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#31
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A quasar, too heavy to be true
On 01 Jan 2018, Gary Harnagel wrote:
G-type stars that are gone now but the intelligent species "hatched" by them have migrated to a younger star. At only 0.1% the speed of light, generation ships could cross the entire galaxy in a mere 0.1 billion years. But they never came here, to Earth. And yet they would have spread out over the galaxy, the same as yeast in a Petri dish. What part of the Petri dish escapes the yeast? None. There is your evidence that no such alien civilizations exist. |
#32
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A quasar, too heavy to be true
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#33
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A quasar, too heavy to be true
On Tuesday, January 2, 2018 at 12:54:07 AM UTC-7, Eric Flesch wrote:
On 01 Jan 2018, Gary Harnagel wrote: G-type stars that are gone now but the intelligent species "hatched" by them have migrated to a younger star. At only 0.1% the speed of light, generation ships could cross the entire galaxy in a mere 0.1 billion years. But they never came here, to Earth. And yet they would have spread out over the galaxy, the same as yeast in a Petri dish. What part of the Petri dish escapes the yeast? None. There is your evidence that no such alien civilizations exist. OTOH, brute-force interstellar travel (i.e., space ships) may be too difficult for civilizations a few thousand years beyond ours, given cosmic radiation and the possibility of collisions with Oort cloud objects. Interstellar travel might have to wait hundreds of thousands of years. I try to imagine what a mature civilization 100,000 years ahead of ours would have as goals. For one thing, they wouldn't be like Captain Kirk, but they may have the Federations non-interference mandate. In any case, they wouldn't be yeast. They would be: There may be millions of inhabited worlds circling other suns, harboring beings who to us would seem godlike, with civilizations and cultures beyond our wildest dreams. --- Arthur C. Clarke |
#34
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A quasar, too heavy to be true
On 03 Jan 2018, Gary Harnagel wrote:
On Tuesday, January 2, 2018 at 12:54:07 AM UTC-7, Eric Flesch wrote: But they never came here, to Earth. And yet they would have spread out over the galaxy, the same as yeast in a Petri dish. What part of the Petri dish escapes the yeast? None. There is your evidence that no such alien civilizations exist. OTOH, brute-force interstellar travel (i.e., space ships) may be too difficult for civilizations a few thousand years beyond ours, given cosmic radiation and the possibility of collisions with Oort cloud objects. Interstellar travel might have to wait hundreds of thousands of years. Well, given that you previously said: "It seems to me that we should be arguing intelligent life developed long ago in the universe until refuted by evidence to the contrary", and you've now shortened that time frame to "a few thousand years beyond ours", it's good to see that you're considering the evidence. I would also point out that there's no operational difference between being the first ones, and being the only ones. |
#35
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A quasar, too heavy to be true
On Wednesday, January 3, 2018 at 3:39:03 AM UTC-7, Eric Flesch wrote:
On 03 Jan 2018, Gary Harnagel wrote: On Tuesday, January 2, 2018 at 12:54:07 AM UTC-7, Eric Flesch wrote: But they never came here, to Earth. And yet they would have spread out over the galaxy, the same as yeast in a Petri dish. What part of the Petri dish escapes the yeast? None. There is your evidence that no such alien civilizations exist. OTOH, brute-force interstellar travel (i.e., space ships) may be too difficult for civilizations a few thousand years beyond ours, given cosmic radiation and the possibility of collisions with Oort cloud objects. Interstellar travel might have to wait hundreds of thousands of years. Well, given that you previously said: "It seems to me that we should be arguing intelligent life developed long ago in the universe until refuted by evidence to the contrary", and you've now shortened that time frame to "a few thousand years beyond ours", it's good to see that you're considering the evidence. Actually, I haven't. It's just easier to imagine a civilization a thousand years older than ours as to one that's a billion years older. I would also point out that there's no operational difference between being the first ones, and being the only ones. That depends upon whether the development of intelligent life is common and nearly coexistent (as is commonly presented in SF novels). And your assertion might be correct if WE are the first or only, but it seems much more likely to me that intelligence arose billions of years ago. Someone else was the first, has the galaxy (or universe) organized and under control while we are Johnny-come-latelies. |
#36
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Observational evidence for life elsewhere
Le 31/12/2017 à 21:48, Phillip Helbig (undress to reply) a écrit :
Whether it is likely that we are the first, and whether it is likely that we are not alone, are other questions. It would be nice if we would argue not just by opinions but opinions based on actual observations. Here is a small overview of "life elsewhere" evidence. A) Mars Mars life has strong observational evidence. 1) "Silica deposits on Mars with features resembling hot spring biosignatures at El Tatio in Chile" Nature communications, Nov 17th 2016 2) Ancient Sedimentary Structures in the 3.7 Ga Gillespie Lake Member, Mars, That Resemble Macroscopic Morphology, Spatial Associations, and Temporal Succession in Terrestrial Microbialites. Astrobiology February 2015, Vol. 15, No. 2: 169-192 3) The Allan Hills meteorite from Mars is peppered with tiny magnetic crystals that on our planet are made only by bacteria. https://science.nasa.gov/science-new...000/ast20dec_1 4) NASA Rover Finds Active and Ancient Organic Chemistry on Mars https://www.jpl.nasa.gov/news/news.php?feature=4413 There are MANY other hints for life in Mars. B) Meteorites: 1) Bacteria in the Tatahouine meteorite: nanometric-scale life in rocks. Earth and Planetary Science Letters 175 (2000) 161^167 C) Bacteria can survive in space without much damage Pete Conrad, the Apollo 12 Commander, took samples of the Surveyor 3 camera and brought samples of "Streptococcus mitis" fropm the moon. The bacteria survived in the moon during 3 years. Pete Conrad said: "I always thought the most significant thing that we ever found on the whole...Moon was that little bacteria who came back and lived and nobody ever said [anything] about it." D) Titan 1) Biologically Enhanced Energy and Carbon Cycling on Titan? Astrobiology. 2005 Aug;5(4):560-7. (https://arxiv.org/pdf/physics/0501068.pdf) 2) Organic Materials Spotted High Above Titan's Surface https://saturn.jpl.nasa.gov/news/232...itans-surface/ E) Encedalus Enceladus's hot, gritty core may cook up ingredients for life https://www.newscientist.com/article...ents-for-life/ The Possible Origin and Persistence of Life on Enceladus and Detection of Biomarkers in the Plume Astrobiology Volume: 8 Issue 5: December 23, 2008 F) Europa 1) Unmasking Europa: The Search for Life on Jupiter's Ocean Moon by Richard Greenberg Praxis/Springer: 2008. 278 pp. £17.50/$27.50 9780387479361 Reviewed in natu https://www.nature.com/articles/457384a G) Venus 1) COULD DARK STREAKS IN VENUS' CLOUDS BE MICROBIAL LIFE? https://www.astrobio.net/venus/dark-...icrobial-life/ |
#37
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A quasar, too heavy to be true
On 01/01/2018 16:09, Eric Flesch wrote:
On 31 Dec 2017, Phillip Helbig wrote: ... Could an intelligent but non-technological species at a level of intelligence similar to humans have arisen sometime in the past but left no fossil or other record? About 40 years ago the "Planetary Report" magazine carried an article about how, about a million years before the dinosaurs vanished, a new human-sized upright-walking dinosaur appeared with stereoscopic vision (I don't have the exact reference, sorry). When reading it, I Sounds like one of the T. Rex walks like a kangaroo claims from before the time when they realised that it used its tail for balance and walked more like a modern day bird with a long tail (eg pheasant). Footprint tracks show no signs of it dragging its tail like a kangaroo would... couldn't help but wonder if they'd built a civilization and then immolated themselves -- that would thus be the true cause of the dinosaurs' disappearance. That may sound absurd, but if we vanished tomorrow, what trace of our civilization would survive 66 million years later? Not a nail. I suspect slabs of refined gold in bulk storage repositories and nuclear waste would easily survive for that long in a form where they would be easily recognisable as technological artefacts. Some of the better grades of stainless steel might also last that long once covered by mud. -- Regards, Martin Brown |
#38
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A quasar, too heavy to be true
Le 01/01/2018 Ã* 17:09, Eric Flesch a écritÂ*:
but if we vanished tomorrow That's one way of seeing the future. Personally, I do not think that we will vanish tomorrow. Why would we? The history of homo sapiens is relatively new in human history, millions of years old. We discovered fire, and with it cooking. That allowed us to eat better, pre-digesting food and hence enlarging the amount of food available to us. Then, we grew, and population growth made old methods unpracticable. We figured out a symbiosis with certain kinds of plants we choose. We settled down and developed agriculture. We constructed a symbiosis with certain kinds of animals that provided meat easier and better than hunting around for meat. We used a bit our brains. That's what they are for, anyway. Use your brain. Sapiens knows that. Because we grew, and population growth makes old methods unpracticable. We expanded through the whole planet and we constructed a human environment. We setup fields of plants we planted, and our work made more food available. And we built cities, developed writing, started to look at the stars. And we started to fly. Humans are too heavy to fly. That's why they build machines heavier than the air that fly. In this manner, Sapiens has been able to start flying. Higher and faster than ever a bird would dream of. I like being born in the suburbs. Unlike downtown, where all stars are so near each other, from here we have a much better view of the Way, spinning like a gigantic inclined wheel, right in front of you. What a nice view! The problem of suburbs, as everybody knows, is that there is no transportation. Downtown, since the distances between the stars are smaller and the stars older, life has solved the transportation problem eons ago. Not in the suburbs, way countryside like here. To meet the others, we have to develop our own transportation. But I think that using our brains we will develop transportation, eventually. An essential part in the development of transport, is the fact that we see the stars, we see the Way. Astronomy. It motivates Sapiens. |
#39
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A quasar, too heavy to be true
In article ,
Martin Brown writes: I suspect slabs of refined gold in bulk storage repositories and nuclear waste would easily survive [60 Myr] in a form where they would be easily recognisable as technological artefacts. Some of the better grades of stainless steel might also last that long once covered by mud. I was thinking of glass. Suitable conditions would be required for any specific object to be preserved, but if fossilized bones could survive, then I'd expect anything not chemically reactive to survive if conditions were right. -- Help keep our newsgroup healthy; please don't feed the trolls. Steve Willner Phone 617-495-7123 Cambridge, MA 02138 USA |
#40
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scientific proof and disproof (was: A quasar, too heavy to be true)
Phillip Helbig (undress to reply) wrote:
Of course, technically, one can never prove the non-existence of something; On the contrary, one can indeed prove the non-existence of some things. For example, I am currently in a room which is approximately 2.5 meters by 5 meters by 2.5 meters in size. Given the known size of adult elephants, I can prove the non-existence of adult elephants in this room by looking around and not seeing any adult elephants. Abstracting a bit, for propositions X and Y, (a) if X implies Y, and (b) we observe not-Y, then (c) we have proven not-X. In the above example, X = "there is an adult elephant in this room" and Y = "I can see an adult elephant when I look around in this room". In the same way, one can prove the non-existence of (for example) hitherto-unknown Jupiter-mass planets orbiting within 10 astronomical units of the Sun: if such a planet or planets existed, they would cause substantial gravitational perturbations to the orbits of other planets. But we observe that there are no (unexplained) substantial gravitational perturbations to the orbits of the known planets in our solar system. Here we are taking X = "there is a hitherto-unknown Jupiter-mass planet orbiting within 10 astronomical units of the Sun" and Y = "there are substantial unexplained gravitational perturbations to the orbits of other (known) planets in our solar system". -- -- "Jonathan Thornburg [remove -animal to reply]" Dept of Astronomy & IUCSS, Indiana University, Bloomington, Indiana, USA currently visiting Max-Plack-Institute fuer Gravitationsphysik (Albert-Einstein-Institut), Potsdam-Golm, Germany "There was of course no way of knowing whether you were being watched at any given moment. How often, or on what system, the Thought Police plugged in on any individual wire was guesswork. It was even conceivable that they watched everybody all the time." -- George Orwell, "1984" |
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