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Posts Tagged ‘SETI

“I’m sure the universe is full of intelligent life. It’s just been too intelligent to come here.”*…

 

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The Fermi paradox, named for physicist Enrico Fermi, is the apparent contradiction between the lack of evidence for extraterrestrial civilizations and various high estimates for their probability (e.g., some of the optimistic estimates for the Drake equation).  Fermi wondered, “where are they?”

By way of context, Tim Urban in his wonderful Wait But Why?:

As many stars as there are in our galaxy (100 – 400 billion), there are roughly an equal number of galaxies in the observable universe—so for every star in the colossal Milky Way, there’s a whole galaxy out there. All together, that comes out to the typically quoted range of between 1022 and 1024 total stars, which means that for every grain of sand on every beach on Earth, there are 10,000 stars out there.

The science world isn’t in total agreement about what percentage of those stars are “sun-like” (similar in size, temperature, and luminosity)—opinions typically range from 5% to 20%. Going with the most conservative side of that (5%), and the lower end for the number of total stars (1022), gives us 500 quintillion, or 500 billion billion sun-like stars.

There’s also a debate over what percentage of those sun-like stars might be orbited by an Earth-like planet (one with similar temperature conditions that could have liquid water and potentially support life similar to that on Earth). Some say it’s as high as 50%, but let’s go with the more conservative 22% that came out of a recent PNAS study. That suggests that there’s a potentially-habitable Earth-like planet orbiting at least 1% of the total stars in the universe—a total of 100 billion billion Earth-like planets.

So there are 100 Earth-like planets for every grain of sand in the world. Think about that next time you’re on the beach.

Moving forward, we have no choice but to get completely speculative. Let’s imagine that after billions of years in existence, 1% of Earth-like planets develop life (if that’s true, every grain of sand would represent one planet with life on it). And imagine that on 1% of those planets, the life advances to an intelligent level like it did here on Earth. That would mean there were 10 quadrillion, or 10 million billion intelligent civilizations in the observable universe.

Moving back to just our galaxy, and doing the same math on the lowest estimate for stars in the Milky Way (100 billion), we’d estimate that there are 1 billion Earth-like planets and 100,000 intelligent civilizations in our galaxy.1

SETI (Search for Extraterrestrial Intelligence) is an organization dedicated to listening for signals from other intelligent life. If we’re right that there are 100,000 or more intelligent civilizations in our galaxy, and even a fraction of them are sending out radio waves or laser beams or other modes of attempting to contact others, shouldn’t SETI’s satellite dish array pick up all kinds of signals?

But it hasn’t. Not one. Ever…

Perhaps. as we’ve mused here at (R)D before, life is there, but we’re not seeing it because it isn’t a form of life that we recognize: c.f., “Two possibilities exist: Either we are alone in the Universe or we are not. Both are equally terrifying” and “That is a very Earthling question to ask, Mr. Pilgrim.”

But there are some who’ve refused to give up on the search for more traditionally-defined life; indeed, a new study quantifies the “fraction” (to which Urban alludes, above) of civilizations that could (should?) be communicating around our galaxy:

One of the biggest and longest-standing questions in the history of human thought is whether there are other intelligent life forms within our Universe. Obtaining good estimates of the number of possible extraterrestrial civilizations has however been very challenging.

A new study led by the University of Nottingham and published [earlier this month] in The Astrophysical Journal has taken a new approach to this problem. Using the assumption that intelligent life forms on other planets in a similar way as it does on Earth, researchers have obtained an estimate for the number of intelligent communicating civilizations within our own galaxy -the Milky Way. They calculate that there could be over 30 active communicating intelligent civilizations in our home Galaxy…

Details at (the slightly misleadingly-titled): “Research sheds new light on intelligent life existing across the galaxy.”

* Arthur C. Clarke

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As we stay tuned, we might send far-seeing birthday greeting to Fred Hoyle; he was born on this date in 1915.  A prominent astronomer, he formulated the theory of stellar nucleosynthesis.  But he is rather better remembered for his controversial stances on other scientific matters—in particular his rejection of the “Big Bang” theory (a term he coined, derisively, in one of his immensely-popular series The Nature of the Universe on BBC radio) and his promotion of panspermia as the source of life on Earth.

220px-Fred_Hoyle source

 

Written by LW

June 24, 2020 at 1:01 am

“Everyone’s quick to blame the alien”*…

 

In August of 1977, volunteer astronomer Jerry Ehman reviewed readings from Ohio State’s Big Ear Radio Observatory (that’s a scan, above, of Ehman’s notations on the print-out he was assessing)…

He was sitting in his kitchen when he spotted a pattern that a couple of physicists had theorized 18 years earlier would signify alien chatter, according to Michael Brooks, the author of 13 Things That Don’t Make Sense . The printout read 6EQUJ5, a human way of cataloging the 72-second burst of sound registering at a frequency of 1420 MHz. The significance? E.T. may have phoned our home long before Spielberg set otherworldly hearts aglow with his 1982 film…

Scientists have rules out terrestrial sources– the signal came from “out there.”  So there are two possibilities: It was an actual alien communication, or Ehman stumbled across a previously undiscovered natural astrophysical phenomenon.  And as H. Paul Shuch (an engineer, radio astronomer, and executive director emeritus of the SETI League) observes, “either one would be worthy of a Nobel Prize, if only we knew which.”

Read the whole story at “The ‘Wow’ Signal. or That Time Jerry Ehman May Have Heard From Aliens.”

* Aeschylus, The Suppliant Maidens

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As we phone home, we might spare a thought for Martin Gardner; he died on this date in 2010.  Though not an academic, nor ever a formal student of math or science, he wrote widely and prolifically on both subjects in such popular books as The Ambidextrous Universe and The Relativity Explosion and as the “Mathematical Games” columnist for Scientific American.  Indeed, his elegant– and understandable– puzzles delighted professional and amateur readers alike, and helped inspire a generation of young mathematicians.

Gardner’s interests were wide; in addition to the math and science that were his power alley, he studied and wrote on topics that included magic, philosophy, religion, and literature (c.f., especially his work on Lewis Carroll– including the delightful Annotated Alice— and on G.K. Chesterton).  And he was a fierce debunker of pseudoscience: a founding member of CSICOP, and contributor of a monthly column (“Notes of a Fringe Watcher,” from 1983 to 2002) in Skeptical Inquirer, that organization’s monthly magazine.

 

 source

 

Written by LW

May 22, 2015 at 1:01 am

Oh, THERE you are…

image by Lynett Cook

From i09:

Astrophysicist Ragbir Bhathal works with SETI [Search for Extraterrestrial Intelligence] to scan the skies for possible communications from extraterrestrial intelligences. Unlike most SETI facilities, which look for radio signals, Bhathal’s looks for laser pulses. And now he’s found one.

Several years ago Bhathal, a researcher at the University of Western Sydney, suggested that a likely form of extraterrestrial communication would be laser bursts. He set up a facility at his lab which sweeps a nearby volume of space, within about 100 light years, for laser bursts that come in a regular pattern. Any kind of communication would likely be distinguished from background noise by coming in repeated or non-random patterns.

And a few months ago, Bhathal found the kind of regular pattern he’s been looking for. He’s been analyzing it and seeking a repeat pattern in the same area of space ever since. Though he’s cautious about claiming it as a genuine extraterrestrial signal, his discovery has been making local news. Read all about it in The Australian.

As we rethink our place in the cosmos, we might that it was on this date in 1953 that the first 3-D science fiction film, It Came from Outer Space, opened– the anniversary of Irish novelist Bram Stoker’s 1897 introduction of “the thirsty Count,” Dracula.  (Stoker’s buddy, the great Victorian actor Sir Henry Irving– with his dramatic presence, gentlemanly mannerisms and affinity for playing villain roles– was the model for the Count. Irving, however, never agreed to play the part on stage.)

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