For Bbella: transient alien life (Introduction)
by David Turell 
, Thursday, January 21, 2016, 15:37 (3017 days ago)
A weird new theory that the appearance of life 'elsewhere' is transient:-http://phys.org/news/2016-01-aliens-silent-theyre-dead.html-"In research aiming to understand how life might develop, the scientists realised new life would commonly die out due to runaway heating or cooling on their fledgling planets.-"'The universe is probably filled with habitable planets, so many scientists think it should be teeming with aliens," said Dr Aditya Chopra from the ANU Research School of Earth Sciences and lead author on the paper, which is published in Astrobiology.-"'Early life is fragile, so we believe it rarely evolves quickly enough to survive."-"'Most early planetary environments are unstable. To produce a habitable planet, life forms need to regulate greenhouse gases such as water and carbon dioxide to keep surface temperatures stable."-"About four billion years ago Earth, Venus and Mars may have all been habitable. However, a billion years or so after formation, Venus turned into a hothouse and Mars froze into an icebox.-"'Early microbial life on Venus and Mars, if there was any, failed to stabilise the rapidly changing environment, said co-author Associate Professor Charley Lineweaver from the ANU Planetary Science Institute.-"'Life on Earth probably played a leading role in stabilising the planet's climate," he said.-Dr Chopra said their theory solved a puzzle.-"'The mystery of why we haven't yet found signs of aliens may have less to do with the likelihood of the origin of life or intelligence and have more to do with the rarity of the rapid emergence of biological regulation of feedback cycles on planetary surfaces," he said.-"Wet, rocky planets, with the ingredients and energy sources required for life seem to be ubiquitous, however, as physicist Enrico Fermi pointed out in 1950, no signs of surviving extra-terrestrial life have been found.-"A plausible solution to Fermi's paradox, say the researchers, is near universal early extinction, which they have named the Gaian Bottleneck.-"'One intriguing prediction of the Gaian Bottleneck model is that the vast majority of fossils in the universe will be from extinct microbial life, not from multicellular species such as dinosaurs or humanoids that take billions of years to evolve," said Associate Professor Lineweaver."-Comment: Weird because I don't see how microbial life stabilizes a planet. It is the other way around. A proper rocky planet has characteristics that allow life to develop.
For Bbella: transient alien life
by BBella , Thursday, January 21, 2016, 15:56 (3017 days ago) @ David Turell
> "'The mystery of why we haven't yet found signs of aliens may have less to do with the likelihood of the origin of life or intelligence and have more to do with the rarity of the rapid emergence of biological regulation of feedback cycles on planetary surfaces," he said. > -Said a voice from a speck of dust in the universe.
For Bbella: transient alien life
by David Turell , Sunday, June 12, 2016, 23:17 (2874 days ago) @ David Turell
Another article on the issue of the difficulty in getting alien life started, and that active biological life stabilizes a young planet:-http://phys.org/news/2016-06-alien-life-exoplanets-dies-young.html-"Many scientists and commentators equate "more planets" with "more E.T.s". However, the violence and instability of the early formation and evolution of rocky planets suggests that most aliens will be extinct fossil microbes.-***-"In research published in the journal Astrobiology, we argue that early extinction could be the cosmic default for life in the universe. This is because the earliest habitable conditions may be unstable.-"In our "Gaian Bottleneck" model, planets need to be inhabited in order to remain habitable. So even if the emergence of life is common, its persistence may be rare.-"Mars, Venus and Earth were more similar to each other in their first billion years than they are today. Even if only one of the planets saw the emergence of life, this era coincided with heavy bombardment from asteroids, which could have spread life between the planets.-"But about 1.5 billion years after formation, Venus started to experience runaway heating and Mars experienced runaway cooling. If Mars and Venus once harboured life, that life quickly went extinct.-"Even if wet rocky Earth-like planets are in the "Goldilocks Zone" of their host stars, it seems that runaway freezing or heating may be their default fate.-"Large impactors and huge variation in the amounts of water and greenhouse gases can induce positive feedbacks cycles that push planets away from habitable conditions.-"The carbonate-silicate weathering cycle, which provides the major negative feedback to stabilise Earth's climate today, was probably inoperative, or at least inefficient, until about 3 billion years ago.-"However, life on Earth may have had the fortuitous ability to create stability by suppressing the positive runaway feedback loops and enhancing the negative feedback loops.-***-"As soon as life became widespread on Earth, the earliest metabolisms began to modulate the greenhouse gas composition of the atmosphere. It is no coincidence that methane, carbon dioxide, hydrogen and water are all potent greenhouse gases and also the reactants and products of metabolic reactions of the earliest microbial mats and biofilms.-"The emergence of life's ability to regulate initially non-biological feedback mechanisms (what we call "Gaian regulation") could be the most significant factor responsible for life's persistence on Earth.-***-"We hypothesise that even if life does emerge on a planet, it rarely evolves quickly enough to regulate greenhouse gases, and thereby keep surface temperatures compatible with liquid water and habitability.-"Maintaining life on an initially wet rocky planet in the habitable zone may be like trying to ride a wild bull. Most riders falls off. So inhabited planets may be rare in the universe, not because emergent life is rare, but because habitable environments are difficult to maintain during the first billion years.-***-"We should not expect technological or spacefaring civilisations because there is no evidence that biological evolution converges to human-like intelligence. And subjective philosophical notions of life in the universe should not inform our estimates of the probability of life beyond Earth."-Comment: Our current atmosphere was provided by biologic activity. The authors have made a very interesting point, and we know it worked on Earth. We are a privileged planet.
For Bbella: possible alien contact
by David Turell , Friday, June 17, 2016, 18:29 (2869 days ago) @ David Turell
We are limited by the speed of light in receiving or making alien contact. Current estimates are perhaps in 1,500 years:-http://phys.org/news/2016-06-itll-years-aliens-contact.html- "If you're expecting to hear from aliens from across the universe, it could be a while. -"Deconstructing the Fermi paradox and pairing it with the mediocrity principle into a fresh equation, Cornell astronomers say extraterrestrials likely won't phone home - or Earth - for 1,500 years.-***-"It's possible to hear any time at all, but it becomes likely we will have heard around 1,500 years from now," said Solomonides. "Until then, it is possible that we appear to be alone - even if we are not. But if we stop listening or looking, we may miss the signals. So we should keep looking."-"The Fermi paradox says billions of Earthlike planets exist in our galaxy, yet no aliens have contacted or visited us. Thus the paradox: the cosmos teems with possibility. The mediocrity principle - originated by 16th-century mathematician Copernicus - says Earth's physical attributes are not unique, as natural processes are likely common throughout the cosmos, and therefore aliens won't discover us for a while.-"Hunting for extraterrestrials means sending out signals like television broadcasts, for example. As Earth's electronic ambassador, TV and radio signals are sent into space as a byproduct of broadcasting. These signals have been traveling from Earth for 80 years at the speed of light. For aliens receiving these transmissions, they would likely be indecipherable, said Solomonides, as the extraterrestrials would need to decode light waves into sounds, then parse 3,000 human languages to grasp the message.-"Nonetheless, Earth's broadcast signals have reached every star within about 80 light years from the sun - about 8,531 stars and 3,555 Earthlike planets, as our Milky Way galaxy alone contains 200 billion stars.-"Even our mundane, typical spiral galaxy - not exceptionally large compared to other galaxies - is vast beyond imagination," said Solomonides. "Those numbers are what make the Fermi Paradox so counterintuitive. We have reached so many stars and planets, surely we should have reached somebody by now, and in turn been reached … this demonstrates why we appear to be alone."-"Combining the equations for the Fermi paradox and the mediocrity principle, the authors suggests Earth might hear from an alien civilization when approximately half of the Milky Way Galaxy has been signaled in about 1,500 years. "This is not to say that we must be reached by then or else we are, in fact, alone. We simply claim that it is somewhat unlikely that we will not hear anything before that time," Solomonides said.-***-"'We are on the third planet around a tediously boring star surrounded by other completely normal stars about two-thirds of the way along one of several arms of a remarkably average spiral galaxy. The mediocrity principle is the idea that because we are not in any special location in the universe, we should not be anything special in the universe.'" -Comment: Unless several generations of aliens survived on a space ship, assuming they have the same lifespan, no one has visited us. On the other hand, if they had lifespans as in the Old Testament, the aliens might have gotten here from the planets within the 80 year range now contacted. Our galaxy is not giant, but it is about 100,000 light years across, but may be as much as 180,000 lys. We are on the second spiral arm about 2/3rds of the way out from the center, a quiet area which is good for us, but also puts us more central so the possible travel distances are less than the diameter.-https://en.wikipedia.org/wiki/Carina%E2%80%93Sagittarius_Arm
For Bbella: a mathematician's take
by David Turell , Sunday, June 19, 2016, 14:57 (2867 days ago) @ David Turell
We are only a sample of one. If life is present elsewhere, we cannot calculate odds, even if planets are popping up everywhere, even rocky ones with water:-http://www.theatlantic.com/science/archive/2016/06/fancy-math-cant-make-aliens-real/487589/-"Adam Frank, a professor of astrophysics at the University of Rochester, wrote the essay that appeared in the Times. Frank is a gifted scientist, and a thoughtful science writer. He begins the op-ed with an enthusiastic update on the ongoing exoplanet revolution. I must confess I share his enthusiasm. I suspect that future historians of science will wonder what it was like to live in this moment. A little more than two decades ago, we weren't sure whether there were any planets outside our solar system. Now we have reason to believe that nearly all stars host planets, and that many of them are rocky and wet like our own. No generation of humans has ever gazed up at night skies so pregnant with possibility.-***-"The simple fact is that no matter how much we wish to live in a universe that teems with life—and many of us wish quite fervently—we haven't the slightest clue how often it evolves. Indeed, we aren't even sure how life arose on this planet. We have our just-so stories about lightning strikes and volcanic vents, but no one has come close to duplicating abiogenesis in a lab. Nor do we know whether basic organisms reliably evolve into beings like us.-"We can't extrapolate from our experience on this planet, because it's only one data point. We could be the only intelligent beings in the universe, or we could be one among trillions, and either way Earth's natural history would look the exact same. Even if we could draw some crude inferences, the takeaways might not be so reassuring. It took two billion years for simple, single-celled life to spawn our primordial lineage, the eukaryotes. And so far as we can tell, it only happened once. It took another billion years for eukaryotes to bootstrap into complex animal life, and hundreds of millions of years more for the development of language and sophisticated tool-making. And unlike the eye, or bodies with legs—adaptations that have arisen independently on many branches of life's tree—intelligence of the spaceship-making sort has only emerged once, in all of Earth's history. It just doesn't seem like one of evolution's go-to solutions.-"Frank compresses each of these important, billions-of-years-in-the-making leaps in evolution into a single “biotechnical” probability, which is meant to capture the likelihood of the whole sequence. For all we know, each step could be a highly contingent cosmic lottery win. Perhaps eukaryotes “usually” take tens of billions of years to evolve, and we lucked into an early outlier on the distribution curve. Perhaps we have been fortunate at every step of the way. Frank's argument skips over these probabilities. Or rather, it bundles them up into a single, tidy unknown, that he can hammer with a big italicized number: - “'What our calculation revealed is that even if this probability [that technological civilization evolves] is assumed to be extremely low, the odds that we are not the first technological civilization are actually high. Specifically, unless the probability for evolving a civilization on a habitable-zone planet is less than one in 10 billion trillion, then we are not the first.”-"Absent a clear account of how often we can expect planets to spawn technological civilizations, we don't have any way to evaluate that “10 billion trillion” number. We certainly don't have grounds to say that the “odds are high” that some civilization preceded ours, or enough evidence to suggest that skepticism about the possibility “borders on the irrational.'”-Comment: No evidence so far, but Bbella has shown us evidence on Earth that is not explained.
For Bbella: a mathematician's take
by David Turell , Monday, July 18, 2016, 14:44 (2838 days ago) @ David Turell
A response to the previous article:-http://www.npr.org/sections/13.7/2016/07/14/485992587/were-there-aliens-before-us-"Today, I would like, once again, to present our argument and dive a little deeper into its meaning and its limits. In particular, I want to address two excellent rebuttals written by Ross Andersen in The Atlantic and Ethan Siegel in Forbes. Neither Andersen or Siegel was buying some of my contentions and they both made good points. The thing about science (take note climate deniers) is that it's really a call and response. Both Andersen and Siegel are great writers. Their skepticism made me think even harder about the ideas in our paper and that was really helpful.-[I've skipped Drake equation discussion]-"By looking at the problem this way — and using the new exo-planet data and rearranging things — our results provide an empirical constraint to a very different question than the one Drake's equation usually focuses on. Here is our question:-"What would the bio-technical probability per planet have to be for us to be the only civilization that ever occurred in the entire history of the universe?-"Putting in our exo-planet date, we found the answer is 10^22 or one in 10 billion trillion. We call this number the "pessimism line," and you can think about its meaning in a bunch of ways.-***-"Also, while its true that we can't say anything explicitly data-driven past our derivation of the pessismism line, the history of debate about the Drake equation provides ample material to think more deeply about our result. While many have argued that exo-civilizations would be rare, the sense of what rare means is rarely specified explicitly. If you scratch below the surface, rare often means orders of magnitude above our 10^22 pessimism line.-"To see this point, let's take a particularly famous example. In 1983, the physicist Brandon Carter developed an absolutely ingenious argument against exo-civilizations based on the observation that the time for intelligence to arise on Earth was close the total age of the sun. Using this one fact, he further made the case that intelligence required evolution to pass through a series of "hard steps," each of which would be highly improbable.-"Imagining there were 10 evolutionary "hard steps," he did a calculation where he found the total probability for exo-civilizations to form to be 10^20. He then claimed, this value "is more than sufficient to ensure that our stage of development is unique in the visible universe."-"But it's not! The pessimism line we derived shows that Carter's 1983 calculation still allows 100 exo-civilizations. Carter intended his calculation to be hyper-pessimistic, but it turns out to be optimistic instead. It should also be noted that researchers now believe only five hard steps exist (if they exist at all). This, along the other values in Carter's original paper, imply a probability of 10^10 which, along with our pessimism line, implies a trillion exo-civilizations across cosmic history. (It's also noteworthy that authors like Mario Livio present arguments that undermine the basis for Carter's work).-"Of course, it's still possible to construct arguments leaving the probability far below our pessimism line, ensuring we're the only exo-civilization that ever formed. But it's here that, I believe, the most important implication of our result emerges.-***-"Thus skeptics are entirely right that without any more data one must remain formally agnostic about exo-civilizations. You can't assign a probability to an unknown process. But to stop there misses a key point about our moment in science and in history. Astrobiology, the study of life in the universe, has made tremendous strides through studies of our world, the other worlds in our solar system and, famously, the newly discovered exo-planets. The study Woody Sullivan and I carried out is firmly situated in the midst of these expanding astrobiological horizons. Taken together, I believe our results mean that most pessimists (on the question we asked) are actually optimists and the remaining hyper-pessimists — well, they really have some 'splaining to do.-"Finally note that our study said nothing about the existence of civilizations now. We were dealing with a kind of exo-civilization archeology. If that all important lifetime factor L is not long, then our neighborhood the Milky Way galaxy might be entirely empty (other than us) in the current cosmic epoch."-Comment: Huge article worth reading. Previous alien civilizations are slightly possible.
For Bbella: a mathematician's take
by BBella , Monday, July 18, 2016, 17:16 (2838 days ago) @ David Turell
A response to the previous article: > > http://www.npr.org/sections/13.7/2016/07/14/485992587/were-there-aliens-before-us&#... >Here is our question: > > "What would the bio-technical probability per planet have to be for us to be the only civilization that ever occurred in the entire history of the universe?-> Comment: Huge article worth reading. Previous alien civilizations are slightly possible.-Regardless of what the thinkers think of the probabilities of life elsewhere, if there is there is or if there isn't there isn't. For me, evidence as well as logic weighs heavily on the side that there is.
For Bbella: light from brains
by David Turell , Monday, October 03, 2016, 15:47 (2761 days ago) @ BBella
There is a correlation between types of light and size of smarter brain:-http://www.the-scientist.com/?articles.view/articleNo/47099/title/Do-Brighter-Species--Brains-Emit-Redder-Light-/&utm_source=hs_email&utm_medium=email&utm_content=35232151&_hsenc=p2ANqtz-9OvSD8zPpkMNmINuCWdQR_7_bgiWrEzrtLBdjtD2SJVjAisITDzvrX5dBekru36XN34jCoVq9-_GGrHuiRAxKTxsr5bg&_hsmi=35232151-"Neurons can emit ultraweak photons when stimulated by the abundant neurotransmitter glutamate, and experiments suggest that the emitted light can travel along rat nerve fibers. Yet most researchers don't believe there's enough evidence to say whether these so-called biophotons act as communication signals, according to Michal Cifra, who studies the phenomenon at the Institute of Photonics and Electronics in the Czech Academy of Sciences.-"To test for a biological role for biophotons, a team in China analyzed brain slices from six species of roughly increasing intelligence: bullfrog, chicken, mouse, pig, rhesus monkey, and human. The group doused the tissues with the neurotransmitter glutamate and determined the photon emissions' wavelengths using a newly designed spectrometer.-"For the most part, the more intelligent the species, the longer the biophoton wavelength: from about 600 nm among bullfrogs to 700 nm among humans, on average. (Chickens' biophotons had longer wavelengths than mice's, suggesting to the authors that chickens are smarter.) Because red-shifted light has lower energy, this spectral slide could help species, if they do use light biologically, to expend less energy, says study coauthor Jiapei Dai of South-Central University for Nationalities in Wuhan. “It's a correlation,” says Dai. “But maybe [it] gives an explanation for human high intelligence.”-"Cifra and Vahid Salari, who studies biophotons at Isfahan University of Technology in Tehran, concur that the findings are novel. But the team's conclusions overreach. Cifra doubts “whether this spectral shift is [really] caused by some evolutionary function, or [if] it is just a coincidental artifact of having tissues of differing molecular content.'”-Comment: Kabbalah philosophy says life is light
For Bbella: light from stars suggest alien signal
by David Turell , Thursday, October 13, 2016, 02:03 (2752 days ago) @ David Turell
The critics think not:
http://www.astronomy.com/news/2016/10/be-extraordinarily-cautious-about-the-newest-alie...
"According to their research, it’s not just one star candidate. There are several, all coming from data in the Sloan Digital Sky Survey. These stars experienced rapid bursts of light that, to some researchers, would be the calling card of an intelligent civilization turning on an optical (rather than radio) beacon. There’s something quite tantalizing about the conclusion, “We find that the detected signals have exactly the shape of an ETI signal predicted in the previous publication and are therefore in agreement with this hypothesis,” and the paper has been accepted into Publications of the Astronomical Society of the Pacific.
***
“'Apparently several — more than three or four — referees have been disinclined to see this published,” Seth Shostak, senior astronomer at the SETI Institute says in an email. “I am quite skeptical, in particular of the data processing that can take spectrally sampled data, and infer time variations. So I’d be a little careful.”
Similarly, Andrew Siemion, director of SETI Berkeley, urged skepticism. Along with heading up SETI Berkeley, Siemion heads up the Breakthrough Listen initiative, a global $100 million decade long survey to hunt for potential extraterrestrial signals using dedicated telescope time.
“'Punch line is that this is interesting but needs to be followed up on other facilities, which we will be doing with Breakthrough Listen,” he says in an email.
***
"The one in 10,000 objects with unusual spectra seen by Borra and Trottier are certainly worthy of additional study. However, extraordinary claims require extraordinary evidence. It is too early to unequivocally attribute these purported signals to the activities of extraterrestrial civilizations.
***
"The statement goes on to say that on a 10 point scale used by international SETI researchers when ranking potential signals called the Rio Scale, this barely rises above a 0 rating, listed as "insignificant." What would be needed to see that rank climb? Independent verification by another telescope would go a long way to, at the very least, notching it up a little more on the scale.
"Some of those will be carried out by instruments utilized by the Breakthrough Listen consortium, which includes several stakeholders in the field. The group will use the Automated Planet Finder to target a handful of stars to see if any similar "beacons" appear — something that, while not ruled out, isn't seeming likely.
"Like everything — promising signals, megastructures, Mars rocks, whatever else — it's too early to tell if this is anything. And so far, it's looking incredibly unlikely."
Comment: We must keep looking.