At first, this article seems like a bit of a downer:
Search for advanced civilizations beyond Earth finds nothing obvious in 100,000 galaxies — ScienceDaily.
After searching 100,000 galaxies for signs of highly advanced life, a team of scientists has found no evidence of advanced civilizations there. The idea behind the research is that, if an entire galaxy had been colonized by an advanced spacefaring civilization, the energy produced by that civilization’s technologies would be detectable in mid-infrared wavelengths.
…”Whether an advanced spacefaring civilization uses the large amounts of energy from its galaxy’s stars to power computers, space flight, communication, or something we can’t yet imagine, fundamental thermodynamics tells us that this energy must be radiated away as heat in the mid-infrared wavelengths,” Wright said. “This same basic physics causes your computer to radiate heat while it is turned on.”
Theoretical physicist Freeman Dyson proposed in the 1960s that advanced alien civilizations beyond Earth could be detected by the telltale evidence of their mid-infrared emissions. It was not until space-based telescopes like the WISE satellite that it became possible to make sensitive measurements of this radiation emitted by objects in space.
However, somewhat contradicting the title of the article and its opening passage, we have this snippet:
Wright reports, “We found about 50 galaxies that have unusually high levels of mid-infrared radiation. Our follow-up studies of those galaxies may reveal if the origin of their radiation results from natural astronomical processes, or if it could indicate the presence of a highly advanced civilization.”
I’m not entirely sure what to make of this passage given the apparent contradiction, but it sounds like we have 50 possible candidate galaxies for advanced civilizations. (Emphasis on the word “possible” here.)
Based on the information the article provides, it seems obvious that the scientists were looking for Type III civilizations on the Kardashev scale. A Type I civilization has harnessed all of the energy on its native planet. (We’re not a Type I civilization yet). A Type II civilization has harnessed all of the energy of its native star, possibly using concepts like Dyson spheres or swarms. And a Type III civilization will have harnessed all of the energy in its galaxy, or, at least for purposes of this study, enough to be noticeable across intergalactic distances.
Of course, we have no real idea how possible a Type III civilization actually is. It would involve engineering on scales that currently seem hard to imagine. But given enough time (think hundreds of millions of years), there doesn’t seem to be anything in the laws of physics that prevent it. We also can’t be sure that some observed astronomical phenomena that we’re chalking up to nature might not turn out to be mega-structures created by extraterrestrial intelligence.
But given the age of the universe, and the fact that there’s no evidence of Earth ever having been colonized in its 4.5 billion year history, it seems likely that if there are advanced civilizations out there, they’re too far away to have reached us yet. 50 out of 100,000 galaxies sounds like about the right number. The nearest advanced civilization may be several hundred million light years away.
Unless they find natural explanations for the high levels of mid-infrared radiation. Then the closest advanced civilization might might be billions of light years away, or even outside our visible universe.
SelfAwarePatterns 
Your posts are always really interesting SAP.
Unrelated, but I’m curious, have you ever seen any science related to how many stars might be outside our visible universe, or do scientists claim this is entirely unknown?
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Thanks Howie!
I think the number of stars outside our visible universe is considered completely unknown. All of the measurements taken so far indicate that the topology of space on the largest scales is flat, implying that it’s infinite in extent.
Although it’s possible that it’s curved within the uncertainty of the measurements. I read a few years ago that if it is in fact curved within that uncertainty, it is at least 250 times the size of the observable universe.
http://www.dailygalaxy.com/my_weblog/2013/02/the-real-universe-is-250-times-bigger-than-the-visible-hubble-volume-todays-most-popular-1.html
Measurements of the flatness have probably gotten more precise, increasing that minimum size.
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the world is so obsessed with the self at times they hardly know their neighbors for starters, and if there was an alien living next door, they wouldn’t be long before they are given the heave, considering the habits of many, ….the human that is, hahaha
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Could be. I suspect if evidence of an advanced civilization was found, people would freak, at first, even if that advanced civ. was billions of light years away. Then once it became obvious that their daily life wouldn’t be effected, they’d lose interest and carry on as before.
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I keep wondering about all the assumptions in these models. Would an advanced civilization really do this? Would an advanced civilization use technologies that would make their energy emissions undetectable? Would they develop in this direction to begin with (hence, our own assumptions in what constitutes an advanced civilization). It’s good that they enumerate what they’re looking for, but after a while it seems that there are so many conditions, that I have to wonder at just what they’re seeking.
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That’s an excellent point. It may be that most advanced civilizations learn to live within resources to such as extent that they are not detectable at those distances. If you think about it, a Type III civilization that actually needed that much energy would likely have something like the equivalent of a trillion trillion citizens.
That said, I wouldn’t take the term “advanced” in “advanced civilization” as a value judgment here. I think the scientists are looking for detectable civilizations, and the only ones that could be detectable across intergalactic distances would be ones that are pretty far advanced technologically, and that do end up using a substantial portion of the energy in their galaxy.
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One consideration: a galaxy that emits enough heat to be noticeable is emitting a lot of heat being wasted by the presumed galactic civilization. They make limit or recapture their waste heat for purely economic reasons — we’re talking a vast amount of energy.
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The article implied that the laws of physics (particularly thermodynamics) make it inevitable that these emissions would exist. Of course, when talking about civilizations millions of years more advanced than us, who knows?
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Exactly. Thermodynamics means there’s always going to be waste heat, but I don’t see where it would prohibit using it some other way than as IR.
I’m not talking total conservation here. Just enough to put what waste heat there is low enough to make it hard to detect in the possible natural galactic range.
It would be interesting to see some numbers. Just how much waste heat does a galactic civilization generate and radiate into space?
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If you accept the basic implied assumptions of the Kardeshev Scale, then any advanced civilization that established itself in a galaxy would inevitably grow to a Type III given enough time, and assuming that it didn’t succumb to some catastrophe. The larger it becomes, the more robust it becomes, especially if light speed is a barrier.
Energy emissions are a basic law of thermodynamics, so detectability would seem to be unavoidable. In any case, if such emissions really have been detected, it would seem pointless arguing that they are undetectable.
So if the upper limit of 50 in 100,000 galaxies is correct, and these really are Type III civilizations, this would imply that roughly 1 in a thousand galaxies contains an advanced civilization. And if we assume 100 billion star systems per galaxy, this implies that 1 star system in every 100,000,000,000 star systems may give birth to an advanced civilization. I could easily believe that, despite the large number of “ifs” at play.
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I could too. An advanced civilization arising in one out of 100-200 trillion stars feels plausible. That doesn’t mean that life isn’t far more prevalent. It’s just intelligent life that develops to the extent of creating mega-structures that would be that rare.
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They’re on their way, and they’re type 3, so they’re gonna kick our collective asses. Get ready!
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LOLS! Of course, if it’s going to take them 500 million years to get here, I’m not motivated to panic just quite yet.
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I guess I’m just an overachiever. 😉
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Unless they set off 499,999,999 years ago …
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Maybe due to a terrible miscalculation of scale they’ll be eaten by a small dog.
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I used to wonder if some of the more energetic astrophysical events might be what happens when a civilization thinks it’s found a way to tap into the vacuum energy but hasn’t gotten it quite right.
The assumptions behind a Type III civilization seem a bit iffy to me. As I said above, I can easily see energy conservation being a thing. It already is for us. The whole point of a Dyson sphere is to trap all the energy of the star. Who’s to say an advanced civilization can’t also trap its waste heat?
Maybe we’ll get really good telescopes some day and discover a galaxy that’s using its emitted energy to spell out advertising. Visit Us! Best Galactic Pizza!!
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Freeman Dyson himself seemed to think that a D. Sphere would radiate in the infrared. He was the one who suggested this type of search. Of course, as I admitted above, when it comes to a Type III civilization, who can say for sure?
That would pretty much broaden what might go on pizzas 🙂
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Sure would! 😉
I know what Dyson said; who says he’s right? 😛
The same economic argument applies to a D. Sphere as to a galaxy. If you have the technology to use waste heat, you use it. What if there was a network of coolant lines that channeled the heat somewhere useful?
As far as I know, there’s nothing in physics that says something can’t be very stingy with what it radiates — a black body if not a black hole.
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I don’t necessarily disagree, but I can see the argument that the feasibility of ever achieving a 100% efficient recapture of energy is questionable. The question is, can waste heat emissions be kept low enough, across a galactic scale, to be undetectable? I won’t claim to know the answer to that one.
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Actually, my bad, the light bulb just went on; I’ve been looking at this wrong!
Civilizations don’t produce energy. They transform useful forms of energy into low-level heat spread throughout the system. Ultimately, only the stars and gravity produce energy. Everyone else just moves it around. But losses doing that end up as waste heat.
It’s not a matter of looking for extra energy (that happens to be IR). It’s that the energy curve we see is different due to a civilization transforming useful energy into heat (IR).
We’re looking for the effect civilization might have on the natural energy we see from stars or galaxies.
Yeah, that might work. As you say, it implies an extremely advanced civilization.
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It seems like a more fruitful approach than seeking out deliberate messages from alien civilizations. A galactic-wide civilization harnessing stellar energy and leaving a residual waste footprint is a much easier signal to spot, compared with expecting aliens to be actively sending a high-powered signal aimed at our star system.
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The “deliberate message” part always did bother me.
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I went looking to answer the question: What does the Sun’s energy spectrum look like and found this image, which illustrates the idea perfectly:
Radiant energy-wise (photon-wise), the Sun peaks in the visible and eases into the near IR. The Earth emits randomized long-wave IR so far away in the spectrum they had to break it in halves to display both.
Yeah, that would be a hell of a signal!
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Interesting. I guess the searchers in that study are looking for a bump in the mid infrared, where it shouldn’t be. Thanks Wyrd!
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Correct me if I’m wrong, but I think we should be looking for non-random patterns of energy that defy known laws of physics. This might either imply intentional activity or at least motivate us to review our known laws of physics. Just looking for gross energy in the mid-IR spectrum would not preclude a natural unintentional physical phenomenon. Fascinating article, incidentally!
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There have been cases where it appeared like something like that had been stumbled on. When astronomers first detected quasars, no one knew what they were. I remember as a boy reading speculation they might be the thrust of alien starships, or the white holes on the other side of black holes. Another one were gamma ray bursts, which initially looked so powerful they violated the laws of physics.
Eventually it was figured out that both of those things actually related to black holes. Quasars are the supermassive black holes at the center of a young galaxy, generating radiation as they consume large quantities of gas. And gamma ray bursts shoot out along the axes of stars as they collapse into black holes.
But one day we might find something that can’t be explained.
Thanks!
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