Are We alone; fun and games (Introduction)

by David Turell , Saturday, April 30, 2016, 19:32 (2911 days ago)

The Drake equation is now being updated, since we now know how many stars have planets in this galaxy:-http://phys.org/news/2016-04-limits-uniqueness.html-
"Are humans unique and alone in the vast universe? This question—summed up in the famous Drake equation—has for a half-century been one of the most intractable and uncertain in science. -"But a new paper shows that the recent discoveries of exoplanets combined with a broader approach to the question makes it possible to assign a new empirically valid probability to whether any other advanced technological civilizations have ever existed.-"And it shows that unless the odds of advanced life evolving on a habitable planet are astonishingly low, then human kind is not the universe's first technological, or advanced, civilization.-***-"'We've known for a long time approximately how many stars exist. We didn't know how many of those stars had planets that could potentially harbor life, how often life might evolve and lead to intelligent beings, and how long any civilizations might last before becoming extinct."-"'Thanks to NASA's Kepler satellite and other searches, we now know that roughly one-fifth of stars have planets in "habitable zones," where temperatures could support life as we know it. So one of the three big uncertainties has now been constrained."-"Frank said that the third big question—how long civilizations might survive—is still completely unknown. "The fact that humans have had rudimentary technology for roughly ten thousand years doesn't really tell us if other societies would last that long or perhaps much longer," he explained.-"But Frank and his coauthor, Woodruff Sullivan of the astronomy department and astrobiology program at the University of Washington, found they could eliminate that term altogether by simply expanding the question.-***-"Rather than guessing at the odds of advanced life developing, they calculate the odds against it occurring in order for humanity to be the only advanced civilization in the entire history of the observable universe. With that, Frank and Sullivan then calculated the line between a Universe where humanity has been the sole experiment in civilization and one where others have come before us.-***-"Using this approach, Frank and Sullivan calculate how unlikely advanced life must be if there has never been another example among the universe's ten billion trillion stars, or even among our own Milky Way galaxy's hundred billion.-"The result? By applying the new exoplanet data to the universe's 2 x 10 to the 22nd power stars, Frank and Sullivan find that human civilization is likely to be unique in the cosmos only if the odds of a civilization developing on a habitable planet are less than about one in 10 billion trillion, or one part in 10 to the 22th power.-***- "Their equation, A=Nast*fbt, describes A as the product of Nast - the number of habitable planets in a given volume of the Universe - multiplied by fbt - the likelihood of a technological species arising on one of these planets. The volume considered could be, for example, the entire Universe, or just our Galaxy.-***-"As Frank puts it "We don't even know if it's possible to have a high-tech civilization that lasts more than a few centuries." With Frank and Sullivan's new result, scientists can begin using everything they know about planets and climate to begin modeling the interactions of an energy-intensive species with their home world knowing that a large sample of such cases has already existed in the cosmos. "Our results imply that our evolution has not been unique and has probably happened many times before. The other cases are likely to include many energy intensive civilizations dealing with their feedbacks onto their planets as their civilizations grow. That means we can begin exploring the problem using simulations to get a sense of what leads to long lived civilizations and what doesn't.'"-Comment: Fun and games. How will religions react if there are other humans? Aftere all there is fine tuning!