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Antropički princip, da li je čovek sam i poseban u svemiru?

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Humanity is cosmically special. Here’s how we know.

 

By Howard A. Smith November 25

 

Howard A. Smith is a lecturer in the Harvard University Department of Astronomy and a senior astrophysicist at the Harvard-Smithsonian Center for Astrophysics.

 

As we give thanks for our many obvious blessings, let’s reflect on a blessing that is less well known, a gift from modern astronomy: how we view ourselves.

 

There was a time, back when astronomy put Earth at the center of the universe, that we thought we were special. But after Copernicus kicked Earth off its pedestal, we decided we were cosmically inconsequential, partly because the universe is vast and about the same everywhere. Astronomer Carl Sagan put it this way: “We find that we live on an insignificant planet of a humdrum star.” Stephen Hawking was even blunter: “The human race is just a chemical scum on a moderate-sized planet.”

An objective look, however, at just two of the most dramatic discoveries of astronomy — big bang cosmology and planets around other stars (exoplanets) — suggests the opposite. We seem to be cosmically special, perhaps even unique — at least as far as we are likely to know for eons.

The first result — the anthropic principle — has been accepted by physicists for 43 years. The universe, far from being a collection of random accidents, appears to be stupendously perfect and fine-tuned for life. The strengths of the four forces that operate in the universe — gravity, electromagnetism, and the strong and weak nuclear interactions (the latter two dominate only at the level of atoms) — for example, have values critically suited for life, and were they even a few percent different, we would not be here. The most extreme example is the big bang creation: Even an infinitesimal change to its explosive expansion value would preclude life. The frequent response from physicists offers a speculative solution: an infinite number of universes — we are just living in the one with the right value. But modern philosophers such as Thomas Nagel and pioneering quantum physicists such as John Wheeler have argued instead that intelligent beings must somehow be the directed goal of such a curiously fine-tuned cosmos.

It seems likely that exoplanets could host extraterrestrial intelligence. But intelligence is not so easy to produce. Paleontologist Peter Ward and astronomer Donald Brownlee summarize the many constraints in their book “Rare Earth: Why Complex Life is Uncommon in the Universe ” and show why it takes vastly more than liquid water and a pleasant environment to give birth even to simple (much less complex) life. At a minimum, it takes an environment stable for billions of years of evolution, plus all the right ingredients. Biologists from Jacques Monod to Stephen Jay Gould have emphasized the extraordinary circumstances that led to intelligence on Earth, while geneticists have found that DNA probably resulted from many accidents. So although the same processes operate everywhere, some sequences could be unlikely, even astronomically unlikely. The evolution of intelligence could certainly be such a sequence.

There is, moreover, a well-known constraint: the finite speed of light, which ensures that even over thousands of years we will only be able to communicate with the comparatively few stars (tens of millions) in our cosmic neighborhood. If the combined astronomical, biological and evolutionary chances for life to form and evolve to intelligence are only 1 in 10 million, then we probably have no one to talk to.

The discovery of exoplanets was dramatic but not unexpected: Since the Greeks, we have imagined planets were common. Textbooks even taught that our solar system was typical. But the exotic diversity of exoplanets came as a surprise. Many have highly elliptical orbits around unstable stars, making evolution over billions of years difficult if not impossible; other systems contain giant planets that may have drifted inward, disrupting orbits; and there are many other unanticipated properties. These unexpected discoveries are helping scientists unravel Earth’s complex history.

The bottom line for extraterrestrial intelligence is that it is probably rarer than previously imagined, a conclusion called the misanthropic principle. For all intents and purposes, we could be alone in our cosmic neighborhood, and if we expand the volume of our search we will have to wait even longer to find out. Life might be common in the very distant universe — or it might not be — and we are unlikely to know. We are probably rare — and it seems likely we will be alone for eons. This is the second piece of new evidence that we are not ordinary.

 

Some of my colleagues strongly reject this notion. They would echo Hawking: “I can’t believe the whole universe exists for our benefit.” Yes, we all have beliefs — but beliefs are not proof. Hawking’s belief presumes that we are nothing but ordinary, a “chemical scum.” All the observations so far, however, are consistent with the idea that humanity is not mediocre at all and that we won’t know otherwise for a long time. It seems we might even serve some cosmic role. So this season let us be grateful for the amazing gifts of life and awareness, and acknowledge the compelling evidence to date that humanity and our home planet, Earth, are rare and cosmically precious. And may we act accordingly.

 

Edited by slow

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Time Crisis

Možda će sijati sunce, a možda će padati kiša, ništa specijalno novo u ovom članku. :)

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slow

Ima bolji domaći članak od pre desetak godina:

 

 

Antropičko načelo i svet na velikoj skali

Pitanje da li je Univerzum mogao biti drugačiji nego što jeste, te ima li svet koji vidimo oko nas svrhu jedno je od najstarijih pitanja koje je čovek postavljao sebi. Piše: dr Milan M. Ćirković

 

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slow

http://www.anthropic-principle.com/

 

   

Was the Universe made for us?

 

It appears that there is a set of fundamental physical constants that are such that had they been very slightly different, the universe would have been void of intelligent life. It's as if we're balancing on a knife’s edge. Some philosophers and physicists take the 'fine-tuning' of these constants to be an explanandum that cries out for an explanans, but is this the right way to think?

The data we collect about the Universe is filtered not only by our instruments' limitations, but also by the precondition that somebody be there to “have” the data yielded by the instruments (and to build the instruments in the first place). This precondition causes observation selection effects - biases in our data that may call into question how we interpret evidence that the Universe is fine-tuned at all.

 

 

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Time Crisis

 

Alien life could thrive in the clouds of failed stars

By Joshua Sokol

Dec. 2, 2016 , 3:00 AM

There’s an abundant new swath of cosmic real estate that life could call home—and the views would be spectacular. Floating out by themselves in the Milky Way galaxy are perhaps a billion cold brown dwarfs, objects many times as massive as Jupiter but not big enough to ignite as a star. According to a new study, layers of their upper atmospheres sit at temperatures and pressures resembling those on Earth, and could host microbes that surf on thermal updrafts.

The idea expands the concept of a habitable zone to include a vast population of worlds that had previously gone unconsidered. “You don’t necessarily need to have a terrestrial planet with a surface,” says Jack Yates, a planetary scientist at the University of Edinburgh in the United Kingdom, who led the study.

Atmospheric life isn’t just for the birds. For decades, biologists have known about microbes that drift in the winds high above Earth’s surface. And in 1976, Carl Sagan envisioned the kind of ecosystem that could evolve in the upper layers of Jupiter, fueled by sunlight. You could have sky plankton: small organisms he called “sinkers.” Other organisms could be balloonlike “floaters,” which would rise and fall in the atmosphere by manipulating their body pressure. In the years since, astronomers have also considered the prospects of microbes in the carbon dioxide atmosphere above Venus’s inhospitable surface.

Yates and his colleagues applied the same thinking to a kind of world Sagan didn’t know about. Discovered in 2011, some cold brown dwarfs have surfaces roughly at room temperature or below; lower layers would be downright comfortable. In March 2013, astronomers discovered WISE 0855-0714, a brown dwarf only 7 light-years away that seems to have water clouds in its atmosphere. Yates and his colleagues set out to update Sagan’s calculations and to identify the sizes, densities, and life strategies of microbes that could manage to stay aloft in the habitable region of an enormous atmosphere of predominantly hydrogen gas. Sink too low and you are cooked or crushed. Rise too high and you might freeze.

On such a world, small sinkers like the microbes in Earth’s atmosphere or even smaller would have a better chance than Sagan’s floaters, the researchers will report in an upcoming issue of The Astrophysical Journal. But a lot depends on the weather: If upwelling winds are powerful on free-floating brown dwarfs, as seems to be true in the bands of gas giants like Jupiter and Saturn, heavier creatures can carve out a niche. In the absence of sunlight, they could feed on chemical nutrients. Observations of cold brown dwarf atmospheres reveal most of the ingredients Earth life depends on: carbon, hydrogen, nitrogen, and oxygen, though perhaps not phosphorous.

The idea is speculative but worth considering, says Duncan Forgan, an astrobiologist at the University of St. Andrews in the United Kingdom, who did not participate in the study but says he is close to the team. “It really opens up the field in terms of the number of objects that we might then think, well, these are habitable regions.”

So far, only a few dozen cold brown dwarfs have been discovered, though statistics suggest there should be about 10 within 30 light-years of Earth. These should be ripe targets for the James Webb Space Telescope (JWST), which is sensitive in the infrared where brown dwarfs shine brightest. After it launches in 2018, the JWST should reveal the weather and the composition of their atmospheres, says Jackie Faherty, an astronomer at the Carnegie Institution for Science in Washington, D.C. “We’re going to start getting gorgeous spectra of these objects,” she says. “This is making me think about it.”

Testing for life would require anticipating a strong spectral signature of microbe byproducts like methane or oxygen, and then differentiating it from other processes, Faherty says. Another issue would be explaining how life could arise in an environment that lacks the water-rock interfaces, like hydrothermal vents, where life is thought to have begun on Earth. Perhaps life could develop through chemical reactions on the surfaces of dust grains in the brown dwarf’s atmosphere, or perhaps it gained a foothold after arriving as a hitchhiker on an asteroid. “Having little microbes that float in and out of a brown dwarf atmosphere is great,” Forgan says. “But you’ve got to get them there first.”

Posted in:

DOI: 10.1126/science.aal0456

 

http://www.sciencemag.org/news/2016/12/alien-life-could-thrive-clouds-failed-stars

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hazard

Mislim da nama generalno fali malo maste kada zamisljamo vanzemaljski zivot. Zasto bi zivot morao da bude kao ovozemaljski?

 

Evo npr. interesantne pricice na tu temu koja to plasticno ilustruje:

 

http://www.terrybisson.com/page6/page6.html

 

 


THEY'RE MADE OUT OF MEAT
 
 
"They're made out of meat."
 
"Meat?"
 
"Meat. They're made out of meat."
 
"Meat?"
 
"There's no doubt about it. We picked up several from different parts of the planet, took them aboard our recon vessels, and probed them all the way through. They're completely meat."
 
"That's impossible. What about the radio signals? The messages to the stars?"
 
"They use the radio waves to talk, but the signals don't come from them. The signals come from machines."
 
"So who made the machines? That's who we want to contact."
 
"They made the machines. That's what I'm trying to tell you. Meat made the machines."
 
"That's ridiculous. How can meat make a machine? You're asking me to believe in sentient meat."
 
"I'm not asking you, I'm telling you. These creatures are the only sentient race in that sector and they're made out of meat."

 

ostatak:

 

 

 

"Maybe they're like the orfolei. You know, a carbon-based intelligence that goes through a meat stage."
 
"Nope. They're born meat and they die meat. We studied them for several of their life spans, which didn't take long. Do you have any idea what's the life span of meat?"
 
"Spare me. Okay, maybe they're only part meat. You know, like the weddilei. A meat head with an electron plasma brain inside."
 
"Nope. We thought of that, since they do have meat heads, like the weddilei. But I told you, we probed them. They're meat all the way through."
 
"No brain?"
 
"Oh, there's a brain all right. It's just that the brain is made out of meat! That's what I've been trying to tell you."
 
"So ... what does the thinking?"
 
"You're not understanding, are you? You're refusing to deal with what I'm telling you. The brain does the thinking. The meat."
 
"Thinking meat! You're asking me to believe in thinking meat!"
 
"Yes, thinking meat! Conscious meat! Loving meat. Dreaming meat. The meat is the whole deal!  Are you beginning to get the picture or do I have to start all over?"
 
"Omigod. You're serious then. They're made out of meat."
 
"Thank you. Finally. Yes. They are indeed made out of meat. And they've been trying to get in touch with us for almost a hundred of their years."
 
"Omigod. So what does this meat have in mind?"
 
"First it wants to talk to us. Then I imagine it wants to explore the Universe, contact other sentiences, swap ideas and information. The usual."
 
"We're supposed to talk to meat."
 
"That's the idea. That's the message they're sending out by radio. 'Hello. Anyone out there. Anybody home.' That sort of thing."
 
"They actually do talk, then. They use words, ideas, concepts?"
"Oh, yes. Except they do it with meat."
 
"I thought you just told me they used radio."
 
"They do, but what do you think is on the radio? Meat sounds. You know how when you slap or flap meat, it makes a noise? They talk by flapping their meat at each other. They can even sing by squirting air through their meat."
 
"Omigod. Singing meat. This is altogether too much. So what do you advise?"
 
"Officially or unofficially?"
 
"Both."
 
"Officially, we are required to contact, welcome and log in any and all sentient races or multibeings in this quadrant of the Universe, without prejudice, fear or favor. Unofficially, I advise that we erase the records and forget the whole thing."
 
"I was hoping you would say that."
 
"It seems harsh, but there is a limit. Do we really want to make contact with meat?"
 
"I agree one hundred percent. What's there to say? 'Hello, meat. How's it going?' But will this work? How many planets are we dealing with here?"
 
"Just one. They can travel to other planets in special meat containers, but they can't live on them. And being meat, they can only travel through C space. Which limits them to the speed of light and makes the possibility of their ever making contact pretty slim. Infinitesimal, in fact."
 
"So we just pretend there's no one home in the Universe."
 
"That's it."
 
"Cruel. But you said it yourself, who wants to meet meat? And the ones who have been aboard our vessels, the ones you probed? You're sure they won't remember?"
 
"They'll be considered crackpots if they do. We went into their heads and smoothed out their meat so that we're just a dream to them."
 
"A dream to meat! How strangely appropriate, that we should be meat's dream."
 
"And we marked the entire sector unoccupied."
 
"Good. Agreed, officially and unofficially. Case closed. Any others? Anyone interesting on that side of the galaxy?"
 
"Yes, a rather shy but sweet hydrogen core cluster intelligence in a class nine star in G445 zone. Was in contact two galactic rotations ago, wants to be friendly again." 
 
"They always come around."
 
"And why not? Imagine how unbearably, how unutterably cold the Universe would be if one were all alone ..."

 

 

 

Ko hoce detaljnije razmatranje na tu temu u knjizevnosti, nek cita Lemov Solaris npr. :)

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dragance

Ja samo da vidim kakve su to antropičke.

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MancMellow

Mislim da nama generalno fali malo maste kada zamisljamo vanzemaljski zivot. Zasto bi zivot morao da bude kao ovozemaljski?

 

Evo npr. interesantne pricice na tu temu koja to plasticno ilustruje:

 

http://www.terrybisson.com/page6/page6.html

 

 

mislim da je ovo 1 vrlo optimističan scenario :D 

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Shan Jan

Mislis da je realnije da bi bilo jedno KILL THE MEAT!!!

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MancMellow

Mislis da je realnije da bi bilo jedno KILL THE MEAT!!!

 

ne znam, ja mislim da je malo blesavo to slanje signala nasumice svuda gde možemo da dobacimo. ne bih voleo da svedočim nekom eventualnom susretu sa civilizacijom koja može da stigne do nas a mi ne možemo da vidimo ni gde su. 

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slow

Mislim da nama generalno fali malo maste kada zamisljamo vanzemaljski zivot. Zasto bi zivot morao da bude kao ovozemaljski?

 

Evo npr. interesantne pricice na tu temu koja to plasticno ilustruje:

 

http://www.terrybisson.com/page6/page6.html

 

 

 

ostatak:

 

 

 

"Maybe they're like the orfolei. You know, a carbon-based intelligence that goes through a meat stage."
 
"Nope. They're born meat and they die meat. We studied them for several of their life spans, which didn't take long. Do you have any idea what's the life span of meat?"
 
"Spare me. Okay, maybe they're only part meat. You know, like the weddilei. A meat head with an electron plasma brain inside."
 
"Nope. We thought of that, since they do have meat heads, like the weddilei. But I told you, we probed them. They're meat all the way through."
 
"No brain?"
 
"Oh, there's a brain all right. It's just that the brain is made out of meat! That's what I've been trying to tell you."
 
"So ... what does the thinking?"
 
"You're not understanding, are you? You're refusing to deal with what I'm telling you. The brain does the thinking. The meat."
 
"Thinking meat! You're asking me to believe in thinking meat!"
 
"Yes, thinking meat! Conscious meat! Loving meat. Dreaming meat. The meat is the whole deal!  Are you beginning to get the picture or do I have to start all over?"
 
"Omigod. You're serious then. They're made out of meat."
 
"Thank you. Finally. Yes. They are indeed made out of meat. And they've been trying to get in touch with us for almost a hundred of their years."
 
"Omigod. So what does this meat have in mind?"
 
"First it wants to talk to us. Then I imagine it wants to explore the Universe, contact other sentiences, swap ideas and information. The usual."
 
"We're supposed to talk to meat."
 
"That's the idea. That's the message they're sending out by radio. 'Hello. Anyone out there. Anybody home.' That sort of thing."
 
"They actually do talk, then. They use words, ideas, concepts?"
"Oh, yes. Except they do it with meat."
 
"I thought you just told me they used radio."
 
"They do, but what do you think is on the radio? Meat sounds. You know how when you slap or flap meat, it makes a noise? They talk by flapping their meat at each other. They can even sing by squirting air through their meat."
 
"Omigod. Singing meat. This is altogether too much. So what do you advise?"
 
"Officially or unofficially?"
 
"Both."
 
"Officially, we are required to contact, welcome and log in any and all sentient races or multibeings in this quadrant of the Universe, without prejudice, fear or favor. Unofficially, I advise that we erase the records and forget the whole thing."
 
"I was hoping you would say that."
 
"It seems harsh, but there is a limit. Do we really want to make contact with meat?"
 
"I agree one hundred percent. What's there to say? 'Hello, meat. How's it going?' But will this work? How many planets are we dealing with here?"
 
"Just one. They can travel to other planets in special meat containers, but they can't live on them. And being meat, they can only travel through C space. Which limits them to the speed of light and makes the possibility of their ever making contact pretty slim. Infinitesimal, in fact."
 
"So we just pretend there's no one home in the Universe."
 
"That's it."
 
"Cruel. But you said it yourself, who wants to meet meat? And the ones who have been aboard our vessels, the ones you probed? You're sure they won't remember?"
 
"They'll be considered crackpots if they do. We went into their heads and smoothed out their meat so that we're just a dream to them."
 
"A dream to meat! How strangely appropriate, that we should be meat's dream."
 
"And we marked the entire sector unoccupied."
 
"Good. Agreed, officially and unofficially. Case closed. Any others? Anyone interesting on that side of the galaxy?"
 
"Yes, a rather shy but sweet hydrogen core cluster intelligence in a class nine star in G445 zone. Was in contact two galactic rotations ago, wants to be friendly again." 
 
"They always come around."
 
"And why not? Imagine how unbearably, how unutterably cold the Universe would be if one were all alone ..."

 

 

 

Ko hoce detaljnije razmatranje na tu temu u knjizevnosti, nek cita Lemov Solaris npr. :)

 

Mašta može svašta ali realnost fizičkih zakona je neumoljiva. Barem se vodećim astrofizičarima ne može zamerati nedostatak mašte. Jedan od tvoraca antropičkog principa kosmolog Hojl je i sam pisao science fiction zajedno sa svojim sinom. Postoji problem fino podešenog svemira i fizičkih konstanti.

 

 

 

Ključnu ulogu u razjašnjavanju "trostruke alfa" reakcije, toliko bitne za postojanje sveta kakav znamo, odigrao je veliki engleski kosmolog i jedan od najoriginalnijih mislilaca ovog veka, ser Fred Hojl. Polazeći od onoga što će se tek kasnije nazvati antropičkim razmišljanjem, on je zaključio da bi, bez "trostruke alfa" reakcije, stvaranje težih elemenata bilo nemoguće. Među tim elementima nalazi se i ugljenik, koji predstavlja osnovu života na Zemlji, kiseonik, koji udišu svi viši organizmi, kao i drugi elementi bez kojih ne bi bilo nas, a samim tim se i pitanja nastanka hemijskih elemenata ne bi ni postavljalo. 

 

U tom smislu se reakcija (*) mora odigravati, a ako je tako, onda mora da postoji neki način da se uveća njena verovatnoća, tj. mora da postoji ono što se u žargonu fizičara zove rezonanca u jezgru C-12, i to na energiji bliskoj 7,7 MeV. Zapazimo značaj ovog rezonovanja: polazeći od sopstvenog postojanja, Hojl je došao do krajnje konkretnog predviđanja iz oblasti nuklearne fizike. Kada je sugerisao nuklearnim fizičarima-eksperimentatorima da izvrše laboratorijske oglede u cilju provere postojanja rezonatnog nivoa, oni ga u prvi mah nisu shvatali ozbiljno. Ipak je ubrzo posle toga jedan takav eksperiment i izvršen, i pronađen je rezonantni nivo na energiji od E = 7,656 ± 0,008 MeV, dakle, veoma blizu predviđene rezonance. 

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slow

ne znam, ja mislim da je malo blesavo to slanje signala nasumice svuda gde možemo da dobacimo. ne bih voleo da svedočim nekom eventualnom susretu sa civilizacijom koja može da stigne do nas a mi ne možemo da vidimo ni gde su. 

 

Ne mora da se čeka odgovor na signale koji smo mi poslali. Nismo uspeli da u celom spektru zračenja nađemo bilo šta što bi imalo naznake inteligencije koja traži nekog drugog ili da upadnemo u neki njihov kanal komunikacije. Projekat SETI osluškuje svemir decenijama, ništa nije pronađeno. Holivud je jedini našao nešto za sebe:

 

 

Edited by slow

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Shan Jan

ne znam, ja mislim da je malo blesavo to slanje signala nasumice svuda gde možemo da dobacimo. ne bih voleo da svedočim nekom eventualnom susretu sa civilizacijom koja može da stigne do nas a mi ne možemo da vidimo ni gde su. 

 

To je dobro pitanje. U principu jeste neodgovorno (sto tvrdi npr. i Hoking). Sa druge strane, nosim se mislju da oni koji imaju tehnologiju da nas nadju bi nas nasli i bez toga. Meni ovo vise deluje kao ocajnicki pokusaj da se kontaktira neko na slicnom nivou kao mi. 

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