A Billion Years: My Escape from a Life in the Highest Ranks of Scientology

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A series of experiments starting in 1997 showed that amino acids and peptides could form in the presence of carbon monoxide and hydrogen sulfide with iron sulfide and nickel sulfide as catalysts. In 2003 it was proposed that porous metal sulfide precipitates would assist RNA synthesis at about 100°C (212°F) and at ocean-bottom pressures near hydrothermal vents. An experiment in 1953 by Stanley Miller and Harold Urey showed that such molecules could form in an atmosphere of water, methane, ammonia and hydrogen with the aid of sparks to mimic the effect of lightning.

John Perry's neglected critique of Kelvin's age for the Earth: A missed opportunity in geodynamics". Boltwood's paper pointed out that samples taken from comparable layers of strata had similar lead-to-uranium ratios, and that samples from older layers had a higher proportion of lead, except where there was evidence that lead had leached out of the sample. An alternative hypothesis is that enough carbon dioxide escaped through volcanic outgassing that the resulting greenhouse effect raised global temperatures.At the time, Rutherford was only guessing at the relationship between alpha particles and helium atoms, but he would prove the connection four years later. Though some mammalian lines began to separate during this period, existing mammals were probably small animals resembling shrews. Additional complexity could have been reached from at least three possible starting points: self-replication, an organism's ability to produce offspring that are similar to itself; metabolism, its ability to feed and repair itself; and external cell membranes, which allow food to enter and waste products to leave, but exclude unwanted substances. billion years ago, [9] [10] [11] during the Eoarchean Era, after a geological crust started to solidify following the earlier molten Hadean Eon. Such extremophile organisms are restricted to otherwise inhospitable environments such as hot springs and hydrothermal vents.

A similar hypothesis presents self-replicating iron-rich clays as the progenitors of nucleotides, lipids and amino acids.

The snowball may have been partly due to the location of the supercontinent Rodinia straddling the Equator.

Ma detrital zircons in the Southern Cross Granite–Greenstone Terrane, Western Australia: implications for the early evolution of the Yilgarn Craton". The first step in the emergence of life may have been chemical reactions that produced many of the simpler organic compounds, including nucleobases and amino acids, that are the building blocks of life. Smith's nephew and student, John Phillips, later calculated by such means that Earth was about 96 million years old. The water must have been supplied by meteorites from the outer asteroid belt and some large planetary embryos from beyond 2. Techniques for radioactive dating have been tested and fine-tuned on an ongoing basis since the 1960s.Planetesimals at a distance of 1 astronomical unit (AU), the distance of the Earth from the Sun, probably did not contribute any water to the Earth because the solar nebula was too hot for ice to form and the hydration of rocks by water vapor would have taken too long. Estimates on the number of Earth's current species range from 10 million to 14 million, [21] of which about 1.