This past Friday I participated in a discussion on Paul Gilster’s blog Centauri Dreams. Paul concentrates on mainstream astronomy, real-science interstellar travel and the search for extraterrestrial intelligence (SETI or ETI). Believe it or not, I hang out there often and sometimes manage to throw in an intelligent comment or two. The post in discussion was Dyson Spheres: Hoping to be Surprised. The discussion was not only should we be searching for radio signals from ETI (looking more and more unlikely), we should be looking for signs of ‘astroengineering’. Examples of astroengineering would be Ring Worlds, Alderson Disks, whole planetary systems swept clean of dust other than the system’s Kuiper Belt, worlds or stars travelling at extraordinary speeds (already been detected) and Dyson Spheres, or ‘Shells’. A Dyson shell totally envelopes it’s star, using all of the solar energy available. When observed from outside of it’s system, the Shell would resemble a red dwarf star, emitting huge amounts of infrared radiation. There are some astronomers trying to detect potential Dyson Shell candidates now using methods that measures a candidate star’s infrared emissions.

Gilster also brings up an excellent point that I have postulated on other science sites, “How could we detect engineering projects from intelligences thousands, maybe millions of years ahead of us?” Would ants living in an anthill by an Interstate highway recognise the highway for what it is? Would chimps using sticks to pick out insects from termite hills know what a fork is? Would beavers know what Boulder Dam is?

See the point?

And as large as these structures are supposed to be and visible using 20th century tech, so far in our computer assisted 21st century we’ve yet to see such objects. How come we haven’t seen any of these things yet? 

In my view, astroengineering projects by beings million of years beyond us, if they still built anything at all, would be indistinguishable from observing objects appearing natural. According to science-fiction author Karl Schroeder, being in harmony with nature is an efficient method of data storage and engineering:

…the logic behind such monstrous engineering projects as the “Kardashev-II civilization,” where a species decides to capture all the energy radiated by its sun, generally by building a giant Dyson sphere around it.  I think the idea’s a perfect example of homocentrism, or more exactly the kind of techno-centrism that assumes that future civilizations will orient themselves around the same central issue as 20th century humanity (in this case energy use).  Here’s my off-the-cuff comments to Milan about energy efficiency as it relates to the visibility of spacefaring civilizations:

Notes to Milan

I’ve been doing  a lot of consulting/writing about “green” technologies lately, and one idea that comes up a lot is the concept of ecosystem services.  An ecosystem service is something you get for free from nature, whose value can be directly calculated by estimating what it would cost for us to provide the service ourselves.  For instance, water treatment:  recently a greenbelt area was declared around Toronto, basically a crescent-shaped region where real estate and industrial development is banned.  A key reason for doing this was the discovery that these forested lands filter and treat the entire aquifer for the Toronto region.  If they were developed, much of the fresh water in the region would dry up.  We’d then have to import/produce fresh water ourselves, and the cost of doing that can be directly calculated, and compared to the financial benefits of developing the land.  It turns out that the land, left alone, provides a set of essential services more cheaply than we can provide them technologically.

Now in the realm of information processing, it turns out to be cheaper for many organisms to offload calculations into the natural world; cockroaches use a clever mechanism that’s directly tied in to air movement and shadow angle to directly cause leg movement (they scurry away when something swings at them).  This mechanism essentially bypasses the nervous system because that’s too slow.  A partial program is in general any algorithm where key steps in the algorithm are offloaded in this manner:  the classic example is (for Americans) how do you catch a pop-fly in baseball?  AI researchers used to think that it required a sophisticated internal model and some nasty differential equations solved by the nervous system; in fact, runners catch a ball by running backward while keeping the ball at a fixed angle with respect to the horizon.  This combination of factors substitutes successfully for the calculation.

 Combining these two ideas, of ecosystem services and partial programs, we can propose an economic argument for the invisibility of advanced civilizations.  A settlement that uses solely ecosystem services is called a ‘zero footprint’ settlement (another word for sustainable).  Zero-footprint means environmentally neutral; it also means invisible to the mechanisms we usually use to detect the presence of technological activity (because our means for doing so generally involve detecting the waste products of systems running against or in parallel to natural processes).  In addition, a civilization that offloads as much of its data processing as possible into natural processes in the physical world, through partial programs, is more energy-efficient than one that builds “computronium” to do its thinking, and probably calculates faster (because the energy required by an algorithmic process and the speed with which it’s executed are related).  The more such processes are substituted by integration with the natural world, the harder it will be for us to see the operations of that civilization from interstellar distances.  In fact, I would argue that a civilization that integrates efficiently with its environment on these two levels will be invisible by definition. 

After I read this, I had one of those ‘Wow, I could’ve had a V-8!’ moments and it made perfect sense. But after thinking about it for a while, this involves a certain amount of ‘homocentric’ attitude too. Do most intelligences develop energy sustainable technologies as their civilization progresses? Do they go through a form of ‘Technological Singularity’ as a result? If so, do they ‘upload’ into the environment? Should we look for a civilizations’ ‘upload’ or ‘transcension’ fossil instead? And how would we recognise one?

You see, because we have only one sample of an intelligent technological civilization, us, any  discussion about ETI, astroengineering and SETI is going to be homocentric, it can’t help being anything but!

This was a great thought experiment and Paul still has the post up. Schroeder’s post is still up at his site too. If you’re curious about SETI and why we haven’t detected any ETIs yet, check these out.