Astrophysics: "Will Humans and Alien Life Share a Universal Genetic Code?"
"Will Humans and Alien Life Share a Universal Genetic Code?"
by Luke McKinney with Casey Kazan
"A recent mathematical analysis says that life as we know it is written into the laws of reality. DNA is built from a set of twenty amino acids - the first ten of those can create simple prebiotic life, and now it seems that those ten are thermodynamically destined to occur wherever they can. For those unfamiliar with thermodynamics, it's the Big Brother of all energy equations and science itself. You can apply quantum mechanics at certain scales, and Newtonian mechanics work at the right speeds, but if thermodynamics says something, then everyone listens.
An energy analysis by Ralph Pudritz, a theoretical astrophysicist and director of the Origins Institute at McMaster University shows that the first ten amino acids are likely to form at relatively low temperatures and pressures, and the calculated odds of formation match the concentrations of these life-chemicals found in meteorite samples. They also match those in simulations of early Earth, and most critically, those simulations were performed by other people. The implications are staggering: good news for anyone worried about how we're alone, and bad news for anyone who demands some kind of "Designer" to put life together - it seems that physics can assemble the organic jigsaw all by itself, thank you very much, and has probably done so throughout space since the beginning of everything.
The study indicates that you don't need a miracle to arrive at the chemical cocktail for early life, just a decently large asteroid with the right components. That's all. The entire universe could be stuffed with life, from the earliest prebiotic protein-a-likes to fully DNAed descendants. The path from one to the other is long, but we've had thirteen and a half billion years so far and it's happened at least once. The other ten amino acids aren't as easy to form, but they'll still turn up - and the process of "stepwise evolution" means that once the simpler systems work, they can grab the rarer "epic drops" of more sophisticated chemicals as they occur - kind of a World of Lifecraft except you literally get a life when you play. And once even the most sophisticated structure is part of a replicating organism, there's plenty to go round.
Early Earth was covered with carbonaceous material from meteorites and comets that provided the raw materials from which first life emerged. In his new book, The Eerie Silence, astrophysicist Paul Davies of Arizona State University suggests that the original cells would have been able to pick and choose from the early Earth's organic cocktail. To the best of our knowledge, he writes, "the twenty-one chosen by known life do not constitute a unique set; other choices could have been made, and maybe were made if life started elsewhere many times."
An energy analysis by Ralph Pudritz, a theoretical astrophysicist and director of the Origins Institute at McMaster University shows that the first ten amino acids are likely to form at relatively low temperatures and pressures, and the calculated odds of formation match the concentrations of these life-chemicals found in meteorite samples. They also match those in simulations of early Earth, and most critically, those simulations were performed by other people. The implications are staggering: good news for anyone worried about how we're alone, and bad news for anyone who demands some kind of "Designer" to put life together - it seems that physics can assemble the organic jigsaw all by itself, thank you very much, and has probably done so throughout space since the beginning of everything.
The study indicates that you don't need a miracle to arrive at the chemical cocktail for early life, just a decently large asteroid with the right components. That's all. The entire universe could be stuffed with life, from the earliest prebiotic protein-a-likes to fully DNAed descendants. The path from one to the other is long, but we've had thirteen and a half billion years so far and it's happened at least once. The other ten amino acids aren't as easy to form, but they'll still turn up - and the process of "stepwise evolution" means that once the simpler systems work, they can grab the rarer "epic drops" of more sophisticated chemicals as they occur - kind of a World of Lifecraft except you literally get a life when you play. And once even the most sophisticated structure is part of a replicating organism, there's plenty to go round.
Early Earth was covered with carbonaceous material from meteorites and comets that provided the raw materials from which first life emerged. In his new book, The Eerie Silence, astrophysicist Paul Davies of Arizona State University suggests that the original cells would have been able to pick and choose from the early Earth's organic cocktail. To the best of our knowledge, he writes, "the twenty-one chosen by known life do not constitute a unique set; other choices could have been made, and maybe were made if life started elsewhere many times."
- http://www.dailygalaxy.com/
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"We Are Made of Star Dust"
by Aditya Chopra and Charles H. Lineweaver
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"We Are Made of Star Dust"
by Aditya Chopra and Charles H. Lineweaver
"One way of answering the question ‘What is life?’ is to look at the ingredients of life on Earth. In terms of chemical elements, oxygen, carbon, hydrogen and nitrogen, make up 96.8 ± 0.1% of the mass of life (based on humans and bacteria). Phosphorus and sulfur together make up 1.0 ± 0.3%. The remaining 2.2 ± 0.2% is dominated by potassium, sodium, calcium, magnesium and chlorine, while 0.03 ± 0.01% is attributed to trace elements such as iron, copper and zinc.
All atoms that are or have been part of living matter on Earth have either been produced during big bang nucleosynthesis or in different processes of the stellar nucleosynthetic pathways that take place in stars. Around ~4.5 billion years ago our Sun was formed out of a collapsing molecular cloud that was polluted by earlier stellar processes and a proto-planetary disk that was made of the remaining dust gave rise to terrestrial planets like the Earth.
While the elemental composition of planets reflects to a large extent the composition of the Sun, relative to the Sun, the Earth is depleted in the most volatile elements hydrogen, helium and the noble gases. These elements were swept away by the solar wind from the region of the solar nebula where rocky planets like Earth formed. However, later input of volatile elements from chondritic material, comets and other objects from the outer solar system led to a surface crust on the Earth which exhibits elemental abundances more like the Sun depleted in volatile elements than the bulk Earth.
Life does not reside in the mantle or the core of the Earth and so its elemental abundances are more reflective of abundances in the crust (specifically the biosphere) than abundances in the bulk Earth. Since the abundance of most elements in life forms and their environments on Earth follow cosmic abundances (as represented by the Sun), perhaps extraterrestrial life on Mars or moons of Jupiter and Saturn or perhaps extra-solar planetary systems, will also exhibit elemental abundances similar to those found in life on Earth."
All atoms that are or have been part of living matter on Earth have either been produced during big bang nucleosynthesis or in different processes of the stellar nucleosynthetic pathways that take place in stars. Around ~4.5 billion years ago our Sun was formed out of a collapsing molecular cloud that was polluted by earlier stellar processes and a proto-planetary disk that was made of the remaining dust gave rise to terrestrial planets like the Earth.
While the elemental composition of planets reflects to a large extent the composition of the Sun, relative to the Sun, the Earth is depleted in the most volatile elements hydrogen, helium and the noble gases. These elements were swept away by the solar wind from the region of the solar nebula where rocky planets like Earth formed. However, later input of volatile elements from chondritic material, comets and other objects from the outer solar system led to a surface crust on the Earth which exhibits elemental abundances more like the Sun depleted in volatile elements than the bulk Earth.
Life does not reside in the mantle or the core of the Earth and so its elemental abundances are more reflective of abundances in the crust (specifically the biosphere) than abundances in the bulk Earth. Since the abundance of most elements in life forms and their environments on Earth follow cosmic abundances (as represented by the Sun), perhaps extraterrestrial life on Mars or moons of Jupiter and Saturn or perhaps extra-solar planetary systems, will also exhibit elemental abundances similar to those found in life on Earth."
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