update] - NASA</ref>

==See also==

==See also==