In 1960, Freeman Dyson proposed an audacious form that future technology might take: the Dyson Sphere. It’s a simple idea, once you stop thinking in terms of “I wonder how that could be done?” and start thinking along the lines of “I wonder what is physically possible?” Dyson reasoned that an efficient civilization wouldn’t want all of the valuable energy from its home star to fly uselessly into outer space, so they would try to capture it. The solution is then obvious: a sphere of matter that encircles the entire star. It’s worth quoting a bit from Dyson’s original paper:
The material factors which ultimately limit the expansion of a technically advanced species are the supply of matter and the supply of energy. At present the material resources being exploited by the human species are roughly limited to the biosphere of the earth, a mass of the order of 5 x 1019 grams. Our present energy supply may be generously estimated at 1020 ergs per second. The quantities of matter and energy which might conceivably become accessible to us within the solar system are 2 x 1030 grams (the mass of Jupiter) and 4 x 1033 ergs per second (the total energy output of the sun).
The reader may well ask in what sense can anyone speak of the mass of Jupiter or the total radiation from the sun as being accessible to exploitation. The following argument is intended to show that an exploitation of this magnitude is not absurd. First of all, the time required for an expansion of population and industry by a factor of 1012 is quite short, say 3000 years if an average growth rate of 1 percent per year is maintained. Second, the energy required to disassemble and rearrange a planet the size of Jupiter is about 1044 ergs, equal to the energy radiated by the sun in 800 years. Third, the mass of Jupiter, if distributed in a spherical shell revolving around the sun at twice the Earth’s distance from it, would have a thickness such that the mass is 200 grams per square centimeter of surface area (2 to 3 meters, depending on the density). A shell of this thickness could be made comfortably habitable, and could contain all the machinery required for exploiting the solar radiation falling onto it from the inside.
Old news, right. What I hadn’t realized is that there is something called the Fermilab Dyson Sphere search program, led by Richard Carrigan, which recently updated its results (summarized in the title of this post). A star like the Sun radiates something pretty close to a blackbody spectrum; but if you capture all of the energy in the Sun’s radiation, and then re-radiate it from a much larger sphere (e.g. one astronomical unit in radius), it comes out at a much lower temperature — a few hundred Kelvin. Dyson therefore proposed a search strategy, looking for blackbody objects radiating in the far infrared, around 10 microns in wavelength.
And the search is now going on! Indeed, Carrigan’s most recent results were just released on astro-ph a few weeks ago:
IRAS-based whole-sky upper limit on Dyson Spheres
Authors: Richard A. Carrigan JrAbstract: A Dyson Sphere is a hypothetical construct of a star purposely cloaked by a thick swarm of broken-up planetary material to better utilize all of the stellar energy. A clean Dyson Sphere identification would give a significant signature for intelligence at work. A search for Dyson Spheres has been carried out using the 250,000 source database of the IRAS infrared satellite which covered 96% of the sky. The search has used the Calgary data collection of the IRAS Low Resolution Spectrometer (LRS) to look for fits to blackbody spectra. Searches have been conducted for both pure (fully cloaked) and partial Dyson Spheres in the blackbody temperature region 100 < T < 600 deg K. Other stellar signatures that resemble a Dyson Sphere are reviewed. When these signatures are used to eliminate sources that mimic Dyson Spheres very few candidates remain and even these are ambiguous. Upper limits are presented for both pure and partial Dyson Spheres. The sensitivity of the LRS was enough to find solar-sized Dyson Spheres out to 300 pc, a reach that encompasses a million solar- type stars.
It’s too bad the search has thus far not turned up too many promising candidates. The Fermi Paradox continues to be paradoxical.
One famous account of the first contact between an extraterrestrial civilization and the human race was told in the classic 1951 Robert Wise film, The Day the Earth Stood Still. It’s now been remade by director Scott Derrickson, starring Keanu Reeves as the alien Klaatu, and will open next Friday. In the emerging spirit of science and entertainment exchanges, there will be a panel discussion at Caltech’s Beckman Auditorium this Friday (the 5th) with Derrickson and Reeves holding up the Hollywood side of things, and roboticist Joel Burdick and I holding up the science end. Don’t quote me on this, but I think it’s at 6:00, and the movie will be screened before the panel. Should be fun.
I thought this was goint to be about the new Dyson vacuum cleaners that pivot on a ball. The shame!
Sean,
I was just about to ask, after reading this line: The solution is then obvious: a sphere of matter that encircles the entire star.
Isn’t it a swarm? “Sphere” though popularized by trekkers is nothing like a sphere in the sense we know it.
And then I just read the line by Richard A. Carrigan, A Dyson Sphere is a hypothetical construct of a star purposely cloaked by a thick swarm of broken-up planetary material to better utilize all of the stellar energy. So that clears it. 🙂
Your article that points out that there is ACTUALLY a program dedicated to finding Dyson Spheres was very interesting. In the meanwhile, there are some interesting variations to the Dyson Sphere idea like the Matrioshka Brains, now if something like a matrioshka brain existed finding it would be very difficult than a Dyson sphere as you described it.
This is what I like about Dyson, no fear in proposing something that mainstream physicists would smirk at at best, basically for the sheer “less likely coefficient” of the ideas. 🙂
Took me a while to understand the logic, but it really is beautiful: a search strategy for extraterrestrial intelligence that explicitly, almost deliberately, excludes us. I suppose we cannot hold our own as respectable species until we build this contraption, now it’s a matter of pride.
What with the recent “invisibility cloak” research going on, where some sort of nano-meta-material is able to do very strange things with light, it seems likely that a civilization twelve orders of magnitude beyond ours would have some way of redirecting the used energy to some other goal – perhaps focusing it into a long-range communication system with other advanced civilizations.
Yes, I know, thermodynamics and all, but if we’re talking about Dyson spheres we can think outside the box a little.
Perhaps the universe is densely populated by Matrioshka brains that are almost impossible to detect … and we have an explanation for the dark matter. (Just joking 🙂
Actually Radoslav,
Robert Bradbury (the originator of the idea of Matrioshka Brains) once told me over e-mail exactly the same thing as you said. And he was not joking. He said that a small “component” COULD be matrioshka brains or similar structures.
But these are speculations. The universe is so HUGE, we can’t say what to expect.
and thus:
We should not be afraid to speculate but we should be careful to separate speculation from fact.
The irony.. I was just reading about this project a few weeks ago. In my opinion, it seems to be one of the least likely projects to find evidence of intelligent non-terrestrial life, almost as unlikely as SETI, primarily because of the monumental amount of time & resources it would (seemingly) take to construct such a device (a Dyson sphere) when there would likely be other alternatives, likely more efficient an powerful to be invented or discovered (i.e. exotic matter or negative mass propulsion/powerplant technology, anti-matter reactors, etc.) . Optical SETI would appear more promising of the three (to me, at least), considering the time-frame in which laser technology would be used is more likely to be greater than that of radio communication, but I could be wrong. Regardless, it can’t hurt to look, whether it be for traces of Dyson spheres (even if they’re relics of a long-dead civilization) or extra-terrestrial radio signals of some sort.
nice article about DS observation programme here:
http://physicsworld.com/cws/article/print/33579
This is a fascinating project, and worth a look given that how much easier the search is than when Dyson first proposed it. However, it doesn’t seem too likely to bear fruit, at least not in its simplest form; even of aliens built such a structure, it’s not at all clear what temperature they would radiate at. For one thing, it’s hard to guess what ambient temperature they prefer. For another, they would probably have the technical capability, and very possibly the motivation, to hide themselves a bit better.
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Repost – there were posting errors in teh first post:
Personally, I’m in the camp that while life may be common, intelligent life is not. On our own planet, intelligent life capable of space travel and radio communications has been around for only one million of the 4 billion years that life has existed – that’s 0.025% of the history of life on earth. And of that million years, only in the last 100 years have we developed the requisite technology – that’s 0.0000025% of the history of life. In terms of the Drake equation (http://en.wikipedia.org/wiki/Drake_equation), the probability that intelligent life exists on a planet is given by fi and the probability that it has developed sufficiently advamced technology is given by fc.
The current estimate for the product fi*fc is .01%. But I think the value that I derived above is a better estimate given our one data point (Earth); that is, fi*fc = 0.0000025%. In evolutionary terms, intelligence requires time to develop and is only one strategy for survival. Other factors such as big teeth, sharp claws, and size are simpler to evolve and have been shown to be very effective in helping a species survive. The rarity of intelligent life would explain the negative result of SETI and the Fermi paradox and the search for Dyson spheres.
Any civilization with the capability and interest in redesigning an entire solar system also ought to be interested in interstellar travel, which at this level of technology becomes almost trivial (although still slow). We should therefore not be surprised that we don’t find one in our neighborhood, if one existed it would most likely have absorbed our solar system too. Maybe, if they were very ethical, they’d have left Earth alone as already inhabited, but Jupiter would be way too tempting.
Metre: I agree.
It could be just too early. The age of the universe is about 14 billion years, the age of the solar system is about 8 billion year and it took about 4 billions years to develop intelligent life on the Earth. The age of the galaxy seems about the same as the age of the sun. So we could be just early arrivals in our galaxy, and not far behind other galaxies too. We also have no idea how fast intelligence can evolve, with or without technological singularity. The developing tech for dismantling gas giants can take another billion years of sentient evolution.
“In the emerging spirit of science and entertainment exchanges, there will be a panel discussion at Caltech’s Beckman Auditorium this Friday (the 6th) with Derrickson and Reeves”
————————————————————————————————————————————–
and of course Sean will be pitching the winning idea(s) from the elevator pitch contest to both of these gentlemen…….
e.
I see no mention of the event on any of Caltech’s websites, and Friday is the fifth, not the sixth.
Caltech does not yet have its act together, but hopefully information will be up soon. I personally got my act together by fixing the typo.
Sure, no Dyson spheres – but an entire sphere around a star is a rather ambitious and perhaps physically unstable project (well, I suppose the proper rotation rate might average out stresses OK, I wouldn’t know.) The Larry Niven Ringworld type idea – just a band all around in the equatorial plane of the star, same as a solar system (more or less) is much more credible and likely to be out there. Even more cool, you can stack them up since at a distance, a narrow enough ring recedes in angular width relative to the disk of the star. That might actually be out there – are our methods capable of finding them? After all, few thought we’d have real pictures of planets around other stars so soon.
http://en.wikipedia.org/wiki/Ringworld
A ringworld around a star is a logical precursor to a full-on Dyson sphere, and ought to be detectable as it occults the star and makes it “blink” (assuming we’re lucky enough to be close to edge-on to the ring).
A ringworld that is simply a kind of large open-topped space station – in other words, one that does not necessarily encircle a star – is another logical step towards a star-encircling ringworld. Anyone who has seen the “Halo” video games has seen a representation of this smaller kind of ringworld. I don’t know that they would be particularly detectable.
Sean- Did you mean 1 AU in *radius*, not diameter, for the reradiating sphere, or did you really mean a sphere that had a radius half of the Earth’s orbit when saying it would reradiate in the far IR..? Intriguing post! -M
What about other celestial bodies like asteroids, meteors, and the like. Even if the sphere is strong enough to withstand the constant bombardment how will it stay in one place? Its an accident waiting to happen. What about when our star dies? Seems like a bad idea to me.
I meant “radius,” of course. That’s what I get for late-night posting.
Serge,
I concur. It may turn out that we among the first generation of intelligent life to emerge in the cosmos. It took 4 billion years for intelligence to develop on earth, and earth has a number of special features (beside liquid water) that have allowed life not just to exist here, but to fluorish: a protective atmoshere, a protective magnetic field, and a large moon. Take away any one of these and life would still exist on earth but only in limited, protected niches. Big brains are complex devices that take a lot of evolutionary time and trial and error to develop. If life is constrained to a few limited areas on a planet, the chances of intelligence developing become nil. Only on a planet where life flourishes virtually everywhere and for much of the planet’s history will intelligence have a chance to develop. So if we include all of the earth-like features (atmosphere, mag field, moon), I believe the number of earth-like planets is over-estimated in the Drake equation as well.
C’mon guys–we use dark energy for our “civilizations”, ’cause there’s a lot more of it. Once y’all figure out how to measure it, and start lookin’ around, we’ll be out of the closet. Current Milky Way betting is that some sort of Prop 8 will keep you from ever gettin’ to that point–I’ve got a sizable bet that way myself.