Because Tim would never post this: 100,000 galaxies scanned, no sign of aliens

[alfred russel]

A Scan Of 100,000 Galaxies Shows No Sign Of Alien Mega-Civilizations

A pioneering infrared scan of 100,000 galaxies by Penn State astronomers has failed to detect any signs of galaxy-spanning extraterrestrial supercivilizations. This result, though very preliminary, may be a sign that aliens aren't capable of conquering entire galaxies.

Above: A false-color image of the mid-infrared emission from the Great Galaxy in Andromeda, as seen by Nasa's WISE space telescope. The G-HAT team used images such as these to search 100,000 nearby galaxies for unusually large amounts of this mid-infrared emission that might arise from alien civilizations. Caption and image credit: NASA/JPL-Caltech/WISE Team/Penn State/Roger L. Griffith et al.

Back in the 1960s, Russian cosmologist Nikolai Kardashev devised the famous scale that now bears his name . He proposed a simple numbering system — from one to three — that can be used to classify hypothetical alien civilizations according to the amount of energy at their disposal. According to the scale, a K1 civ has captured the entire energy output of its home planet, while a K2 civ has tapped into all the power produced by its home star.


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But then there are K3 civs — so-called supercivilizations — who have tapped into virtually all of the energy produced by their own galaxy. As study co-author Jason Wright told io9: "Type III civilizations in the sense that Nikolai Kardashev originally defined them, were 'maximal' energy users: they command all of the starlight in their galaxy."

This could be accomplished by ETIs in any number of ways, including vast complexes of Dyson spheres and the establishment of Matrioshka Brains.

K3 civilizations should be reasonably easy to detect from a distance. According to fundamental thermodynamics, the energy pulled in by a K3 civ must still be radiated away as heat in the mid-infrared wavelengths. These galactic-scale signatures, though far away, can still be detected from Earth.

Seeking Alien Signatures

With this in mind, a team of astronomers from Penn State recently completed a survey, known as the Glimpsing Heat from Alien Technologies Survey (G-HAT), of 100,000 galaxies to see if they could find traces of galaxy-spanning supercivilizations. Their results now appear in the Astrophysical Journal.

The G-HAT team, led by postbaccalaureate researcher Roger Griffith, analyzed practically the entire catalog of detections made by NASA's WISE orbiting observatory. That's nearly 100 million entries. The researchers honed this list down to ~100,000 of the most promising candidates, looking for objects consistent with galaxies emitting too much mid-infrared radiation.

No obvious alien-filled galaxies were detected.

"We have shown that among the 100,000 galaxies that WISE can resolve, none of them contain such civilizations," Wright told io9. "This doesn't mean, however, that there are not galaxy-spanning civilizations in any of those galaxies, just that if there are, they aren't using most of the starlight for their own purposes."

That said, 50 galaxies did feature higher-than-usual levels of mid-infrared radiation. Further analysis will be required to determine if they're caused by some natural astronomic process, or if they're an indication of highly advanced extraterrestrial civilizations.

Whither K3?

This poses a bit of a problem for astrobiologists. Back in 1975, astronomer Michael H. Hart conjectured that super-advanced aliens should be able to colonize an entire galaxy within a reasonably short amount of time (at least from a cosmological perspective). Either that or humanity is alone in the Milky Way. It's this line of reasoning that led the Penn State researchers to conduct their inter-galactic survey.

"There has been a line of argument, originating with Michael Hart, that there should not be any advanced civilization in the Milky Way, because if there were, they would have taken over the entire galaxy by now," Wright told io9. "If this is correct, then our search for civilizations spanning other galaxies is the best approach."

Wright concedes that there may be a flaw in this reasoning, adding that many respected SETI researchers believe it's incorrect.

"So if, even as we refine our techniques, we continue to find no hint of intelligent life pandemic to other galaxies, this would strengthen the arguments of those who disagree with Hart's argument, and make searches within our own Milky Way an even more promising venue," he added.

The Search Continues

The next step for the G-HAT team is to scale things down a bit to see if less energy-intensive civilizations might exist in these galaxies. This is where Carl Sagan's adjunct to the Kardashev Scale might come in handy.

"On Sagan's scale, we want to push down from Type 3.0 to Type 2.9 or 2.8," says Wright. "That is, search for civilizations using 10% or even 1% of the starlight in a galaxy."

Encouragingly, the new study shows that WISE has the sensitivity and resolution to do this, but as Wright told io9, it would require careful examination of the light from these galaxies across the full range of the electromagnetic spectrum, and not just the emission WISE sees.

Also, the researchers want to extend their method to K2 civilizations. In other words, they want to search for Dyson spheres and/or other megascale artifacts produced by advanced aliens.

"This will require us to be able to distinguish distant, dusty giant stars from nearby, Sun-like stars with much of their starlight being collected by an advanced civilization," says Wright. "This is very hard because it requires spectra or distance measurements, which we do not have for most stars — but the ESA space telescope GAIA will measure distances to all of the nearby stars, making this search possible for the first time. We look forward to using those data to extend our search to the Milky Way."

Read the entire study at the Astrophysical Journal: "The Ĝ Infrared Search for Extraterrestrial Civilizations with Large Energy Supplies. III. The Reddest Extended Sources in WISE.".

http://io9.com/a-scan-of-100-000-galaxies-shows-no-sign-of-kardashev-i-1697932767

If I ever see an article on a space related study, it seems inevitable Tim will post it here. For some reason, I thought he might skip over this one.

[Eddie Teach]

That said, 50 galaxies did feature higher-than-usual levels of mid-infrared radiation. Further analysis will be required to determine if they're caused by some natural astronomic process, or if they're an indication of highly advanced extraterrestrial civilizations.

It's aliens! /Tim

[Monoriu]

This simply means we are at turn 1 of the Space 4x civilisation game. 

[Razgovory]

Excellent news.

[jimmy olsen]

K3 civilizations? That's setting the bar a bit high don't you think?

[Martinus]

The thread title makes Tim a paragon of journalistic accuracy.

[Crazy_Ivan80]

K3 civilizations? That's setting the bar a bit high don't you think?

what about K9 civilizations?

[Archy]

K3 civilizations? That's setting the bar a bit high don't you think?

what about K9 civilizations?

only furries would approve

[celedhring]

Since these galaxies are millions of light years away, aren't we picking up their radiations from eons ago? Their presumed civilizations just may not have existed back then.

[Berkut]

Since these galaxies are millions of light years away, aren't we picking up their radiations from eons ago? Their presumed civilizations just may not have existed back then.

But a million years is just a moment in galactic time scales. The idea is that even if you postulate very slow (by human standards) spread of an intelligent civilization from star to star, you still have some civilization filling up its galaxy in a matter of a few hundred thousand years. Since galaxies have been around for billions of years, one would expect that if it were possible at all, it would have happened already.

There are, of course, all kinds of assumptions built into that hypothesis of course. But it is an interesting argument.

http://www.open.edu/openlearn/science-maths-technology/science/physics-and-astronomy/how-long-would-it-take-colonise-the-galaxy

[DontSayBanana]

Of course, humanity isn't even a K1 civilization on the Kardashev scale.  And there's the question of how to use that peak energy without triggering a cataclysmic event (thank you, thermodynamics).  Not to mention that energy consumption doesn't necessarily go hand-in-hand with technological advancement; our electronics have been the product of reducing energy requirements for decades, so isn't it a little callous to think that an even more advanced civilization might not also engage in energy reduction practices?  Seriously- a computer used to require a separate circuit to the power grid; then it worked just fine on outlet power, mostly powering things through the 12V rail, and now we have 5V computer systems- barely 1% of the 400V power requirement of the Internet's first server.

Just to be clear, that's almost a five-fold decrease in power requirements in 30 years.

[KRonn]

This simply means we are at turn 1 of the Space 4x civilisation game.

The greatest Space 4X game of all time!!

[alfred russel]

The thread title makes Tim a paragon of journalistic accuracy.

The article title wouldn't fit (at least without Tim commentary, which was the most important part), and it is factually accurate. 100,000 galaxies were scanned, and evidence of aliens was not detected.

[Baron von Schtinkenbutt]

But a million years is just a moment in galactic time scales. The idea is that even if you postulate very slow (by human standards) spread of an intelligent civilization from star to star, you still have some civilization filling up its galaxy in a matter of a few hundred thousand years. Since galaxies have been around for billions of years, one would expect that if it were possible at all, it would have happened already.

It is a short time, but it is far from a "moment".  If a million years were a moment, i.e. a second, the universe would be less than four hours old.  Now, our planet is relatively young so other species may have millions of years worth of a head start on us.  However, who knows how long it would take for a civilization to not only span a galaxy but do so in a way that is visible from another galaxy.  Hell, it might not even be possible.

As an aside, the article you posted is an interesting thought experiment, but it is a gross oversimplification that does not account for the size of our galaxy.  The farthest points in the Milky Way are over 76,666 light years from Earth, so it would take almost 690,000 years of continuous travel just to reach them at the article's postulated sublight speed of 0.11c.

[Berkut]

That is the point though - 690,000 years is a blip in the galactic time scale. If you bump up the estimate by an order of magnitude, you get up to a million years, two orders you get to 10 million years. Still hardly any time at all in a multi-billion year old galaxy.

Obviously there are lots of assumptions. Maybe intelligent species just don't have the drive to spread like that. Maybe there aren't enough habitable planets to allow it. Maybe maybe maybe. The point of the thought experiment though is to note that given what we do know, and can reasonable speculate, the galaxy does seem kind of empty...why?

That is the one thing we DO know - we have never detected any sign of any other intelligent life. Why?

We don't know the answer of course, but it is definitely an interesting question.