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Posts Tagged ‘extraterrestrial

“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

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

 

couldoumuamu

Artist’s impression of the first interstellar asteroid/comet, “Oumuamua”

 

Or not…

On October 19th, 2017, the Panoramic Survey Telescope and Rapid Response System-1 (Pan-STARRS-1) in Hawaii announced the first-ever detection of an interstellar asteroid, named 1I/2017 U1 (aka, ‘Oumuamua). In the months that followed, multiple follow-up observations were conducted that allowed astronomers to get a better idea of its size and shape, while also revealing that it had the characteristics of both a comet and an asteroid.

Interestingly enough, there has also been some speculation that based on its shape, ‘Oumuamua might actually be an interstellar spacecraft (Breakthrough Listen even monitored it for signs of radio signals!). A new study by a pair of astronomers from the Harvard Smithsonian Center for Astrophysics (CfA) has taken it a step further, suggesting that ‘Oumuamua may actually be a light sail of extra-terrestrial origin…

As for what an extra-terrestrial light sail would be doing in our solar system, [Harvard astronomers Shmuel Bialy and Prof. Abraham Loeb] offer some possible explanations for that. First, they suggest that the probe may actually be a defunct sail floating under the influence of gravity and stellar radiation, similar to debris from ship wrecks floating in the ocean. This would help explain why Breakthrough Listen found no evidence of radio transmissions.

Loeb further illustrated this idea in a recent article he penned for Scientific American, where he suggested that ‘Oumuamua could be the first known case of an artificial relic which floated into our solar system from . What’s more, he notes that lightsails with similar dimensions have been designed and constructed by humans, including the Japanese-designed IKAROS project and the Starshot Initiative with which he is involved.

“This opportunity establishes a potential foundation for a new frontier of space archaeology, namely the study of relics from past civilizations in space,” Loeb wrote. “Finding evidence for space junk of artificial origin would provide an affirmative answer to the age-old question “Are we alone?”. This would have a dramatic impact on our culture and add a new cosmic perspective to the significance of human activity.”

On the other hand, as Loeb told Universe Today, ‘Oumuamua could be an active piece of alien technology that came to explore our solar system, the same way we hope to explore Alpha Centauri using Starshot and similar technologies”…

More provocative detail at “Could ‘Oumuamua be an extraterrestrial solar sail?

* Arthur C. Clarke

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As we ask if we’re alone, we might recall that it was on this date in 1572 that Wolfgang Schüler first noted a supernova in the W-shaped constellation of Cassiopeia.  It was subsequently seen by other observers, including Tycho Brahe, who included an account of the sighting in his De nova stellaConsequently, the supernova– one of eight visible to the naked eye in historical records– is known as “Tycho’s Supernova.”

Tycho_Cas_SN1572

Star map of the constellation Cassiopeia showing the position (labelled I) of the supernova of 1572; from Tycho Brahe’s De nova stella

source

 

 

Written by LW

November 6, 2018 at 2:01 am

“Who you gonna call?”*…

 

Let’s say your house is on fire, or overrun by a gang of psychotic raccoons. You don’t hesitate—you take out your phone, and you call the fire department, or animal control, and then firemen/raccoon-wranglers are promptly dispatched to your home. These are well-established protocols, essential to the maintenance of a mostly not-on-fire, feral-animal-free society.

But what about UFOs? What about extraterrestrial beings? Faced with some six-eyed slime-being rooting through your trash, or a spacecraft idling above your backyard (provided it’s not Elon Musk’s “nuclear alien UFO” again), who exactly would you think to call? And what would whoever you called do, when you called them?…

Find out at: “If You Find Aliens, Who Do You Call?

[Picture above: source]

* Ray Parker, Jr., theme from Ghostbusters

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As we let our fingers do the walking, we might recall that it was on this date in 1953 that the Air Force declassified and released a file in which Lt. David C. Brigham, the pilot of an F-84 “Thunderjet,” reported that a small, metallic, disc-shaped object made a controlled, sweeping pass at the American jet fighter-bomber over the Sea of Japan.  “It closed rapidly and just before it would have flown into his fuselage, it decelerated to his air-speed almost instantaneously, the pilot reported.  “In doing so it flipped up its edge at approximately a 90-degree bank. Then it fluttered within 20 feet of his fuselage for perhaps two or three seconds, pulled away and around his starboard (right) wing, appearing to flip once as it hit the slipstream behind his wing tip fuel tank…  Then it passed him, crossed in front of him and pulled up abruptly, appearing to accelerate, and shot out of sight in a steep, almost vertical climb.  It did so more sharply than a plane could have done.  Its maneuvering throughout was always clear and precise.”

F-84 “Thunderjet,” ca. 1952

source

HAPPY MOZART’S BIRTHDAY!

 

Written by LW

January 27, 2018 at 1:01 am

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