Alien Civilizations May Number In The Trillions, New Study Says
Aug. 3, 2016
The possibility that we earthlings are not truly alone in the universe has gained some added credibility, thanks to a new study that coincides with NASA’s recent planetary discoveries. The research, published in the journal Astrobiology last week, suggests that more planets in the Milky Way galaxy may harbor advanced civilizations than we previously imagined.
Study co-authors Adam Frank and Woodruff Sullivan looked at recent discoveries of potentially habitable exoplanets and considered the odds of whether sophisticated civilizations existed on them in the past or present.
“What we showed was the ‘floor’ on the probability for a civilization to form on any randomly chosen planet,” Frank, a University of Rochester physics and astronomy professor, told The Huffington Post in an email. “If we are the only civilization in cosmic history, then that what we calculated is the actual probability nature has set. But if the actual probability is higher than that floor, then civilizations have happened before.”
Frank says the potential number of planets orbiting their parent stars within a habitable distance is staggering.
“Even if you are pretty pessimistic and think that you’d have to search through 100 billion (habitable zone) planets before you found one where a civilization developed, then there have still been a trillion civilizations over cosmic history!” Frank wrote. “When I think about that, my mind reels — even if there is just a one in a 100 billion chance of evolution creating exo-civilizations, the universe still has made so many of them that we are swamped by histories other than our own.”
In 1961, astronomer Frank Drake — founder of the SETI Institute (SETI stands for “Search for Extraterrestrial Intelligence”) — devised what is now known as the “Drake equation” to estimate the number of planets that may be home to civilizations with the ability to communicate beyond their world.
Frank and Sullivan created a new equation, which appears at the bottom of the illustration below. While the Drake equation calculates the number of advanced alien civilizations that could exist in the Milky Way galaxy, Frank and Sullivan’s equation expands the question to calculate the number of advanced civilizations that have existed in our galaxy throughout the whole history of the universe.
UNIVERSITY OF ROCHESTER Two equations consider the possibilities of technological alien civilizations in the Milky Way galaxy: At top, the 1961 Drake equation and, at bottom, a more recent equation by Adam Frank and Woodruff Sullivan.
NASA, ESA, and the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration A stellar nursery in the Large Magellanic Cloud, a satellite galaxy of the Milky Way. By surveying star clusters and field stars in and out of our galaxy, as well as measuring the extent of the Milky Way, we can simply determine the number and types of stars that exist.
In 1961, scientist Frank Drake wrote down a simple-looking equation for estimating the number of active, technologically-advanced, communicating civilizations in the Milky Way. From first principles, there was no good way to simply estimate a number, but Drake had the brilliant idea of writing down a large number of parameters that could be estimated, which you would then multiply together. If your numbers were accurate, you'd arrive at an accurate figure for the number of technologically advanced civilizations that humanity could communicate with, within our own galaxy, at any given moment. It's a brilliant idea in concept, but one that's become less and less useful as we've learned more about our Universe. As it stands today, the Drake equation is broken, but we know enough about the Universe to construct an even better framework.
The Drake equation, to be specific, said that the number of civilizations (N) we have at any given time within our galaxy, is equal to the product of seven different unknown quantities from astronomy, geology, biology, and anthropology, each of which build off of the previous element. They are:
R∗, the average rate of star formation, fp, the fraction of stars with planets, ne the average number stars-with-planets that have one that could support life, fl, the fraction of those planets that developed life, fi, the fraction of life-bearing planets that developed intelligent life, fc, the fraction of these intelligence-having planets that are technologically communicative across interstellar space, and L, the length of time such a civilization can broadcast-or-listen.
Multiply these numbers all together, in theory, and that will give you the number of technologically advanced, broadcasting civilizations we have in the Milky Way today.
Only, there are huge problems with this setup. There are a number of unspoken assumptions that simply writing down the equation this way makes, that simply don't reflect reality. Problems for its modern-day usefulness include:
*The fact that the equation was written before the Big Bang was validated and the Steady State model was disfavored. *The equation assumes that only one planet per star system could support life. *That intelligent, technologically advanced life will never spread to other worlds. *And that broadcasting-and-listening-for radio signals is the method by which an intelligent species would choose to communicate across interstellar space.
That last assumption, in particular, was the motivation for SETI — the search for extraterrestrial intelligence (with radio dishes) — which has, of course, come up empty.
This doesn't mean, however, that there aren't other worlds out there with intelligent life on them! Despite our uncertainties about what's out there or whether/how they might attempt to search for or contact us, the possibility of intelligent, communicative, or spacefaring extraterrestrials is one of tremendous interest to not only scientists, but all of humanity. Many of the steps of the Drake equation may be problematic, and they contain the major issue that there are huge uncertainties associated with them: so large that they render any conclusion about N, the number of civilizations within our galaxy, meaningless. But it's 2018 now, and there are a huge number of things we know about our galaxy and our Universe that we didn't know in 1961. Here's a better approach.
skywalker: Very funny, ghost boy
Jun 3, 2018 14:58:58 GMT -6
lois: Casper he should come fix mine. Mine is doomed
Jun 26, 2018 21:54:27 GMT -6
spotless38: Iam back after a long break . What a couple of years I had . After what had happened I lost my brother and had to bury him and then I had caught that type A flue and I was a very sick puppy I also needed blood for the loss of it .
Jul 7, 2018 13:30:41 GMT -6
lois: Very Happy to see you Ron. Missed you. Glad you are doing better now. Sorry for your lost. I did not know your brother had passed. hugs lois
Jul 10, 2018 0:52:45 GMT -6
paulette: Ron - hope you've hit a quiet spot. Sorry for your loss.
Aug 3, 2018 10:49:30 GMT -6
lois: I picked up my phone a few days ago and I looked at the name of the caller. Boy was I surprise. It has been a couple of years. So good to hear your voice Ron. Hope you make it a habit again. love and hugs .
Aug 15, 2018 23:21:38 GMT -6
leia77: Spotless, I am glad that you are feeling better and welcome back! I too am back from a long time away...
Aug 31, 2018 2:08:32 GMT -6
jcurio: I am much relieved to see that you have been on here, Spotless! I hope that things are going much better for you now
Sept 19, 2018 16:46:42 GMT -6
jcurio: And Lois, And Lorelei!
Sept 19, 2018 16:47:07 GMT -6
casper: And Meeeeeee!!
Oct 16, 2018 18:41:31 GMT -6
lois: Sorry guys I cannot see the print. On is tiny hand computer
Oct 21, 2018 20:42:09 GMT -6
lois: Casper your page stops at page five in 2016
Nov 15, 2018 23:54:01 GMT -6
lois: How did your Halloween night go this year?
Nov 15, 2018 23:54:58 GMT -6
skywalker: He posted on the Halloween thread this year.
Nov 25, 2018 18:33:36 GMT -6
lois: Oh ok Sky I will check it out. Thanks.
Dec 21, 2018 21:45:31 GMT -6
lois: What topic was it under.
Dec 21, 2018 21:51:07 GMT -6