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Abiogenesis

Abiogenesis
Scientific hypotheses about the origins of life can be divided into a number of categories. Many approaches investigate how self-replicating molecules or their components came into existence. On the assumption that life originated spontaneously on Earth, the Miller–Urey experiment and similar experiments demonstrated that most amino acids, often called "the building blocks of life", can be racemically synthesized in conditions which were intended to be similar to those of the early Earth. Several mechanisms have been investigated, including lightning and radiation. Other approaches ("metabolism first" hypotheses) focus on understanding how catalysis in chemical systems in the early Earth might have provided the precursor molecules necessary for self-replication. Early conditions[edit] The Hadean Earth is thought to have had a secondary atmosphere, formed through degassing of the rocks that accumulated from planetesimal impactors. The earliest life on Earth[edit] Current models[edit]

How Incomprehensible Could Extraterrestrials Be? A few days ago Paul Gilster, the author of Centauri Dreams: Imagining and Planning Interstellar Exploration and the curator of Centauri Dreams , posted a thoughtful discussion of a blog entry I wrote (titled What's The Connection Between Deafness and SETI? ) His discussion and the resulting comments were fascinating, and in this post I want to carry on that conversation. I want to ask: Will extraterrestrials be so different from us as to be truly incomprehensible? I think the answer is no. In one of the comments, Christopher Phoenix argued that aliens could be so different from us as to be incomprehensible. "How can we expect to use extraterrestrials as a mirror for human behavior? Excellent point. Okay. Still, it’s fair to ask if an alien species might be so different from us that even our science wouldn’t be able to get a grip on it. I don’t think biology in itself would create that kind of radical incomprehensibility. Technology presents us with a more difficult problem.

Origin of life Stromatolites from Bolivia, from the Proterozoic (2.3 bilion years ago). Vertical polished section. The origin of life on Earth is a scientific problem which is not yet solved. There are plenty of ideas, but few clear facts.[1] It is not known whether metabolism or genetics came first. Another big problem is how cells develop. Melvin Calvin, recipient of the Nobel Prize in Chemistry, wrote a book on the subject,[4] and so did Alexander Oparin.[5] What links most of the early work on the origin of life is the idea that before life began there must have been a process of chemical change.[6] Another question which has been discussed by J.D. Many religions teach that life did not evolve spontaneously, but was deliberately created by a god. Fossil record[change | change source] Earliest claimed life on Earth[change | change source] The earliest claimed lifeforms are fossilized microorganisms (or microfossils). These rocks are as old as 4.28 billion years. Darwin[change | change source]

Life...As We Don't Know It | Experts' Corner This article originally appeared in ReaClearScience's Newton Blog. You can read the original here. It's amusing and intellectually stimulating to seriously ponder the existence and characteristics of alien life. But like quantum mechanics, such contemplations can easily wrack the mind, leaving one quite discombobulated. I can only imagine the self-inflicted vexations suffered by astrobiologists, whose livelihoods require daily ruminations about life on inconceivably faraway worlds. After all, the vast randomness inherent to the evolutionary process can give rise to creatures the likes of which we cannot fathom. So what would life resemble instead? My favorite answer to that question originated from the 1976 paper "Particles, Environments, and Possible Ecologies in the Jovian Atmosphere," penned by astrophysicists Carl Sagan and E. Over many thousands of years, these sinkers could evolve or coalesce into new life forms: "floaters." "It will show us what else is possible." (Images: 1.

Edward Ricketts 1932 Unpublished Essay on Wave Shock as a Factor in Littoral Ecology The Tide as an Environmental Factor Chiefly with Reference to Ecological Zonation on the California Coast byEdward F. Ricketts 1934 Unpublished Essay Excerpts From Joel Hedgpeth Sources: Living Edge & The Outer Shores Compiled byRobert 'Roy' J. van de Hoek Field Biologist & Geographer Sierra Club, Wetlands Action Network, National Audubon Society Ed Ricketts' 1934 Essay Excerpts: "At least the most obvious regulatory factor in the vertical distribution of littoral life is the tide. By substituting the uniform oceanic environment obtain at flood, for the varying temperatures, salinity, desiccation, wave shock and light conditions obtainable during intervals of ebb, the alternating tide effects all littoral organisms. This study was originally the outcome of primitive attempts some years ago on the part of the writer to determine the shape of the tidal wave with reference to fixed heights on the shore, ........... Conclusions and derived discussions. 1. 2. 3.

Xenology Home Page Between Pacific Tides Between Pacific Tides is a 1939 book by Ed Ricketts and Jack Calvin that explores the intertidal ecology of the Pacific coast of the United States. The book was originally titled "Between Pacific Tides: An Account of the Habits and Habitats of Some Five Hundred of the Common, Conspicuous Seashore Invertebrates of the Pacific Coast Between Sitka, Alaska, and Northern Mexico". Prior to Ricketts' work, the standard descriptive text of intertidal species of the Pacific was Myrtle E. Between Pacific Tides was out of print from 1942 to 1948,[1] but it has since been revised and updated to keep it current, and is now in its fifth edition with the size increasing around twenty percent from the original.

Exoplanet Discoveries to Date Are Just a Drop in the Bucket [Interactive] Astronomers have in the past 20 years located several hundred planets orbiting distant stars, and they have only scratched the surface. In a small patch of stars—less than 1 percent of the sky—in the Northern Hemisphere, NASA's Kepler mission has already found more than 100 planets, along with strong hints of thousands more. Stars across the sky ought to be similarly laden with planets. Graphics and interactive by Jan Willem Tulp (Sources: the Exoplanet Data Explorer at exoplanets.org; planetquest.jpl.nasa.gov; “The Exoplanet Orbit Database,” by J.

The Great Tidepool | Bruce Byers Consulting New 0 0 0 0 August 2017. Chapter VI of Cannery Row, John Steinbeck’s fond short novel about his marine biologist friend Ed Ricketts, starts like this: “Doc was collecting marine animals in the Great Tide Pool on the tip of the Peninsula. It is a fabulous place: when the tide is in, a wave-churned basin, creamy with foam, whipped by the combers that roll in from the whistling buoy on the reef. But when the tide goes out the little water world becomes quiet and lovely. The sea is very clear and the bottom becomes fantastic with hurrying, fighting, feeding, breeding animals.” Ed Ricketts collecting at low tide. Edward F. Doc’s Great Tide Pool was one of the sites for my Ph.D. research on the ecology, behavior, and genetics of a common intertidal snail of the North American Pacific Coast, commonly known as the black turban snail, and scientifically asTegula funebralis. Black Turban Snail, Tegula funebralis, August 2017. In August I had the chance to revisit my Great Tidepool.

Une nouvelle idée pour détecter les extraterrestres "Le silence éternel de ces espaces infinis m'effraie", écrivait Blaise Pascal face au cosmos. Une manière moderne de réinterpréter cette phrase célèbre consiste à la rapprocher de l'échec qui, jusqu'à présent, a sanctionné toutes les tentatives des astronomes pour découvrir les signes d'une vie extraterrestre. E.T. se tait et son silence obstiné nous fait nous demander, encore et toujours, si nous sommes seuls dans l'Univers. Aujourd'hui, dans un article paru sur le site de pré-publications arXiv, deux chercheurs espagnols soumettent à la communauté scientifique une nouvelle idée. Ils sont partis de l'hypothèse selon laquelle une civilisation avancée serait capable d'explorer d'autres systèmes solaires que le sien, soit pour la science, soit pour exploiter leurs ressources, soit pour s'éloigner de son étoile en fin de vie avant qu'elle n'explose. Taille et vitesse.

review of Between Pacific Tides by Edward F. Ricketts Between Pacific Tides by Edward F. Ricketts et al Review by Bill MeyersGo to Amazon.com to Order There are many books about the seashore, including some nice guides to Pacific Coast shells and invertebrates. For the most part the book is not set up to make it easy to identify specimens. This ecosystem, which at first looks so simple, is in fact so complicated that in many ways it remains sparsely documented. Looking for Alien 'Bubbles' in Other Galaxies When I was under the velvet black skies of western Texas a few months ago I had a magnificent view of the star-studded bulge of our galaxy, in the direction of the summer constellation Sagittarius. How many advanced civilizations might be in this hub of the Milky Way? I pondered. After all, this is the direction where the mysterious “WOW” radio signal that was detected three decades ago came from. The problem is that we are embedded in a thick forest of stars, and identifying the location of an extraterrestrial civilization — one that’s attempting to contact us — is the proverbial needle-in-haystack search as the SETI scientists always say. Therefore, it would make sense to go looking at a neighboring “forest,” or rather nearby galaxy, for evidence of extraterrestrial intelligence. ANALYSIS: Could Terrorist Aliens Cyberattack Us? Because even the nearest galaxies are millions of light-years away, any idea of communicating with aliens is unfeasible. Image credit: NASA, ESA

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